Author name code: keenan ADS astronomy entries on 2022-09-14 author:"Keenan, Francis P." ------------------------------------------------------------------------ Title: The SLED project and the dynamics of coronal flux ropes Authors: Malherbe, Jean-Marie; Mein, Pierre; Sayède, Frédéric; Rudawy, Pawel; Phillips, Kenneth; Keenan, Francis; Rybák, Jan Bibcode: 2022AdSpR..70.1562M Altcode: Investigations of the dynamics of the hot coronal plasma are crucial for understanding various space weather phenomena and making in-depth analyzes of the global heating of the solar corona. We present here numerical simulations of observations of siphon flows along loops (simple semi-circular flux ropes) to demonstrate the capabilities of the Solar Line Emission Dopplerometer (SLED), a new instrument under construction for imaging spectroscopy. It is based on the Multi-channel Subtractive Double Pass (MSDP) technique, which combines the advantages of filters and slit spectrographs. SLED will observe coronal structures in the forbidden lines of FeX 6374 Å and FeXIV 5303 Å, and will measure Doppler shifts up to 150 km s-1 at high precision (50 m s-1) and cadence (1 Hz). It is optimized for studies of the dynamics of fast evolving events such as flares or Coronal Mass Ejections (CMEs), as well as for the detection of high-frequency waves. Observations will be performed with the coronagraph at Lomnický Štít Observatory (LSO), and will also occur during total solar eclipses as SLED is a portable instrument. Title: High frequency waves in chromospheric spicules Authors: Bate, William; Nakariakov, Valery; Jafarzadeh, Shahin; Jess, David; Stangalini, Marco; Grant, Samuel; Keys, Peter; Christian, Damian; Keenan, Francis Bibcode: 2022cosp...44.2548B Altcode: Using high cadence observations from the Hydrogen-alpha Rapid Dynamics camera imaging system on the Dunn Solar Telescope, we present an investigation of the statistical properties of transverse oscillations in spicules captured above the solar limb. At five equally separated atmospheric heights, spanning approximately $4900-7500$~km, we have detected a total of $15{\,}959$ individual wave events, with a mean displacement amplitude of $151\pm 124$~km, a mean period of $54\pm 45$~s, and a mean projected velocity amplitude of $21\pm 13$~km{\,}s$^{-1}$. We find that both the displacement and velocity amplitudes increase with height above the solar limb, ranging from $132\pm 111$~km and $17.7\pm 10.6$~km{\,}s$^{-1}$ at $\approx4900$~km, and $168\pm 125$~km and $26.3\pm 14.1$~km{\,}s$^{-1}$ at $\approx7500$~km, respectively. Following the examination of neighboring oscillations in time and space, we find 45% of the waves to be upwardly propagating, 49% to be downwardly propagating, and 6% to be standing, with mean absolute phase velocities for the propagating waves on the order of $75-150$~km{\,}s$^{-1}$. While the energy flux of the waves propagating downwards does not appear to depend on height, we find the energy flux of the upwardly propagating waves decreases with atmospheric height at a rate of $-13{\,}200\pm6500$~W{\,}m$^{-2}$/Mm. As a result, this decrease in energy flux as the waves propagate upwards may provide significant thermal input into the local plasma. Title: High-frequency Waves in Chromospheric Spicules Authors: Bate, W.; Jess, D. B.; Nakariakov, V. M.; Grant, S. D. T.; Jafarzadeh, S.; Stangalini, M.; Keys, P. H.; Christian, D. J.; Keenan, F. P. Bibcode: 2022ApJ...930..129B Altcode: 2022arXiv220304997B Using high-cadence observations from the Hydrogen-alpha Rapid Dynamics camera imaging system on the Dunn Solar Telescope, we present an investigation of the statistical properties of transverse oscillations in spicules captured above the solar limb. At five equally separated atmospheric heights, spanning approximately 4900-7500 km, we have detected a total of 15,959 individual wave events, with a mean displacement amplitude of 151 ± 124 km, a mean period of 54 ± 45 s, and a mean projected velocity amplitude of 21 ± 13 km s-1. We find that both the displacement and velocity amplitudes increase with height above the solar limb, ranging from 132 ± 111 km and 17.7 ± 10.6 km s-1 at ≍4900 km, and 168 ± 125 km and 26.3 ± 14.1 km s-1 at ≍7500 km, respectively. Following the examination of neighboring oscillations in time and space, we find 45% of the waves to be upwardly propagating, 49% to be downwardly propagating, and 6% to be standing, with mean absolute phase velocities for the propagating waves on the order of 75-150 km s-1. While the energy flux of the waves propagating downwards does not appear to depend on height, we find the energy flux of the upwardly propagating waves decreases with atmospheric height at a rate of -13,200 ± 6500 W m-2/Mm. As a result, this decrease in energy flux as the waves propagate upwards may provide significant thermal input into the local plasma. Title: The Solar Line Emission Dopplerometer project Authors: Malherbe, Jean-Marie; Mein, Pierre; Sayède, Frédéric; Rudawy, Pawel; Phillips, Kenneth; Keenan, Francis; Rybák, Jan Bibcode: 2022ExA....53...83M Altcode: 2021ExA...tmp..125M; 2021arXiv211001645M Observations of the dynamics of solar coronal structures are necessary to investigate space weather phenomena and global heating of the corona. The profiles of high temperature lines emitted by the hot plasma are usually integrated by narrow band filters or recorded by classical spectroscopy. We present in this paper details of a new transportable instrument (under construction) for imaging spectroscopy: the Solar Line Emission Dopplerometer (SLED). It uses the Multi-channel Subtractive Double Pass (MSDP) technique, which combines the advantages of both filters and narrow slit spectrographs, i.e. high temporal, spatial and spectral resolutions. The SLED will measure at high cadence (1 Hz) the line-of-sight velocities (Doppler shifts) of hot coronal loops, in the forbidden lines of FeX 6374 Å and FeXIV 5303 Å. It will follow the dynamics of fast evolving events of solar activity such as flares or Coronal Mass Ejections (CMEs), and also study coronal heating by short period waves. Observations will be performed with the coronagraph at the Lomnický Štít Observatory (LSO, in Slovakia) or during total eclipses. The SLED will also observe the dynamics of solar prominences in Hα 6563 Å or He D3 5876 Å lines when mounted on the Białków coronagraph (near Wrocław, Poland). It is fully compatible with polarimetric measurements by various techniques. Title: Four Decades of Advances from MSDP to S4I and SLED Imaging Spectrometers Authors: Mein, P.; Malherbe, J. -M.; Sayède, F.; Rudawy, P.; Phillips, K. J. H.; Keenan, F. P. Bibcode: 2021SoPh..296...30M Altcode: 2021arXiv210103918M The Multichannel Subtractive Double Pass (MSDP) is an imaging spectroscopy technique, which allows observations of spectral line profiles over a 2D field of view with high spatial and temporal resolution. It has been intensively used since 1977 on various spectrographs (Meudon, Pic du Midi, the German Vacuum Tower Telescope, THEMIS, Wrocław). We summarize previous developments and describe the capabilities of a new design that has been developed at Meudon and that has higher spectral resolution and increased channel number: Spectral Sampling with Slicer for Solar Instrumentation (S4I), which can be combined with a new and fast polarimetry analysis. This new generation MSDP technique is well adapted to large telescopes. Also presented are the goals of a derived compact version of the instrument, the Solar Line Emission Dopplerometer (SLED), dedicated to dynamic studies of coronal loops observed in the forbidden iron lines, and prominences. It is designed for observing total solar eclipses, and for deployment on the Wrocław and Lomnicky peak coronagraphs respectively for prominence and coronal observations. Title: Improved Fe II Emission-line Models for AGNs Using New Atomic Data Sets Authors: Sarkar, A.; Ferland, G. J.; Chatzikos, M.; Guzmán, F.; van Hoof, P. A. M.; Smyth, R. T.; Ramsbottom, C. A.; Keenan, F. P.; Ballance, C. P. Bibcode: 2021ApJ...907...12S Altcode: 2020arXiv201109007S Understanding the Fe II emission from active galactic nuclei (AGNs) has been a grand challenge for many decades. The rewards from understanding the AGN spectra would be immense, involving both quasar classification schemes such as "Eigenvector 1" and tracing the chemical evolution of the cosmos. Recently, three large Fe II atomic data sets with radiative and electron collisional rates have become available. We have incorporated these into the spectral synthesis code CLOUDY and examined predictions using a new generation of AGN spectral energy distribution (SED), which indicates that the ultraviolet (UV) emission can be quite different depending on the data set utilized. The Smyth et al. data set better reproduces the observed Fe II template of the I ZW 1 Seyfert galaxy in the UV and optical regions, and we adopt these data. We consider both thermal and microturbulent clouds and show that a microturbulence of ≍100 km s-1 reproduces the observed shape and strength of the so-called Fe II "UV bump." Comparing our predictions to the observed Fe II template, we derive a typical cloud density of 1011 cm-3 and photon flux of 1020 cm-2 s-1, and show that these largely reproduce the observed Fe II emission in the UV and optical. We calculate the I(Fe II)/I(Mg II) emission-line intensity ratio using our best-fitting model and obtain log(I(Fe II)/I(Mg II)) ∼ 0.7, suggesting many AGNs have a roughly solar Fe/Mg abundance ratio. Finally, we vary the Eddington ratio and SED shape as a step in understanding the Eigenvector 1 correlation. Title: Electron-impact Excitation of Fe I Authors: Conroy, Andrew T.; Ballance, Connor P.; Ramsbottom, Catherine A.; Keenan, Francis P. Bibcode: 2020ApJ...902...68C Altcode: The Fe I spectra emitted by astrophysical sources contain information on plasma parameters such as chemical abundances and magnetic fields. However, to determine these parameters requires detailed plasma modeling, which in turn needs accurate atomic data for processes such as radiative decay and electron-impact excitation in Fe I. A lack of fine-structure resolved collision strengths for transitions in Fe I is addressed in this paper with the presentation of data obtained from a Dirac R-matrix calculation. The suitability of our choice of target description is shown, with our energies generally within 7% of literature values. Various A-values are compared with other theoretical and experimental results, and the quality of the collision strengths produced in this work demonstrated. A comparison of 300- and 1000-level close-coupling expansions is made, the latter shown to eliminate pseudoresonances in the collision strengths at electron energies between 0.5 and 1.0 Ry. Maxwell-averaged effective collision strengths are presented, and the convergence of our data is shown in the temperature range 1000-100,000 K. Title: Generation of photoionized plasmas in the laboratory: Analogues to astrophysical sources Authors: White, S.; Irwin, R.; Warwick, R.; Sarri, G.; Gribakin, G. F.; Keenan, F. P.; Hill, E.; Rose, S. J.; Ferland, G. J.; Wang, F.; Zhao, G.; Han, B.; Riley, D. Bibcode: 2020IAUS..350..321W Altcode: Implementation of a novel experimental approach using a bright source of narrowband x-ray emission has enabled the production of a photoionized argon plasma of relevance to astrophysical modelling codes such as Cloudy. We present results showing that the photoionization parameter ζ = 4πF/ne generated using the VULCAN laser was ≈ 50 erg cm s-1, higher than those obtained previously with more powerful facilities. Comparison of our argon emission-line spectra in the 4.15 - 4.25 Å range at varying initial gas pressures with predictions from the Cloudy code and a simple time-dependent code are also presented. Finally we briefly discuss how this proof-of-principle experiment may be scaled to larger facilities such as ORION to produce the closest laboratory analogue to a photoionized plasma. Title: A Search for High-Frequency Coronal Brightness Variations in the 21 August 2017 Total Solar Eclipse Authors: Rudawy, P.; Radziszewski, K.; Berlicki, A.; Phillips, K. J. H.; Jess, D. B.; Keys, P. H.; Keenan, F. P. Bibcode: 2019SoPh..294...48R Altcode: 2019arXiv190306076R We report on a search for short-period intensity variations in the green-line (Fe XIV 530.3 nm) emission from the solar corona during the 21 August 2017 total eclipse viewed from Idaho in the United States. Our experiment was performed with a much more sensitive detection system, and with better spatial resolution, than on previous occasions (1999 and 2001 eclipses), allowing fine details of quiet coronal loops and an active-region loop system to be seen. A guided 200-mm-aperture Schmidt-Cassegrain telescope was used with a state-of-the-art CCD camera having 16-bit intensity discrimination and a field-of-view (0.43∘×0.43∘) that encompassed approximately one third of the visible corona. The camera pixel size was 1.55 arcseconds, while the seeing during the eclipse enabled features of ≈2 arcseconds (1450 km on the Sun) to be resolved. A total of 429 images were recorded during a 122.9 second portion of the totality at a frame rate of 3.49 s−1. In the analysis, we searched particularly for short-period intensity oscillations and travelling waves, since theory predicts fast-mode magneto-hydrodynamic (MHD) waves with short periods may be important in quiet coronal and active-region heating. Allowing first for various instrumental and photometric effects, we used a wavelet technique to search for periodicities in some 404 ,000 pixels in the frequency range 0.5 -1.6 Hz (periods 2 seconds to 0.6 seconds). We also searched for travelling waves along some 65 coronal structures. However, we found no statistically significant evidence in either. This negative result considerably refines the limit that we obtained from our previous analyses, and it indicates that future searches for short-period coronal waves may be better directed towards Doppler shifts as well as intensity oscillations. Title: Towards converged electron-impact excitation calculations of low-lying transitions in Fe II Authors: Smyth, R. T.; Ramsbottom, C. A.; Keenan, F. P.; Ferland, G. J.; Ballance, C. P. Bibcode: 2019MNRAS.483..654S Altcode: 2018MNRAS.tmp.3048S Absorption and emission lines of the iron-peak species Fe II are prominent in the infrared, optical, and ultraviolet spectra of a myriad of astrophysical sources, requiring extensive and highly reliable sets of atomic structure and collisional data for an accurate quantitative analysis. However, comparisons among existing calculations reveal large discrepancies in the effective collision strengths, often up to factors of three, highlighting the need for further steps towards new converged calculations. Here we report a new 20 configuration, 6069 level atomic structure model, calculated using the multiconfigurational Dirac-Fock method. Collision strengths and effective collision strengths are presented, for a wide range of temperatures of astrophysical relevance, from substantial 262 level and 716 level Dirac R-matrix calculations, plus a 716 level Breit-Pauli R-matrix calculation. Convergence of the scattering calculations is discussed, and results are critically compared with existing data in the literature, providing us with error estimates for our data. As a consequence, we assign an uncertainty of ±15 per cent to relevant forbidden and allowed transitions encompassed within a 50 level subset of the 716 level Dirac R-matrix data set. To illustrate the implications of our new data sets for the analysis of astronomical observations of Fe II, they are incorporated into the CLOUDY modelling code, sample Fe II spectra are generated and compared. Title: Benchmarking Current Capabilities for the Generation of Excitation and Photoionisation Atomic Data Authors: Ramsbottom, Catherine; Ballance, Connor; Smyth, Ryan; Conroy, Andrew; Fernández-Menchero, Luis; Turkington, Michael; Keenan, Francis Bibcode: 2018Galax...6...90R Altcode: The spectra currently emerging from modern ground- and space-based astronomical instruments are of exceptionally high quality and resolution. To meaningfully analyse these spectra, researchers utilise complex modelling codes to replicate the observations. The main inputs to these codes are atomic data such as excitation and photoionisation cross sections, as well as radiative transition probabilities, energy levels, and line strengths. In this publication, the current capabilities of the numerical methods and computer packages used in the generation of these data are discussed. Particular emphasis is given to Fe-peak species and the heavy systems of tungsten and molybdenum. Some of the results presented to highlight certain issues and/or advances have already been published in the literature, while other sections present new recently evaluated atomic data for the first time. Title: Towards the Provision of Accurate Atomic Data for Neutral Iron Authors: Conroy, Andrew; Ramsbottom, Catherine; Ballance, Connor; Keenan, Francis Bibcode: 2018Galax...6...91C Altcode: The rich emission and absorption line spectra of Fe I may be used to extract crucial information on astrophysical plasmas, such as stellar metallicities. There is currently a lack, in quality and quantity, of accurate level-resolved effective electron-impact collision strengths and oscillator strengths for radiative transitions. Here, we discuss the challenges in obtaining an accurate model of the neutral iron atom and compare our theoretical fine-structure energy levels with observation for several increasingly large models. Radiative data is presented for several transitions for which the atomic data is accurately known. Title: Production of photoionized plasmas in the laboratory with x-ray line radiation Authors: White, S.; Irwin, R.; Warwick, J. R.; Gribakin, G. F.; Sarri, G.; Keenan, F. P.; Riley, D.; Rose, S. J.; Hill, E. G.; Ferland, G. J.; Han, B.; Wang, F.; Zhao, G. Bibcode: 2018PhRvE..97f3203W Altcode: 2018arXiv180505767W In this paper we report the experimental implementation of a theoretically proposed technique for creating a photoionized plasma in the laboratory using x-ray line radiation. Using a Sn laser plasma to irradiate an Ar gas target, the photoionization parameter, ξ =4 π F /Ne , reached values of order 50 ergcm s-1 , where F is the radiation flux in ergc m-2s-1 . The significance of this is that this technique allows us to mimic effective spectral radiation temperatures in excess of 1 keV. We show that our plasma starts to be collisionally dominated before the peak of the x-ray drive. However, the technique is extendable to higher-energy laser systems to create plasmas with parameters relevant to benchmarking codes used to model astrophysical objects. Title: Photospheric Observations of Surface and Body Modes in Solar Magnetic Pores Authors: Keys, Peter H.; Morton, Richard J.; Jess, David B.; Verth, Gary; Grant, Samuel D. T.; Mathioudakis, Mihalis; Mackay, Duncan H.; Doyle, John G.; Christian, Damian J.; Keenan, Francis P.; Erdélyi, Robertus Bibcode: 2018ApJ...857...28K Altcode: 2018arXiv180301859K Over the past number of years, great strides have been made in identifying the various low-order magnetohydrodynamic wave modes observable in a number of magnetic structures found within the solar atmosphere. However, one aspect of these modes that has remained elusive, until now, is their designation as either surface or body modes. This property has significant implications for how these modes transfer energy from the waveguide to the surrounding plasma. Here, for the first time to our knowledge, we present conclusive, direct evidence of these wave characteristics in numerous pores that were observed to support sausage modes. As well as outlining methods to detect these modes in observations, we make estimates of the energies associated with each mode. We find surface modes more frequently in the data, as well as that surface modes appear to carry more energy than those displaying signatures of body modes. We find frequencies in the range of ∼2-12 mHz, with body modes as high as 11 mHz, but we do not find surface modes above 10 mHz. It is expected that the techniques we have applied will help researchers search for surface and body signatures in other modes and in differing structures from those presented here. Title: A Si IV/O IV Electron Density Diagnostic for the Analysis of IRIS Solar Spectra Authors: Young, P. R.; Keenan, F. P.; Milligan, R. O.; Peter, H. Bibcode: 2018ApJ...857....5Y Altcode: 2018arXiv180301721Y Solar spectra of ultraviolet bursts and flare ribbons from the Interface Region Imaging Spectrograph (IRIS) have suggested high electron densities of > {10}12 cm-3 at transition region temperatures of 0.1 MK, based on large intensity ratios of Si IV λ1402.77 to O IV λ1401.16. In this work, a rare observation of the weak O IV λ1343.51 line is reported from an X-class flare that peaked at 21:41 UT on 2014 October 24. This line is used to develop a theoretical prediction of the Si IV λ1402.77 to O IV λ1401.16 ratio as a function of density that is recommended to be used in the high-density regime. The method makes use of new pressure-dependent ionization fractions that take account of the suppression of dielectronic recombination at high densities. It is applied to two sequences of flare kernel observations from the October 24 flare. The first shows densities that vary between 3× {10}12 and 3× {10}13 cm-3 over a seven-minute period, while the second location shows stable density values of around 2× {10}12 cm-3 over a three-minute period. Title: X-ray line coincidence photopumping in a solar flare Authors: Keenan, F. P.; Poppenhaeger, K.; Mathioudakis, M.; Rose, S. J.; Flowerdew, J.; Hynes, D.; Christian, D. J.; Nilsen, J.; Johnson, W. R. Bibcode: 2018MNRAS.474.3782K Altcode: 2017arXiv171107761K Line coincidence photopumping is a process where the electrons of an atomic or molecular species are radiatively excited through the absorption of line emission from another species at a coincident wavelength. There are many instances of line coincidence photopumping in astrophysical sources at optical and ultraviolet wavelengths, with the most famous example being Bowen fluorescence (pumping of O III 303.80 Å by He II), but none to our knowledge in X-rays. However, here we report on a scheme where a He-like line of Ne IX at 11.000 Å is photopumped by He-like Na X at 11.003 Å, which predicts significant intensity enhancement in the Ne IX 82.76 Å transition under physical conditions found in solar flare plasmas. A comparison of our theoretical models with published X-ray observations of a solar flare obtained during a rocket flight provides evidence for line enhancement, with the measured degree of enhancement being consistent with that expected from theory, a truly surprising result. Observations of this enhancement during flares on stars other than the Sun would provide a powerful new diagnostic tool for determining the sizes of flare loops in these distant, spatially unresolved, astronomical sources. Title: The 2017 Release Cloudy Authors: Ferland, G. J.; Chatzikos, M.; Guzmán, F.; Lykins, M. L.; van Hoof, P. A. M.; Williams, R. J. R.; Abel, N. P.; Badnell, N. R.; Keenan, F. P.; Porter, R. L.; Stancil, P. C. Bibcode: 2017RMxAA..53..385F Altcode: 2017arXiv170510877F We describe the 2017 release of the spectral synthesis code Cloudy, summarizing the many improvements to the scope and accuracy of the physics which have been made since the previous release. Exporting the atomic data into external data files has enabled many new large datasets to be incorporated into the code. The use of the complete datasets is not realistic for most calculations, so we describe the limited subset of data used by default, which predicts significantly more lines than the previous release of Cloudy. This version is nevertheless faster than the previous release, as a result of code optimizations. We give examples of the accuracy limits using small models, and the performance requirements of large complete models. We summarize several advances in the H- and He-like iso-electronic sequences and use our complete collisional-radiative models to establish the densities where the coronal and local thermodynamic equilibrium approximations work. Title: The formation of small-scale umbral brightenings in sunspot atmospheres Authors: Nelson, C. J.; Henriques, V. M. J.; Mathioudakis, M.; Keenan, F. P. Bibcode: 2017A&A...605A..14N Altcode: 2017arXiv170505617N Context. Sunspot atmospheres have been shown to be highly inhomogeneous hosting both quasi-stable and transient features, such as small-scale umbral brightenings (previously named "umbral micro-jets") and dark fibril-like events.
Aims: We seek to understand the morphological properties and formation mechanisms of small-scale umbral brightenings (analogous to umbral micro-jets). In addition, we aim to understand whether links between these events and short dynamic fibrils, umbral flashes, and umbral dots can be established.
Methods: A Swedish 1 m Solar Telescope (SST) filtergram time-series sampling the Ca II H line and a CRisp Imaging Spectro-Polarimeter (SST/CRISP) full-Stokes 15-point Ca II 8542 Å line scan dataset were used. The spatial resolutions of these datasets are close to 0.1'' and 0.18'' with cadences of 1.4 s and 29 s, respectively. These data allowed us to construct light-curves, plot line profiles, and to perform a weak-field approximation in order to infer the magnetic field strength.
Results: The average lifetime and lengths of the 54 small-scale brightenings identified in the sunspot umbra are found to be 44.2 s (σ = 20 s) and 0.56'' (σ = 0.14''), respectively. The spatial positioning and morphological evolution of these events in Ca II H filtergrams was investigated finding no evidence of parabolic or ballistic profiles nor a preference for co-spatial formation with umbral flashes. Line scans in Ca II 8542 Å and the presence of Stokes V profile reversals provided evidence that these events could form in a similar manner to umbral flashes in the chromosphere (I.e. through the formation of shocks either due to the steepening of localised wavefronts or due to the impact of returning material from short dynamic fibrils, a scenario we find evidence for). The application of the weak-field approximation indicated that changes in the line-of-sight magnetic field were not responsible for the modifications to the line profile and suggested that thermodynamic effects are, in fact, the actual cause of the increased emission. Finally, a sub-set of small-scale brightenings were observed to form at the foot-points of short dynamic fibrils.
Conclusions: The small-scale umbral brightenings studied here do not appear to be jet-like in nature. Instead they appear to be evidence of shock formation in the lower solar atmosphere. We found no correlation between the spatial locations where these events were observed and the occurrence of umbral dots and umbral flashes. These events have lifetimes and spectral signatures comparable to umbral flashes and are located at the footpoints of short dynamic fibrils, during or at the end of the red-shifted stage. It is possible that these features form due to the shocking of fibrilar material in the lower atmosphere upon its return under gravity. Title: Spectroscopic Inversions of the Ca II 8542 Å Line in a C-class Solar Flare Authors: Kuridze, D.; Henriques, V.; Mathioudakis, M.; Koza, J.; Zaqarashvili, T. V.; Rybák, J.; Hanslmeier, A.; Keenan, F. P. Bibcode: 2017ApJ...846....9K Altcode: 2017arXiv170800472K We study the C8.4-class solar flare SOL2016-05-14T11:34 UT using high-resolution spectral imaging in the Ca II 8542 Å line obtained with the CRISP imaging spectropolarimeter on the Swedish 1 m Solar Telescope. Spectroscopic inversions of the Ca II 8542 Å line using the non-LTE code NICOLE are used to investigate the evolution of the temperature and velocity structure in the flaring chromosphere. A comparison of the temperature stratification in flaring and non-flaring areas reveals strong footpoint heating during the flare peak in the lower atmosphere. The temperature of the flaring footpoints between {log} {τ }500 ≈ -2.5 {and} -3.5, where τ 500 is the continuum optical depth at 500 nm, is ∼ 5{--}6.5 {kK} close to the flare peak, reducing gradually to ∼ 5 {kK}. The temperature in the middle and upper chromosphere, between {log} {τ }500≈ -3.5 and -5.5, is estimated to be ∼6.5-20 kK, decreasing to preflare temperatures, ∼5-10 kK, after approximately 15 minutes. However, the temperature stratification of the non-flaring areas is unchanged. The inverted velocity fields show that the flaring chromosphere is dominated by weak downflowing condensations at the formation height of Ca II 8542 Å. Title: The Origin of B-type Runaway Stars: Non-LTE Abundances as a Diagnostic Authors: McEvoy, Catherine M.; Dufton, Philip L.; Smoker, Jonathan V.; Lambert, David L.; Keenan, Francis P.; Schneider, Fabian R. N.; de Wit, Willem-Jan Bibcode: 2017ApJ...842...32M Altcode: 2017arXiv170803527M There are two accepted mechanisms to explain the origin of runaway OB-type stars: the binary supernova (SN) scenario and the cluster ejection scenario. In the former, an SN explosion within a close binary ejects the secondary star, while in the latter close multibody interactions in a dense cluster cause one or more of the stars to be ejected from the region at high velocity. Both mechanisms have the potential to affect the surface composition of the runaway star. tlusty non-LTE model atmosphere calculations have been used to determine the atmospheric parameters and the C, N, Mg, and Si abundances for a sample of B-type runaways. These same analytical tools were used by Hunter et al. for their analysis of 50 B-type open-cluster Galactic stars (I.e., nonrunaways). Effective temperatures were deduced using the Si-ionization balance technique, surface gravities from Balmer line profiles, and microturbulent velocities derived using the Si spectrum. The runaways show no obvious abundance anomalies when compared with stars in the open clusters. The runaways do show a spread in composition that almost certainly reflects the Galactic abundance gradient and a range in the birthplaces of the runaways in the Galactic disk. Since the observed Galactic abundance gradients of C, N, Mg, and Si are of a similar magnitude, the abundance ratios (e.g., N/Mg) are as obtained essentially uniform across the sample. Title: An assessment of Fe xx-Fe xxii emission lines in SDO/EVE data as diagnostics for high-density solar flare plasmas using EUVE stellar observations Authors: Keenan, F. P.; Milligan, R. O.; Mathioudakis, M.; Christian, D. J. Bibcode: 2017MNRAS.468.1117K Altcode: 2017arXiv170208714K The Extreme Ultraviolet Variability Experiment (EVE) on the Solar Dynamics Observatory obtains extreme-ultraviolet (EUV) spectra of the full-disc Sun at a spectral resolution of ∼1 Å and cadence of 10 s. Such a spectral resolution would normally be considered to be too low for the reliable determination of electron density (Ne) sensitive emission line intensity ratios, due to blending. However, previous work has shown that a limited number of Fe xxi features in the 90-160 Å wavelength region of EVE do provide useful Ne-diagnostics at relatively low flare densities (Ne ≃ 1011-1012 cm-3). Here, we investigate if additional highly ionized Fe line ratios in the EVE 90-160 Å range may be reliably employed as Ne-diagnostics. In particular, the potential for such diagnostics to provide density estimates for high Ne (∼1013 cm-3) flare plasmas is assessed. Our study employs EVE spectra for X-class flares, combined with observations of highly active late-type stars from the EUVE satellite plus experimental data for well-diagnosed tokamak plasmas, both of which are similar in wavelength coverage and spectral resolution to those from EVE. Several ratios are identified in EVE data, which yield consistent values of electron density, including Fe xx 113.35/121.85 and Fe xxii 114.41/135.79, with confidence in their reliability as Ne-diagnostics provided by the EUVE and tokamak results. These ratios also allow the determination of density in solar flare plasmas up to values of ∼1013 cm-3. Title: Radiative Rates and Electron Impact Excitation Rates for Transitions in He II Authors: Aggarwal, Kanti; Igarashi, Akinori; Keenan, Francis; Nakazaki, Shinobu Bibcode: 2017Atoms...5...19A Altcode: 2017arXiv170407275A We report calculations of energy levels, radiative rates, collision strengths, and effective collision strengths for transitions among the lowest 25 levels of the n <= 5 configurations of He~II. The general-purpose relativistic atomic structure package (GRASP) and Dirac atomic R-matrix code (DARC) are adopted for the calculations. Radiative rates, oscillator strengths, and line strengths are reported for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions among the 25 levels. Furthermore, collision strengths and effective collision strengths are listed for all 300 transitions among the above 25 levels over a wide energy (temperature) range up to 9 Ryd (10**5.4 K). Comparisons are made with earlier available results and the accuracy of the data is assessed. Title: Emission Line Ratios of FE III as Astrophysical Plasma Diagnostics Authors: Laha, Sibasish; Tyndall, Niall B.; Keenan, Francis P.; Ballance, Connor P.; Ramsbottom, Catherine A.; Ferland, Gary J.; Hibbert, Alan Bibcode: 2017ApJ...841....3L Altcode: 2017arXiv170500207L Recent, state-of-the-art calculations of A-values and electron impact excitation rates for Fe III are used in conjunction with the Cloudy modeling code to derive emission-line intensity ratios for optical transitions among the fine-structure levels of the 3d6 configuration. A comparison of these with high-resolution, high signal-to-noise spectra of gaseous nebulae reveals that previous discrepancies found between theory and observation are not fully resolved by the latest atomic data. Blending is ruled out as a likely cause of the discrepancies, because temperature- and density-independent ratios (arising from lines with common upper levels) match well with those predicted by theory. For a typical nebular plasma with electron temperature {T}{{e}}=9000 K and electron density {N}{{e}}={10}4 {{cm}}-3, cascading of electrons from the levels {}3{{{G}}}5, {}3{{{G}}}4 and {}3{{{G}}}3 plays an important role in determining the populations of lower levels, such as {}3{{{F}}}4, which provide the density diagnostic emission lines of Fe III, such as {}5{{{D}}}4 - {}3{{{F}}}4 at 4658 Å. Hence, further work on the A-values for these transitions is recommended, ideally including measurements if possible. However, some Fe III ratios do provide reliable {N}{{e}}-diagnostics, such as 4986/4658. The Fe III cooling function, calculated with Cloudy using the most recent atomic data, is found to be significantly greater at T e ≃ 30,000 K than predicted with the existing Cloudy model. This is due to the presence of additional emission lines with the new data, particularly in the 1000-4000 Å wavelength region. Title: Energy levels and radiative rates for transitions in Fe V, Co VI and Ni VII Authors: Aggarwal, K. M.; Bogdanovich, P.; Keenan, F. P.; Kisielius, R. Bibcode: 2017ADNDT.114....1A Altcode: 2016arXiv160508212A Energy levels, Landé g-factors and radiative lifetimes are reported for the lowest 182 levels of the 3d4, 3d34s and 3d34p configurations of Fe V, Co VI and Ni VII. Additionally, radiative rates (A-values) have been calculated for the E1, E2 and M1 transitions among these levels. The calculations have been performed in a quasi-relativistic approach (QR) with a very large configuration interaction (CI) wavefunction expansion, which has been found to be necessary for these ions. Our calculated energies for all ions are in excellent agreement with the available measurements, for most levels. Discrepancies among various calculations for the radiative rates of E1 transitions in Fe V are up to a factor of two for stronger transitions (f ≥ 0.1), and larger (over an order of magnitude) for weaker ones. The reasons for these discrepancies have been discussed and mainly are due to the differing amount of CI and methodologies adopted. However, there are no appreciable discrepancies in similar data for M1 and E2 transitions, or the g-factors for the levels of Fe V, the only ion for which comparisons are feasible. Title: Observations and Simulations of the Na I D1 Line Profiles in an M-class Solar Flare Authors: Kuridze, D.; Mathioudakis, M.; Christian, D. J.; Kowalski, A. F.; Jess, D. B.; Grant, S. D. T.; Kawate, T.; Simões, P. J. A.; Allred, J. C.; Keenan, F. P. Bibcode: 2016ApJ...832..147K Altcode: 2016arXiv160908120K We study the temporal evolution of the Na I D1 line profiles in the M3.9 flare SOL2014-06-11T21:03 UT, using observations at high spectral resolution obtained with the Interferometric Bidimensional Spectrometer instrument on the Dunn Solar Telescope combined with radiative hydrodynamic simulations. Our results show a significant increase in the intensities of the line core and wings during the flare. The analysis of the line profiles from the flare ribbons reveals that the Na I D1 line has a central reversal with excess emission in the blue wing (blue asymmetry). We combine RADYN and RH simulations to synthesize Na I D1 line profiles of the flaring atmosphere and find good agreement with the observations. Heating with a beam of electrons modifies the radiation field in the flaring atmosphere and excites electrons from the ground state 3s 2S to the first excited state 3p 2P, which in turn modifies the relative population of the two states. The change in temperature and the population density of the energy states make the sodium line profile revert from absorption into emission. Furthermore, the rapid changes in temperature break the pressure balance between the different layers of the lower atmosphere, generating upflow/downflow patterns. Analysis of the simulated spectra reveals that the asymmetries of the Na I D1 flare profile are produced by the velocity gradients in the lower solar atmosphere. Title: Kelvin-Helmholtz Instability in Solar Chromospheric Jets: Theory and Observation Authors: Kuridze, D.; Zaqarashvili, T. V.; Henriques, V.; Mathioudakis, M.; Keenan, F. P.; Hanslmeier, A. Bibcode: 2016ApJ...830..133K Altcode: 2016arXiv160801497K Using data obtained by the high-resolution CRisp Imaging SpectroPolarimeter instrument on the Swedish 1 m Solar Telescope, we investigate the dynamics and stability of quiet-Sun chromospheric jets observed at the disk center. Small-scale features, such as rapid redshifted and blueshifted excursions, appearing as high-speed jets in the wings of the Hα line, are characterized by short lifetimes and rapid fading without any descending behavior. To study the theoretical aspects of their stability without considering their formation mechanism, we model chromospheric jets as twisted magnetic flux tubes moving along their axis, and use the ideal linear incompressible magnetohydrodynamic approximation to derive the governing dispersion equation. Analytical solutions of the dispersion equation indicate that this type of jet is unstable to Kelvin-Helmholtz instability (KHI), with a very short (few seconds) instability growth time at high upflow speeds. The generated vortices and unresolved turbulent flows associated with the KHI could be observed as a broadening of chromospheric spectral lines. Analysis of the Hα line profiles shows that the detected structures have enhanced line widths with respect to the background. We also investigate the stability of a larger-scale Hα jet that was ejected along the line of sight. Vortex-like features, rapidly developing around the jet’s boundary, are considered as evidence of the KHI. The analysis of the energy equation in the partially ionized plasma shows that ion-neutral collisions may lead to fast heating of the KH vortices over timescales comparable to the lifetime of chromospheric jets. Title: Electron impact excitation of N IV: calculations with the DARC code and a comparison with ICFT results Authors: Aggarwal, K. M.; Keenan, F. P.; Lawson, K. D. Bibcode: 2016MNRAS.461.3997A Altcode: 2016arXiv160804406A There have been discussions in the recent literature regarding the accuracy of the available electron impact excitation rates (equivalently effective collision strengths Υ) for transitions in Be-like ions. In the present paper we demonstrate, once again, that earlier results for Υ are indeed overestimated (by up to four orders of magnitude), for over 40 per cent of transitions and over a wide range of temperatures. To do this we have performed two sets of calculations for N IV, with two different model sizes consisting of 166 and 238 fine-structure energy levels. As in our previous work, for the determination of atomic structure the GRASP (General-purpose Relativistic Atomic Structure Package) is adopted and for the scattering calculations (the standard and parallelised versions of) the Dirac Atomic R-matrix Code (DARC) are employed. Calculations for collision strengths and effective collision strengths have been performed over a wide range of energy (up to 45 Ryd) and temperature (up to 2.0 × 106 K), useful for applications in a variety of plasmas. Corresponding results for energy levels, lifetimes and A-values for all E1, E2, M1 and M2 transitions among 238 levels of N IV are also reported. Title: Electron impact excitation rates for transitions in Mg V Authors: Aggarwal, K M; Keenan, F P Bibcode: 2016arXiv160908351A Altcode: Energy levels, radiative rates (A-values) and lifetimes, calculated with the GRASP code, are reported for an astrophysically important O-like ion Mg~V. Results are presented for transitions among the lowest 86 levels belonging to the 2s$^2$2p$^4$, 2s2p$^5$, 2p$^6$, and 2s$^2$2p$^3$3$\ell$ configurations. There is satisfactory agreement with earlier data for most levels/transitions, but scope remains for improvement. Collision strengths are also calculated, with the DARC code, and the results obtained are comparable for most transitions (at energies above thresholds) with earlier work using the DW code. In thresholds region, resonances have been resolved in a fine energy mesh to determine values of effective collision strengths ($\Upsilon$) as accurately as possible. Results are reported for all transitions at temperatures up to 10$^6$~K, which should be sufficient for most astrophysical applications. However, a comparison with earlier data reveals discrepancies of up to two orders of magnitude for over 60\% of transitions, at all temperatures. The reasons for these discrepancies are discussed in detail. Title: Departure of High-temperature Iron Lines from the Equilibrium State in Flaring Solar Plasmas Authors: Kawate, T.; Keenan, F. P.; Jess, D. B. Bibcode: 2016ApJ...826....3K Altcode: 2016arXiv160602049K The aim of this study is to clarify if the assumption of ionization equilibrium and a Maxwellian electron energy distribution is valid in flaring solar plasmas. We analyze the 2014 December 20 X1.8 flare, in which the Fe xxi 187 Å, Fe xxii 253 Å, Fe xxiii 263 Å, and Fe xxiv 255 Å emission lines were simultaneously observed by the EUV Imaging Spectrometer on board the Hinode satellite. Intensity ratios among these high-temperature Fe lines are compared and departures from isothermal conditions and ionization equilibrium examined. Temperatures derived from intensity ratios involving these four lines show significant discrepancies at the flare footpoints in the impulsive phase, and at the looptop in the gradual phase. Among these, the temperature derived from the Fe xxii/Fe xxiv intensity ratio is the lowest, which cannot be explained if we assume a Maxwellian electron distribution and ionization equilibrium, even in the case of a multithermal structure. This result suggests that the assumption of ionization equilibrium and/or a Maxwellian electron energy distribution can be violated in evaporating solar plasma around 10 MK. Title: Ultraviolet Emission Lines of Si II in Quasars: Investigating the "Si II Disaster" Authors: Laha, Sibasish; Keenan, Francis P.; Ferland, Gary J.; Ramsbottom, Catherine A.; Aggarwal, Kanti M. Bibcode: 2016ApJ...825...28L Altcode: 2016arXiv160407364L The observed line intensity ratios of the Si II λ1263 and λ1307 multiplets to that of Si II λ1814 in the broad-line region (BLR) of quasars are both an order of magnitude larger than the theoretical values. This was first pointed out by Baldwin et al., who termed it the “Si II disaster,” and it has remained unresolved. We investigate the problem in the light of newly published atomic data for Si II. Specifically, we perform BLR calculations using several different atomic data sets within the CLOUDY modeling code under optically thick quasar cloud conditions. In addition, we test for selective pumping by the source photons or intrinsic galactic reddening as possible causes for the discrepancy, and we also consider blending with other species. However, we find that none of the options investigated resolve the Si II disaster, with the potential exception of microturbulent velocity broadening and line blending. We find that a larger microturbulent velocity (∼ 500 {km} {{{s}}}-1) may solve the Si II disaster through continuum pumping and other effects. The CLOUDY models indicate strong blending of the Si II λ1307 multiplet with emission lines of O I, although the predicted degree of blending is incompatible with the observed λ1263/λ1307 intensity ratios. Clearly, more work is required on the quasar modeling of not just the Si II lines but also nearby transitions (in particular those of O I) to fully investigate whether blending may be responsible for the Si II disaster. Title: VizieR Online Data Catalog: Early-type stars in SMC and LMC (Smoker+, 2015) Authors: Smoker, J. V.; Fox, A. J.; Keenan, F. P. Bibcode: 2016yCat..74514346S Altcode: FLAMES observations towards four open clusters in the LMC and SMC were retrieved from the ESO archive and are used to study the I/HVCs towards these galaxies and their variation on small scales.

(1 data file). Title: Quiet-Sun Hα Transients and Corresponding Small-scale Transition Region and Coronal Heating Authors: Henriques, V. M. J.; Kuridze, D.; Mathioudakis, M.; Keenan, F. P. Bibcode: 2016ApJ...820..124H Altcode: 2016arXiv160204820H Rapid blue- and redshifted excursions (RBEs and RREs) are likely to be the on-disk counterparts of Type II spicules. Recently, heating signatures from RBEs/RREs have been detected in IRIS slit-jaw images dominated by transition region (TR) lines around network patches. Additionally, signatures of Type II spicules have been observed in Atmospheric Imaging Assembly (AIA) diagnostics. The full-disk, ever-present nature of the AIA diagnostics should provide us with sufficient statistics to directly determine how important RBEs and RREs are to the heating of the TR and corona. We find, with high statistical significance, that at least 11% of the low coronal brightenings detected in a quiet-Sun region in He II 304 Å can be attributed to either RBEs or RREs as observed in Hα, and a 6% match of Fe IX 171 Å detected events to RBEs or RREs with very similar statistics for both types of Hα features. We took a statistical approach that allows for noisy detections in the coronal channels and provides us with a lower, but statistical significant, bound. Further, we consider matches based on overlapping features in both time and space, and find strong visual indications of further correspondence between coronal events and co-evolving but non-overlapping, RBEs and RREs. Title: Energy levels and radiative rates for transitions in Cr-like Co IV and Ni V Authors: Aggarwal, K. M.; Bogdanovich, P.; Karpuškienė, R.; Keenan, F. P.; Kisielius, R.; Stancalie, V. Bibcode: 2016ADNDT.107..140A Altcode: 2015arXiv150907648A We report calculations of energy levels and radiative rates (A-values) for transitions in Cr-like Co IV and Ni V. The quasi-relativistic Hartree-Fock (QRHF) code is adopted for calculating the data although GRASP (general-purpose relativistic atomic structure package) and flexible atomic code (FAC) have also been employed for comparison purposes. No radiative rates are available in the literature to compare with our results, but our calculated energies are in close agreement with those compiled by NIST for a majority of the levels. However, there are discrepancies for a few levels of up to 3%. The A-values are listed for all significantly contributing E1, E2 and M1 transitions, and the corresponding lifetimes reported, although unfortunately no previous theoretical or experimental results exist to compare with our data. Title: Ultraviolet emission lines of Si II in cool star and solar spectra Authors: Laha, Sibasish; Keenan, Francis P.; Ferland, Gary J.; Ramsbottom, Catherine A.; Aggarwal, Kanti M.; Ayres, Thomas R.; Chatzikos, Marios; van Hoof, Peter A. M.; Williams, Robin J. R. Bibcode: 2016MNRAS.455.3405L Altcode: 2015arXiv151008755L Recent atomic physics calculations for Si II are employed within the CLOUDY modelling code to analyse Hubble Space Telescope (HST) STIS ultraviolet spectra of three cool stars, β Geminorum, α Centauri A and B, as well as previously published HST/GHRS observations of α Tau, plus solar quiet Sun data from the High Resolution Telescope and Spectrograph. Discrepancies found previously between theory and observation for line intensity ratios involving the 3s23p 2PJ-3s3p2 4P_{J^' }} intercombination multiplet of Si II at ∼ 2335 Å are significantly reduced, as are those for ratios containing the 3s23p 2PJ-3s3p2 2D_{J^' }} transitions at ∼1816 Å. This is primarily due to the effect of the new Si II transition probabilities. However, these atomic data are not only very different from previous calculations, but also show large disagreements with measurements, specifically those of Calamai et al. for the intercombination lines. New measurements of transition probabilities for Si II are hence urgently required to confirm (or otherwise) the accuracy of the recently calculated values. If the new calculations are confirmed, then a long-standing discrepancy between theory and observation will have finally been resolved. However, if the older measurements are found to be correct, then the agreement between theory and observation is simply a coincidence and the existing discrepancies remain. Title: Hα Line Profile Asymmetries and the Chromospheric Flare Velocity Field Authors: Kuridze, D.; Mathioudakis, M.; Simões, P. J. A.; Rouppe van der Voort, L.; Carlsson, M.; Jafarzadeh, S.; Allred, J. C.; Kowalski, A. F.; Kennedy, M.; Fletcher, L.; Graham, D.; Keenan, F. P. Bibcode: 2015ApJ...813..125K Altcode: 2015arXiv151001877K The asymmetries observed in the line profiles of solar flares can provide important diagnostics of the properties and dynamics of the flaring atmosphere. In this paper the evolution of the Hα and Ca ii λ8542 lines are studied using high spatial, temporal, and spectral resolution ground-based observations of an M1.1 flare obtained with the Swedish 1 m Solar Telescope. The temporal evolution of the Hα line profiles from the flare kernel shows excess emission in the red wing (red asymmetry) before flare maximum and excess in the blue wing (blue asymmetry) after maximum. However, the Ca ii λ8542 line does not follow the same pattern, showing only a weak red asymmetry during the flare. RADYN simulations are used to synthesize spectral line profiles for the flaring atmosphere, and good agreement is found with the observations. We show that the red asymmetry observed in Hα is not necessarily associated with plasma downflows, and the blue asymmetry may not be related to plasma upflows. Indeed, we conclude that the steep velocity gradients in the flaring chromosphere modify the wavelength of the central reversal in the Hα line profile. The shift in the wavelength of maximum opacity to shorter and longer wavelengths generates the red and blue asymmetries, respectively. Title: The large- and small-scale Ca II K structure of the Milky Way from observations of Galactic and Magellanic sightlines⋆ Authors: Smoker, J. V.; Keenan, F. P.; Fox, A. J. Bibcode: 2015A&A...582A..59S Altcode: 2015arXiv151100470S
Aims: The large and small-scale (pc) structure of the Galactic interstellar medium can be investigated by utilising spectra of early-type stellar probes of known distances in the same region of the sky. This paper determines the variation in line strength of Ca ii at 3933.661 Å as a function of probe separation for a large sample of stars, including a number of sightlines in the Magellanic Clouds.
Methods: FLAMES-GIRAFFE data taken with the Very Large Telescope towards early-type stars in 3 Galactic and 4 Magellanic open clusters in Ca ii are used to obtain the velocity, equivalent width, column density, and line width of interstellar Galactic calcium for a total of 657 stars, of which 443 are Magellanic Cloud sightlines. In each cluster there are between 43 and 111 stars observed. Additionally, FEROS and UVES Ca ii K and Na i D spectra of 21 Galactic and 154 Magellanic early-type stars are presented and combined with data from the literature to study the calcium column density - parallax relationship.
Results: For the four Magellanic clusters studied with FLAMES, the strength of the Galactic interstellar Ca ii K equivalent width on transverse scales from ~0.05-9 pc is found to vary by factors of ~1.8-3.0, corresponding to column density variations of ~0.3-0.5 dex in the optically-thin approximation. Using FLAMES, FEROS, and UVES archive spectra, the minimum and maximum reduced equivalent widths for Milky Way gas are found to lie in the range ~35-125 mÅ and ~30-160 mÅ for Ca ii K and Na i D, respectively. The range is consistent with a previously published simple model of the interstellar medium consisting of spherical cloudlets of filling factor ~0.3, although other geometries are not ruled out. Finally, the derived functional form for parallax (π) and Ca ii column density (NCaII) is found to be π(mas) = 1 / (2.39 × 10-13 × NCaII (cm-2) + 0.11). Our derived parallax is ~25 per cent lower than predicted by Megier et al. (2009, A&A, 507, 833) at a distance of ~100 pc and ~15 percent lower at a distance of ~200 pc, reflecting inhomogeneity in the Ca ii distribution in the different sightlines studied.

Reduced spectra and Tables A.1-A.17 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/582/A59Figures A.1-A.37 are available in electronic form at http://www.aanda.org Title: Large- and small-scale structure of the intermediate- and high-velocity clouds towards the LMC and SMC Authors: Smoker, J. V.; Fox, A. J.; Keenan, F. P. Bibcode: 2015MNRAS.451.4346S Altcode: 2015arXiv151100843S We employ Ca II K and Na I D interstellar absorption-line spectroscopy of early-type stars in the Large and Small Magellanic Clouds (LMC, SMC) to investigate the large- and small-scale structure in foreground intermediate- and high-velocity clouds (I/HVCs). Data include FLAMES-GIRAFFE Ca II K observations of 403 stars in four open clusters, plus FEROS or UVES spectra of 156 stars in the LMC and SMC. The FLAMES observations are amongst the most extensive probes to date of Ca II structures on ∼20 arcsec scales in Magellanic I/HVCs. From the FLAMES data within a 0.5° field of view, the Ca II K equivalent width in the I/HVC components towards three clusters varies by factors of ≥10. There are no detections of molecular gas in absorption at intermediate or high velocities, although molecular absorption is present at LMC and Galactic velocities towards some sightlines. The FEROS/UVES data show Ca II K I/HVC absorption in ∼60 per cent of sightlines. The range in the Ca II/Na I ratio in I/HVCs is from -0.45 to +1.5 dex, similar to previous measurements for I/HVCs. In 10 sightlines we find Ca II/O I ratios in I/HVC gas ranging from 0.2 to 1.5 dex below the solar value, indicating either dust or ionization effects. In nine sightlines I/HVC gas is detected in both H I and Ca II at similar velocities, implying that the two elements form part of the same structure. Title: Early-type stars observed in the ESO UVES Paranal Observatory Project - V. Time-variable interstellar absorption Authors: McEvoy, Catherine M.; Smoker, Jonathan V.; Dufton, Philip L.; Smith, Keith T.; Kennedy, Michael B.; Keenan, Francis P.; Lambert, David L.; Welty, Daniel E.; Lauroesch, James T. Bibcode: 2015MNRAS.451.1396M Altcode: 2015arXiv150601348M The structure and properties of the diffuse interstellar medium (ISM) on small scales, sub-au to 1 pc, are poorly understood. We compare interstellar absorption lines, observed towards a selection of O- and B-type stars at two or more epochs, to search for variations over time caused by the transverse motion of each star combined with changes in the structure in the foreground ISM. Two sets of data were used: 83 VLT/UVES spectra with approximately 6 yr between epochs and 21 McDonald observatory 2.7-m telescope echelle spectra with 6-20 yr between epochs, over a range of scales from ∼0-360 au. The interstellar absorption lines observed at the two epochs were subtracted and searched for any residuals due to changes in the foreground ISM. Of the 104 sightlines investigated with typically five or more components in Na I D, possible temporal variation was identified in five UVES spectra (six components), in Ca II, Ca I and/or Na I absorption lines. The variations detected range from 7 per cent to a factor of 3.6 in column density. No variation was found in any other interstellar species. Most sightlines show no variation, with 3σ upper limits to changes of the order 0.1-0.3 dex in Ca II and Na I. These variations observed imply that fine-scale structure is present in the ISM, but at the resolution available in this study, is not very common at visible wavelengths. A determination of the electron densities and lower limits to the total number density of a sample of the sightlines implies that there is no striking difference between these parameters in sightlines with, and sightlines without, varying components. Title: Electron impact excitation of Astrophysically Important C III Ion Authors: Aggarwal, Kanti M.; KEENAN, FRANCIS P. Bibcode: 2015IAUGA..2253165A Altcode: Emission lines of many Be-like ions, including C~III, have been observed in the solar and stellar plasmas and are useful for density and temperature diagnostics. C~III is also important for studies of fusion plasmas. For modelling and diagnostics, atomic data for energy levels, radiative rates (A-values) and excitation rates (equivalently effective collision strengths) are required. Therefore, we have adopted the GRASP code to calculate energy levels, A-values (for E1, E2, M1 and M2 transitions) and lifetimes among 166 levels of the n <= 5 configurations. Energy levels are assessed to be accurate to better than 1% for most levels, and A-values to better than 20% for most transitions. For A-values and lifetimes there are no large discrepancies between theory and measurement. For collision strengths DARC is adopted, resonances are resolved in a fine energy mesh and are averaged over a Maxwellian velocity distribution to determine effective collision strengths up to a temperature of 800,000 K. Unfortunately, a comparison with the similar R-matrix calculations of Fernandez-Menchero et al [A&A 566 (2014) A104] shows differences up to over an order of magnitude for about 20% transitions (among the lowest 78 levels) over the complete temperature range of the results. In most cases their results are larger, up to a factor of 20, and the differences are similar and comparable to those already noted for other Be-like ions, namely Al~X, Cl~XIV, K~XVI, Ti~XIX and Ge~XXIX - see Aggarwal & Keenan [MNRAS 447 (2015) 3849]. Based on several comparisons and considering the wide range of partial waves included (up to 40.5) and the energy range adopted for collision strengths (up to 21 Ryd), our results are estimated to be accurate to better than 20% for a majority of transitions, allowed and forbidden. Detailed comparisons for all parameters for C~III and possible reasons for discrepancies will be presented during the conference and will also be soon available in MNRAS. Title: VizieR Online Data Catalog: CaIIK spectra of 7 Galactic and MC open clusters (Smoker+, 2015) Authors: Smoker, J.; Keenan, F. P.; Fox, A. J. Bibcode: 2015yCat..35820059S Altcode: The data on which the current paper is based were extracted from the ESO archive and are FLAMES-GIRAFFE observations towards three open clusters located in the Milky Way, and two in each of the Large and Small Magellanic Clouds, plus FEROS and UVES observations towards stars located in the Magellanic system and Milky Way.

(18 data files). Title: Stout: Cloudy's Atomic and Molecular Database Authors: Lykins, M. L.; Ferland, G. J.; Kisielius, R.; Chatzikos, M.; Porter, R. L.; van Hoof, P. A. M.; Williams, R. J. R.; Keenan, F. P.; Stancil, P. C. Bibcode: 2015ApJ...807..118L Altcode: 2015arXiv150601741L We describe a new atomic and molecular database we developed for use in the spectral synthesis code Cloudy. The design of Stout is driven by the data needs of Cloudy, which simulates molecular, atomic, and ionized gas with kinetic temperatures 2.8 {{K}}\lt T\lt {10}10 {{K}} and densities spanning the low-to high-density limits. The radiation field between photon energies 10-8 Ry and 100 MeV is considered, along with all atoms and ions of the lightest 30 elements, and ∼102 molecules. For ease of maintenance, the data are stored in a format as close as possible to the original data sources. Few data sources include the full range of data we need. We describe how we fill in the gaps in the data or extrapolate rates beyond their tabulated range. We tabulate data sources both for the atomic spectroscopic parameters and for collision data for the next release of Cloudy. This is not intended as a review of the current status of atomic data, but rather a description of the features of the database which we will build upon. Title: Radiative hydrodynamic modelling and observations of the X-class solar flare on 2011 March 9 Authors: Kennedy, Michael B.; Milligan, Ryan O.; Allred, Joel C.; Mathioudakis, Mihalis; Keenan, Francis P. Bibcode: 2015A&A...578A..72K Altcode: 2015arXiv150407541K
Aims: We investigated the response of the solar atmosphere to non-thermal electron beam heating using the radiative transfer and hydrodynamics modelling code RADYN. The temporal evolution of the parameters that describe the non-thermal electron energy distribution were derived from hard X-ray observations of a particular flare, and we compared the modelled and observed parameters.
Methods: The evolution of the non-thermal electron beam parameters during the X1.5 solar flare on 2011 March 9 were obtained from analysis of RHESSI X-ray spectra. The RADYN flare model was allowed to evolve for 110 s, after which the electron beam heating was ended, and was then allowed to continue evolving for a further 300 s. The modelled flare parameters were compared to the observed parameters determined from extreme-ultraviolet spectroscopy.
Results: The model produced a hotter and denser flare loop than that observed and also cooled more rapidly, suggesting that additional energy input in the decay phase of the flare is required. In the explosive evaporation phase a region of high-density cool material propagated upward through the corona. This material underwent a rapid increase in temperature as it was unable to radiate away all of the energy deposited across it by the non-thermal electron beam and via thermal conduction. A narrow and high-density (ne ≤ 1015 cm-3) region at the base of the flare transition region was the source of optical line emission in the model atmosphere. The collision-stopping depth of electrons was calculated throughout the evolution of the flare, and it was found that the compression of the lower atmosphere may permit electrons to penetrate farther into a flaring atmosphere compared to a quiet Sun atmosphere. Title: Energy levels, radiative rates and electron impact excitation rates for transitions in C III Authors: Aggarwal, Kanti M.; Keenan, Francis P. Bibcode: 2015MNRAS.450.1151A Altcode: 2015arXiv150307673A We report energy levels, radiative rates (A-values) and lifetimes for the astrophysically important Be-like ion C III. For the calculations, 166 levels belonging to the n ≤ 5 configurations are considered and the GRASP (General-purpose Relativistic Atomic Structure Package) is adopted. Einstein A-coefficients are provided for all E1, E2, M1 and M2 transitions, while lifetimes are compared with available measurements as well as theoretical results, and no large discrepancies noted. Our energy levels are assessed to be accurate to better than 1 per cent for a majority of levels, and A-values to better than 20 per cent for most transitions. Collision strengths are also calculated, for which the Dirac Atomic R-matrix Code (DARC) is used. A wide energy range, up to 21 Ryd, is considered and resonances resolved in a fine energy mesh in the thresholds region. The collision strengths are subsequently averaged over a Maxwellian velocity distribution to determine effective collision strengths up to a temperature of 8.0 × 105 K, sufficient for most astrophysical applications. Our data are compared with the recent R-matrix calculations of Fernández-Menchero et al., and significant differences (up to over an order of magnitude) are noted for several transitions over the complete temperature range of the results. Title: The Radiated Energy Budget Of Chromospheric Plasma In A Major Solar Flare Deduced From Multi-Wavelength Observations Authors: Milligan, Ryan; Kerr, Graham Stewart; Dennis, Brian; Hudson, Hugh; Fletcher, Lyndsay; Allred, Joel; Chamberlin, Phillip; Ireland, Jack; Mathioudakis, Mihalis; Keenan, Francis Bibcode: 2015TESS....130209M Altcode: The response of the lower solar atmosphere is an important diagnostic tool for understanding energy transport during solar flares. The 15 February 2011 X-class flare was fortuitously observed by a host of space-based instruments that sampled the chromospheric response over a range of lines and continua at <20s cadence. These include the free-bound EUV continua of H I (Lyman), He I, and He II, plus the emission lines of He II at 304Å and H I (Lyα) at 1216Å by SDO/EVE, the UV continua at 1600Å and 1700Å by SDO/AIA, and the white light continuum at 4504Å, 5550Å, and 6684Å, along with the Ca II H line at 3968Å using Hinode/SOT. RHESSI also observed the entire event at energies up to ~100keV, making it possible to determine the properties of the nonthermal electrons deemed to be responsible for driving the enhanced chromospheric emission under the assumption of thick-target collisions. Integrating over the duration of the impulsive phase, the total energy contained in the nonthermal electrons was found to be >2×1031 erg. By comparison, the summed energy detected by instruments onboard SDO and Hinode amounted to ~3×1030 erg; about 15% of the total nonthermal energy. The Lyα line was found to dominate the measured radiative losses in contrast to the predictions of numerical simulations. Parameters of both the driving electron distribution and the resulting chromospheric response are presented in detail to encourage the numerical modeling of flare heating for this event to determine the depth of the solar atmosphere at which these line and continuum processes originate, and the mechanism(s) responsible for their generation. Title: Electron impact excitation of Be-like ions: a comparison of DARC and ICFT results Authors: Aggarwal, Kanti M.; Keenan, Francis P. Bibcode: 2015MNRAS.447.3849A Altcode: 2015arXiv150100808A Emission lines of Be-like ions are frequently observed in astrophysical plasmas, and many are useful for density and temperature diagnostics. However, accurate atomic data for energy levels, radiative rates (A-values) and effective electron excitation collision strengths (Υ) are required for reliable plasma modelling. In general, it is reasonably straightforward to calculate energy levels and A-values to a high level of accuracy. By contrast, considerable effort is required to calculate Υ, and hence it is not always possible to assess the accuracy of available data. Recently, two independent calculations (adopting the R-matrix method) but with different approaches (DARC and ICFT) have appeared for a range of Be-like ions. Therefore, in this work we compare the two sets of Υ, highlight the large discrepancies for a significant number of transitions and suggest possible reasons for these. Title: The Dynamics of Rapid Redshifted and Blueshifted Excursions in the Solar Hα Line Authors: Kuridze, D.; Henriques, V.; Mathioudakis, M.; Erdélyi, R.; Zaqarashvili, T. V.; Shelyag, S.; Keys, P. H.; Keenan, F. P. Bibcode: 2015ApJ...802...26K Altcode: 2015arXiv150106205K We analyze high temporal and spatial resolution time-series of spectral scans of the Hα line obtained with the CRisp Imaging SpectroPolarimeter instrument mounted on the Swedish Solar Telescope. The data reveal highly dynamic, dark, short-lived structures known as Rapid Redshifted and Blueshifted Excursions (RREs, RBEs) that are on-disk absorption features observed in the red and blue wings of spectral lines formed in the chromosphere. We study the dynamics of RREs and RBEs by tracking their evolution in space and time, measuring the speed of the apparent motion, line of sight (LOS) Doppler velocity, and transverse velocity of individual structures. A statistical study of their measured properties shows that RREs and RBEs have similar occurrence rates, lifetimes, lengths, and widths. They also display non-periodic, nonlinear transverse motions perpendicular to their axes at speeds of 4-31 km s-1. Furthermore, both types of structures either appear as high speed jets and blobs that are directed outwardly from a magnetic bright point with speeds of 50-150 km s-1, or emerge within a few seconds. A study of the different velocity components suggests that the transverse motions along the LOS of the chromospheric flux tubes are responsible for the formation and appearance of these redshifted/blueshifted structures. The short lifetime and fast disappearance of the RREs/RBEs suggests that, similar to type II spicules, they are rapidly heated to transition region or even coronal temperatures. We speculate that the Kelvin-Helmholtz instability triggered by observed transverse motions of these structures may be a viable mechanism for their heating. Title: Stable umbral chromospheric structures Authors: Henriques, V. M. J.; Scullion, E.; Mathioudakis, M.; Kiselman, D.; Gallagher, P. T.; Keenan, F. P. Bibcode: 2015A&A...574A.131H Altcode: 2014arXiv1412.6100H
Aims: We seek to understand the morphology of the chromosphere in sunspot umbra. We investigate if the horizontal structures observed in the spectral core of the Ca II H line are ephemeral visuals caused by the shock dynamics of more stable structures, and examine their relationship with observables in the H-alpha line.
Methods: Filtergrams in the core of the Ca II H and H-alpha lines as observed with the Swedish 1-m Solar Telescope are employed. We utilise a technique that creates composite images and tracks the flash propagation horizontally.
Results: We find 0.̋15 wide horizontal structures, in all of the three target sunspots, for every flash where the seeing is moderate to good. Discrete dark structures are identified that are stable for at least two umbral flashes, as well as systems of structures that live for up to 24 min. We find cases of extremely extended structures with similar stability, with one such structure showing an extent of 5''. Some of these structures have a correspondence in H-alpha, but we were unable to find a one-to-one correspondence for every occurrence. If the dark streaks are formed at the same heights as umbral flashes, there are systems of structures with strong departures from the vertical for all three analysed sunspots.
Conclusions: Long-lived Ca II H filamentary horizontal structures are a common and likely ever-present feature in the umbra of sunspots. If the magnetic field in the chromosphere of the umbra is indeed aligned with the structures, then the present theoretical understanding of the typical umbra needs to be revisited.

Movies associated to Figs. 3 and 4 are available in electronic form at http://www.aanda.org Title: Energy levels, radiative rates and electron impact excitation rates for transitions in Fe XIV Authors: Aggarwal, Kanti M.; Keenan, Francis P. Bibcode: 2014MNRAS.445.2015A Altcode: 2014arXiv1409.4214A Energies and lifetimes are reported for the lowest 136 levels of Fe XIV, belonging to the (1s22s22p6) 3s23p, 3s3p2, 3s23d, 3p3, 3s3p3d, 3p23d, 3s3d2, 3p3d2 and 3s24ℓ configurations. Additionally, radiative rates, oscillator strengths and line strengths are calculated for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2) and magnetic quadrupole (M2) transitions. Theoretical lifetimes determined from these radiative rates for most levels show satisfactory agreement with earlier calculations, as well as with measurements. Electron impact excitation collision strengths are also calculated with the Dirac atomic R-matrix code (DARC) over a wide energy range up to 260 Ryd. Furthermore, resonances have been resolved in a fine energy mesh to determine effective collision strengths, obtained after integrating the collision strengths over a Maxwellian distribution of electron velocities. Results are listed for all 9180 transitions among the 136 levels over a wide range of electron temperatures, up to 107.1 K. Comparisons are made with available results in the literature, and the accuracy of the present data is assessed. Title: Energy levels, radiative rates and electron impact excitation rates for transitions in Be-like Cl XIV, K XVI and Ge XXIX Authors: Aggarwal, Kanti M.; Keenan, Francis P. Bibcode: 2014PhyS...89l5401A Altcode: 2014arXiv1409.3745A Results for energy levels, radiative rates and electron impact excitation (effective) collision strengths for transitions in Be-like Cl XIV, K XVI and Ge XXIX are reported. For the calculations of energy levels and radiative rates the general-purpose relativistic atomic structure package is adopted, while for determining the collision strengths and subsequently the excitation rates, the Dirac atomic R-matrix code is used. Oscillator strengths, radiative rates and line strengths are listed for all E1, E2, M1 and M2 transitions among the lowest 98 levels of the n≤slant 4 configurations. Furthermore, lifetimes are provided for all levels and comparisons made with available theoretical and experimental results. Resonances in the collision strengths are resolved in a fine energy mesh and averaged over a Maxwellian velocity distribution to obtain the effective collision strengths. Results obtained are listed over a wide temperature range up to 107.8 K, depending on the ion. Title: The Radiated Energy Budget of Chromospheric Plasma in a Major Solar Flare Deduced from Multi-wavelength Observations Authors: Milligan, Ryan O.; Kerr, Graham S.; Dennis, Brian R.; Hudson, Hugh S.; Fletcher, Lyndsay; Allred, Joel C.; Chamberlin, Phillip C.; Ireland, Jack; Mathioudakis, Mihalis; Keenan, Francis P. Bibcode: 2014ApJ...793...70M Altcode: 2014arXiv1406.7657M This paper presents measurements of the energy radiated by the lower solar atmosphere, at optical, UV, and EUV wavelengths, during an X-class solar flare (SOL2011-02-15T01:56) in response to an injection of energy assumed to be in the form of nonthermal electrons. Hard X-ray observations from RHESSI were used to track the evolution of the parameters of the nonthermal electron distribution to reveal the total power contained in flare accelerated electrons. By integrating over the duration of the impulsive phase, the total energy contained in the nonthermal electrons was found to be >2 × 1031 erg. The response of the lower solar atmosphere was measured in the free-bound EUV continua of H I (Lyman), He I, and He II, plus the emission lines of He II at 304 Å and H I (Lyα) at 1216 Å by SDO/EVE, the UV continua at 1600 Å and 1700 Å by SDO/AIA, and the white light continuum at 4504 Å, 5550 Å, and 6684 Å, along with the Ca II H line at 3968 Å using Hinode/SOT. The summed energy detected by these instruments amounted to ~3 × 1030 erg about 15% of the total nonthermal energy. The Lyα line was found to dominate the measured radiative losses. Parameters of both the driving electron distribution and the resulting chromospheric response are presented in detail to encourage the numerical modeling of flare heating for this event, to determine the depth of the solar atmosphere at which these line and continuum processes originate, and the mechanism(s) responsible for their generation. Title: Energy levels, radiative rates and electron impact excitation rates for transitions in Si II Authors: Aggarwal, Kanti M.; Keenan, Francis P. Bibcode: 2014MNRAS.442..388A Altcode: 2014arXiv1405.0184A Energies for the lowest 56 levels, belonging to the 3s2 3p, 3s 3p2, 3p3, 3s2 3d, 3s 3p 3d, 3s2 4ℓ and 3s2 5ℓ configurations of Si II, are calculated using the General-purpose Relativistic Atomic Structure Package (GRASP) code. Analogous calculations have also been performed (for up to 175 levels) using the Flexible Atomic Code (FAC). Furthermore, radiative rates are calculated for all E1, E2, M1 and M2 transitions. Extensive comparisons are made with available theoretical and experimental energy levels, and the accuracy of the present results is assessed to be better than 0.1 Ryd. Similarly, the accuracy for radiative rates (and subsequently lifetimes) is estimated to be better than 20 per cent for most of the (strong) transitions. Electron impact excitation collision strengths are also calculated, with the Dirac Atomic R-matrix Code (DARC), over a wide energy range up to 13 Ryd. Finally, to determine effective collision strengths, resonances are resolved in a fine energy mesh in the thresholds region. These collision strengths are averaged over a Maxwellian velocity distribution and results listed over a wide range of temperatures, up to 105.5 K. Our data are compared with earlier R-matrix calculations and differences noted, up to a factor of 2, for several transitions. Although scope remains for improvement, the accuracy for our results of collision strengths and effective collision strengths is assessed to be about 20 per cent for a majority of transitions. Title: Dynamic properties of bright points in an active region Authors: Keys, P. H.; Mathioudakis, M.; Jess, D. B.; Mackay, D. H.; Keenan, F. P. Bibcode: 2014A&A...566A..99K Altcode: 2014arXiv1405.3923K Context. Bright points (BPs) are small-scale, magnetic features ubiquitous across the solar surface. Previously, we have observed and noted their properties for quiet Sun regions. Here, we determine the dynamic properties of BPs using simultaneous quiet Sun and active region data.
Aims: The aim of this paper is to compare the properties of BPs in both active and quiet Sun regions and to determine any difference in the dynamics and general properties of BPs as a result of the varying magnetic activity within these two regions.
Methods: High spatial and temporal resolution G-band observations of active region AR11372 were obtained with the Rapid Oscillations in the Solar Atmosphere instrument at the Dunn Solar Telescope. Three subfields of varying polarity and magnetic flux density were selected with the aid of magnetograms obtained from the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory. Bright points within these subfields were subsequently tracked and analysed.
Results: It is found that BPs within active regions display attenuated velocity distributions with an average horizontal velocity of ~0.6 km s-1, compared to the quiet region which had an average velocity of 0.9 km s-1. Active region BPs are also ~21% larger than quiet region BPs and have longer average lifetimes (~132 s) than their quiet region counterparts (88 s). No preferential flow directions are observed within the active region subfields. The diffusion index (γ) is estimated at ~1.2 for the three regions.
Conclusions: We confirm that the dynamic properties of BPs arise predominately from convective motions. The presence of stronger field strengths within active regions is the likely reason behind the varying properties observed. We believe that larger amounts of magnetic flux will attenuate BP velocities by a combination of restricting motion within the intergranular lanes and by increasing the number of stagnation points produced by inhibited convection. Larger BPs are found in regions of higher magnetic flux density and we believe that lifetimes increase in active regions as the magnetic flux stabilises the BPs. Title: Plasma properties and Stokes profiles during the lifetime of a photospheric magnetic bright point Authors: Hewitt, R. L.; Shelyag, S.; Mathioudakis, M.; Keenan, F. P. Bibcode: 2014A&A...565A..84H Altcode: 2014arXiv1404.0132H
Aims: In this paper we aim to investigate the evolution of plasma properties and Stokes parameters in photospheric magnetic bright points using 3D magneto-hydrodynamical simulations and radiative diagnostics of solar granulation.
Methods: Simulated time-dependent radiation parameters and plasma properties were investigated throughout the evolution of a bright point. Synthetic Stokes profiles for the FeI 630.25 nm line were calculated, which also allowed the evolution of the Stokes-I line strength and Stokes-V area and amplitude asymmetries to be investigated.
Results: Our results are consistent with theoretical predictions and published observations describing convective collapse, and confirm this as the bright point formation process. Through degradation of the simulated data to match the spatial resolution of SOT, we show that high spatial resolution is crucial for the detection of changing spectro-polarimetric signatures throughout a magnetic bright point's lifetime. We also show that the signature downflow associated with the convective collapse process tends towards zero as the radiation intensity in the bright point peaks, because of the magnetic forces present restricting the flow of material in the flux tube.

Appendix A is available in electronic form at http://www.aanda.org Title: Intensity Enhancement of O VI Ultraviolet Emission Lines in Solar Spectra due to Opacity Authors: Keenan, F. P.; Doyle, J. G.; Madjarska, M. S.; Rose, S. J.; Bowler, L. A.; Britton, J.; McCrink, L.; Mathioudakis, M. Bibcode: 2014ApJ...784L..39K Altcode: 2014arXiv1403.1470K Opacity is a property of many plasmas. It is normally expected that if an emission line in a plasma becomes optically thick, then its intensity ratio to that of another transition that remains optically thin should decrease. However, radiative transfer calculations undertaken both by ourselves and others predict that under certain conditions the intensity ratio of an optically thick to an optically thin line can show an increase over the optically thin value, indicating an enhancement in the former. These conditions include the geometry of the emitting plasma and its orientation to the observer. A similar effect can take place between lines of differing optical depths. While previous observational studies have focused on stellar point sources, here we investigate the spatially resolved solar atmosphere using measurements of the I(1032 Å)/I(1038 Å) intensity ratio of O VI in several regions obtained with the Solar Ultraviolet Measurements of Emitted Radiation instrument on board the Solar and Heliospheric Observatory satellite. We find several I(1032 Å)/I(1038 Å) ratios observed on the disk to be significantly larger than the optically thin value of 2.0, providing the first detection (to our knowledge) of intensity enhancement in the ratio arising from opacity effects in the solar atmosphere. The agreement between observation and theory is excellent and confirms that the O VI emission originates from a slab-like geometry in the solar atmosphere, rather than from cylindrical structures. Title: Early-type stars observed in the ESO UVES Paranal Observatory Project - IV. Studies of CN, CH+ and CH in the interstellar medium Authors: Smoker, J.; Ledoux, C.; Jehin, E.; Keenan, F. P.; Kennedy, M.; Cabanac, R.; Melo, C. Bibcode: 2014MNRAS.438.1127S Altcode: 2013MNRAS.tmp.2928S High spectral resolution (∼80 000) and signal-to-noise observations from the Ultraviolet and Visual Echelle Spectrograph Paranal Observatory Project (UVES-POP) are used to study the interstellar molecular lines CN (3874 Å), CH+ (3957, 4232 Å) and CH (3886, 4300 Å) towards 74 O- and B-type stellar sightlines. Additionally, archive data are presented for 140 ELODIE early-type stellar sightlines at R = 42 000, plus 25 FEROS at R = 48 000 and 3 UVES at R > 50 000, mainly in the CH+ (4232 Å) and CH (3886, 4300 Å) transitions. Detection rates are ∼45 per cent for CN and ∼67 per cent for the other lines in the POP sample, and ∼10-15 per cent for CH+ and CH lines in the additional sample. CH and CH+ are well correlated between log[N(CH) cm-2]∼12-14, implying that these clouds are CH+-like CH and not CN-like CH. CH is also very well correlated with Na I D in the range log[N(Na I cm-2]) ∼12.2-14.2. A few sightlines show tentative velocity shifts of ∼2 km s-1 between CH and CH+, which appear to be caused by differences in component strength in blends, and hence do not provide firm evidence for shocks. Finally, we describe a search for 13CH+ in a sightline towards HD 76341. No 13CH+ is detected, placing a limit on the 13CH+ to 12CH+ ratio of ∼0.01. If a formal fit is attempted, the equivalent width ratio in the two isotopes is a factor ∼90 but with large errors. Title: Energy levels, radiative rates and electron impact excitation rates for transitions in Al X Authors: Aggarwal, Kanti M.; Keenan, Francis P. Bibcode: 2014MNRAS.438.1223A Altcode: 2013MNRAS.tmp.2966A; 2013arXiv1311.5516A Energy levels, radiative rates and lifetimes are calculated among the lowest 98 levels of the n ≤ 4 configurations of Be-like Al X. The GRASP (General-purpose Relativistic Atomic Structure Package) is adopted and data are provided for all E1, E2, M1 and M2 transitions. Similar data are also obtained with the FAC (Flexible Atomic Code) to assess the accuracy of the calculations. Based on comparisons between calculations with the two codes as well as with available measurements, our listed energy levels are assessed to be accurate to better than 0.3 per cent. However, the accuracy for radiative rates and lifetimes is estimated to be about 20 per cent. Collision strengths are also calculated for which the DARC (Dirac Atomic R-matrix Code) is used. A wide energy range (up to 380 Ryd) is considered and resonances resolved in a fine energy mesh in the thresholds region. The collision strengths are subsequently averaged over a Maxwellian velocity distribution to determine effective collision strengths up to a temperature of 1.6 × 107 K. Our results are compared with the previous (limited) atomic data and significant differences (up to a factor of 4) are noted for several transitions, particularly those which are not allowed in jj coupling. Title: Electron-impact Excitation Collision Strengths and Theoretical Line Intensities for Transitions in S III Authors: Grieve, M. F. R.; Ramsbottom, C. A.; Hudson, C. E.; Keenan, F. P. Bibcode: 2014ApJ...780..110G Altcode: 2013arXiv1308.0241G We present Maxwellian-averaged effective collision strengths for the electron-impact excitation of S III over a wide range of electron temperatures of astrophysical importance, log Te (K) = 3.0-6.0. The calculation incorporates 53 fine-structure levels arising from the six configurations—3s 23p 2, 3s3p 3, 3s 23p3d, 3s 23p4s, 3s 23p4p, and 3s 23p4d—giving rise to 1378 individual lines and is undertaken using the recently developed RMATRX II plus FINE95 suite of codes. A detailed comparison is made with a previous R-matrix calculation and significant differences are found for some transitions. The atomic data are subsequently incorporated into the modeling code CLOUDY to generate line intensities for a range of plasma parameters, with emphasis on allowed ultraviolet extreme-ultraviolet emission lines detected from the Io plasma torus. Electron density-sensitive line ratios are calculated with the present atomic data and compared with those from CHIANTI v7.1, as well as with Io plasma torus spectra obtained by Far-Ultraviolet Spectroscopic Explorer and Extreme-Ultraviolet Explorer. The present line intensities are found to agree well with the observational results and provide a noticeable improvement on the values predicted by CHIANTI. Title: Characteristics of Transverse Waves in Chromospheric Mottles Authors: Kuridze, D.; Verth, G.; Mathioudakis, M.; Erdélyi, R.; Jess, D. B.; Morton, R. J.; Christian, D. J.; Keenan, F. P. Bibcode: 2013ApJ...779...82K Altcode: 2013arXiv1310.3628K Using data obtained by the high temporal and spatial resolution Rapid Oscillations in the Solar Atmosphere instrument on the Dunn Solar Telescope, we investigate at an unprecedented level of detail transverse oscillations in chromospheric fine structures near the solar disk center. The oscillations are interpreted in terms of propagating and standing magnetohydrodynamic kink waves. Wave characteristics including the maximum transverse velocity amplitude and the phase speed are measured as a function of distance along the structure's length. Solar magnetoseismology is applied to these measured parameters to obtain diagnostic information on key plasma parameters (e.g., magnetic field, density, temperature, flow speed) of these localized waveguides. The magnetic field strength of the mottle along the ~2 Mm length is found to decrease by a factor of 12, while the local plasma density scale height is ~280 ± 80 km. Title: Solar Flare Impulsive Phase Emission Observed with SDO/EVE Authors: Kennedy, Michael B.; Milligan, Ryan O.; Mathioudakis, Mihalis; Keenan, Francis P. Bibcode: 2013ApJ...779...84K Altcode: 2013arXiv1310.4649K Differential emission measures (DEMs) during the impulsive phase of solar flares were constructed using observations from the EUV Variability Experiment (EVE) and the Markov-Chain Monte Carlo method. Emission lines from ions formed over the temperature range log Te = 5.8-7.2 allow the evolution of the DEM to be studied over a wide temperature range at 10 s cadence. The technique was applied to several M- and X-class flares, where impulsive phase EUV emission is observable in the disk-integrated EVE spectra from emission lines formed up to 3-4 MK and we use spatially unresolved EVE observations to infer the thermal structure of the emitting region. For the nine events studied, the DEMs exhibited a two-component distribution during the impulsive phase, a low-temperature component with peak temperature of 1-2 MK, and a broad high-temperature component from 7 to 30 MK. A bimodal high-temperature component is also found for several events, with peaks at 8 and 25 MK during the impulsive phase. The origin of the emission was verified using Atmospheric Imaging Assembly images to be the flare ribbons and footpoints, indicating that the constructed DEMs represent the spatially average thermal structure of the chromospheric flare emission during the impulsive phase. Title: Energy levels and radiative rates for transitions in Ti VII Authors: Aggarwal, Kanti M.; Keenan, Francis P. Bibcode: 2013PhyS...88f5304A Altcode: 2013arXiv1311.0650A We report calculations of energy levels, radiative rates, oscillator strengths and line strengths for transitions among the lowest 231 levels of Ti VII. The general-purpose relativistic atomic structure package and flexible atomic code are adopted for the calculations. Radiative rates, oscillator strengths and line strengths are provided for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2) and magnetic quadrupole (M2) transitions among the 231 levels, although calculations have been performed for a much larger number of levels (159 162). In addition, lifetimes for all 231 levels are listed. Comparisons are made with existing results and the accuracy of the data is assessed. In particular, the most recent calculations reported by Singh et al (2012 Can. J. Phys. 90 833) are found to be unreliable, with discrepancies for energy levels of up to 1 Ryd and for radiative rates of up to five orders of magnitude for several transitions, particularly the weaker ones. Based on several comparisons among a variety of calculations with two independent codes, as well as with the earlier results, our listed energy levels are estimated to be accurate to better than 1% (within 0.1 Ryd), whereas results for radiative rates and other related parameters should be accurate to better than 20%. Title: Electron impact excitation of Mg VIII . Collision strengths, transition probabilities and theoretical EUV and soft X-ray line intensities for Mg VIII Authors: Grieve, M. F. R.; Ramsbottom, C. A.; Keenan, F. P. Bibcode: 2013A&A...556A..24G Altcode: Context. Mg viii emission lines are observed in a range of astronomical objects such as the Sun, other cool stars and in the coronal line region of Seyfert galaxies. Under coronal conditions Mg viii emits strongly in the extreme ultraviolet (EUV) and soft X-ray spectral regions which makes it an ideal ion for plasma diagnostics.
Aims: Two theoretical atomic models, consisting of 125 fine structure levels, are developed for the Mg viii ion. The 125 levels arise from the 2s22p, 2s2p2, 2p3, 2s23s, 2s23p, 2s23d, 2s2p3s, 2s2p3p, 2s2p3d, 2p23s, 2p23p and 2p23d configurations. Electron impact excitation collision strengths and radiative transition probabilities are calculated for both Mg viii models, compared with existing data, and the best model selected to generate a set of theoretical emission line intensities. The EUV lines, covering 312-790 Å, are compared with existing solar spectra (SERTS-89 and SUMER), while the soft X-ray transitions (69-97 Å) are examined for potential density diagnostic line ratios and also compared with the limited available solar and stellar observational data.
Methods: The R-matrix codes Breit-Pauli RMATRXI and RMATRXII are utilised, along with the PSTGF code, to calculate the collision strengths for two Mg viii models. Collision strengths are averaged over a Maxwellian distribution to produce the corresponding effective collision strengths for use in astrophysical applications. Transition probabilities are also calculated using the CIV3 atomic structure code. The best data are then incorporated into the modelling code CLOUDY and line intensities generated for a range of electron temperatures and densities appropriate to solar and stellar coronal plasmas.
Results: The present effective collision strengths are compared with two previous calculations. Good levels of agreement are found with the most recent, but there are large differences with the other for forbidden transitions. The resulting line intensities compare favourably with the observed values from the SERTS-89 and SUMER spectra. Theoretical soft X-ray emission lines are presented and several density diagnostic line ratios examined, which are in reasonable agreement with the limited observational data available.

The effective collision strength data are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/556/A24 Title: Expanded Iron UTA Spectra—Probing the Thermal Stability Limits in AGN Clouds Authors: Ferland, G. J.; Kisielius, R.; Keenan, F. P.; van Hoof, P. A. M.; Jonauskas, V.; Lykins, M. L.; Porter, R. L.; Williams, R. J. R. Bibcode: 2013ApJ...767..123F Altcode: 2013arXiv1303.0316F The Fe unresolved transition arrays (UTAs) produce prominent features in the ~15-17 Å wavelength range in the spectra of active galactic nuclei (AGNs). Here, we present new calculations of the energies and oscillator strengths of inner-shell lines from Fe XIV, Fe XV, and Fe XVI. These are crucial ions since they are dominant at inflection points in the gas thermal stability curve, and UTA excitation followed by autoionization is an important ionization mechanism for these species. We incorporate these, and data reported in previous papers, into the plasma simulation code Cloudy. This updated physics is subsequently employed to reconsider the thermally stable phases in absorbing media in AGNs. We show how the absorption profile of the Fe XIV UTA depends on density, due to the changing populations of levels within the ground configuration. Title: Transit timing variations in WASP-10b induced by stellar activity Authors: Barros, S. C. C.; Boué, G.; Gibson, N. P.; Pollacco, D. L.; Santerne, A.; Keenan, F. P.; Skillen, I.; Street, R. A. Bibcode: 2013MNRAS.430.3032B Altcode: 2013arXiv1301.3760B; 2013MNRAS.tmp..760B The hot-Jupiter WASP-10b was reported by Maciejewski et al. to show transit timing variations (TTVs) with an amplitude of ∼3.5 min. These authors proposed that the observed TTVs were caused by a 0.1MJup perturbing companion with an orbital period of ∼5.23 d, and hence, close to the outer 5:3 mean-motion resonance with WASP-10b. To test this scenario, we present eight new transit light curves of WASP-10b obtained with the Faulkes Telescope North and the Liverpool Telescope. The new light curves, together with 22 previously published ones, were modelled with a Markov Chain Monte Carlo transit fitting code. Transit depth differences reported for WASP-10b are thought to be due to starspot-induced brightness modulation of the host star. Assuming the star is brighter at the activity minimum, we favour a small planetary radius. We find R_p =1.039^{+0.043}_{-0.049} {R_Jup} in agreement with Johnson et al. and Maciejewski et al. Recent studies find no evidence for a significant eccentricity in this system. We present consistent system parameters for a circular orbit and refine the orbital ephemeris of WASP-10b. Our homogeneously derived transit times do not support the previous claimed TTV signal, which was strongly dependent on two previously published transits that have been incorrectly normalized. Nevertheless, a linear ephemeris is not a statistically good fit to the transit times of WASP-10b. We show that the observed transit time variations are due to spot occultation features or systematics. We discuss and exemplify the effects of occultation spot features in the measured transit times and show that despite spot occultation during egress and ingress being difficult to distinguish in the transit light curves, they have a significant effect in the measured transit times. We conclude that if we account for spot features, the transit times of WASP-10b are consistent with a linear ephemeris with the exception of one transit (epoch 143) which is a partial transit. Therefore, there is currently no evidence for the existence of a companion to WASP-10b. Our results support the lack of TTVs of hot-Jupiters reported for the Kepler sample. Title: Failed filament eruption inside a coronal mass ejection in active region 11121 Authors: Kuridze, D.; Mathioudakis, M.; Kowalski, A. F.; Keys, P. H.; Jess, D. B.; Balasubramaniam, K. S.; Keenan, F. P. Bibcode: 2013A&A...552A..55K Altcode: 2013arXiv1302.5931K
Aims: We study the formation and evolution of a failed filament eruption observed in NOAA active region 11121 near the southeast limb on November 6, 2010.
Methods: We used a time series of SDO/AIA 304, 171, 131, 193, 335, and 94 Å images, SDO/HMI magnetograms, as well as ROSA and ISOON Hα images to study the erupting active region.
Results: We identify coronal loop arcades associated with a quadrupolar magnetic configuration, and show that the expansion and cancellation of the central loop arcade system over the filament is followed by the eruption of the filament. The erupting filament reveals a clear helical twist and develops the same sign of writhe in the form of inverse γ-shape.
Conclusions: The observations support the "magnetic breakout" process in which the eruption is triggered by quadrupolar reconnection in the corona. We propose that the formation mechanism of the inverse γ-shape flux rope is the magnetohydrodynamic helical kink instability. The eruption has failed because of the large-scale, closed, overlying magnetic loop arcade that encloses the active region.

Movies are available in electronic form at http://www.aanda.org Title: Tracking magnetic bright point motions through the solar atmosphere Authors: Keys, P. H.; Mathioudakis, M.; Jess, D. B.; Shelyag, S.; Christian, D. J.; Keenan, F. P. Bibcode: 2013MNRAS.428.3220K Altcode: 2012MNRAS.tmp..182K; 2012arXiv1210.5904K High-cadence, multiwavelength observations and simulations are employed for the analysis of solar photospheric magnetic bright points (MBPs) in the quiet Sun. The observations were obtained with the Rapid Oscillations in the Solar Atmosphere (ROSA) imager and the Interferometric Bidimensional Spectrometer at the Dunn Solar Telescope. Our analysis reveals that photospheric MBPs have an average transverse velocity of approximately 1 km s-1, whereas their chromospheric counterparts have a slightly higher average velocity of 1.4 km s-1. Additionally, chromospheric MBPs were found to be around 63 per cent larger than the equivalent photospheric MBPs. These velocity values were compared with the output of numerical simulations generated using the muram code. The simulated results were similar, but slightly elevated, when compared to the observed data. An average velocity of 1.3 km s-1 was found in the simulated G-band images and an average of 1.8 km s-1 seen in the velocity domain at a height of 500 km above the continuum formation layer. Delays in the change of velocities were also analysed. Average delays of ∼4 s between layers of the simulated data set were established and values of ∼29 s observed between G-band and Ca ii K ROSA observations. The delays in the simulations are likely to be the result of oblique granular shock waves, whereas those found in the observations are possibly the result of a semi-rigid flux tube. Title: Vortices in the Solar Photosphere Authors: Shelyag, S.; Fedun, V.; Erdélyi, R.; Keenan, F. P.; Mathioudakis, M. Bibcode: 2012ASPC..463..107S Altcode: 2012arXiv1202.1966S Using numerical simulations of the magnetized solar photosphere and radiative diagnostics of the simulated photospheric models, we further analyse the physical nature of magnetic photospheric intergranular vortices. We confirm the magnetic nature of the vortices and find that most MHD Umov-Poynting flux is produced by horizontal vortex motions in the magnetised intergranular lanes. In addition, we consider possible ways to directly observe photospheric magnetic vortices using spectropolarimetry. Although horizontal plasma motions cannot be detected in the spectropolarimetric observations of solar disk center, we find an observational signature of photospheric vortices in simulated observations of Stokes-V amplitude asymmetry close to the solar limb. Potential ways to find the vortices in the observations are discussed. Title: The Source of 3 Minute Magnetoacoustic Oscillations in Coronal Fans Authors: Jess, D. B.; De Moortel, I.; Mathioudakis, M.; Christian, D. J.; Reardon, K. P.; Keys, P. H.; Keenan, F. P. Bibcode: 2012ApJ...757..160J Altcode: 2012arXiv1208.3194J We use images of high spatial, spectral, and temporal resolution, obtained using both ground- and space-based instrumentation, to investigate the coupling between wave phenomena observed at numerous heights in the solar atmosphere. Analysis of 4170 Å continuum images reveals small-scale umbral intensity enhancements, with diameters ~0farcs6, lasting in excess of 30 minutes. Intensity oscillations of ≈3 minutes are observed to encompass these photospheric structures, with power at least three orders of magnitude higher than the surrounding umbra. Simultaneous chromospheric velocity and intensity time series reveal an 87° ± 8° out-of-phase behavior, implying the presence of standing modes created as a result of partial wave reflection at the transition region boundary. We find a maximum waveguide inclination angle of ≈40° between photospheric and chromospheric heights, combined with a radial expansion factor of <76%. An average blueshifted Doppler velocity of ≈1.5 km s-1, in addition to a time lag between photospheric and chromospheric oscillatory phenomena, confirms the presence of upwardly propagating slow-mode waves in the lower solar atmosphere. Propagating oscillations in EUV intensity are detected in simultaneous coronal fan structures, with a periodicity of 172 ± 17 s and a propagation velocity of 45 ± 7 km s-1. Numerical simulations reveal that the damping of the magnetoacoustic wave trains is dominated by thermal conduction. The coronal fans are seen to anchor into the photosphere in locations where large-amplitude umbral dot (UD) oscillations manifest. Derived kinetic temperature and emission measure time series display prominent out-of-phase characteristics, and when combined with the previously established sub-sonic wave speeds, we conclude that the observed EUV waves are the coronal counterparts of the upwardly propagating magnetoacoustic slow modes detected in the lower solar atmosphere. Thus, for the first time, we reveal how the propagation of 3 minute magnetoacoustic waves in solar coronal structures is a direct result of amplitude enhancements occurring in photospheric UDs. Title: Time-dependent Density Diagnostics of Solar Flare Plasmas Using SDO/EVE Authors: Milligan, Ryan O.; Kennedy, Michael B.; Mathioudakis, Mihalis; Keenan, Francis P. Bibcode: 2012ApJ...755L..16M Altcode: 2012arXiv1207.1990M Temporally resolved electron density measurements of solar flare plasmas are presented using data from the EUV Variability Experiment (EVE) on board the Solar Dynamics Observatory. The EVE spectral range contains emission lines formed between 104 and 107 K, including transitions from highly ionized iron (gsim10 MK). Using three density-sensitive Fe XXI ratios, peak electron densities of 1011.2-1012.1 cm-3 were found during four X-class flares. While previous measurements of densities at such high temperatures were made at only one point during a flaring event, EVE now allows the temporal evolution of these high-temperature densities to be determined at 10 s cadence. A comparison with GOES data revealed that the peak of the density time profiles for each line ratio correlated well with that of the emission measure time profile for each of the events studied. Title: Mechanisms for MHD Poynting Flux Generation in Simulations of Solar Photospheric Magnetoconvection Authors: Shelyag, S.; Mathioudakis, M.; Keenan, F. P. Bibcode: 2012ApJ...753L..22S Altcode: 2012arXiv1206.0030S We investigate the generation mechanisms of MHD Poynting flux in the magnetized solar photosphere. Using radiative MHD modeling of the solar photosphere with initial magnetic configurations that differ in their field strength and geometry, we show the presence of two different mechanisms for MHD Poynting flux generation in simulations of solar photospheric magnetoconvection. The weaker mechanism is connected to vertical transport of weak horizontal magnetic fields in the convectively stable layers of the upper photosphere, while the stronger is the production of Poynting flux in strongly magnetized intergranular lanes experiencing horizontal vortex motions. These mechanisms may be responsible for the energy transport from the solar convection zone to the higher layers of the solar atmosphere. Title: Solar Flare Observations of the EUV Continua Authors: Milligan, Ryan O.; Chamberlin, P.; Hudson, H.; Woods, T.; Mathioudakis, M.; Fletcher, L.; Kowalski, A.; Keenan, F. Bibcode: 2012AAS...22052105M Altcode: Recent solar flare simulations suggest that the energy deposited in the chromosphere by nonthermal electrons during a flare's impulsive phase is re-emitted in the form of recombination (free-bound) continua, in particular, the Lyman, Balmer, and Paschen continua of hydrogen, and the He I and He II continua (Allred et al. 2005). However, definitive observations of free-bound emission during solar flares have been scarce in recent years as many modern, space-based instruments do not have the required sensitivity, wavelength coverage, or duty cycle. With the launch of SDO, these observations are now routinely available thanks to the EUV Variability Experiment (EVE) instrument. Here we present unambiguous, spectrally and temporally resolved detections of enhanced free-free and free-bound continua during the first X-class solar flare of Solar Cycle 24. While we find that the flare energy in the EVE spectral range amounts to at most a few percent of the total flare energy, these findings highlight the capability of EVE in giving us the first comprehensive look at these diagnostically important continuum components. Title: Electron Impact Excitation Of Ti XIX Authors: Aggarwal, Kanti M.; Keenan, F. P. Bibcode: 2012AAS...22020801A Altcode: Emission lines of Ti XIX are important for the modeling and diagnostics of lasing, fusion and astrophysical plasmas, for which atomic data are required for a variety of parameters, such as energy levels, radiative rates (A- values), and excitation rates or equivalently the effective collision strengths (Υ), which are obtained from the electron impact collision strengths (Ω). Experimentally, energy levels are available for Ti XIX on the NIST website, but there is paucity for accurate collisional atomic data. Therefore, here we report a complete set of results (namely energy levels, radiative rates, and effective collision strengths) for all transitions among the lowest 98 levels of Ti XIX. These levels belong to the (1s2) 2s2, 2s2p, 2p2, 2s3l, 2p3l, 2s4l, and 2p4l configurations. Finally, we also report the A- values for four types of transitions, namely electric dipole (E1), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2), because these are also required for plasma modeling. For our calculations of wavefunctions, we have adopted the fully relativistic GRASP code, and for the calculations of Ω, the Dirac atomic R-matrix code (DARC) of PH Norrington and IP Grant. Additionally, parallel calculations have also been performed with the Flexible Atomic Code (FAC) of Gu, so that all atomic parameters can be rigorously assessed for accuracy. Title: Transverse Oscillations in Chromospheric Mottles Authors: Kuridze, D.; Morton, R. J.; Erdélyi, R.; Dorrian, G. D.; Mathioudakis, M.; Jess, D. B.; Keenan, F. P. Bibcode: 2012ApJ...750...51K Altcode: 2012arXiv1202.5697K A number of recent investigations have revealed that transverse waves are ubiquitous in the solar chromosphere. The vast majority of these have been reported in limb spicules and active region fibrils. We investigate long-lived, quiet-Sun, on-disk features such as chromospheric mottles (jet-like features located at the boundaries of supergranular cells) and their transverse motions. The observations were obtained with the Rapid Oscillations in the Solar Atmosphere instrument at the Dunn Solar Telescope. The data set is comprised of simultaneous imaging in the Hα core, Ca II K, and G band of an on-disk quiet-Sun region. Time-distance techniques are used to study the characteristics of the transverse oscillations. We detect over 40 transverse oscillations in both bright and dark mottles, with periods ranging from 70 to 280 s, with the most frequent occurrence at ~165 s. The velocity amplitudes and transverse displacements exhibit characteristics similar to limb spicules. Neighboring mottles oscillating in-phase are also observed. The transverse oscillations of individual mottles are interpreted in terms of magnetohydrodynamic kink waves. Their estimated periods and damping times are consistent with phase mixing and resonant mode conversion. Title: Observations of Enhanced Extreme Ultraviolet Continua during an X-Class Solar Flare Using SDO/EVE Authors: Milligan, Ryan O.; Chamberlin, Phillip C.; Hudson, Hugh S.; Woods, Thomas N.; Mathioudakis, Mihalis; Fletcher, Lyndsay; Kowalski, Adam F.; Keenan, Francis P. Bibcode: 2012ApJ...748L..14M Altcode: 2012arXiv1202.1731M Observations of extreme ultraviolet (EUV) emission from an X-class solar flare that occurred on 2011 February 15 at 01:44 UT are presented, obtained using the EUV Variability Experiment (EVE) on board the Solar Dynamics Observatory. The complete EVE spectral range covers the free-bound continua of H I (Lyman continuum), He I, and He II, with recombination edges at 91.2, 50.4, and 22.8 nm, respectively. By fitting the wavelength ranges blueward of each recombination edge with an exponential function, light curves of each of the integrated continua were generated over the course of the flare, as was emission from the free-free continuum (6.5-37 nm). The He II 30.4 nm and Lyα 121.6 nm lines, and soft X-ray (SXR; 0.1-0.8 nm) emission from GOES are also included for comparison. Each free-bound continuum was found to have a rapid rise phase at the flare onset similar to that seen in the 25-50 keV light curves from RHESSI, suggesting that they were formed by recombination with free electrons in the chromosphere. However, the free-free emission exhibited a slower rise phase seen also in the SXR emission from GOES, implying a predominantly coronal origin. By integrating over the entire flare the total energy emitted via each process was determined. We find that the flare energy in the EVE spectral range amounts to at most a few percent of the total flare energy, but EVE gives us a first comprehensive look at these diagnostically important continuum components. Title: VizieR Online Data Catalog: Intermediate high-velocity clouds distances (Smoker+, 2011) Authors: Smoker, J. V.; Fox, A. J.; Keenan, F. P. Bibcode: 2012yCat..74151105S Altcode: We use a combination of new observations and data from various astronomical archives. The FEROS observations were taken on the nights of 2006 December 8 and 9.

(1 data file). Title: Propagating Wave Phenomena Detected in Observations and Simulations of the Lower Solar Atmosphere Authors: Jess, D. B.; Shelyag, S.; Mathioudakis, M.; Keys, P. H.; Christian, D. J.; Keenan, F. P. Bibcode: 2012ApJ...746..183J Altcode: 2012arXiv1201.1981J We present high-cadence observations and simulations of the solar photosphere, obtained using the Rapid Oscillations in the Solar Atmosphere imaging system and the MuRAM magnetohydrodynamic (MHD) code, respectively. Each data set demonstrates a wealth of magnetoacoustic oscillatory behavior, visible as periodic intensity fluctuations with periods in the range 110-600 s. Almost no propagating waves with periods less than 140 s and 110 s are detected in the observational and simulated data sets, respectively. High concentrations of power are found in highly magnetized regions, such as magnetic bright points and intergranular lanes. Radiative diagnostics of the photospheric simulations replicate our observational results, confirming that the current breed of MHD simulations are able to accurately represent the lower solar atmosphere. All observed oscillations are generated as a result of naturally occurring magnetoconvective processes, with no specific input driver present. Using contribution functions extracted from our numerical simulations, we estimate minimum G-band and 4170 Å continuum formation heights of 100 km and 25 km, respectively. Detected magnetoacoustic oscillations exhibit a dominant phase delay of -8° between the G-band and 4170 Å continuum observations, suggesting the presence of upwardly propagating waves. More than 73% of MBPs (73% from observations and 96% from simulations) display upwardly propagating wave phenomena, suggesting the abundant nature of oscillatory behavior detected higher in the solar atmosphere may be traced back to magnetoconvective processes occurring in the upper layers of the Sun's convection zone. Title: The Origin of Type I Spicule Oscillations Authors: Jess, D. B.; Pascoe, D. J.; Christian, D. J.; Mathioudakis, M.; Keys, P. H.; Keenan, F. P. Bibcode: 2012ApJ...744L...5J Altcode: 2011arXiv1111.5464J We use images of high spatial and temporal resolution, obtained with the Rapid Oscillations in the Solar Atmosphere instrument at the Dunn Solar Telescope, to reveal how the generation of transverse waves in Type I spicules is a direct result of longitudinal oscillations occurring in the photosphere. Here we show how pressure oscillations, with periodicities in the range of 130-440 s, manifest in small-scale photospheric magnetic bright points, and generate kink waves in the Sun's outer atmosphere with transverse velocities approaching the local sound speed. Through comparison of our observations with advanced two-dimensional magnetohydrodynamic simulations, we provide evidence for how magnetoacoustic oscillations, generated at the solar surface, funnel upward along Type I spicule structures, before undergoing longitudinal-to-transverse mode conversion into waves at twice the initial driving frequency. The resulting kink modes are visible in chromospheric plasma, with periodicities of 65-220 s, and amplitudes often exceeding 400 km. A sausage mode oscillation also arises as a consequence of the photospheric driver, which is visible in both simulated and observational time series. We conclude that the mode conversion and period modification is a direct consequence of the 90° phase shift encompassing opposite sides of the photospheric driver. The chromospheric energy flux of these waves are estimated to be ≈3 × 105 W m-2, which indicates that they are sufficiently energetic to accelerate the solar wind and heat the localized corona to its multi-million degree temperatures. Title: High-precision transit observations of the exoplanet WASP-13b with the RISE instrument Authors: Barros, S. C. C.; Pollacco, D. L.; Gibson, N. P.; Keenan, F. P.; Skillen, I.; Steele, I. A. Bibcode: 2012MNRAS.419.1248B Altcode: 2011arXiv1108.3996B; 2011MNRAS.tmp.1769B WASP-13b is a sub-Jupiter mass exoplanet orbiting a G1V type star with a period of 4.35 d. The current uncertainty in its impact parameter (0 < b < 0.46) results in poorly defined stellar and planetary radii. To better constrain the impact parameter, we have obtained high-precision transit observations with the rapid imager to search for exoplanets (RISE) instrument mounted on 2.0-m Liverpool Telescope. We present four new transits which are fitted with a Markov chain Monte Carlo routine to derive accurate system parameters. We found an orbital inclination of 85?2 ± 0?3 resulting in stellar and planetary radii of 1.56 ± 0.04 R⊙ and 1.39 ± 0.05RJup, respectively. This suggests that the host star has evolved off the main sequence and is in the hydrogen-shell-burning phase. We also discuss how the limb darkening affects the derived system parameters. With a density of 0.17ρJ, WASP-13b joins the group of low-density planets whose radii are too large to be explained by standard irradiation models. We derive a new ephemeris for the system, T0= 245 5575.5136 ± 0.0016 (HJD) and P= 4.353 011 ± 0.000 013 d. The planet equilibrium temperature (Tequ= 1500 K) and the bright host star (V= 10.4 mag) make it a good candidate for follow-up atmospheric studies. Title: New transiting exoplanets from the SuperWASP-North survey Authors: Faedi, Francesca; Barros, Susana C. C.; Pollacco, Don; Simpson, Elaine K.; McCormac, James; Moulds, Victoria; Watson, Chris; Todd, Ian; Keenan, F.; Fitzsimmons, Alan; Chew, Yilen Gómez Maqueo Bibcode: 2011IAUS..276..143F Altcode: The Wide Angle Search for Planet (WASP) project is one of the leading projects in the discovery of transiting exoplanets. We present 1) the current status of the WASP-North survey, 2) our recent exoplanet discoveries, and 3) we exemplify how these results fit into our understanding of transiting exoplanet properties and how they can help to understand exoplanet diversity. Title: The Velocity Distribution of Solar Photospheric Magnetic Bright Points Authors: Keys, P. H.; Mathioudakis, M.; Jess, D. B.; Shelyag, S.; Crockett, P. J.; Christian, D. J.; Keenan, F. P. Bibcode: 2011ApJ...740L..40K Altcode: 2011arXiv1109.3565K We use high spatial resolution observations and numerical simulations to study the velocity distribution of solar photospheric magnetic bright points. The observations were obtained with the Rapid Oscillations in the Solar Atmosphere instrument at the Dunn Solar Telescope, while the numerical simulations were undertaken with the MURaM code for average magnetic fields of 200 G and 400 G. We implemented an automated bright point detection and tracking algorithm on the data set and studied the subsequent velocity characteristics of over 6000 structures, finding an average velocity of approximately 1 km s-1, with maximum values of 7 km s-1. Furthermore, merging magnetic bright points were found to have considerably higher velocities, and significantly longer lifetimes, than isolated structures. By implementing a new and novel technique, we were able to estimate the background magnetic flux of our observational data, which is consistent with a field strength of 400 G. Title: A search for line intensity enhancements in the far-UV spectra of active late-type stars arising from opacity Authors: Keenan, F. P.; Christian, D. J.; Rose, S. J.; Mathioudakis, M. Bibcode: 2011A&A...534A..71K Altcode: 2011arXiv1109.0513K Context. Radiative transfer calculations have predicted intensity enhancements for optically thick emission lines, as opposed to the normal intensity reductions, for astrophysical plasmas under certain conditions. In particular, the results are predicted to be dependent both on the geometry of the emitting plasma and the orientation of the observer. Hence in principle the detection of intensity enhancement may provide a way of determining the geometry of an unresolved astronomical source.
Aims: To investigate such enhancements we have analysed a sample of active late-type stars observed in the far ultraviolet spectral region.
Methods: Emission lines of O vi in the FUSE satellite spectra of ɛ Eri, II Peg and Prox Cen were searched for intensity enhancements due to opacity.
Results: We have found strong evidence for line intensity enhancements due to opacity during active or flare-like activity for all three stars. The O vi 1032/1038 line intensity ratios, predicted to have a value of 2.0 in the optically thin case, are found to be up to ~30% larger during several orbital phases.
Conclusions: Our measurements, combined with radiative transfer models, allow us to constrain both the geometry of the O vi emitting regions in our stellar sources and the orientation of the observer. A spherical emitting plasma can be ruled out, as this would lead to no intensity enhancement. In addition, the theory tells us that the line-of-sight to the plasma must be close to perpendicular to its surface, as observations at small angles to the surface lead to either no intensity enhancement or the usual line intensity decrease over the optically thin value. For the future, we outline a laboratory experiment, that could be undertaken with current facilities, which would provide an unequivocal test of predictions of line intensity enhancement due to opacity, in particular the dependence on plasma geometry. Title: A lower mass for the exoplanet WASP-21b Authors: Barros, S. C. C.; Pollacco, D. L.; Gibson, N. P.; Howarth, I. D.; Keenan, F. P.; Simpson, E. K.; Skillen, I.; Steele, I. A. Bibcode: 2011MNRAS.416.2593B Altcode: 2011MNRAS.tmp.1200B; 2011arXiv1106.2118B We present high-precision transit observations of the exoplanet WASP-21b, obtained with the Rapid Imager to Search for Exoplanets instrument mounted on the 2.0-m Liverpool Telescope. A transit model is fitted, coupled with a Markov chain Monte Carlo routine, to derive accurate system parameters. The two new high-precision transits allow us to estimate the stellar density directly from the light curve. Our analysis suggests that WASP-21 is evolving off the main sequence which led to a previous overestimation of the stellar density. Using isochrone interpolation, we find a stellar mass of 0.86 ± 0.04 M⊙, which is significantly lower than previously reported (1.01 ± 0.03 M⊙). Consequently, we find a lower planetary mass of 0.27 ± 0.01 MJup. A lower inclination (87?4 ± 0?3) is also found for the system than previously reported, resulting in a slightly larger stellar (R*= 1.10 ± 0.03 R⊙) and planetary radius (Rp= 1.14 ± 0.04 RJup). The planet radius suggests a hydrogen/helium composition with no core which strengthens the correlation between planetary density and host star metallicity. A new ephemeris is determined for the system, i.e. T0= 245 5084.519 74 ± 0.000 20 (HJD) and P= 4.322 5060 ± 0.000 0031 d. We found no transit timing variations in WASP-21b. Title: Small-scale Hα jets in the solar chromosphere Authors: Kuridze, D.; Mathioudakis, M.; Jess, D. B.; Shelyag, S.; Christian, D. J.; Keenan, F. P.; Balasubramaniam, K. S. Bibcode: 2011A&A...533A..76K Altcode: 2011arXiv1108.1043K
Aims: High temporal and spatial resolution observations from the Rapid Oscillations in the Solar Atmosphere (ROSA) multiwavelength imager on the Dunn Solar Telescope are used to study the velocities of small-scale Hα jets in an emerging solar active region.
Methods: The dataset comprises simultaneous imaging in the Hα core, Ca ii K, and G band, together with photospheric line-of-sight magnetograms. Time-distance techniques are employed to determine projected plane-of-sky velocities.
Results: The Hα images are highly dynamic in nature, with estimated jet velocities as high as 45 km s-1. These jets are one-directional, with their origin seemingly linked to underlying Ca ii K brightenings and G-band magnetic bright points.
Conclusions: It is suggested that the siphon flow model of cool coronal loops is suitable for interpreting our observations. The jets are associated with small-scale explosive events, and may provide a mass outflow from the photosphere to the corona. Title: Distance limits to intermediate- and high-velocity clouds Authors: Smoker, J. V.; Fox, A. J.; Keenan, F. P. Bibcode: 2011MNRAS.415.1105S Altcode: 2011MNRAS.tmp..967S We present optical spectra of 403 stars and quasi-stellar objects in order to obtain distance limits towards intermediate- and high-velocity clouds (IHVCs), including new Fibre-fed Extended Range Optical Spectrograph (FEROS) observations plus archival ELODIE, FEROS, High Resolution Echelle Spectrometer (HIRES) and Ultraviolet and Visual Echelle Spectrograph (UVES) data. The non-detection of Ca II K interstellar (IS) absorption at a velocity of -130 to -60 km s-1 towards HDE 248894 (d∼ 3 kpc) and HDE 256725 (d∼ 8 kpc) in data at signal-to-noise ratio (S/N) > 450 provides a new firm lower distance limit of 8 kpc for the anti-centre shell HVC. Similarly, the non-detection of Ca II K IS absorption towards HD 86248 at S/N ∼ 500 places a lower distance limit of 7.6 kpc for Complex EP, unsurprising since this feature is probably related to the Magellanic System. The lack of detection of Na I D at S/N = 35 towards Mrk 595 puts an improved upper limit for the Na I column density of log (NNaD <) 10.95 cm-2 towards this part of the Cohen Stream where Ca II was detected by Wakker et al. Absorption at ∼-40 km s-1 is detected in Na I D towards the Galactic star PG 0039+049 at S/N = 75, placing a firm upper distance limit of 1 kpc for the intermediate-velocity cloud south (IVS), where a tentative detection had previously been obtained by Centurión et al. Ca II K and Na I D absorption is detected at -53 km s-1 towards HD 93521, which confirms the upper distance limit of 2.4 kpc for part of the IV arch complex obtained using the International Ultraviolet Explorer (IUE) data by Danly. Towards HD 216411 in Complex H a non-detection in Na D towards gas with log(?) = 20.69 cm-2 puts a lower distance limit of 6.6 kpc towards this HVC complex. Additionally, Na I D absorption is detected at -43.7 km s-1 in the star HD 218915 at a distance of 5.0 kpc in gas in the same region of the sky as Complex H. Finally, the Na I/Ca II and Ca II/H I ratios of the current sample are found to lie in the range observed for previous studies of IHVCs. Based on European Southern Observatory (ESO) programme IDs 078.C-0493(A) and 171.D-0237(B). Title: The spin-orbit angles of the transiting exoplanets WASP-1b, WASP-24b, WASP-38b and HAT-P-8b from Rossiter-McLaughlin observations Authors: Simpson, E. K.; Pollacco, D.; Cameron, A. Collier; Hébrard, G.; Anderson, D. R.; Barros, S. C. C.; Boisse, I.; Bouchy, F.; Faedi, F.; Gillon, M.; Hebb, L.; Keenan, F. P.; Miller, G. R. M.; Moutou, C.; Queloz, D.; Skillen, I.; Sorensen, P.; Stempels, H. C.; Triaud, A.; Watson, C. A.; Wilson, P. A. Bibcode: 2011MNRAS.414.3023S Altcode: 2010arXiv1011.5664S; 2011MNRAS.tmp..600S We present observations of the Rossiter-McLaughlin effect for the transiting exoplanets WASP-1b, WASP-24b, WASP-38b and HAT-P-8b, and deduce the orientations of the planetary orbits with respect to the host stars' rotation axes. The planets WASP-24b, WASP-38b and HAT-P-8b appear to move in prograde orbits and be well aligned, having sky-projected spin-orbit angles consistent with zero: λ=-4?7 ± 4?0, 15°+33-43 and ?, respectively. The host stars have Teff < 6250 K and conform with the trend of cooler stars having low obliquities. WASP-38b is a massive planet on a moderately long period, eccentric orbit so may be expected to have a misaligned orbit given the high obliquities measured in similar systems. However, we find no evidence for a large spin-orbit angle. By contrast, WASP-1b joins the growing number of misaligned systems and has an almost polar orbit, λ=?. It is neither very massive, eccentric nor orbiting a hot host star, and therefore does not share the properties of many other misaligned systems. This work is based on observations collected with the SOPHIE spectrograph on the 1.93-m telescope at Observatoire de Haute-Provence (CNRS), France, by the SOPHIE Consortium; the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias and the HARPS spectrograph mounted on the European Southern Observatory (ESO) 3.6-m telescope at the La Silla Observatory in Chile under proposal 084.C-0185. Title: WASP-39b: a highly inflated Saturn-mass planet orbiting a late G-type star Authors: Faedi, F.; Barros, S. C. C.; Anderson, D. R.; Brown, D. J. A.; Collier Cameron, A.; Pollacco, D.; Boisse, I.; Hébrard, G.; Lendl, M.; Lister, T. A.; Smalley, B.; Street, R. A.; Triaud, A. H. M. J.; Bento, J.; Bouchy, F.; Butters, O. W.; Enoch, B.; Haswell, C. A.; Hellier, C.; Keenan, F. P.; Miller, G. R. M.; Moulds, V.; Moutou, C.; Norton, A. J.; Queloz, D.; Santerne, A.; Simpson, E. K.; Skillen, I.; Smith, A. M. S.; Udry, S.; Watson, C. A.; West, R. G.; Wheatley, P. J. Bibcode: 2011A&A...531A..40F Altcode: 2011arXiv1102.1375F We present the discovery of WASP-39b, a highly inflated transiting Saturn-mass planet orbiting a late G-type dwarf star with a period of 4.055259 ± 0.000008 d, Transit Epoch T0 = 2 455 342.9688 ± 0.0002 (HJD), of duration 0.1168 ± 0.0008 d. A combined analysis of the WASP photometry, high-precision follow-up transit photometry, and radial velocities yield a planetary mass of Mpl = 0.28 ± 0.03 MJ and a radius of Rpl = 1.27 ± 0.04 RJ, resulting in a mean density of 0.14 ± 0.02 ρJ. The stellar parameters are mass M⋆ = 0.93 ± 0.03 M⊙, radius R⋆ = 0.895 ± 0.23 R⊙, and age 9+3-4 Gyr. Only WASP-17b and WASP-31b have lower densities than WASP-39b, although they are slightly more massive and highly irradiated planets. From our spectral analysis, the metallicity of WASP-39 is measured to be [Fe/H] = -0.12 ± 0.1 dex, and we find the planet to have an equilibrium temperature of 1116+33-32 K. Both values strengthen the observed empirical correlation between these parameters and the planetary radius for the known transiting Saturn-mass planets.

Spectroscopic and photometric data are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/531/A40 Title: Early-type stars observed in the ESO UVES Paranal Observatory Project - III. Sub-parsec and au-scale structure in the interstellar medium* Authors: Smoker, J. V.; Bagnulo, S.; Cabanac, R.; Keenan, F. P.; Fossati, L.; Ledoux, C.; Jehin, E.; Melo, C. Bibcode: 2011MNRAS.414...59S Altcode: 2011MNRAS.tmp..681S UVES interstellar observations from the Paranal Observatory Project are presented for early-type stars located in the line of sight to the nearby open clusters IC 2391 (Omni Vel) and NGC 6475 (M7), with spectroscopic resolution R∼ 80 000 and signal-to-noise ratios in the Ti ii (3383 Å), Ca ii K, CH+ (4232 Å), Na i D and K i (7698 Å) lines of several hundred. The sightlines are a mixture of cluster and non-cluster objects. A total of 22 early-type stars (A and B type) are present in our sample towards IC 2391, with 21 towards NGC 6475/M7, and enable us to probe for differences in column density on scales from ∼0.07 to 7.3 and ∼0.05 to 4.9 pc in the respective clusters. Additionally, towards Praesepe the Na i D interstellar variation only is probed towards 13 sightlines and transverse scales of ∼0.16-10.7 pc at R= 70 000. Towards IC 2391 variations are found in Ti ii, Ca ii K and Na i D column density in different sightlines of up to 0.7, 1.0 and 1.8 dex (excluding one star), respectively. This kind of variability correlates well with the Hipparcos parallax of the objects, and probes structure within the Local Bubble. For cluster-only objects the variations are 0.3, 0.3 and 0.5 dex, respectively. For the field of view towards NGC 6475 the corresponding maximum variations are somewhat smaller, being 0.5, 0.3, 0.8 and 1.0 dex for Ti ii, Ca ii K, Na i and K i, respectively, for all objects and 0.4, 0.2, 0.6 and 0.7 dex for the cluster-only objects. These are uncorrelated with parallax, and again demonstrate that Ca ii K tends to be more smoothly distributed than Na i D. A few likely cluster sightlines show evidence for CH+ and variations in this molecular species of a factor of 10 in equivalent width over sub-pc scales. Towards Praesepe variation in interstellar Na i D is small, being a maximum of only ∼0.4 dex (including measurement errors), but with fewer sightlines studied. Overall, the scatter in the data is similar for the singly ionized species Ti ii and Ca ii, lending more support to the hypothesis that these two species sample similar parts of the interstellar medium (ISM). This also appears to be the case for the neutral species Na i D and K i in the one cluster studied. Finally, multiple-epoch observations from a variety of archive sources are used to search for astronomical unit (au) scale structure in the ISM towards 46 sightlines. There are tentative indications of structure on scales of tens to thousands of au for three sightlines. Future observations will confirm the veracity or otherwise of the time-variable components and others presented. Title: Independent Discovery of the Transiting Exoplanet HAT-P-14b Authors: Simpson, E. K.; Barros, S. C. C.; Brown, D. J. A.; Collier Cameron, A.; Pollacco, D.; Skillen, I.; Stempels, H. C.; Boisse, I.; Faedi, F.; Hébrard, G.; McCormac, J.; Sorensen, P.; Street, R. A.; Anderson, D.; Bento, J.; Bouchy, F.; Butters, O. W.; Enoch, B.; Haswell, C. A.; Hebb, L.; Hellier, C.; Holmes, S.; Horne, K.; Keenan, F. P.; Lister, T. A.; Maxted, P. F. L.; Miller, G. R. M.; Moulds, V.; Moutou, C.; Norton, A. J.; Parley, N.; Santerne, A.; Smalley, B.; Smith, A. M. S.; Todd, I.; Watson, C. A.; West, R. G.; Wheatley, P. J. Bibcode: 2011AJ....141..161S Altcode: 2010arXiv1009.3470S We present SuperWASP observations of HAT-P-14b, a hot Jupiter discovered by Torres et al. The planet was found independently by the SuperWASP team and named WASP-27b after follow-up observations had secured the discovery, but prior to the publication by Torres et al. Our analysis of HAT-P-14/WASP-27 is in good agreement with the values found by Torres et al. and we provide additional evidence against astronomical false positives. Due to the brightness of the host star, V mag = 10, HAT-P-14b is an attractive candidate for further characterization observations. The planet has a high impact parameter and the primary transit is close to grazing. This could readily reveal small deviations in the orbital parameters indicating the presence of a third body in the system, which may be causing the small but significant orbital eccentricity. Our results suggest that the planet may undergo a grazing secondary eclipse. However, even a non-detection would tightly constrain the system parameters. Title: ROSA: A High-cadence, Synchronized Multi-camera Solar Imaging System Authors: Christian, Damian Joseph; Jess, D. B.; Mahtioudakis, M.; Keenan, F. P. Bibcode: 2011SPD....42.1507C Altcode: 2011BAAS..43S.1507C The Rapid Oscillations in the Solar Atmosphere (ROSA) instrument is a synchronized, six-camera high-cadence solar imaging instrument developed by Queen's University Belfast and recently commissioned at the Dunn Solar Telescope at the National Solar Observatory in Sunspot, New Mexico, USA, as a common-user instrument. Consisting of six 1k x 1k Peltier-cooled frame-transfer CCD cameras with very low noise (0.02 - 15 e/pixel/s), each ROSA camera is capable of full-chip readout speeds in excess of 30 Hz, and up to 200 Hz when the CCD is windowed. ROSA will allow for multi-wavelength studies of the solar atmosphere at a high temporal resolution. We will present the current instrument set-up and parameters, observing modes, and future plans, including a new high QE camera allowing 15 Hz for Halpha. Interested parties should see https://habu.pst.qub.ac.uk/groups/arcresearch/wiki/de502/ROSA.html Title: Chromospheric velocities of a C-class flare Authors: Keys, P. H.; Jess, D. B.; Mathioudakis, M.; Keenan, F. P. Bibcode: 2011A&A...529A.127K Altcode: 2011arXiv1103.4252K
Aims: We use high spatial and temporal resolution observations from the Swedish Solar Telescope to study the chromospheric velocities of a C-class flare originating from active region NOAA 10969.
Methods: A time-distance analysis is employed to estimate directional velocity components in Hα and Ca ii K image sequences. Also, imaging spectroscopy has allowed us to determine flare-induced line-of-sight velocities. A wavelet analysis is used to analyse the periodic nature of associated flare bursts.
Results: Time-distance analysis reveals velocities as high as 64 km s-1 along the flare ribbon and 15 km s-1 perpendicular to it. The velocities are very similar in both the Hα and Ca ii K time series. Line-of-sight Hα velocities are red-shifted with values up to 17 km s-1. The high spatial and temporal resolution of the observations have allowed us to detect velocities significantly higher than those found in earlier studies. Flare bursts with a periodicity of ≈60 s are also detected. These bursts are similar to the quasi-periodic oscillations observed at hard X-ray and radio wavelength data.
Conclusions: Some of the highest velocities detected in the solar atmosphere are presented. Line-of-sight velocity maps show considerable mixing of both the magnitude and direction of velocities along the flare path. A change in direction of the velocities at the flare kernel has also been detected which may be a signature of chromospheric evaporation.

Movies associated to Fig. 5 are only available in electronic form at http://www.aanda.org Title: Vorticity in the solar photosphere Authors: Shelyag, S.; Keys, P.; Mathioudakis, M.; Keenan, F. P. Bibcode: 2011A&A...526A...5S Altcode: 2010arXiv1010.5604S
Aims: We use magnetic and non-magnetic 3D numerical simulations of solar granulation and G-band radiative diagnostics from the resulting models to analyse the generation of small-scale vortex motions in the solar photosphere.
Methods: Radiative MHD simulations of magnetoconvection are used to produce photospheric models. Our starting point is a non-magnetic model of solar convection, where we introduce a uniform magnetic field and follow the evolution of the field in the simulated photosphere. We find two different types of photospheric vortices, and provide a link between the vorticity generation and the presence of the intergranular magnetic field. A detailed analysis of the vorticity equation, combined with the G-band radiative diagnostics, allows us to identify the sources and observational signatures of photospheric vorticity in the simulated photosphere.
Results: Two different types of photospheric vorticity, magnetic and non-magnetic, are generated in the domain. Non-magnetic vortices are generated by the baroclinic motions of the plasma in the photosphere, while magnetic vortices are produced by the magnetic tension in the intergranular magnetic flux concentrations. The two types of vortices have different shapes. We find that the vorticity is generated more efficiently in the magnetised model. Simulated G-band images show a direct connection between magnetic vortices and rotary motions of photospheric bright points, and suggest that there may be a connection between the magnetic bright point rotation and small-scale swirl motions observed higher in the atmosphere. Title: New exoplanets from the SuperWASP-North survey Authors: Faedi, F.; Barros, S. C. C.; Pollacco, D.; Simpson, E. K.; McCormac, J.; Moulds, V.; Watson, C.; Todd, I.; Keenan, F.; Fitzsimmons, A. Bibcode: 2011EPJWC..1101003F Altcode: We present the current status of the WASP search for transiting exoplanets, focusing on recent planet discoveries from SuperWASP-North and the joint equatorial region (-20≤Dec≤+20) observed by both WASP telescopes. We report the results of monitoring of WASP planets, and discuss how these contribute to our understanding of planet properties and their diversity. Title: WASP-37b: A 1.8 M J Exoplanet Transiting a Metal-poor Star Authors: Simpson, E. K.; Faedi, F.; Barros, S. C. C.; Brown, D. J. A.; Collier Cameron, A.; Hebb, L.; Pollacco, D.; Smalley, B.; Todd, I.; Butters, O. W.; Hébrard, G.; McCormac, J.; Miller, G. R. M.; Santerne, A.; Street, R. A.; Skillen, I.; Triaud, A. H. M. J.; Anderson, D. R.; Bento, J.; Boisse, I.; Bouchy, F.; Enoch, B.; Haswell, C. A.; Hellier, C.; Holmes, S.; Horne, K.; Keenan, F. P.; Lister, T. A.; Maxted, P. F. L.; Moulds, V.; Moutou, C.; Norton, A. J.; Parley, N.; Pepe, F.; Queloz, D.; Segransan, D.; Smith, A. M. S.; Stempels, H. C.; Udry, S.; Watson, C. A.; West, R. G.; Wheatley, P. J. Bibcode: 2011AJ....141....8S Altcode: 2010arXiv1008.3096S We report on the discovery of WASP-37b, a transiting hot Jupiter orbiting an m v = 12.7 G2-type dwarf, with a period of 3.577469 ± 0.000011 d, transit epoch T 0 = 2455338.6188 ± 0.0006 (HJD; dates throughout the paper are given in Coordinated Universal Time (UTC)), and a transit duration 0.1304+0.0018 -0.0017 d. The planetary companion has a mass M p = 1.80 ± 0.17 M J and radius R p = 1.16+0.07 -0.06 R J, yielding a mean density of 1.15+0.12 -0.15 ρJ. From a spectral analysis, we find that the host star has M sstarf = 0.925 ± 0.120 M sun, R sstarf = 1.003 ± 0.053 R sun, T eff = 5800 ± 150 K, and [Fe/H] = -0.40 ± 0.12. WASP-37 is therefore one of the lowest metallicity stars to host a transiting planet. Title: WASP-38b: a transiting exoplanet in an eccentric, 6.87d period orbit Authors: Barros, S. C. C.; Faedi, F.; Collier Cameron, A.; Lister, T. A.; McCormac, J.; Pollacco, D.; Simpson, E. K.; Smalley, B.; Street, R. A.; Todd, I.; Triaud, A. H. M. J.; Boisse, I.; Bouchy, F.; Hébrard, G.; Moutou, C.; Pepe, F.; Queloz, D.; Santerne, A.; Segransan, D.; Udry, S.; Bento, J.; Butters, O. W.; Enoch, B.; Haswell, C. A.; Hellier, C.; Keenan, F. P.; Miller, G. R. M.; Moulds, V.; Norton, A. J.; Parley, N.; Skillen, I.; Watson, C. A.; West, R. G.; Wheatley, P. J. Bibcode: 2011A&A...525A..54B Altcode: 2010arXiv1010.0849B
Aims: We report the discovery of WASP-38b, a long period transiting planet in an eccentric 6.871815 day orbit. The transit epoch is 2 455 335.92050 ± 0.00074 (HJD) and the transit duration is 4.663 h.
Methods: WASP-38b's discovery was enabled due to an upgrade to the SuperWASP-North cameras. We performed a spectral analysis of the host star HD 146389/BD+10 2980 that yielded Teff = 6150 ± 80 K, log g = 4.3 ± 0.1, v sin i = 8.6 ± 0.4 km s-1, M_* = 1.16 ± 0.04 M⊙ and R_* = 1.33 ± 0.03 R⊙, consistent with a dwarf of spectral type F8. Assuming a main-sequence mass-radius relation for the star, we fitted simultaneously the radial velocity variations and the transit light curves to estimate the orbital and planetary parameters.
Results: The planet has a mass of 2.69 ± 0.06 MJup and a radius of 1.09 ± 0.03 RJup giving a density, ρp = 2.1 ± 0.1 ρJ. The high precision of the eccentricity e = 0.0314 ± 0.0044 is due to the relative transit timing from the light curves and the RV shape. The planet equilibrium temperature is estimated at 1292 ± 33 K. WASP-38b is the longest period planet found by SuperWASP-North and with a bright host star (V = 9.4 mag), is a good candidate for followup atmospheric studies.

Photometry and RV data are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/525/A54 Title: VizieR Online Data Catalog: WASP-39b: a highly inflated Saturn-mass planet orbiting a late G-type star. Authors: Faedi, F.; Barros, S. C. C.; Anderson, D. R.; Brown, D. J. A.; Collier, Cameron A.; Pollacco, D.; Boisse, I.; Hebrard, G.; Lendl, M.; Lister, T. A.; Smalley, B.; Street, R. A.; Triaud, A. H. M. J.; Bento, J.; Butters, O. W.; Enoch, B.; Bouchy, F.; Haswell, C. A.; Hellier, C.; Keenan, F. P.; Miller, G. R. M.; Moulds, V.; Moutou, C.; Norton, A. J.; Queloz, D.; Santerne, A.; Simpson, E. K.; Skillen, I.; Smith, A. M. S.; Udry, S.; Watson, C. A.; West, R. G.; Wheatley, P. J. Bibcode: 2011yCat..35310040F Altcode: 2011yCat..35319040F We report the discovery WASP-39b a highly inflated transiting extrasolar planet. We performed a simultaneous fit to transit photometry and radial velocity measurements and obtained a planetary density of 0.141+/-0.02rhoJ (where rhoJ is the density of Jupiter). Thus, WASP-39b is the third least dense planet identified by a ground-based transit survey.

(4 data files). Title: Search for Rapid Changes in the Visible-Light Corona during the 21 June 2001 Total Solar Eclipse Authors: Rudawy, P.; Phillips, K. J. H.; Buczylko, A.; Williams, D. R.; Keenan, F. P. Bibcode: 2010SoPh..267..305R Altcode: 2010arXiv1009.5205R; 2010SoPh..tmp..183R Some 8000 images obtained with the Solar Eclipse Coronal Imaging System (SECIS) fast-frame CCD camera instrument located at Lusaka, Zambia, during the total eclipse of 21 June 2001 have been analysed to search for short-period oscillations in intensity that could be a signature of solar coronal heating mechanisms by MHD wave dissipation. Images were taken in white-light and Fe XIV green-line (5303 Å) channels over 205 seconds (frame rate 39 s−1), approximately the length of eclipse totality at this location, with a pixel size of four arcseconds square. The data are of considerably better quality than those that we obtained during the 11 August 1999 total eclipse (Rudawy et al.: Astron. Astrophys. 416, 1179, 2004), in that the images are much better exposed and enhancements in the drive system of the heliostat used gave a much improved image stability. Classical Fourier and wavelet techniques have been used to analyse the emission at 29 518 locations, of which 10 714 had emission at reasonably high levels, searching for periodic fluctuations with periods in the range 0.1 - 17 seconds (frequencies 0.06 - 10 Hz). While a number of possible periodicities were apparent in the wavelet analysis, none of the spatially and time-limited periodicities in the local brightness curves was found to be physically important. This implies that the pervasive Alfvén wave-like phenomena (Tomczyk et al.: Science317, 1192, 2007) using polarimetric observations with the Coronal Multi-Channel Polarimeter (CoMP) instrument do not give rise to significant oscillatory intensity fluctuations. Title: VizieR Online Data Catalog: Transits of WASP-38b (Barros+, 2011) Authors: Barros, S. C. C.; Faedi, F.; Collier, Cameron A.; Lister, T. A.; McCormac, J.; Pollacco, D.; Simpson, E. K.; Smalley, B.; Street, R. A.; Todd, I.; Triaud, A. H. M. J.; Boisse, I.; Bouchy, F.; Hebrard, G.; Moutou, C.; Pepe, F.; Queloz, D.; Santerne, A.; Segransan, D.; Udry, S.; Bento, J.; Butters, O. W.; Enoch, B.; Haswell, C. A.; Hellier, C.; Keenan, F. P.; Miller, G. R. M.; Moulds, V.; Norton, A. J.; Parley, N.; Skillen, I.; Watson, C. A.; West, R. G.; Wheatleys, P. J. Bibcode: 2010yCat..35250054B Altcode: 2010yCat..35259054B WASP-38b's discovery was enabled due to an upgrade to the SuperWASP-North cameras. We performed a spectral analysis of the host star HD 146389/BD+10 2980.

(6 data files). Title: The Area Distribution of Solar Magnetic Bright Points Authors: Crockett, P. J.; Mathioudakis, M.; Jess, D. B.; Shelyag, S.; Keenan, F. P.; Christian, D. J. Bibcode: 2010ApJ...722L.188C Altcode: 2010arXiv1009.2410C Magnetic bright points (MBPs) are among the smallest observable objects on the solar photosphere. A combination of G-band observations and numerical simulations is used to determine their area distribution. An automatic detection algorithm, employing one-dimensional intensity profiling, is utilized to identify these structures in the observed and simulated data sets. Both distributions peak at an area of ≈45,000 km2, with a sharp decrease toward smaller areas. The distributions conform with log-normal statistics, which suggests that flux fragmentation dominates over flux convergence. Radiative magneto-convection simulations indicate an independence in the MBP area distribution for differing magnetic flux densities. The most commonly occurring bright point size corresponds to the typical width of inter-granular lanes. Title: A Study of Magnetic Bright Points in the Na I D1 Line Authors: Jess, D. B.; Mathioudakis, M.; Christian, D. J.; Crockett, P. J.; Keenan, F. P. Bibcode: 2010ApJ...719L.134J Altcode: 2010arXiv1007.2515J High-cadence, multiwavelength, optical observations of solar magnetic bright points (MBPs), captured at the disk center using the ROSA and IBIS imaging systems on the Dunn Solar Telescope, are presented. MBPs manifesting in the Na I D1 core are found to preferentially exist in regions containing strong downflows, in addition to cospatial underlying photospheric magnetic field concentrations. Downdrafts within Na I D1 bright points exhibit speeds of up to 7 km s-1, with preferred structural symmetry in intensity, magnetic field, and velocity profiles about the bright point center. Excess intensities associated with G-band and Ca II K observations of MBPs reveal a power-law trend when plotted as a function of the magnetic flux density. However, Na I D1 observations of the same magnetic features indicate an intensity plateau at weak magnetic field strengths below ≈150 G, suggesting the presence of a two-component heating process: one which is primarily acoustic and the other predominantly magnetic. We suggest that this finding is related to the physical expansion of magnetic flux tubes, with weak field strengths (≈50 G) expanding by ~76%, compared to a ~44% expansion when higher field strengths (≈150 G) are present. These observations provide the first experimental evidence of rapid downdrafts in Na I D1 MBPs and reveal the nature of a previously unresolved intensity plateau associated with these structures. Title: Highly Ionized sodium X-ray line emission from the solar corona and the abundance of sodium Authors: Phillips, K. J. H.; Aggarwal, K. M.; Landi, E.; Keenan, F. P. Bibcode: 2010A&A...518A..41P Altcode: 2010arXiv1005.4375P Context. The Na X X-ray lines between 10.9 and 11.2 Å have attracted little attention but are of interest since they enable an estimate of the coronal abundance of Na to be made. This is of great interest in the continuing debate on the nature of the FIP (first ionization potential) effect.
Aims: Observations of the Na X lines with the Solar Maximum Mission Flat Crystal Spectrometer and a rocket-borne X-ray spectrometer are used to measure the Na/Ne abundance ratio, i.e. the ratio of an element with very low FIP to one with high FIP.
Methods: New atomic data are used to generate synthetic spectra which are compared with the observations, with temperature and the Na/Ne abundance ratio as free parameters.
Results: Temperature estimates from the observations indicate that the line emission is principally from non-flaring active regions, and that the Na/Ne abundance ratio is 0.07 ± 50%.
Conclusions: The Na/Ne abundance ratio is close to a coronal value for which the abundances of low-FIP elements (FIP < 10 eV) are enhanced by a factor of 3 to 4 over those found in the photosphere. For low-temperature (Te ≤slant 1.5 MK) spectra, the presence of Fe XVII lines requires that either a higher-temperature component is present or a revision of ionization or recombination rates is needed. Title: Aristarchos RISE2: A Wide-Field Fast Imager for Exoplanet Transit Timing Authors: Boumis, P.; Pollacco, D.; Steele, I.; Meaburn, J.; Xilouris, E. M.; Katsiyannis, A. C.; Bode, M.; Bates, S. D.; Goudis, C. D.; Keenan, F. P.; Watson, C. Bibcode: 2010ASPC..424..426B Altcode: The detection of exoplanets is currently of great topical interest in astronomy. The Rapid Imager for Surveys of Exoplanets 2 (RISE2) camera will be built for exoplanet studies and in particular for detection of transit timing variations (TTV) induced by the presence of a third body in the system. It will be identical to RISE which has been running successfully on the 2m Liverpool Telescope since 2008 but modified for the 2.3m ARISTARCHOS telescope. For TTV work the RISE/LT combination is regularly producing timings with accuracy <10 seconds making it the best suited instrument for this work. Furthermore, RISE2/AT has the added benefit of being located at a significantly different longitude to the LT/RISE on La Palma, hence extending the transit coverage. Title: The spin-orbit alignment of the transiting exoplanet WASP-3b from Rossiter-McLaughlin observations Authors: Simpson, E. K.; Pollacco, D.; Hébrard, G.; Gibson, N. P.; Barros, S. C. C.; Boisse, I.; Bouchy, F.; Collier Cameron, A.; Miller, G. R. M.; Watson, C. A.; Keenan, F. P. Bibcode: 2010MNRAS.405.1867S Altcode: 2010MNRAS.tmp..548S; 2009arXiv0912.3643S We present an observation of the Rossiter-McLaughlin effect for the planetary system WASP-3. Radial velocity measurements were made during transit using the SOPHIE spectrograph at the 1.93-m telescope at Haute-Provence Observatory. The shape of the effect shows that the sky-projected angle between the stellar rotation axis and planetary orbital axis (λ) is small and consistent with zero within . WASP-3b joins the ~two-thirds of planets with measured spin-orbit angles that are well aligned and are thought to have undergone a dynamically gentle migration process such as planet-disc interactions. We find a systematic effect which leads to an anomalously high determination of the projected stellar rotational velocity (vsini = 19.6+2.2-2.1kms-1) compared to the value found from spectroscopic line broadening (vsini = 13.4 +/- 1.5kms-1). This is thought to be caused by a discrepancy in the assumptions made in the extraction and modelling of the data. Using a model developed by Hirano et al. designed to address this issue, we find vsini to be consistent with the value obtained from spectroscopic broadening measurements (vsini = 15.7+1.4-1.3kms-1).

Based on observations collected with the SOPHIE spectrograph on the 1.93-m telescope at Observatoire de Haute-Provence (CNRS), France, by the SOPHIE Consortium (program 08B.PNP.SIMP).

E-mail: esimpson05@qub.ac.uk Title: A photospheric bright point model Authors: Shelyag, S.; Mathioudakis, M.; Keenan, F. P.; Jess, D. B. Bibcode: 2010A&A...515A.107S Altcode: 2010arXiv1003.1653S
Aims: A magneto-hydrostatic model is constructed with spectropolarimetric properties close to those of solar photospheric magnetic bright points.
Methods: Results of solar radiative magneto-convection simulations are used to produce the spatial structure of the vertical component of the magnetic field. The horizontal component of magnetic field is reconstructed using the self-similarity condition, while the magneto-hydrostatic equilibrium condition is applied to the standard photospheric model with the magnetic field embedded. Partial ionisation processes are found to be necessary for reconstructing the correct temperature structure of the model.
Results: The structures obtained are in good agreement with observational data. By combining the realistic structure of the magnetic field with the temperature structure of the quiet solar photosphere, the continuum formation level above the equipartition layer can be found. Preliminary results are shown of wave propagation through this magnetic structure. The observational consequences of the oscillations are examined in continuum intensity and in the Fe I 6302 Å magnetically sensitive line. Title: Emission lines of FeXI in the 257-407Å wavelength region observed in solar spectra from EIS/Hinode and SERTS Authors: Keenan, F. P.; Milligan, R. O.; Jess, D. B.; Aggarwal, K. M.; Mathioudakis, M.; Thomas, R. J.; Brosius, J. W.; Davila, J. M. Bibcode: 2010MNRAS.404.1617K Altcode: 2010MNRAS.tmp..299K; 2010arXiv1001.3627K Theoretical emission-line ratios involving FeXI transitions in the 257-407Å wavelength range are derived using fully relativistic calculations of radiative rates and electron impact excitation cross-sections. These are subsequently compared with both long wavelength channel Extreme-Ultraviolet Imaging Spectrometer (EIS) spectra from the Hinode satellite (covering 245-291Å) and first-order observations (~235-449Å) obtained by the Solar Extreme-ultraviolet Research Telescope and Spectrograph (SERTS). The 266.39, 266.60 and 276.36Å lines of FeXI are detected in two EIS spectra, confirming earlier identifications of these features, and 276.36Å is found to provide an electron density (Ne) diagnostic when ratioed against the 257.55Å transition. Agreement between theory and observation is found to be generally good for the SERTS data sets, with discrepancies normally being due to known line blends, while the 257.55Å feature is detected for the first time in SERTS spectra. The most useful FeXI electron density diagnostic is found to be the 308.54/352.67 intensity ratio, which varies by a factor of 8.4 between Ne = 108 and 1011cm-3, while showing little temperature sensitivity. However, the 349.04/352.67 ratio potentially provides a superior diagnostic, as it involves lines which are closer in wavelength, and varies by a factor of 14.7 between Ne = 108 and 1011cm-3. Unfortunately, the 349.04Å line is relatively weak, and also blended with the second-order FeX 174.52Å feature, unless the first-order instrument response is enhanced. Title: Microflare Activity Driven by Forced Magnetic Reconnection Authors: Jess, D. B.; Mathioudakis, M.; Browning, P. K.; Crockett, P. J.; Keenan, F. P. Bibcode: 2010ApJ...712L.111J Altcode: 2010arXiv1002.3792J High cadence, multiwavelength, optical observations of a solar active region, obtained with the Swedish Solar Telescope, are presented. Two magnetic bright points are seen to separate in opposite directions at a constant velocity of 2.8 km s-1. After a separation distance of ≈4400 km is reached, multiple Ellerman bombs are observed in both Hα and Ca-K images. As a result of the Ellerman bombs, periodic velocity perturbations in the vicinity of the magnetic neutral line, derived from simultaneous Michelson Doppler Imager data, are generated with amplitude ±6 km s-1 and wavelength ≈1000 km. The velocity oscillations are followed by an impulsive brightening visible in Hα and Ca-K, with a peak intensity enhancement of 63%. We interpret these velocity perturbations as the magnetic field deformation necessary to trigger forced reconnection. A time delay of ≈3 minutes between the Hα-wing and Ca-K observations indicates that the observed magnetic reconnection occurs at a height of ~200 km above the solar surface. These observations are consistent with theoretical predictions and provide the first observational evidence of microflare activity driven by forced magnetic reconnection. Title: ROSA: A High-cadence, Synchronized Multi-camera Solar Imaging System Authors: Jess, D. B.; Mathioudakis, M.; Christian, D. J.; Keenan, F. P.; Ryans, R. S. I.; Crockett, P. J. Bibcode: 2010SoPh..261..363J Altcode: 2009arXiv0912.4118J; 2010SoPh..tmp...12J The Rapid Oscillations in the Solar Atmosphere (ROSA) instrument is a synchronized, six-camera high-cadence solar imaging instrument developed by Queen's University Belfast. The system is available on the Dunn Solar Telescope at the National Solar Observatory in Sunspot, New Mexico, USA, as a common-user instrument. Consisting of six 1k × 1k Peltier-cooled frame-transfer CCD cameras with very low noise (0.02 - 15 e s−1 pixel−1), each ROSA camera is capable of full-chip readout speeds in excess of 30 Hz, or 200 Hz when the CCD is windowed. Combining multiple cameras and fast readout rates, ROSA will accumulate approximately 12 TB of data per 8 hours observing. Following successful commissioning during August 2008, ROSA will allow for multi-wavelength studies of the solar atmosphere at a high temporal resolution. Title: A transit timing analysis of seven RISE light curves of the exoplanet system HAT-P-3 Authors: Gibson, N. P.; Pollacco, D. L.; Barros, S.; Benn, C.; Christian, D.; Hrudková, M.; Joshi, Y. C.; Keenan, F. P.; Simpson, E. K.; Skillen, I.; Steele, I. A.; Todd, I. Bibcode: 2010MNRAS.401.1917G Altcode: 2009MNRAS.tmp.1666G; 2009MNRAS.tmp.1684G; 2009arXiv0909.4170G We present seven light curves of the exoplanet system HAT-P-3, taken as part of a transit timing programme using the rapid imager to search for exoplanets instrument on the Liverpool Telescope. The light curves are analysed using a Markov chain Monte Carlo algorithm to update the parameters of the system. The inclination is found to be i = 86.75+0.22-0.21°, the planet-star radius ratio to be Rp/R* = 0.1098+0.0010-0.0012 and the stellar radius to be R* = 0.834+0.018-0.026Rsolar, consistent with previous results but with a significant improvement in the precision. Central transit times and uncertainties for each light curve are also determined, and a residual permutation algorithm is used as an independent check on the errors. The transit times are found to be consistent with a linear ephemeris, and a new ephemeris is calculated as Tc(0) = 2454856.70118 +/- 0.00018 HJD and P = 2.899738 +/- 0.000007 d. Model timing residuals are fitted to the measured timing residuals to place upper mass limits for a hypothetical perturbing planet as a function of the period ratio. These show that we have probed for planets with masses as low as 0.33 and 1.81 M⊕ in the interior and exterior 2:1 resonances, respectively, assuming the planets are initially in circular orbits. Title: Radiative rates and electron impact excitation rates for transitions in Cr VIII Authors: Aggarwal, K. M.; Kato, T.; Keenan, F. P.; Murakami, I. Bibcode: 2009A&A...506.1501A Altcode: Aims: In this paper we report on calculations of energy levels, radiative rates, oscillator strengths, line strengths, and effective collision strengths for transitions among the lowest 362 levels of the (1s^22s^22p^6) 3s^23p^5, 3s3p^6, 3s^23p^43d, 3s3p^53d, 3s^23p^33d^2, 3s3p^43d^2, 3p^63d, and 3s^23p^44ℓ configurations of Cr viii.
Methods: The general-purpose relativistic atomic structure package (grasp) and flexible atomic code (fac) are adopted for the calculations.
Results: Radiative rates, oscillator strengths, and line strengths are reported for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions among the 362 levels. Comparisons are made with earlier available results and the accuracy of the data is assessed. Additionally, lifetimes for all 362 levels are listed, although comparisons with other theoretical results are limited to only a few levels. Our energy levels are estimated to be accurate to better than 3% (within 0.4 Ryd), whereas results for other parameters are probably accurate to better than 20%. Finally, electron impact collision strengths and excitation rates are computed for all transitions over a wide energy (temperature) range. For these calculations, FAC is adopted and results in the form of effective collision strengths are reported over a wide temperature range of 105.0-106.6 K.

Full Tables [see full textsee full text], [see full textsee full text], and Table 6 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/506/1501 Title: SN 2008S: an electron-capture SN from a super-AGB progenitor? Authors: Botticella, M. T.; Pastorello, A.; Smartt, S. J.; Meikle, W. P. S.; Benetti, S.; Kotak, R.; Cappellaro, E.; Crockett, R. M.; Mattila, S.; Sereno, M.; Patat, F.; Tsvetkov, D.; van Loon, J. Th.; Abraham, D.; Agnoletto, I.; Arbour, R.; Benn, C.; di Rico, G.; Elias-Rosa, N.; Gorshanov, D. L.; Harutyunyan, A.; Hunter, D.; Lorenzi, V.; Keenan, F. P.; Maguire, K.; Mendez, J.; Mobberley, M.; Navasardyan, H.; Ries, C.; Stanishev, V.; Taubenberger, S.; Trundle, C.; Turatto, M.; Volkov, I. M. Bibcode: 2009MNRAS.398.1041B Altcode: 2009arXiv0903.1286B We present comprehensive photometric and spectroscopic observations of the faint transient SN 2008S discovered in the nearby galaxy NGC 6946. SN 2008S exhibited slow photometric evolution and almost no spectral variability during the first nine months, implying a long photon diffusion time and a high-density circumstellar medium. Its bolometric luminosity (~=1041ergs-1 at peak) is low with respect to most core-collapse supernovae but is comparable to the faintest Type II-P events. Our quasi-bolometric light curve extends to 300 d and shows a tail phase decay rate consistent with that of 56Co. We propose that this is evidence for an explosion and formation of 56Ni (0.0014 +/- 0.0003Msolar). Spectra of SN 2008S show intense emission lines of Hα, [CaII] doublet and CaII near-infrared (NIR) triplet, all without obvious P-Cygni absorption troughs. The large mid-infrared (MIR) flux detected shortly after explosion can be explained by a light echo from pre-existing dust. The late NIR flux excess is plausibly due to a combination of warm newly formed ejecta dust together with shock-heated dust in the circumstellar environment. We reassess the progenitor object detected previously in Spitzer archive images, supplementing this discussion with a model of the MIR spectral energy distribution. This supports the idea of a dusty, optically thick shell around SN 2008S with an inner radius of nearly 90AU and outer radius of 450AU, and an inferred heating source of 3000K. The luminosity of the central star is L ~= 104.6Lsolar. All the nearby progenitor dust was likely evaporated in the explosion leaving only the much older dust lying further out in the circumstellar environment. The combination of our long-term multiwavelength monitoring data and the evidence from the progenitor analysis leads us to support the scenario of a weak electron-capture supernova explosion in a super-asymptotic giant branch progenitor star (of initial mass 6-8Msolar) embedded within a thick circumstellar gaseous envelope. We suggest that all of main properties of the electron-capture SN phenomenon are observed in SN 2008S and future observations may allow a definitive answer. Title: Possible evidence of asymmetry in SN 2007rt, a type IIn supernova Authors: Trundle, C.; Pastorello, A.; Benetti, S.; Kotak, R.; Valenti, S.; Agnoletto, I.; Bufano, F.; Dolci, M.; Elias-Rosa, N.; Greiner, T.; Hunter, D.; Keenan, F. P.; Lorenzi, V.; Maguire, K.; Taubenberger, S. Bibcode: 2009A&A...504..945T Altcode: 2009arXiv0904.0119T An optical photometric and spectroscopic analysis of the slowly-evolving type IIn SN 2007rt is presented, covering a duration of 481 days after discovery. Its earliest spectrum, taken approximately 100 days after the explosion epoch, indicates the presence of a dense circumstellar medium, with which the supernova ejecta is interacting. This is supported by the slowly-evolving light curve. A notable feature in the spectrum of SN 2007rt is the presence of a broad He i 5875 line, not usually detected in type IIn supernovae. This may imply that the progenitor star has a high He/H ratio, having shed a significant portion of its hydrogen shell via mass-loss. An intermediate resolution spectrum reveals a narrow Hα P-Cygni profile, the absorption component of which has a width of 128 km s-1. This slow velocity suggests that the progenitor of SN 2007rt recently underwent mass-loss with wind speeds comparable to the lower limits of those detected in luminous blue variables. Asymmetries in the line profiles of H and He at early phases bears some resemblance to double-peaked features observed in a number of Ib/c spectra. These asymmetries may be indicative of an asymmetric or bipolar outflow or alternatively dust formation in the fast expanding ejecta. In addition, the late time spectrum, at over 240 days post-explosion, shows clear evidence for the presence of newly formed dust.

Appendix B is only available in electronic from at http://www.aanda.org Title: VizieR Online Data Catalog: Cr VIII radiative and excitation rates (Aggarwal+, 2009) Authors: Aggarwal, K. M.; Kato, T.; Keenan, F. P.; Murakami, I. Bibcode: 2009yCat..35061501A Altcode: The General purpose relativistic atomic structure package (GRASP) and flexible atomic code (FAC) have been adopted for the calculations.

(5 data files). Title: A Transit Timing Analysis of Nine Rise Light Curves of the Exoplanet System TrES-3 Authors: Gibson, N. P.; Pollacco, D.; Simpson, E. K.; Barros, S.; Joshi, Y. C.; Todd, I.; Keenan, F. P.; Skillen, I.; Benn, C.; Christian, D.; Hrudková, M.; Steele, I. A. Bibcode: 2009ApJ...700.1078G Altcode: 2009arXiv0905.4680G We present nine newly observed transits of TrES-3, taken as part of a transit timing program using the RISE instrument on the Liverpool Telescope. A Markov-Chain Monte Carlo analysis was used to determine the planet-star radius ratio and inclination of the system, which were found to be Rp /R sstarf = 0.1664+0.0011 -0.0018 and i = 81.73+0.13 -0.04, respectively, consistent with previous results. The central transit times and uncertainties were also calculated, using a residual-permutation algorithm as an independent check on the errors. A re-analysis of eight previously published TrES-3 light curves was conducted to determine the transit times and uncertainties using consistent techniques. Whilst the transit times were not found to be in agreement with a linear ephemeris, giving χ2 = 35.07 for 15 degrees of freedom, we interpret this to be the result of systematics in the light curves rather than a real transit timing variation. This is because the light curves that show the largest deviation from a constant period either have relatively little out-of-transit coverage or have clear systematics. A new ephemeris was calculated using the transit times and was found to be Tc (0) = 2454632.62610 ± 0.00006 HJD and P = 1.3061864 ± 0.0000005 days. The transit times were then used to place upper mass limits as a function of the period ratio of a potential perturbing planet, showing that our data are sufficiently sensitive to have probed sub-Earth mass planets in both interior and exterior 2:1 resonances, assuming that the additional planet is in an initially circular orbit. Title: Automated detection and tracking of solar magnetic bright points Authors: Crockett, P. J.; Jess, D. B.; Mathioudakis, M.; Keenan, F. P. Bibcode: 2009MNRAS.397.1852C Altcode: 2009MNRAS.tmp..999C; 2009arXiv0905.3138C Magnetic bright points (MBPs) in the internetwork are among the smallest objects in the solar photosphere and appear bright against the ambient environment. An algorithm is presented that can be used for the automated detection of the MBPs in the spatial and temporal domains. The algorithm works by mapping the lanes through intensity thresholding. A compass search, combined with a study of the intensity gradient across the detected objects, allows the disentanglement of MBPs from bright pixels within the granules. Object growing is implemented to account for any pixels that might have been removed when mapping the lanes. The images are stabilized by locating long-lived objects that may have been missed due to variable light levels and seeing quality. Tests of the algorithm, employing data taken with the Swedish Solar Telescope, reveal that ~90 per cent of MBPs within a 75 × 75 arcsec2 field of view are detected. Title: Electron-impact excitation of OII fine-structure levels Authors: Kisielius, R.; Storey, P. J.; Ferland, G. J.; Keenan, F. P. Bibcode: 2009MNRAS.397..903K Altcode: 2009MNRAS.tmp..870K; 2009arXiv0907.4209K Effective collision strengths for forbidden transitions among the five energetically lowest fine-structure levels of OII are calculated in the Breit-Pauli approximation using the R-matrix method. Results are presented for the electron temperature range 100-100000 K. The accuracy of the calculations is evaluated via the use of different types of radial orbital sets and a different configuration expansion basis for the target wavefunctions. A detailed assessment of previous available data is given, and erroneous results are highlighted. Our results reconfirm the validity of the original Seaton and Osterbrock scaling for the optical OII ratio, a matter of some recent controversy. Finally, we present plasma diagnostic diagrams using the best collision strengths and transition probabilities.

This paper is dedicated to the memory of Don Osterbrock (1924-2007) and Mike Seaton (1923-2007), who first calibrated the OII density indicator, and did so much to advance the study of nebulae.

E-mail: R.Kisielius@itpa.lt Title: The 0.5MJ transiting exoplanet WASP-13b Authors: Skillen, I.; Pollacco, D.; Collier Cameron, A.; Hebb, L.; Simpson, E.; Bouchy, F.; Christian, D. J.; Gibson, N. P.; Hébrard, G.; Joshi, Y. C.; Loeillet, B.; Smalley, B.; Stempels, H. C.; Street, R. A.; Udry, S.; West, R. G.; Anderson, D. R.; Barros, S. C. C.; Enoch, B.; Haswell, C. A.; Hellier, C.; Horne, K.; Irwin, J.; Keenan, F. P.; Lister, T. A.; Maxted, P.; Mayor, M.; Moutou, C.; Norton, A. J.; Parley, N.; Queloz, D.; Ryans, R.; Todd, I.; Wheatley, P. J.; Wilson, D. M. Bibcode: 2009A&A...502..391S Altcode: 2009arXiv0905.3115S We report the discovery of WASP-13b, a low-mass Mp = 0.46 + 0.06 - 0.05 MJ transiting exoplanet with an orbital period of 4.35298 ± 0.00004 days. The transit has a depth of 9 mmag, and although our follow-up photometry does not allow us to constrain the impact parameter well (0 < b < 0.46), with radius in the range Rp 1.06-1.21 RJ the location of WASP-13b in the mass-radius plane is nevertheless consistent with H/He-dominated, irradiated, low core mass and core-free theoretical models. The G1V host star is similar to the Sun in mass (M* = 1.03+0.11_ {- 0.09} M⊙) and metallicity ([M/H] = 0.0±0.2), but is possibly older (8.5+ 5.5 _-4.9 Gyr).

The SuperWASP and JGT differential photometry, and SOPHIE radial velocities of WASP-13 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/502/391 Title: Possible Connection Between Umbral and Bright Point Oscillations Authors: Andic, Aleksandra; Jess, D. B.; Mathioudakis, M.; Keenan, F. P.; Bloomfield, D. S. Bibcode: 2009SPD....40.0909A Altcode: Active region NOAA 10794 was observed using the Rapid Dual Imager (RDI) instrument on the Dunn Solar Telescope at the National Solar Observatory, Sacramento Peak. G-band and H-alpha filters were employed for the observations, and the resulting data were subjected to both speckle reconstruction and wavelet analyses.

Intensity oscillations in the period range 8--584 s were detected. Those with frequencies near the Nyquist value of 125 mHz had a similar behavior to other oscillations detected in the period range of 8 - 60 s.

However, oscillations in the range around 180s observed above bright points show a temporal coincidence in the light curve shape and the number of the emitted frequencies in an umbral flash, indicating a possible connection. Title: VizieR Online Data Catalog: WASP-13b photometry and radial velocities (Skillen+, 2009) Authors: Skillen, I.; Pollacco, D.; Collier Cameron, A.; Hebb, L.; Simpson, E.; Bouchy, F.; Christian, D. J.; Gibson, N. P.; Hebrard, G.; Joshi, Y. C.; Loeillet, B.; Smalley, B.; Stempels, H. C.; Street, R. A.; Udry, S.; West, R. G.; Anderson, D. R.; Barros, S. C. C.; Enoch, B.; Haswell, C. A.; Hellier, C.; Horne, K.; Irwin, J.; Keenan, F. P.; Lister, T. A.; Maxted, P.; Mayor, M.; Moutou, C.; Norton, A. J.; Parley, N.; Queloz, D.; Ryans, R.; Todd, I.; Wheatley, P. J.; Wilson, D. M. Bibcode: 2009yCat..35020391S Altcode: WASP-13 was monitored with the SuperWASP-N Camera (La Palma) from 2006 November 27 to 2007 April 1.

(3 data files). Title: Alfvén Waves in the Lower Solar Atmosphere Authors: Jess, David B.; Mathioudakis, Mihalis; Erdélyi, Robert; Crockett, Philip J.; Keenan, Francis P.; Christian, Damian J. Bibcode: 2009Sci...323.1582J Altcode: 2009arXiv0903.3546J The flow of energy through the solar atmosphere and the heating of the Sun’s outer regions are still not understood. Here, we report the detection of oscillatory phenomena associated with a large bright-point group that is 430,000 square kilometers in area and located near the solar disk center. Wavelet analysis reveals full-width half-maximum oscillations with periodicities ranging from 126 to 700 seconds originating above the bright point and significance levels exceeding 99%. These oscillations, 2.6 kilometers per second in amplitude, are coupled with chromospheric line-of-sight Doppler velocities with an average blue shift of 23 kilometers per second. A lack of cospatial intensity oscillations and transversal displacements rules out the presence of magneto-acoustic wave modes. The oscillations are a signature of Alfvén waves produced by a torsional twist of ±22 degrees. A phase shift of 180 degrees across the diameter of the bright point suggests that these torsional Alfvén oscillations are induced globally throughout the entire brightening. The energy flux associated with this wave mode is sufficient to heat the solar corona. Title: Ultraviolet and extreme-ultraviolet line ratio diagnostics for O IV Authors: Keenan, F. P.; Crockett, P. J.; Aggarwal, K. M.; Jess, D. B.; Mathioudakis, M. Bibcode: 2009A&A...495..359K Altcode: 2009arXiv0901.2222K Aims: We generate theoretical ultraviolet and extreme-ultraviolet emission line ratios for O IV and show their strong versatility as electron temperature and density diagnostics for astrophysical plasmas.
Methods: Recent fully relativistic calculations of radiative rates and electron impact excitation cross sections for O IV, supplemented with earlier data for A-values and proton excitation rates, are used to derive theoretical O IV line intensity ratios for a wide range of electron temperatures and densities.
Results: Diagnostic line ratios involving ultraviolet or extreme-ultraviolet transitions in O IV are presented, that are applicable to a wide variety of astrophysical plasmas ranging from low density gaseous nebulae to the densest solar and stellar flares. Comparisons with observational data, where available, show good agreement between theory and experiment, providing support for the accuracy of the diagnostics. However, diagnostics are also presented involving lines that are blended in existing astronomical spectra, in the hope this might encourage further observational studies at higher spectral resolution. Title: WASP-10b: a 3MJ, gas-giant planet transiting a late-type K star Authors: Christian, D. J.; Gibson, N. P.; Simpson, E. K.; Street, R. A.; Skillen, I.; Pollacco, D.; Collier Cameron, A.; Joshi, Y. C.; Keenan, F. P.; Stempels, H. C.; Haswell, C. A.; Horne, K.; Anderson, D. R.; Bentley, S.; Bouchy, F.; Clarkson, W. I.; Enoch, B.; Hebb, L.; Hébrard, G.; Hellier, C.; Irwin, J.; Kane, S. R.; Lister, T. A.; Loeillet, B.; Maxted, P.; Mayor, M.; McDonald, I.; Moutou, C.; Norton, A. J.; Parley, N.; Pont, F.; Queloz, D.; Ryans, R.; Smalley, B.; Smith, A. M. S.; Todd, I.; Udry, S.; West, R. G.; Wheatley, P. J.; Wilson, D. M. Bibcode: 2009MNRAS.392.1585C Altcode: 2008arXiv0806.1482C We report the discovery of WASP-10b, a new transiting extrasolar planet (ESP) discovered by the Wide Angle Search for Planets (WASP) Consortium and confirmed using Nordic Optical Telescope FIbre-fed Echelle Spectrograph and SOPHIE radial velocity data. A 3.09-d period, 29 mmag transit depth and 2.36 h duration are derived for WASP-10b using WASP and high-precision photometric observations. Simultaneous fitting to the photometric and radial velocity data using a Markov Chain Monte Carlo procedure leads to a planet radius of 1.28RJ, a mass of 2.96MJ and eccentricity of ~0.06. WASP-10b is one of the more massive transiting ESPs, and we compare its characteristics to the current sample of transiting ESP, where there is currently little information for masses greater than ~2MJ and non-zero eccentricities. WASP-10's host star, GSC 2752-00114 (USNO-B1.01214-0586164) is among the fainter stars in the WASP sample, with V = 12.7 and a spectral type of K5. This result shows promise for future late-type dwarf star surveys. Title: WASP-14b: 7.3 MJ transiting planet in an eccentric orbit Authors: Joshi, Y. C.; Pollacco, D.; Collier Cameron, A.; Skillen, I.; Simpson, E.; Steele, I.; Street, R. A.; Stempels, H. C.; Christian, D. J.; Hebb, L.; Bouchy, F.; Gibson, N. P.; Hébrard, G.; Keenan, F. P.; Loeillet, B.; Meaburn, J.; Moutou, C.; Smalley, B.; Todd, I.; West, R. G.; Anderson, D. R.; Bentley, S.; Enoch, B.; Haswell, C. A.; Hellier, C.; Horne, K.; Irwin, J.; Lister, T. A.; McDonald, I.; Maxted, P.; Mayor, M.; Norton, A. J.; Parley, N.; Perrier, C.; Pont, F.; Queloz, D.; Ryans, R.; Smith, A. M. S.; Udry, S.; Wheatley, P. J.; Wilson, D. M. Bibcode: 2009MNRAS.392.1532J Altcode: 2008arXiv0806.1478J We report the discovery of a 7.3 MJ exoplanet WASP-14b, one of the most massive transiting exoplanets observed to date. The planet orbits the 10th-magnitude F5V star USNO-B111118-0262485 with a period of 2.243752 d and orbital eccentricity e = 0.09. A simultaneous fit of the transit light curve and radial velocity measurements yields a planetary mass of 7.3 +/- 0.5 MJ and a radius of 1.28 +/- 0.08 RJ. This leads to a mean density of about 4.6 gcm-3 making it the densest transiting exoplanets yet found at an orbital period less than 3 d. We estimate this system to be at a distance of 160 +/- 20 pc. Spectral analysis of the host star reveals a temperature of 6475 +/- 100 K, logg = 4.07 cms-2 and v sini = 4.9 +/- 1.0 kms-1, and also a high lithium abundance, logN(Li) = 2.84 +/- 0.05. The stellar density, effective temperature and rotation rate suggest an age for the system of about 0.5-1.0 Gyr. Title: Updated parameters for the transiting exoplanet WASP-3b using RISE, a new fast camera for the Liverpool Telescope Authors: Gibson, N. P.; Pollacco, D.; Simpson, E. K.; Joshi, Y. C.; Todd, I.; Benn, C.; Christian, D.; Hrudková, M.; Keenan, F. P.; Meaburn, J.; Skillen, I.; Steele, I. A. Bibcode: 2008A&A...492..603G Altcode: 2008arXiv0810.3526G Some of the first results are reported from RISE - a new fast camera mounted on the Liverpool Telescope primarily designed to obtain high time-resolution light curves of transiting extrasolar planets for the purpose of transit timing. A full and partial transit of WASP-3 are presented, and a Markov-Chain Monte Carlo analysis is used to update the parameters from the discovery paper. This results in a planetary radius of 1.29^+0.05-0.12 RJ and therefore a density of 0.82+0.14-0.09~ρ_J, consistent with previous results. The inclination is 85.06^+0.16-0.15 deg, in agreement (but with a significant improvement in the precision) with the previously determined value. Central transit times are found to be consistent with the ephemeris given in the discovery paper; however, a new ephemeris calculated using the longer baseline results in T_c(0) = 2 454 605.55915 ± 0.00023 HJD and P = 1.846835 ± 0.000002 days. Title: Do All Flares Have White-Light Emission? Authors: Jess, D. B.; Mathioudakis, M.; Crockett, P. J.; Keenan, F. P. Bibcode: 2008ApJ...688L.119J Altcode: 2008arXiv0810.1443J High-cadence, multiwavelength optical observations of a solar active region (NOAA AR 10969), obtained with the Swedish Solar Telescope, are presented. Difference imaging of white light continuum data reveals a white-light brightening, 2 minutes in duration, linked to a cotemporal and cospatial C2.0 flare event. The flare kernel observed in the white-light images has a diameter of 300 km, thus rendering it below the resolution limit of most space-based telescopes. Continuum emission is present only during the impulsive stage of the flare, with the effects of chromospheric emission subsequently delayed by ≈2 minutes. The localized flare emission peaks at 300% above the quiescent flux. This large, yet tightly confined, increase in emission is only resolvable due to the high spatial resolution of the Swedish Solar Telescope. An investigation of the line-of-sight magnetic field derived from simultaneous MDI data shows that the continuum brightening is located very close to a magnetic polarity inversion line. In addition, an Hα flare ribbon is directed along a region of rapid magnetic energy change, with the footpoints of the ribbon remaining cospatial with the observed white-light brightening throughout the duration of the flare. The observed flare parameters are compared with current observations and theoretical models for M- and X-class events and we determine the observed white-light emission is caused by radiative back-warming. We suggest that the creation of white-light emission is a common feature of all solar flares. Title: VizieR Online Data Catalog: SuperWASP-North extrasolar planet candidates (Clarkson+, 2007) Authors: Clarkson, W. I.; Enoch, B.; Haswell, C. A.; Norton, A. J.; Christian, D. J.; Collier Cameron, A.; Kane, S. R.; Horne, K. D.; Lister, T. A.; Street, R. A.; West, R. G.; Wilson, D. M.; Evans, N.; Fitzsimmons, A.; Hellier, C.; Hodgkin, S. T.; Irwin, J.; Keenan, F. P.; Osborne, J. P.; Parley, N. R.; Pollacco, D. L.; Ryans, R.; Skillen, I.; Wheatley, P. J. Bibcode: 2008yCat..73810851C Altcode: The Wide Angle Search for Planets (WASP) photometrically surveys a large number of nearby stars to uncover candidate extrasolar planet systems by virtue of small-amplitude light curve dips on a <=5d time-scale typical of the 'Hot-Jupiters'. Observations with the SuperWASP-North instrument between 2004 April and September produced a rich photometric data set of some 1.3x109 data points from 6.7 million stars. Our custom-built data acquisition and processing system produces ~0.02mag photometric precision at V=13.

We present the transit candidates in the 03h-06h RA range. Out of 141895 light curves with sufficient sampling to provide adequate coverage, 2688 show statistically significant transit-like periodicities. Out of these, 44 pass a visual inspection of the light curve, of which 24 are removed through a set of cuts on the statistical significance of artefacts. All but four of the remaining 20 objects are removed when prior information at higher spatial resolution from existing catalogues is taken into account. Of the four candidates remaining, one is considered a good candidate for follow-up observations with three further second-priority targets. We provide detailed information on these candidates, as well as a selection of the false-positives and astrophysical false-alarms that were eliminated, and discuss briefly the impact of sampling on our results.

(1 data file). Title: Energy levels, radiative rates, and electron impact excitation rates for transitions in O VII Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2008A&A...489.1377A Altcode: Aims: In this paper we report calculations for energy levels, radiative rates, and electron impact excitation rates for transitions in O vii.
Methods: The grasp (general-purpose relativistic atomic structure package) is adopted for calculating energy levels and radiative rates. For determining the collision strengths and subsequently the excitation rates, the Dirac atomic R-matrix code (darc) and the flexible atomic code (fac) are used.
Results: Oscillator strengths, radiative rates, and line strengths are reported for all E1, E2, M1, and M2 transitions among the lowest 49 levels of O vii. Collision strengths have been averaged over a Maxwellian velocity distribution, and the resulting effective collision strengths are reported over a wide temperature range below 2×106 K. Additionally, lifetimes are also listed for all levels.

Tables 2 and 6 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/489/1377 Title: Effective collision strengths for transitions in Ni XIX Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2008A&A...488..365A Altcode: Aims: In this paper we report electron impact collision strengths and excitation rates for transitions among the lowest 89 levels of Ni xix.
Methods: The Dirac atomic R-matrix code (darc) is adopted for the calculations of collision strengths and subsequently the effective collision strengths.
Results: Collision strengths for resonance transitions among 89 levels arising from the (1s^2) 2s^22p^6, 2s^22p^53ℓ, 2s2p^63ℓ, 2s^22p^54ℓ, and 2s2p^64ℓ configurations of Ni xix are reported over a wide energy range below 250 Ryd. Additionally, effective collision strengths for all 3916 transitions among the 89 levels are listed over a wide temperature range below 107 K. Comparisons are made among different calculations and the accuracy of the data is assessed. Finally, comparisons between theoretical and experimental intensity ratios of some prominent lines of Ni xix are discussed.

Table 3 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/488/365 Title: Emission lines of FeX in active region spectra obtained with the Solar Extreme-ultraviolet Research Telescope and Spectrograph Authors: Keenan, F. P.; Jess, D. B.; Aggarwal, K. M.; Thomas, R. J.; Brosius, J. W.; Davila, J. M. Bibcode: 2008MNRAS.389..939K Altcode: 2008MNRAS.tmp..860K; 2008arXiv0806.3354K Fully relativistic calculations of radiative rates and electron impact excitation cross-sections for FeX are used to derive theoretical emission-line ratios involving transitions in the 174-366Å wavelength range. A comparison of these with solar active region observations obtained during the 1989 and 1995 flights of the Solar Extreme-ultraviolet Research Telescope and Spectrograph (SERTS) reveals generally very good agreement between theory and experiment. Several FeX emission features are detected for the first time in SERTS spectra, while the 3s23p52P3/2-3s23p4(1S)3d 2D3/2 transition at 195.32Å is identified for the first time (to our knowledge) in an astronomical source. The most useful FeX electron density (Ne) diagnostic line ratios are assessed to be 175.27/174.53 and 175.27/177.24, which both involve lines close in wavelength and free from blends, vary by factors of 13 between Ne = 108 and 1011cm-3, and yet show little temperature sensitivity. Should these lines not be available, then the 257.25/345.74 ratio may be employed to determine Ne, although this requires an accurate evaluation of the instrument intensity calibration over a relatively large wavelength range. However, if the weak 324.73Å line of FeX is reliably detected, the use of 324.73/345.74 or 257.25/324.73 is recommended over 257.25/345.74. Electron densities deduced from 175.27/174.53 and 175.27/177.24 for the stars Procyon and α Cen, using observations from the Extreme-Ultraviolet Explorer (EUVE) satellite, are found to be consistent and in agreement with the values of Ne determined from other diagnostic ratios in the EUVE spectra. A comparison of several theoretical extreme-ultraviolet FeX line ratios with experimental values for a θ-pinch, for which the plasma parameters have been independently determined, reveals reasonable agreement between theory and observation, providing some independent support for the accuracy of the adopted atomic data. Title: Transition Region Velocity Oscillations Observed by EUNIS-06 Authors: Jess, D. B.; Rabin, D. M.; Thomas, R. J.; Brosius, J. W.; Mathioudakis, M.; Keenan, F. P. Bibcode: 2008ApJ...682.1363J Altcode: 2008arXiv0804.1629J Spectroscopic measurements of NOAA AR 10871, obtained with the Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS) sounding rocket instrument on 2006 April 12, reveal velocity oscillations in the He II 303.8 Å emission line formed at T ≈ 5 × 104 K. The oscillations appear to arise in a bright active region loop arcade about 25'' wide which crosses the EUNIS slit. The period of these transition region oscillations is 26 +/- 4 s, coupled with a velocity amplitude of ±10 km s-1, detected over four complete cycles. Similar oscillations are observed in lines formed at temperatures up to T ≈ 4 × 105 K, but we find no evidence for the coupling of these velocity oscillations with corresponding phenomena in the corona. We interpret the detected oscillations as originating from an almost purely adiabatic plasma, and infer that they are generated by the resonant transmission of MHD waves through the lower active region atmospheres. Through the use of seismological techniques, we establish that the observed velocity oscillations display wave properties most characteristic of fast body global sausage modes. Title: Energy levels, radiative rates, and excitation rates for transitions in O IV Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2008A&A...486.1053A Altcode: Aims: In this paper we report calculations for energy levels, radiative rates, and excitation rates for transitions in O IV.
Methods: The grasp (general-purpose relativistic atomic structure package) and fac (flexible atomic code) were adopted for calculating energy levels and radiative rates, and the Dirac atomic R-matrix code (darc) used to determine the excitation rates.
Results: Oscillator strengths and radiative rates are reported for all E1, E2, M1, and M2 transitions among the lowest 75 levels of O iv. Additionally, lifetimes are reported for all levels and comparisons made with those available in the literature. Finally, effective collision strengths are reported for all transitions over a wide temperature range below 106 K. Comparisons are made with earlier results and the accuracy of the data is assessed.

Tables 3, 5 and 6 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/486/1053 Title: Radiative rates and electron impact excitation rates for H-like Ar XVIII Authors: Aggarwal, K. M.; Hamada, K.; Igarashi, A.; Jonauskas, V.; Keenan, F. P.; Nakazaki, S. Bibcode: 2008A&A...487..383A Altcode: Aims: In this paper we report on calculations for energy levels, radiative rates, collision strengths, and effective collision strengths for transitions among the lowest 25 levels of the n ≤ 5 configurations of H-like Ar xviii.
Methods: The general-purpose relativistic atomic structure package (grasp) and Dirac atomic R-matrix code (darc) are adopted for the calculations.
Results: Radiative rates, oscillator strengths, and line strengths are reported for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions among the 25 levels. Furthermore, collision strengths and effective collision strengths are listed for all 300 transitions among the above 25 levels over a wide energy (temperature) range up to 800 Ryd (107.4 K).

Tables 2-4 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/487/383 Title: VizieR Online Data Catalog: OVII radiative and excitation rates (Aggarwal+, 2008) Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2008yCat..34891377A Altcode: In this paper we report calculations for energy levels, radiative rates, and electron impact excitation rates for transitions in OVII.

The GRASP (general-purpose relativistic atomic structure package) is adopted for calculating energy levels and radiative rates. For determining the collision strengths and subsequently the excitation rates, the Dirac atomic R-matrix code (DARC) and the flexible atomic code (FAC) are used.

Oscillator strengths, radiative rates, and line strengths are reported for all E1, E2, M1, and M2 transitions among the lowest 49 levels of OVII. Collision strengths have been averaged over a Maxwellian velocity distribution, and the resulting effective collision strengths are reported over a wide temperature range below 2x106K. Additionally, lifetimes are also listed for all levels.

(3 data files). Title: RISE: a fast-readout imager for exoplanet transit timing Authors: Steele, I. A.; Bates, S. D.; Gibson, N.; Keenan, F.; Meaburn, J.; Mottram, C. J.; Pollacco, D.; Todd, I. Bibcode: 2008SPIE.7014E..6JS Altcode: 2008SPIE.7014E.217S; 2008arXiv0809.3351S By the precise timing of the low amplitude (0.005 - 0.02 magnitude) transits of exoplanets around their parent star it should be possible to infer the presence of other planetary bodies in the system down to Earth-like masses. We describe the design and construction of RISE, a fast-readout frame transfer camera for the Liverpool Telescope designed to carry out this experiment. The results of our commissioning tests are described as well as the data reduction procedure necessary. We present light curves of two objects, showing that the desired timing and photometric accuracy can be obtained providing that autoguiding is used to keep the target on the same detector pixel for the entire (typically 4 hour) observing run. Title: Radiative rates and electron impact excitation rates for H-like Fe XXVI Authors: Aggarwal, K. M.; Hamada, K.; Igarashi, A.; Jonauskas, V.; Keenan, F. P.; Nakazaki, S. Bibcode: 2008A&A...484..879A Altcode: Aims: In this paper we report on calculations for energy levels, radiative rates, collision strengths, and effective collision strengths for transitions among the lowest 25 levels of the n ≤ 5 configurations of H-like Fe XXVI.
Methods: The general-purpose relativistic atomic structure package (GRASP) and Dirac atomic R-matrix code (DARC) are adopted for the calculations.
Results: Radiative rates, oscillator strengths, and line strengths are reported for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions among the 25 levels. Furthermore, collision strengths and effective collision strengths are reported for all the 300 transitions among the above 25 levels over a wide energy (temperature) range up to 1500 Ryd (107.7 K). Comparisons are made with earlier available results and the accuracy of the data is assessed.

Table 1 is also available and Tables 2-5 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/484/879 Title: Discovery of Spatial Periodicities in a Coronal Loop Using Automated Edge-Tracking Algorithms Authors: Jess, D. B.; Mathioudakis, M.; Erdélyi, R.; Verth, G.; McAteer, R. T. J.; Keenan, F. P. Bibcode: 2008ApJ...680.1523J Altcode: 2008arXiv0802.1971J A new method for automated coronal loop tracking, in both spatial and temporal domains, is presented. Applying this technique to TRACE data, obtained using the 171 Å filter on 1998 July 14, we detect a coronal loop undergoing a 270 s kink-mode oscillation, as previously found by Aschwanden et al. However, we also detect flare-induced, and previously unnoticed, spatial periodicities on a scale of 3500 km, which occur along the coronal loop edge. Furthermore, we establish a reduction in oscillatory power for these spatial periodicities of 45% over a 222 s interval. We relate the reduction in detected oscillatory power to the physical damping of these loop-top oscillations. Title: Line intensity enhancements in stellar coronal X-ray spectra due to opacity effects Authors: Rose, S. J.; Matranga, M.; Mathioudakis, M.; Keenan, F. P.; Wark, J. S. Bibcode: 2008A&A...483..887R Altcode: 2008arXiv0803.3184R Context: The I(15.01 Å)/I(16.78 Å) emission line intensity ratio in Fe xvii has been reported to deviate from its theoretical value in solar and stellar X-ray spectra. This is attributed to opacity in the 15.01 Å line, leading to a reduction in its intensity, and was interpreted in terms of a geometry in which the emitters and absorbers are spatially distinct.
Aims: We study the I(15.01 Å)/I(16.78 Å) intensity ratio for the active cool dwarf EV Lac, in both flare and quiescent spectra.
Methods: The observations were obtained with the Reflection Grating Spectrometer on the XMM-Newton satellite. The emission measure distribution versus temperature reconstruction technique is used for our analysis.
Results: We find that the 15.01 Å line exhibits a significant enhancement in intensity over the optically thin value. To our knowledge, this is the first time that such an enhancement has been detected on such a sound statistical basis. We interpret this enhancement in terms of a geometry in which the emitters and absorbers are not spatially distinct, and where the geometry is such that resonant pumping of the upper level has a greater effect on the observed line intensity than resonant absorption in the line-of-sight. Title: VizieR Online Data Catalog: SuperWASP-North extrasolar planet candidates (Kane+, 2008) Authors: Kane, S. R.; Clarkson, W. I.; West, R. G.; Wilson, D. M.; Christian, D. J.; Collier Cameron, A.; Enoch, B.; Lister, T. A.; Street, R. A.; Evans, A.; Fitzsimmons, A.; Haswell, C. A.; Hellier, C.; Hodgkin, S. T.; Horne, K.; Irwin, J.; Keenan, F. P.; Norton, A. J.; Osborne, J.; Parley, N. R.; Pollacco, D. L.; Ryans, R.; Skillen, I.; Wheatley, P. J. Bibcode: 2008yCat..73841097K Altcode: The SuperWASP-N instrument is a robotic observatory designed to provide precision photometry for large areas of sky. First light was achieved in 2003 November and observations have continued until the present time.

(3 data files). Title: VizieR Online Data Catalog: NiXIX effective collision strengths (Aggarwal+, 2008) Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2008yCat..34880365A Altcode: In this paper we report electron impact collision strengths and excitation rates for transitions among the lowest 89 levels of NiXIX.

The Dirac atomic R-matrix code (DARC) is adopted for the calculations of collision strengths and subsequently the effective collision strengths.

Collision strengths for resonance transitions among 89 levels arising from the (1s2) 2s22p6, 2s22p53l, 2s2p63l, 2s22p54l, and 2s2p64l configurations of NiXIX are reported over a wide energy range below 250Ryd. Additionally, effective collision strengths for all 3916 transitions among the 89 levels are listed over a wide temperature range below 107K. Comparisons are made among different calculations and the accuracy of the data is assessed. Finally, comparisons between theoretical and experimental intensity ratios of some prominent lines of NiXIX are discussed.

(3 data files). Title: Metallicity and Physical Conditions in the Magellanic Bridge Authors: Lehner, N.; Howk, J. C.; Keenan, F. P.; Smoker, J. V. Bibcode: 2008ApJ...678..219L Altcode: 2008arXiv0801.2534L We present a new analysis of the diffuse gas in the Magellanic Bridge (R.A. gtrsim 3h) based on HST STIS E140M and FUSE spectra of two early-type stars lying within the Bridge and a QSO behind it. We derive the column densities of the H I (from Lyα), N I, O I, Ar I, Si II, S II, and Fe II of the gas in the Bridge. Using the atomic species, we determine the first gas-phase metallicity of the Magellanic Bridge, [Z/H] = - 1.02 +/- 0.07 toward one sight line and -1.7 < [Z/H] < - 0.9 toward the other, a factor of 2 or more smaller than the present-day SMC metallicity. Using the metallicity and N(H I), we show that the Bridge gas along our three lines of sight is ~70%-90% ionized, despite high H I columns, log N(H I) simeq 19.6 - 20.1. Possible sources for the ongoing ionization are certainly the hot stars within the Bridge, hot gas (revealed by O VI absorption), and leaking photons from the SMC and LMC. From the analysis of C II*, we deduce that the overall density of the Bridge must be low (<0.03-0.1 cm-3). We argue that our findings combined with other recent observational results should motivate new models of the evolution of the SMC-LMC-Galaxy system.

Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer. FUSE is operated for NASA by The Johns Hopkins University under NASA contract NAS5-32985. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Title: High frequency oscillations in the solar chromosphere and their connection with heating Authors: Andic, Aleksandra; Mathioudakis, M.; Keenan, F. P.; Jess, D. B.; Bloomfield, D. S. Bibcode: 2008IAUS..247..312A Altcode: 2007IAUS..247..312A High frequency acoustic waves have been suggested as a source of mechanical heating in the quiet solar chromosphere. To investigate this, we have observed intensity oscillations of several lines in the frequency interval 1.64-70mHz using data from the VTT Tenerife and the Dunn Solar Telescope at the National Solar Observatory. Our analysis of Fe i 543.45 nm, Fe i 543.29 nm and the G-band, indicate that the majority of oscillations are connected with the magnetic fields and do not provide sufficient mechanical flux for the heating of the chromosphere. This correlation is also observed in quiet Sun areas. Title: Solar feature tracking in both spatial and temporal domains Authors: Jess, D. B.; Mathioudakis, M.; Erdélyi, R.; Verth, G.; McAteer, R. T. J.; Keenan, F. P. Bibcode: 2008IAUS..247..288J Altcode: 2007IAUS..247..288J A new method for automated coronal loop tracking, in both spatial and temporal domains, is presented. The reliability of this technique was tested with TRACE 171 Å observations. The application of this technique to a flare-induced kink-mode oscillation, revealed a 3500 km spatial periodicity which occur along the loop edge. We establish a reduction in oscillatory power, for these spatial periodicities, of 45% over a 322 s interval. We relate the reduction in oscillatory power to the physical damping of these loop-top oscillations. Title: VizieR Online Data Catalog: On IV radiative and excitation rates (Aggarwal+, 2008) Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2008yCat..34861053A Altcode: In this paper we report calculations for energy levels, radiative rates, and excitation rates for transitions in O IV.

The GRASP (general-purpose relativistic atomic structure package) and FAC (flexible atomic code) we adopted for calculating energy levels and radiative rates, and the Dirac atomic R-matrix code (DARC) used to determine the excitation rates.

Oscillator strengths and radiative rates are reported for all E1, E2, M1, and M2 transitions among the lowest 75 levels of O IV. Additionally, lifetimes are reported for all levels and comparisons made with those available in the literature. Finally, effective collision strengths are reported for all transitions over a wide temperature range below 106K. Comparisons are made with earlier results and the accuracy of the data is assessed.

(7 data files). Title: Twisting flux tubes as a cause of micro-flaring activity Authors: Jess, D. B.; McAteer, R. T. J.; Mathioudakis, M.; Keenan, F. P.; Andic, A.; Bloomfield, D. S. Bibcode: 2008IAUS..247..360J Altcode: 2007IAUS..247..360J High-cadence optical observations of an H-α blue-wing bright point near solar AR NOAA 10794 are presented. The data were obtained with the Dunn Solar Telescope at the National Solar Observatory/Sacramento Peak using a newly developed camera system, the rapid dual imager. Wavelet analysis is undertaken to search for intensity-related oscillatory signatures, and periodicities ranging from 15 to 370 s are found with significance levels exceeding 95%. During two separate microflaring events, oscillation sites surrounding the bright point are observed to twist. We relate the twisting of the oscillation sites to the twisting of physical flux tubes, thus giving rise to reconnection phenomena. We derive an average twist velocity of 8.1 km/s and detect a peak in the emitted flux between twist angles of 180° and 230°. Title: VizieR Online Data Catalog: Fe XXVI radiative and excitation rates (Aggarwal+, 2008) Authors: Aggarwal, K. M.; Hamada, K.; Igarashi, A.; Jonauskas, V.; Keenan, F. P.; Nakazaki, S. Bibcode: 2008yCat..34840879A Altcode: In this paper we report on calculations for energy levels, radiative rates, collision strengths, and effective collision strengths for transitions among the lowest 25 levels of the n<=5 configurations of H-like Fe XXVI.

The General purpose relativistic atomic structure package (GRASP) and Dirac atomic R-matrix code (DARC) have been adopted for the calculations.

(5 data files). Title: WASP-3b: a strongly irradiated transiting gas-giant planet Authors: Pollacco, D.; Skillen, I.; Collier Cameron, A.; Loeillet, B.; Stempels, H. C.; Bouchy, F.; Gibson, N. P.; Hebb, L.; Hébrard, G.; Joshi, Y. C.; McDonald, I.; Smalley, B.; Smith, A. M. S.; Street, R. A.; Udry, S.; West, R. G.; Wilson, D. M.; Wheatley, P. J.; Aigrain, S.; Alsubai, K.; Benn, C. R.; Bruce, V. A.; Christian, D. J.; Clarkson, W. I.; Enoch, B.; Evans, A.; Fitzsimmons, A.; Haswell, C. A.; Hellier, C.; Hickey, S.; Hodgkin, S. T.; Horne, K.; Hrudková, M.; Irwin, J.; Kane, S. R.; Keenan, F. P.; Lister, T. A.; Maxted, P.; Mayor, M.; Moutou, C.; Norton, A. J.; Osborne, J. P.; Parley, N.; Pont, F.; Queloz, D.; Ryans, R.; Simpson, E. Bibcode: 2008MNRAS.385.1576P Altcode: 2008MNRAS.tmp..320P; 2007arXiv0711.0126P We report the discovery of WASP-3b, the third transiting exoplanet to be discovered by the WASP and SOPHIE collaboration. WASP-3b transits its host star USNO-B1.01256-0285133 every 1.846834 +/- 0.000002 d. Our high-precision radial velocity measurements present a variation with amplitude characteristic of a planetary-mass companion and in phase with the light curve. Adaptive optics imaging shows no evidence for nearby stellar companions, and line-bisector analysis excludes faint, unresolved binarity and stellar activity as the cause of the radial velocity variations. We make a preliminary spectroscopic analysis of the host star and find it to have Teff = 6400 +/- 100K and log g = 4.25 +/- 0.05 which suggests it is most likely an unevolved main-sequence star of spectral type F7-8V. Our simultaneous modelling of the transit photometry and reflex motion of the host leads us to derive a mass of 1.76+0.08-0.14 MJ and radius 1.31+0.07-0.14 RJ for WASP-3b. The proximity and relative temperature of the host star suggests that WASP-3b is one of the hottest exoplanets known, and thus has the potential to place stringent constraints on exoplanet atmospheric models. Title: SuperWASP-N extrasolar planet candidates from fields 06h < RA < 16h Authors: Kane, S. R.; Clarkson, W. I.; West, R. G.; Wilson, D. M.; Christian, D. J.; Collier Cameron, A.; Enoch, B.; Lister, T. A.; Street, R. A.; Evans, A.; Fitzsimmons, A.; Haswell, C. A.; Hellier, C.; Hodgkin, S. T.; Horne, K.; Irwin, J.; Keenan, F. P.; Norton, A. J.; Osborne, J.; Parley, N. R.; Pollacco, D. L.; Ryans, R.; Skillen, I.; Wheatley, P. J. Bibcode: 2008MNRAS.384.1097K Altcode: 2007arXiv0711.2581K; 2008MNRAS.tmp...80K The Wide Angle Search for Planets (WASP) survey currently operates two installations, designated SuperWASP-N and SuperWASP-S, located in the Northern and Southern hemispheres, respectively. These installations are designed to provide high time-resolution photometry for the purpose of detecting transiting extrasolar planets, asteroids, and transient events. Here, we present results from a transit-hunting observing campaign using SuperWASP-N covering a right ascension (RA) range of 06h < RA < 16h. This paper represents the fifth and final in the series of transit candidates released from the 2004 observing season. In total, 729335 stars from 33 fields were monitored with 130566 having sufficient precision to be scanned for transit signatures. Using a robust transit detection algorithm and selection criteria, six stars were found to have events consistent with the signature of a transiting extrasolar planet based on the photometry, including the known transiting planet XO-1b. These transit candidates are presented here along with discussion of follow-up observations and the expected number of candidates in relation to the overall observing strategy. Title: Effective collision strengths for allowed transitions among the n ≤ 5 degenerate levels of Al XIII Authors: Aggarwal, K. M.; Igarashi, A.; Keenan, F. P.; Nakazaki, S. Bibcode: 2008A&A...479..585A Altcode: Aims:In this paper we report on calculations of collision strengths and effective collision strengths for allowed transitions among the n ≤ 5 degenerate levels of Al xiii.
Methods: The Dirac atomic R-matrix code (darc) has been adopted for these calculations.
Results: Collision strengths are reported over a wide energy range below 300 Ryd, and effective collision strengths are provided for electron temperatures of 4.4 ≤ log Te ≤ 6.8 K. Title: Iron abundances from optical FeIII absorption lines in B-type stellar spectra Authors: Thompson, H. M. A.; Keenan, F. P.; Dufton, P. L.; Trundle, C.; Ryans, R. S. I.; Crowther, P. A. Bibcode: 2008MNRAS.383..729T Altcode: 2007MNRAS.tmp.1131T; 2007arXiv0710.3252T The role of optical FeIII absorption lines in B-type stars as iron abundance diagnostics is considered. To date, ultraviolet Fe lines have been widely used in B-type stars, although line blending can severely hinder their diagnostic power. Using optical spectra, covering a wavelength range ~3560-9200Å, a sample of Galactic B-type main-sequence and supergiant stars of spectral types B0.5 to B7 are investigated. A comparison of the observed FeIII spectra of supergiants, and those predicted from the model atmosphere codes TLUSTY [plane-parallel, non-local thermodynamic equilibrium (LTE)], with spectra generated using SYNSPEC (LTE), and CMFGEN (spherical, non-LTE), reveal that non-LTE effects appear small. In addition, a sample of main-sequence and supergiant objects, observed with the Fiber-fed Extended Range Optical Spectrograph (FEROS), reveal LTE abundance estimates consistent with the Galactic environment and previous optical studies. Based on the present study, we list a number of FeIII transitions which we recommend for estimating the iron abundance from early B-type stellar spectra. Title: VizieR Online Data Catalog: SuperWASP-North extrasolar planet candidates (Street+, 2007) Authors: Street, R. A.; Christian, D. J.; Clarkson, W. I.; Collier Cameron, A.; Enoch, B.; Kane, S. R.; Lister, T. A.; West, R. G.; Wilson, D. M.; Evans, A.; Fitzsimmons, A.; Haswell, C. A.; Hellier, C.; Hodgkin, S. T.; Horne, K.; Irwin, J.; Keenan, F. P.; Norton, A. J.; Osborne, J.; Pollacco, D. L.; Ryans, R.; Skillen, I.; Wheatley, P. J.; Barnes, J. Bibcode: 2008yCat..83790816S Altcode: The SuperWASP-I (Wide Angle Search for Planets-I) instrument observed 6.7 million stars between 8 and 15mag from La Palma during the 2004 May-September season. Our transit-hunting algorithm selected 11626 objects from the 184442 stars within the RA (right ascension) range 18-21h. We describe our thorough selection procedure whereby catalogue information is exploited along with careful study of the SuperWASP data to filter out, as far as possible, transit mimics. We have identified 35 candidates which we recommend for follow-up observations.

(2 data files). Title: Twisting flux tubes as a cause of micro-flaring activity Authors: Jess, D. B.; McAteer, R. T. J.; Mathioudakis, M.; Keenan, F. P.; Andic, A.; Bloomfield, D. S. Bibcode: 2007A&A...476..971J Altcode: 2007arXiv0709.2268J High-cadence optical observations of an H-α blue-wing bright point near solar AR NOAA 10794 are presented. The data were obtained with the Dunn Solar Telescope at the National Solar Observatory/Sacramento Peak using a newly developed camera system, the rapid dual imager. Wavelet analysis is undertaken to search for intensity-related oscillatory signatures, and periodicities ranging from 15 to 370 s are found with significance levels exceeding 95%. During two separate microflaring events, oscillation sites surrounding the bright point are observed to twist. We relate the twisting of the oscillation sites to the twisting of physical flux tubes, thus giving rise to reconnection phenomena. We derive an average twist velocity of 8.1 km s-1 and detect a peak in the emitted flux between twist angles of 180° and 230°.

Figure 4 is available as a movie at http://www.aanda.org Title: Energy levels, radiative rates and excitation rates for transitions in Ni XI Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2007A&A...475..393A Altcode: Aims:In this paper we report calculations for energy levels, radiative rates and excitation rates for transitions in Ni xi.
Methods: The grasp (General-purpose Relativistic Atomic Structure Package) and fac (Flexible Atomic Code) have been adopted for calculating energy levels and radiative rates, and the Dirac Atomic R-matrix Code (darc) has been used to determine the excitation rates.
Results: Oscillator strengths, radiative rates and line strengths are reported for all E1, E2, M1 and M2 transitions among the lowest 250 levels of Ni xi. Additionally, lifetimes are also reported for all levels. However, results for excitation rates are presented only for transitions among the lowest 17 levels.

Tables 1, 3, 4 and 7 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/475/393 Title: An investigation of FeXVI emission lines in solar and stellar extreme-ultraviolet and soft X-ray spectra Authors: Keenan, F. P.; Drake, J. J.; Aggarwal, K. M. Bibcode: 2007MNRAS.381.1727K Altcode: 2007arXiv0708.2640K; 2007MNRAS.tmp..918K New fully relativistic calculations of radiative rates and electron impact excitation cross-sections for FeXVI are used to determine theoretical emission-line ratios applicable to the 251-361 and 32-77Å portions of the extreme-ultraviolet (EUV) and soft X-ray spectral regions, respectively. A comparison of the EUV results with observations from the Solar Extreme-Ultraviolet Research Telescope and Spectrograph (SERTS) reveals excellent agreement between theory and experiment. However, for emission lines in the 32-49Å portion of the soft X-ray spectral region, there are large discrepancies between theory and measurement for both a solar flare spectrum obtained with the X-Ray Spectrometer/Spectrograph Telescope (XSST) and for observations of Capella from the Low-Energy Transmission Grating Spectrometer (LETGS) on the Chandra X-ray Observatory. These are probably due to blending in the solar flare and Capella data from both first-order lines and from shorter wavelength transitions detected in second and third order. By contrast, there is very good agreement between our theoretical results and the XSST and LETGS observations in the 50-77Å wavelength range, contrary to previous results. In particular, there is no evidence that the FeXVI emission from the XSST flare arises from plasma at a much higher temperature than that expected for FeXVI in ionization equilibrium, as suggested by earlier work. Title: VizieR Online Data Catalog: SuperWASP-North extrasolar planet candidates (Lister+, 2007) Authors: Lister, T. A.; West, R. G.; Wilson, D. M.; Collier Cameron, A.; Clarkson, W. I.; Street, R. A.; Enoch, B.; Parley, N. R.; Christian, D. J.; Kane, S. R.; Evans, A.; Fitzsimmons, A.; Haswell, C. A.; Hellier, C.; Hodgkin, S. T.; Horne, K.; Irwin, J.; Keenan, F. P.; Norton, A. J.; Osborne, J.; Pollacco, D. L.; Ryans, R.; Skillen, I.; Wheatley, P. J.; Barnes, J. R. Bibcode: 2007yCat..83790647L Altcode: The photometric data were obtained with the SuperWASP-North (SW-N) instrument at the Observatorio del Roque de los Muchachos, La Palma, Canary Islands, during 2004 May to September. Follow-up spectroscopic observations of a small number of transit candidates were obtained by one of us (JRB) as part of another observing program using the 3.6-m CanadaFranceHawaii Telescope (CFHT) and ESPaDOnS echelle spectrograph on Mauna Kea, Hawaii, on the nights of 2005 September 23-24.

(2 data files). Title: Line intensity enhancements in both stellar and laser-plasma coronal X-ray spectra due to opacity effects Authors: Wark, Justin; Rose, Steven; Keenan, Francis; Mathioudakis, Michail; Matranga, Marco Bibcode: 2007APS..DPPUO4009W Altcode: The intensity of optically thin transitions increase linearly with optical depth. As one might expect an optically thick line to increase less quickly than linearly, the thick to thin ratio is normally thought to decrease with increasing optical depth. However, for systems in coronal equilibrium, this is not necessarily the case, and this ratio can have enhancements that are a function of plasma geometry and viewing angle. Here we consider the X-ray spectra for a number of late-type active stars, obtained with the Reflection Grating Spectrometer on the XMM-Newton satellite. Both flare and quiescent spectra are considered, and intensity ratios studied which involve the Fe XVII 15.01 å and 16.78 å transitions. We consider a large dataset for a number of stars, and in particular the case of EV Lac, where the 15.01 å line exhibits an enhancement in intensity over the optically thin value, which we interpret in terms of a geometry consistent with a largely planar feature on the surface of the star being observed at an angle of order 45 degrees. We show that such enhancements due to opacity should also be observable in laser-produced plasmas of specific geometry. Title: Energy levels and radiative rates for transitions in Co XI Authors: Aggarwal, K. M.; Keenan, F. P.; Msezane, A. Z. Bibcode: 2007A&A...473..995A Altcode: Aims: In this paper we report calculations for energy levels and radiative rates for transitions in Co xi.
Methods: The General purpose Relativistic Atomic Structure Package (grasp) and the Flexible Atomic Code (fac) have been adopted for the calculations of energy levels and radiative rates.
Results: Energies for the lowest 287 levels of Co xi, including those among the (1s^22s^22p^6) 3s^23p^5, 3s3p^6, 3s^23p^43d, 3s3p^53d, 3s^23p^33d^2, and 3s^23p^44s configurations, are reported. Additionally, radiative rates and oscillator strengths are reported for all electric dipole (E1) transitions with f ≥ 10-5 among these levels, and similar results for magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions are reported only for those with f≥10-8. Comparisons are made with the available results in the literature, and the accuracy of the present data is assessed. Finally, lifetimes for all excited levels are also listed, although measurements are presently available for only one of these.

Tables 1 and 3-6 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/473/995 Title: High-frequency oscillations in a solar active region observed with the RAPID DUAL IMAGER Authors: Jess, D. B.; Andić, A.; Mathioudakis, M.; Bloomfield, D. S.; Keenan, F. P. Bibcode: 2007A&A...473..943J Altcode: 2007arXiv0707.2716J High-cadence, synchronized, multiwavelength optical observations of a solar active region (NOAA 10794) are presented. The data were obtained with the Dunn Solar Telescope at the National Solar Observatory/Sacramento Peak using a newly developed camera system: the rapid dual imager. Wavelet analysis is undertaken to search for intensity related oscillatory signatures, and periodicities ranging from 20 to 370 s are found with significance levels exceeding 95%. Observations in the H-α blue wing show more penumbral oscillatory phenomena when compared to simultaneous G-band observations. The H-α oscillations are interpreted as the signatures of plasma motions with a mean velocity of 20 km s-1. The strong oscillatory power over H-α blue-wing and G-band penumbral bright grains is an indication of the Evershed flow with frequencies higher than previously reported. Title: SuperWASP-North extrasolar planet candidates between 3h < RA < 6h Authors: Clarkson, W. I.; Enoch, B.; Haswell, C. A.; Norton, A. J.; Christian, D. J.; Collier Cameron, A.; Kane, S. R.; Horne, K. D.; Lister, T. A.; Street, R. A.; West, R. G.; Wilson, D. M.; Evans, N.; Fitzsimmons, A.; Hellier, C.; Hodgkin, S. T.; Irwin, J.; Keenan, F. P.; Osborne, J. P.; Parley, N. R.; Pollacco, D. L.; Ryans, R.; Skillen, I.; Wheatley, P. J. Bibcode: 2007MNRAS.381..851C Altcode: 2007arXiv0708.0785C; 2007MNRAS.tmp..824C The Wide Angle Search for Planets (WASP) photometrically surveys a large number of nearby stars to uncover candidate extrasolar planet systems by virtue of small-amplitude light curve dips on a <~5-d time-scale typical of the `Hot-Jupiters'. Observations with the SuperWASP-North instrument between 2004 April and September produced a rich photometric data set of some 1.3 × 109 data points from 6.7 million stars. Our custom-built data acquisition and processing system produces ~0.02 mag photometric precision at V = 13.

We present the transit candidates in the 03h-06h RA range. Out of 141895 light curves with sufficient sampling to provide adequate coverage, 2688 show statistically significant transit-like periodicities. Out of these, 44 pass a visual inspection of the light curve, of which 24 are removed through a set of cuts on the statistical significance of artefacts. All but four of the remaining 20 objects are removed when prior information at higher spatial resolution from existing catalogues is taken into account. Of the four candidates remaining, one is considered a good candidate for follow-up observations with three further second-priority targets. We provide detailed information on these candidates, as well as a selection of the false-positives and astrophysical false-alarms that were eliminated, and discuss briefly the impact of sampling on our results. Title: VizieR Online Data Catalog: NiXI radiative and excitation rates (Aggarwal+, 2007) Authors: Aggarwal, M.; Keenan, F. P. Bibcode: 2007yCat..34750393A Altcode: In this paper we report calculations for energy levels, radiative rates and excitation rates for transitions in NiXI. The GRASP (General-purpose Relativistic Atomic Structure Package) and FAC (Flexible Atomic Code) have been adopted for calculating energy levels and radiative rates, and the Dirac Atomic R-matrix Code (DARC) has been used to determine the excitation rates. Oscillator strengths, radiative rates and line strengths are reported for all E1, E2, M1 and M2 transitions among the lowest 250 levels of NiXI. Additionally, lifetimes are also reported for all levels. However, results for excitation rates are presented only for transitions among the lowest 17 levels.

(5 data files). Title: SuperWASP-North extrasolar planet candidates: candidates from fields 17h<RA<18h Authors: Lister, T. A.; West, R. G.; Wilson, D. M.; Collier Cameron, A.; Clarkson, W. I.; Street, R. A.; Enoch, B.; Parley, N. R.; Christian, D. J.; Kane, S. R.; Evans, A.; Fitzsimmons, A.; Haswell, C. A.; Hellier, C.; Hodgkin, S. T.; Horne, Keith; Irwin, J.; Keenan, F. P.; Norton, A. J.; Osborne, J.; Pollacco, D. L.; Ryans, R.; Skillen, I.; Wheatley, P. J.; Barnes, J. R. Bibcode: 2007MNRAS.379..647L Altcode: 2007MNRAS.tmp..555L; 2007arXiv0705.2603L We have performed photometric observations of nearly seven million stars with 8 < V < 15 with the SuperWASP-North instrument from La Palma between 2004 May to September. Fields in the right ascension range 17-18h, yielding over 185000 stars with sufficient quality data, have been searched for transits using a modified box least-squares (BLS) algorithm. We find a total of 58 initial transiting candidates which have high signal-to-noise ratio in the BLS, show multiple transit-like dips and have passed visual inspection. Analysis of the blending and the inferred planetary radii for these candidates leave, a total of seven transiting planet candidates which pass all the tests plus four which pass the majority. We discuss the derived parameters for these candidates and their properties and comment on the implications for future transit searches. Title: SuperWASP-N extrasolar planet candidates between 18 < RA < 21h Authors: Street, R. A.; Christian, D. J.; Clarkson, W. I.; Collier Cameron, A.; Enoch, B.; Kane, S. R.; Lister, T. A.; West, R. G.; Wilson, D. M.; Evans, A.; Fitzsimmons, A.; Haswell, C. A.; Hellier, C.; Hodgkin, S. T.; Horne, K.; Irwin, J.; Keenan, F. P.; Norton, A. J.; Osborne, J.; Pollacco, D. L.; Ryans, R.; Skillen, I.; Wheatley, P. J.; Barnes, J. Bibcode: 2007MNRAS.379..816S Altcode: 2007MNRAS.tmp..572S; 2007arXiv0705.2598S The SuperWASP-I (Wide Angle Search for Planets-I) instrument observed 6.7 million stars between 8 and 15mag from La Palma during the 2004 May-September season. Our transit-hunting algorithm selected 11626 objects from the 184442 stars within the RA (right ascension) range 18-21h. We describe our thorough selection procedure whereby catalogue information is exploited along with careful study of the SuperWASP data to filter out, as far as possible, transit mimics. We have identified 35 candidates which we recommend for follow-up observations. Title: VizieR Online Data Catalog: Energy levels and radiative rates in Co XI (Aggarwal+, 2007) Authors: Aggarwal, K. M.; Keenan, F. P.; Msezane, A. Z. Bibcode: 2007yCat..34730995A Altcode: In this paper we report calculations for energy levels and radiative rates for transitions in Co XI. The General purpose Relativistic Atomic Structure Package GRASP and the Flexible Atomic Code FAC have been adopted for the calculations of energy levels and radiative rates.

Energies for the lowest 287 levels of Co XI, including those among the (1s22s22p6) 3s23p5, 3s3p6, 3s23p43d, 3s3p53d, 3s23p33d2, and 3s23p44s configurations, are reported. Additionally, radiative rates and oscillator strengths are reported for all electric dipole (E1) transitions with f>=10-5 among these levels, and similar results for magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions are reported only for those with f>=10-8. Comparisons are made with the available results in the literature, and the accuracy of the present data is assessed. Finally, lifetimes for all excited levels are also listed, although measurements are presently available for only one of these.

(5 data files). Title: Small Scale Structure in the ISM towards IC 2391 and NGC 6475 Authors: Smoker, J. V.; Hunter, I.; Keenan, F. P.; Ledoux, C.; Jehin, E.; Melo, C.; Bagnulo, S.; Cabanac, R. Bibcode: 2007ASPC..365...82S Altcode: We describe UVES spectroscopic observations towards early-type stars located in the nearby open clusters IC 2391 (D=175 pc) and NGC 6475/M 7 (D=301 pc), with resolution ∼80,000 and S/N ratio per pixel of ∼140 to ∼360. The aim is to investigate the small-scale structure variations within parts of the local ISM and determine how they are dependent on element and ionisation stage observed, thus providing information on cloud parameters such as structure and sizes. The data used are taken from on-line versions of the Paranal Observatory Project (POP: http://www.eso.org/uvespop). A total of 25 early-type stars (A and B-type) are present in our sample towards IC 2391 with 23 towards NGC 6475/M 7, and enable us to probe differences in column densities on scales from ∼0.07--7.3-pc and ∼0.05---4.9-pc (in the respective clusters) for the optical transitions detected (Ti II (3383Å), Ca II (3933Å), Na I (5889, 5895Å) and K I (7698Å)). Towards NGC 6475 the Ca II column density is found to be constant to ∼0.15 dex over scales of ∼0.4--4-pc. A much greater scatter in the measurements for Na I D is observed with differences of up to ∼0.45 dex in sightlines separated by ∼4 pc. In the future work we will perform the same analysis for Ti II and K I towards both clusters. Title: Iron abundances of B-type post-asymptotic giant branch stars in globular clusters: Barnard29 in M13 and ROA5701 in ωCen Authors: Thompson, H. M. A.; Keenan, F. P.; Dufton, P. L.; Ryans, R. S. I.; Smoker, J. V.; Lambert, D. L.; Zijlstra, A. A. Bibcode: 2007MNRAS.378.1619T Altcode: 2007MNRAS.tmp..506T; 2007arXiv0705.2196T High-resolution optical and ultraviolet (UV) spectra of two B-type post-asymptotic giant branch (post-AGB) stars in globular clusters, Barnard29 in M13 and ROA5701 in ωCen, have been analysed using model atmosphere techniques. The optical spectra have been obtained with FEROS on the ESO 2.2-m telescope and the 2d-Coudé spectrograph on the 2.7-m McDonald telescope, while the UV observations are from the Goddard high-resolution spectrograph on the Hubble Space Telescope (HST). Abundances of light elements (C, N, O, Mg, Al and S) plus Fe have been determined from the optical spectra, while the UV data provide additional Fe abundance estimates from FeIII absorption lines in the 1875-1900 Å wavelength region. A general metal underabundance relative to young B-type stars is found for both Barnard29 and ROA5701. These results are consistent with the metallicities of the respective clusters, as well as with previous studies of the objects. The derived abundance patterns suggest that the stars have not undergone a gas-dust separation, contrary to previous suggestions, although they may have evolved from the AGB before the onset of the third dredge-up. However, the Fe abundances derived from the HST spectra are lower than those expected from the metallicities of the respective clusters, by 0.5 dex for Barnard29 and 0.8 dex for ROA5701. A similar systematic underabundance is also found for other B-type stars in environments of known metallicity, such as the Magellanic Clouds. These results indicate that the FeIII UV lines may yield abundance values which are systematically too low by typically 0.6 dex and hence such estimates should be treated with caution.

This paper includes data taken at the McDonald Observatory of the University of Texas at Austin, and on the ESO 2.2-m La Silla, programme 0077.D-025(A).

E-mail: h.thompson@qub.ac.uk Title: Observations towards early-type stars in the ESO-POP Survey - II. Searches for intermediate- and high-velocity clouds Authors: Smoker, J. V.; Hunter, I.; Kalberla, P. M. W.; Keenan, F. P.; Morras, R.; Hanuschik, R.; Thompson, H. M. A.; Silva, D.; Bajaja, E.; Poppel, W. G. L.; Arnal, M. Bibcode: 2007MNRAS.378..947S Altcode: 2007arXiv0704.1315S; 2007MNRAS.tmp..469S We present Ca II K and Ti II optical spectra of early-type stars taken mainly from the ultraviolet and visual echelle spectrograph (UVES) Paranal Observatory Project, plus H I 21-cm spectra, from the Vila-Elisa and Leiden-Dwingeloo Surveys, which are employed to obtain distances to intermediate- and high-velocity clouds (IHVCs). H I emission at a velocity of -117 km s-1 towards the sightline HD 30677 ([ image ]) with column density ~1.7 × 1019 cm-2 has no corresponding Ca II K absorption in the UVES spectrum, which has a signal-to-noise ratio (S/N) of 610 per resolution element. The star has a spectroscopically determined distance of 2.7 kpc, and hence sets this as a firm lower distance limit towards Anti-Centre cloud ACII. Towards another sightline (HD 46185 with [ image ]), H I at a velocity of +122 km s-1 and column density of 1.2 × 1019 cm-2 is seen. The corresponding Ca II K spectrum has a S/N of 780, although no absorption is observed at the cloud velocity. This similarly places a firm lower distance limit of 2.9 kpc towards this parcel of gas that may be an intermediate-velocity (IV) cloud. The lack of IV Ca II absorption towards HD 196426 ([ image ]) at a S/N of 500 reinforces a lower distance limit of ~700 pc towards this part of complex gp, where the H I column density is 1.1 × 1019 cm-2 and velocity is +78 km s-1. Additionally, no IV Ca II is seen in absorption in the spectrum of HD 19445, which is strong in H I with a column density of 8 × 1019 cm-2 at a velocity of ~-42 km s-1, placing a firm although uninteresting lower distance limit of 39 pc to this part of IV South. Finally, no high-velocity Ca II K absorption is seen towards HD 115363 ([ image ]) at a S/N of 410, placing a lower distance of ~3.2 kpc towards the HVC gas at velocity of ~+224 km s-1 and H I column density of 5.2 × 1019 cm-2. This gas is in the same region of the sky as complex WE (Wakker 2001), but at higher velocities. The non-detection of Ca II K absorption sets a lower distance of ~3.2 kpc towards the HVC, which is unsurprising if this feature is indeed related to the Magellanic System. Title: A giant outburst two years before the core-collapse of a massive star Authors: Pastorello, A.; Smartt, S. J.; Mattila, S.; Eldridge, J. J.; Young, D.; Itagaki, K.; Yamaoka, H.; Navasardyan, H.; Valenti, S.; Patat, F.; Agnoletto, I.; Augusteijn, T.; Benetti, S.; Cappellaro, E.; Boles, T.; Bonnet-Bidaud, J. -M.; Botticella, M. T.; Bufano, F.; Cao, C.; Deng, J.; Dennefeld, M.; Elias-Rosa, N.; Harutyunyan, A.; Keenan, F. P.; Iijima, T.; Lorenzi, V.; Mazzali, P. A.; Meng, X.; Nakano, S.; Nielsen, T. B.; Smoker, J. V.; Stanishev, V.; Turatto, M.; Xu, D.; Zampieri, L. Bibcode: 2007Natur.447..829P Altcode: 2007astro.ph..3663P The death of massive stars produces a variety of supernovae, which are linked to the structure of the exploding stars. The detection of several precursor stars of type II supernovae has been reported (see, for example, ref. 3), but we do not yet have direct information on the progenitors of the hydrogen-deficient type Ib and Ic supernovae. Here we report that the peculiar type Ib supernova SN 2006jc is spatially coincident with a bright optical transient that occurred in 2004. Spectroscopic and photometric monitoring of the supernova leads us to suggest that the progenitor was a carbon-oxygen Wolf-Rayet star embedded within a helium-rich circumstellar medium. There are different possible explanations for this pre-explosion transient. It appears similar to the giant outbursts of luminous blue variable stars (LBVs) of 60-100 solar masses, but the progenitor of SN 2006jc was helium- and hydrogen-deficient (unlike LBVs). An LBV-like outburst of a Wolf-Rayet star could be invoked, but this would be the first observational evidence of such a phenomenon. Alternatively, a massive binary system composed of an LBV that erupted in 2004, and a Wolf-Rayet star exploding as SN 2006jc, could explain the observations. Title: VizieR Online Data Catalog: SuperWASP exoplanetary transit survey (Christian+, 2006) Authors: Christian, D. J.; Pollacco, D. L.; Skillen, I.; Street, R. A.; Keenan, F. P.; Clarkson, W. I.; Collier Cameron, A.; Kane, S. R.; Lister, T. A.; West, R. G.; Enoch, B.; Evans, A.; Fitzsimmons, A.; Haswell, C. A.; Hellier, C.; Hodgkin, S. T.; Horne, K.; Irwin, J.; Norton, A. J.; Osborne, J.; Ryans, R.; Wheatley, P. J.; Wilson, D. M. Bibcode: 2007yCat..73721117C Altcode: The SW telescopes were designed to cover a large area of sky and achieve photometric accuracy of a few mmag and improve on the success of the prototype WASP0 instrument

(1 data file). Title: VizieR Online Data Catalog: SuperWASP exoplanetary transit survey (Christian+, 2006) Authors: Christian, D. J.; Pollacco, D. L.; Skillen, I.; Street, R. A.; Keenan, F. P.; Clarkson, W. I.; Collier Cameron, A.; Kane, S. R.; Lister, T. A.; West, R. G.; Enoch, B.; Evans, A.; Fitzsimmons, A.; Haswell, C. A.; Hellier, C.; Hodgkin, S. T.; Horne, K.; Irwin, J.; Norton, A. J.; Osborne, J.; Ryans, R.; Wheatley, P. J.; Wilson, D. M. Bibcode: 2007yCat..83721117C Altcode: The SW telescopes were designed to cover a large area of sky and achieve photometric accuracy of a few mmag and improve on the success of the prototype WASP0 instrument

(1 data file). Title: Erratum: The Super WASP wide-field exoplanetary transit survey: candidates from fields 23 h < RA < 03 h Authors: Christian, D. J.; Pollacco, D. L.; Skillen, I.; Street, R. A.; Keenan, F. P.; Clarkson, W. I.; Collier Cameron, A.; Kane, S. R.; Lister, T. A.; West, R. G.; Enoch, B.; Evans, A.; Fitzsimmons, A.; Haswell, C. A.; Hellier, C.; Hodgkin, S. T.; Horne, K.; Irwin, J.; Norton, A. J.; Osborne, J.; Ryans, R.; Wheatley, P. J.; Wilson, D. M. Bibcode: 2007MNRAS.376.1424C Altcode: 2006astro.ph..8142C; 2007MNRAS.tmp..172C Photometric transit surveys promise to complement the currently known sample of extra-solar planets by providing additional information on the planets and especially their radii. Here we present extra-solar planet (ESP) candidates from one such survey called, the Wide Angle Search for Planets (WASP) obtained with the SuperWASP wide-field imaging system. Observations were taken with SuperWASP-North located in La Palma during the April to October 2004 observing season. The data cover fields between 23hr and 03hr in RA at declinations above +12. This amounts to over $\approx$400,000 stars with V magnitudes 8 to 13.5. For the stars brighter than 12.5, we achieve better than 1 percent photometric precision. Here we present 41 sources with low amplitude variability between $\approx$ 1 and 10 mmag, from which we select 12 with periods between 1.2 and 4.4 days as the most promising extrasolar planet candidates. We discuss the properties of these ESP candidates, the expected fraction of transits recovered for our sample, and implications for the frequency and detection of hot-Jupiters. Title: Fe XIII emission lines in active region spectra obtained with the Solar Extreme-Ultraviolet Research Telescope and Spectrograph Authors: Keenan, F. P.; Jess, D. B.; Aggarwal, K. M.; Thomas, R. J.; Brosius, J. W.; Davila, J. M. Bibcode: 2007MNRAS.376..205K Altcode: 2006astro.ph.12493K; 2007MNRAS.tmp...38K Recent fully relativistic calculations of radiative rates and electron impact excitation cross-sections for Fe XIII are used to generate emission-line ratios involving 3s23p2-3s3p3 and 3s23p2-3s23p3d transitions in the 170-225 and 235-450 Å wavelength ranges covered by the Solar Extreme-Ultraviolet Research Telescope and Spectrograph (SERTS). A comparison of these line ratios with SERTS active region observations from rocket flights in 1989 and 1995 reveals generally very good agreement between theory and experiment. Several new Fe XIII emission features are identified, at wavelengths of 203.79, 259.94, 288.56 and 290.81 Å. However, major discrepancies between theory and observation remain for several Fe XIII transitions, as previously found by Landi and others, which cannot be explained by blending. Errors in the adopted atomic data appear to be the most likely explanation, in particular for transitions which have 3s23p3d 1D2 as their upper level. The most useful Fe XIII electron-density diagnostics in the SERTS spectral regions are assessed, in terms of the line pairs involved being (i) apparently free of atomic physics problems and blends, (ii) close in wavelength to reduce the effects of possible errors in the instrumental intensity calibration, and (iii) very sensitive to changes in Ne over the range 108-1011 cm-3. It is concluded that the ratios which best satisfy these conditions are 200.03/202.04 and 203.17/202.04 for the 170-225 Å wavelength region, and 348.18/320.80, 348.18/368.16, 359.64/348.18 and 359.83/368.16 for 235-450 Å. Title: WASP-1b and WASP-2b: two new transiting exoplanets detected with SuperWASP and SOPHIE Authors: Collier Cameron, A.; Bouchy, F.; Hébrard, G.; Maxted, P.; Pollacco, D.; Pont, F.; Skillen, I.; Smalley, B.; Street, R. A.; West, R. G.; Wilson, D. M.; Aigrain, S.; Christian, D. J.; Clarkson, W. I.; Enoch, B.; Evans, A.; Fitzsimmons, A.; Fleenor, M.; Gillon, M.; Haswell, C. A.; Hebb, L.; Hellier, C.; Hodgkin, S. T.; Horne, K.; Irwin, J.; Kane, S. R.; Keenan, F. P.; Loeillet, B.; Lister, T. A.; Mayor, M.; Moutou, C.; Norton, A. J.; Osborne, J.; Parley, N.; Queloz, D.; Ryans, R.; Triaud, A. H. M. J.; Udry, S.; Wheatley, P. J. Bibcode: 2007MNRAS.375..951C Altcode: 2006astro.ph..9688C; 2007MNRAS.tmp.1491C We have detected low-amplitude radial-velocity variations in two stars, USNO-B1.0 1219-0005465 (GSC 02265-00107 = WASP-1) and USNO-B1.0 0964-0543604 (GSC 00522-01199 = WASP-2). Both stars were identified as being likely host stars of transiting exoplanets in the 2004 SuperWASP wide-field transit survey. Using the newly commissioned radial-velocity spectrograph SOPHIE at the Observatoire de Haute-Provence, we found that both objects exhibit reflex orbital radial-velocity variations with amplitudes characteristic of planetary-mass companions and in-phase with the photometric orbits. Line-bisector studies rule out faint blended binaries as the cause of either the radial-velocity variations or the transits. We perform preliminary spectral analyses of the host stars, which together with their radial-velocity variations and fits to the transit light curves yield estimates of the planetary masses and radii. WASP-1b and WASP-2b have orbital periods of 2.52 and 2.15 d, respectively. Given mass estimates for their F7V and K1V primaries, we derive planet masses 0.80-0.98 and 0.81-0.95 times that of Jupiter, respectively. WASP-1b appears to have an inflated radius of at least 1.33 RJup, whereas WASP-2b has a radius in the range 0.65-1.26 RJup. Title: Energy levels and radiative rates for inner shell transitions of Fe XVI Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2007A&A...463..399A Altcode: Aims:In this paper we report calculations for energy levels and radiative rates for transitions in Fe xvi.
Methods: The General purpose Relativistic Atomic Structure Package (grasp) has been adopted for the calculations of energy levels and radiative rates.
Results: Energies for the lowest 134 levels among the (1s^22s^2) 2p^63ℓ, 2p^53s^2, 2p^53s3p, 2p^53s3d, 2p^53p3d, and 2p^53p2 configurations of Fe xvi are reported. Additionally, radiative rates, oscillator strengths, and line strengths are reported for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), magnetic quadrupole (M2), and electric octupole (E3) transitions among these levels. Comparisons are made with the available results in the literature, and the accuracy of the present results is assessed. Finally, lifetimes for all excited levels are also listed, although no measurements are presently available with which to compare these.

Tables 2, 3 and 5 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/463/399 Title: A fast hybrid algorithm for exoplanetary transit searches Authors: Collier Cameron, A.; Pollacco, D.; Street, R. A.; Lister, T. A.; West, R. G.; Wilson, D. M.; Pont, F.; Christian, D. J.; Clarkson, W. I.; Enoch, B.; Evans, A.; Fitzsimmons, A.; Haswell, C. A.; Hellier, C.; Hodgkin, S. T.; Horne, K.; Irwin, J.; Kane, S. R.; Keenan, F. P.; Norton, A. J.; Parley, N. R.; Osborne, J.; Ryans, R.; Skillen, I.; Wheatley, P. J. Bibcode: 2006MNRAS.373..799C Altcode: 2006MNRAS.tmp.1227C; 2006astro.ph..9418C We present a fast and efficient hybrid algorithm for selecting exoplanetary candidates from wide-field transit surveys. Our method is based on the widely used SysRem and Box Least-Squares (BLS) algorithms. Patterns of systematic error that are common to all stars on the frame are mapped and eliminated using the SysRem algorithm. The remaining systematic errors caused by spatially localized flat-fielding and other errors are quantified using a boxcar-smoothing method. We show that the dimensions of the search-parameter space can be reduced greatly by carrying out an initial BLS search on a coarse grid of reduced dimensions, followed by Newton-Raphson refinement of the transit parameters in the vicinity of the most significant solutions. We illustrate the method's operation by applying it to data from one field of the SuperWASP survey, comprising 2300 observations of 7840 stars brighter than V = 13.0. We identify 11 likely transit candidates. We reject stars that exhibit significant ellipsoidal variations caused indicative of a stellar-mass companion. We use colours and proper motions from the Two Micron All Sky Survey and USNO-B1.0 surveys to estimate the stellar parameters and the companion radius. We find that two stars showing unambiguous transit signals pass all these tests, and so qualify for detailed high-resolution spectroscopic follow-up. Title: Looking towards the detection of exoearths with SuperWASP Authors: Street, R. A.; Christian, D. J.; Clarkson, W. I.; Collier Cameron, A.; Enoch, B.; Evans, A.; Fitzsimmons, A.; Haswell, C. A.; Hellier, C.; Hodgkin, S. T.; Horne, Keith; Irwin, J.; Keenan, F. P.; Kane, S. R.; Lister, T. A.; Norton, A. J.; Osborne, J.; Pollacco, D.; Ryans, R.; Skillen, I.; West, R. G.; Wheatley, P. J.; Wilson, D. Bibcode: 2006IJAsB...5..183S Altcode: No abstract at ADS Title: Energy levels and radiative rates for transitions in Fe IX Authors: Aggarwal, K. M.; Keenan, F. P.; Kato, T.; Murakami, I. Bibcode: 2006A&A...460..331A Altcode: Aims.In this paper we report calculations for energy levels and radiative rates for transitions in Fe IX.
Methods: .The General purpose Relativistic Atomic Structure Package (grasp) has been adopted for the calculation of energy levels and radiative rates.
Results: .Energies for the lowest 360 levels, including those from the (1s^22s^22p^6) 3s^23p^6, 3s^23p^53d, 3s3p^63d, 3s^23p^43d^2, and 3s^23p^54ℓ configurations of Fe IX, are reported. Additionally, radiative rates, oscillator strengths, and line strengths are reported for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions among these levels. Comparisons are made with the available results in the literature, and the accuracy of the present data is assessed. Finally, lifetimes for all excited levels are listed, and comparisons made with earlier available measurements and theoretical results.
Title: Energy levels and radiative rates for transitions in Ni XIX Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2006A&A...460..959A Altcode: Aims.In this paper we report calculations for energy levels and radiative rates for transitions in Ni XIX.
Methods: .The General purpose Relativistic Atomic Structure Package (grasp) has been adopted for the calculation of energy levels and radiative rates.
Results: .Energies for the lowest 89 levels from the (1s^2) 2s^22p^6, 2s^22p^53ℓ, 2s2p^63ℓ, 2s^22p^54ℓ and 2s2p^64ℓ configurations of Ni XIX, are reported. Additionally, radiative rates, oscillator strengths, and line strengths are reported for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions among these levels. Comparisons are made with the available results in the literature, and the accuracy of the present data is assessed. Finally, lifetimes for all excited levels are listed, and comparisons made with earlier available theoretical results.
Title: The SuperWASP wide-field exoplanetary transit survey: candidates from fields 23 h < RA < 03 h Authors: Christian, D. J.; Pollacco, D. L.; Skillen, I.; Street, R. A.; Keenan, F. P.; Clarkson, W. I.; Collier Cameron, A.; Kane, S. R.; Lister, T. A.; West, R. G.; Enoch, B.; Evans, A.; Fitzsimmons, A.; Haswell, C. A.; Hellier, C.; Hodgkin, S. T.; Horne, K.; Irwin, J.; Norton, A. J.; Osborne, J.; Ryans, R.; Wheatley, P. J.; Wilson, D. M. Bibcode: 2006MNRAS.372.1117C Altcode: 2006MNRAS.tmp.1118C Photometric transit surveys promise to complement the currently known sample of extra-solar planets (ESPs) by providing additional information on the planets and especially their radii. Here, we present ESP candidates from one such survey called, the Wide Angle Search for Planets (WASP) obtained with the SuperWASP wide-field imaging system. Observations were taken with SuperWASP North located in La Palma during the 2004 April to October observing season. The data cover fields between 23 and 03 h in RA at declinations above +12. This amounts to over ~400000 stars with V magnitudes 8-13.5. For the stars brighter than 12.5, we achieve better than 1 per cent photometric precision. Here, we present 41 sources with low-amplitude variability between ~1 and 10 mmag, from which we select 12 with periods between 1.2 and 4.4 d as the most promising ESP candidates. We discuss the properties of these ESP candidates, the expected fraction of transits recovered for our sample and implications for the frequency and detection of hot-Jupiters. Title: VizieR Online Data Catalog: Fe XVI radiative rates (Aggarwal+, 2007) Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2006yCat..34630399A Altcode: In this paper we report calculations for energy levels and radiative rates for transitions in Fe XVI. The General purpose Relativistic Atomic Structure Package GRASP has been adopted for the calculations of energy levels and radiative rates.

Energies for the lowest 134 levels among the (1s22s2) 2p63l, 2p53s2, 2p53s3p, 2p53s3d, 2p53p3d, and 2p53p2 configurations of Fe XVI are reported. Additionally, radiative rates, oscillator strengths, and line strengths are reported for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), magnetic quadrupole (M2), and electric octupole (E3) transitions among these levels. Comparisons are made with the available results in the literature, and the accuracy of the present results is assessed. Finally, lifetimes for all excited levels are also listed, although no measurements are presently available with which to compare these.

(4 data files). Title: The Influence of Magnetic Field on Oscillations in the Solar Chromosphere Authors: Bloomfield, D. Shaun; McAteer, R. T. James; Mathioudakis, Mihalis; Keenan, Francis P. Bibcode: 2006ApJ...652..812B Altcode: 2006astro.ph..8314B Two sequences of solar images obtained by the Transition Region and Coronal Explorer in three UV passbands are studied using wavelet and Fourier analysis and compared to the photospheric magnetic flux measured by the Michelson Doppler Interferometer on the Solar Heliospheric Observatory to study wave behavior in differing magnetic environments. Wavelet periods show deviations from the theoretical cutoff value and are interpreted in terms of inclined fields. The variation of wave speeds indicates that a transition from dominant fast-magnetoacoustic waves to slow modes is observed when moving from network into plages and umbrae. This implies preferential transmission of slow modes into the upper atmosphere, where they may lead to heating or be detected in coronal loops and plumes. Title: VizieR Online Data Catalog: Interstellar NaI, TiII & CaIIK obs. (Hunter+, 2006) Authors: Hunter, I.; Smoker, J. V.; Keenan, F. P.; Ledoux, C.; Jehin, E.; Cabanac, R.; Melo, C.; Bagnulo, S. Bibcode: 2006yCat..73671478H Altcode: We have extracted spectra for three interstellar species, namely the NaI UV doublet, TiII and CaII K along the sightlines to 74 O- and B-type field stars from An Atlas of High-Resolution Spectra of Stars across the Hertzsprung-Russell Diagram, available from the Ultraviolet and Visual Echelle Spectrograph Paranal Observatory Project.

The spectra presented in this paper are the merged versions of the POP survey available online at http://www.eso.org/uvespop .

(3 data files). Title: The WASP Project and the SuperWASP Cameras Authors: Pollacco, D. L.; Skillen, I.; Collier Cameron, A.; Christian, D. J.; Hellier, C.; Irwin, J.; Lister, T. A.; Street, R. A.; West, R. G.; Anderson, D. R.; Clarkson, W. I.; Deeg, H.; Enoch, B.; Evans, A.; Fitzsimmons, A.; Haswell, C. A.; Hodgkin, S.; Horne, K.; Kane, S. R.; Keenan, F. P.; Maxted, P. F. L.; Norton, A. J.; Osborne, J.; Parley, N. R.; Ryans, R. S. I.; Smalley, B.; Wheatley, P. J.; Wilson, D. M. Bibcode: 2006PASP..118.1407P Altcode: 2006astro.ph..8454P The SuperWASP cameras are wide-field imaging systems at the Observatorio del Roque de los Muchachos on the island of La Palma in the Canary Islands, and at the Sutherland Station of the South African Astronomical Observatory. Each instrument has a field of view of some 482 deg2 with an angular scale of 13.7" pixel-1, and is capable of delivering photometry with accuracy better than 1% for objects having V~7.0-11.5. Lower quality data for objects brighter than V~15.0 are stored in the project archive. The systems, while designed to monitor fields with high cadence, are capable of surveying the entire visible sky every 40 minutes. Depending on the observational strategy, the data rate can be up to 100 Gbytes per night. We have produced a robust, largely automatic reduction pipeline and advanced archive, which are used to serve the data products to the consortium members. The main science aim of these systems is to search for bright transiting exoplanet systems suitable for spectroscopic follow-up observations. The first 6 month season of SuperWASP-North observations produced light curves of ~6.7 million objects with 12.9 billion data points. Title: VizieR Online Data Catalog: Fe IX radiative and excitation rates (Aggarwal+, 2006) Authors: Aggarwal, K. M.; Keenan, F. P.; Kato, T.; Murakami, I. Bibcode: 2006yCat..34600331A Altcode: In this paper we report calculations for energy levels and radiative rates for transitions in Fe IX. The General purpose Relativistic Atomic Structure Package (GRASP) has been adopted for the calculation of energy levels and radiative rates. Energies for the lowest 360 levels, including those from the (1s22s22p6) 3s23p6, 3s23p53d, 3s3p63d, 3s23p43d2, and 3s23p54l configurations of Fe IX, are reported. Additionally, radiative rates, oscillator strengths, and line strengths are reported for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions among these levels. Comparisons are made with the available results in the literature, and the accuracy of the present data is assessed.

(4 data files). Title: The WASP project in the era of robotic telescope networks Authors: Christian, D. J.; Pollacco, D. L.; Skillen, I.; Irwin, J.; Clarkson, W. I.; Collier Cameron, A.; Evans, N.; Fitzsimmons, A.; Haswell, C. A.; Hellier, C.; Hodgkin, S. T.; Horne, K.; Kane, S. R.; Keenan, F. P.; Lister, T. A.; Norton, A. J.; Osborne, J.; Ryans, R.; Street, R. A.; West, R. G.; Wheatley, P. J. Bibcode: 2006AN....327..800C Altcode: We present the current status of the WASP project, a pair of wide angle photometric telescopes, individually called SuperWASP. SuperWASP-I is located in La Palma, and SuperWASP-II at Sutherland in South Africa. SW-I began operations in April 2004. SW-II is expected to be operational in early 2006. Each SuperWASP instrument consists of up to 8 individual cameras using ultra-wide field lenses backed by high-quality passively cooled CCDs. Each camera covers 7.8×7.8 sq degrees of sky, for nearly 500 sq degrees of total sky coverage. One of the current aims of the WASP project is the search for extra-solar planet transits with a focus on brighter stars in the magnitude range ∼8 to 13. Additionally, WASP will search for optical transients, track Near-Earth Objects, and study many types of variable stars and extragalactic objects. The collaboration has developed a custom-built reduction pipeline that achieves better than 1 percent photometric precision. We discuss future goals, which include: nightly on-mountain reductions that could be used to automatically drive alerts via a small robotic telescope network, and possible roles of the WASP telescopes as providers in such a network. Additional technical details of the telescopes, data reduction, and consortium members and institutions can be found on the web site at: http://www.superwasp.org/. Title: VizieR Online Data Catalog: Ni XIX radiative and excitation rates (Aggarwal+, 2006) Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2006yCat..34600959A Altcode: In this paper we report calculations for energy levels and radiative rates for transitions in Ni XIX. The General purpose Relativistic Atomic Structure Package (GRASP) has been adopted for the calculation of energy levels and radiative rates. Energies for the lowest 89 levels from the (1s2) 2s22p6, 2s22p53l, 2s2p63l, 2s22p54l and 2s2p64l configurations of Ni XIX, are reported. Additionally, radiative rates, oscillator strengths, and line strengths are reported for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions among these levels.

(5 data files). Title: Energy levels and transition probabilities for boron-like Fe XXII Authors: Jonauskas, V.; Bogdanovich, P.; Keenan, F. P.; Kisielius, R.; Foord, M. E.; Heeter, R. F.; Rose, S. J.; Ferland, G. J.; Norrington, P. H. Bibcode: 2006A&A...455.1157J Altcode: The Multiconfiguration Dirac-Fock method is used to calculate the energies of the 407 lowest levels in Fe XXII. These results are cross-checked using a suite of codes which employ the configuration interaction method on the basis set of transformed radial orbitals with variable parameters, and takes into account relativistic corrections in the Breit-Pauli approximation. Transition probabilities, oscillator and line strengths are presented for electric dipole (E1), electric quadrupole (E2) and magnetic dipole (M1) transitions among these levels. The total radiative transition probabilities, as well as the five largest values from each level be it of E1, M1, E2, M2, or E3 type, are also provided. Finally, the results are compared with data compiled by NIST. Title: The WASP Project and SuperWASP Camera Authors: Pollacco, D.; Skillen, I.; Collier Cameron, A.; Christian, D.; Irwin, J.; Lister, T.; Street, R.; West, R.; Clarkson, W.; Evans, N.; Fitzsimmons, A.; Haswell, C.; Hellier, C.; Hodgkin, S.; Horne, K.; Jones, B.; Kane, S.; Keenan, F.; Norton, A.; Osborne, J.; Ryans, R.; Wheatley, P. Bibcode: 2006Ap&SS.304..253P Altcode: 2006Ap&SS.tmp..107P The WASP project and infrastructure supporting the SuperWASP Facility are described. As the instrument, reduction pipeline and archive system are now fully operative we expect the system to have a major impact in the discovery of bright exo-planet candidates as well in more general variable star projects. Title: VizieR Online Data Catalog: Boron-like Fe XXII transition probabilities (Jonauskas+, 2006) Authors: Jonauskas, V.; Bogdanovich, P.; Keenan, F. P.; Kisielius, R.; Foord, M. E.; Heeter, R. F.; Rose, S. J.; Ferland, G. J.; Norrington, P. H. Bibcode: 2006yCat..34551157J Altcode: Energy levels and the corresponding transition probabilities as well as oscillator strengths and line strengths for allowed (E1) and forbidden (E2, M1) transitions among the lowest 407 levels of boron-like Fe XXII are presented. Calculations were performed using the multiconfigurational Dirac-Fock GRASP code.

(4 data files). Title: Opacity in the upper atmospheres of active stars. II. AD Leonis Authors: Christian, D. J.; Mathioudakis, M.; Bloomfield, D. S.; Dupuis, J.; Keenan, F. P.; Pollacco, D. L.; Malina, R. F. Bibcode: 2006A&A...454..889C Altcode: 2006astro.ph..2447C We present FUV and UV spectroscopic observations of AD Leonis, with the aim of investigating opacity effects in the transition regions of late-type stars. The C III lines in FUSE spectra show significant opacity during both the quiescent and flaring states of AD Leonis, with up to 30% of the expected flux being lost during the latter. Other FUSE emission lines tested for opacity include those of O VI, while C IV, Si IV and N V transitions observed with stis are also investigated. These lines only reveal modest amounts of opacity with losses during flaring of up to 20%. Optical depths have been calculated for homogeneous and inhomogeneous geometries, giving path lengths of ≈20-60 km and ≈10-30 km, respectively, under quiescent conditions. However path lengths derived during flaring are ≈2-3 times larger. These values are in excellent agreement with both estimates of the small-scale structure observed in the solar transition region, and path lengths derived previously for several other active late-type stars. Title: First results from SECIS observations of the 2001 total Solar eclipse Authors: Katsiyannis, A. C.; Williams, D. R.; Murtagh, F.; McAteer, R. T. J.; Keenan, F. P. Bibcode: 2006AIPC..848...95K Altcode: SECIS observations of the June 2001 total solar eclipse were taken using an Fe XIV 5303 Å filter. Existing software was modified and new code was developed for the reduction and analysis of these data. The observations, data reduction, study of the atmospheric and instrumental effects, together with some preliminary results are discussed. Emphasis is given to the techniques used for the automated alignment of the 8000 images, the software developed for the automated detection of intensity oscillations using wavelet analysis and the application of the Monte Carlo randomisation test as a means of checking the reliability of those detections. In line with findings from the 1999 SECIS total eclipse observations, intensity oscillations with periods in the range of 7-8 s, lying outside coronal loops were also detected. Title: CaII K interstellar observations towards early-type disc and halo stars, abundances and distances of intermediate- and high-velocity clouds Authors: Smoker, J. V.; Lynn, B. B.; Christian, D. J.; Keenan, F. P. Bibcode: 2006MNRAS.370..151S Altcode: 2006MNRAS.tmp..635S We present CaII K (λair = 3933.661Å) interstellar observations towards 20 early-type stars, to place lower distance limits to intermediate- and high-velocity clouds (IHVCs) in their lines of sight. The spectra are also employed to estimate the Ca abundance in the low-velocity gas towards these objects, when combined with Leiden-Dwingeloo 21-cm HI survey data of spatial resolution . Nine of the stars, which lie towards IHVC complexes H, K and gp, were observed with the intermediate dispersion spectrograph on the Isaac Newton Telescope at a resolution R = λ/Δλ of 9000 (~33kms-1) and signal-to-noise ratio (S/N) per pixel of 75-140. A further nine objects were observed with the Utrecht Echelle Spectrograph on the William Herschel Telescope at R = 40000 (~7.5kms-1) and S/N per pixel of 10-25. Finally, two objects were observed in both CaII K and NaI D lines using the 2D COUDÉ spectrograph on the McDonald 2.7-m telescope at R = 35000 (~8.5 kms-1). The abundance of CaII K {log10(A) = log10[N(CaII K)]-log10[N(HI)]} plotted against HI column density for the objects in the current sample with heights above the Galactic plane (z) exceeding 1000pc is found to obey the Wakker & Mathis (2000) relation. Also, the reduced column density of CaII K as function of z is consistent with the larger sample taken from Smoker et al. (2003). Higher S/N observations than those previously taken towards HVC complex H stars HD13256 and HILT 190 reinforce the assertion that this lies at a distance exceeding 4000pc. No obvious absorption is detected in observations of ALS10407 and HD357657 towards IVC complex gp. The latter star has a spectroscopically estimated distance of ~2040pc, although this was derived assuming the star lies on the main sequence and without any reddening correction being applied. Finally, no CaII K absorption is detected towards two stars along the line of sight to complex K, namely PG1610+529 and PG1710+490. The latter is at a distance of ~700pc, hence placing a lower distance limit to this complex, where previously only an upper distance limit of 6800pc was available. Title: Observational Evidence of Gentle and Explosive Chromospheric Evaporation Authors: Milligan, R. O.; Gallagher, P. T.; Mathioudakis, M.; Keenan, F. P. Bibcode: 2006ESASP.617E.138M Altcode: 2006soho...17E.138M No abstract at ADS Title: Soft X-Ray Emission Lines of Fe XV in Solar Flare Observations and the Chandra Spectrum of Capella Authors: Keenan, F. P.; Drake, J. J.; Chung, S.; Brickhouse, N. S.; Aggarwal, K. M.; Msezane, A. Z.; Ryans, R. S. I.; Bloomfield, D. S. Bibcode: 2006ApJ...645..597K Altcode: 2006astro.ph..1591K Recent calculations of atomic data for Fe XV have been used to generate theoretical line ratios involving n=3-4 transitions in the soft X-ray spectral region (~52-83 Å), for a wide range of electron temperatures and densities applicable to solar and stellar coronal plasmas. A comparison of these with solar flare observations from a rocket-borne spectrograph (X-Ray Spectrometer/Spectrograph Telescope [XSST]) reveals generally good agreement between theory and experiment. In particular, the 82.76 Å emission line in the XSST spectrum is identified, for the first time to our knowledge in an astrophysical source, as the 3s3d3D3-3s4p3P2 transition of Fe XV. Most of the Fe XV transitions that are blended have had the species responsible clearly identified, although there remain a few instances in which this has not been possible. The line ratio calculations are also compared with a co-added spectrum of Capella obtained with the Chandra satellite, which is probably the highest signal-to-noise ratio observation achieved for a stellar source in the ~25-175 Å soft X-ray region. Good agreement is found between theory and experiment, indicating that the Fe XV lines are reliably detected in Chandra spectra and hence may be employed as diagnostics to determine the temperature and/or density of the emitting plasma. However, the line blending in the Chandra data is such that individual emission lines are difficult to measure accurately, and fluxes may only be reliably determined via detailed profile fitting of the observations. The co-added Capella spectrum is made available to hopefully encourage further exploration of the soft X-ray region in astronomical sources. Title: Observational Evidence of Chromospheric Evaporation Authors: Milligan, Ryan O.; Gallagher, P. T.; Mathioudakis, M.; Keenan, F. P. Bibcode: 2006SPD....37.0828M Altcode: 2006BAAS...38R.662M Observational evidence for chromospheric evaporation during the impulsive phase of two solar flares is presented using data from the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) and the Coronal Diagnostic Spectrometer (CDS) on board SOHO. For the first time, co-spatial imaging and spectroscopy have been used to observe both gentle and explosive evaporation processes within HXR emitting regions. For a GOES C9.1 flare, a low flux of non-thermal electrons was found to produce low-velocity upflows in the cool He I and O V emission lines and moderate upflows in the 8 MK Fe XIX line indicative of gentle evaporation. An M2.2 flare, on the other hand, showed low-velocity downflows in the He I and O V lines and high-velocity upflows in the Fe XIX line, for an electron flux value which was an order of magnitude higher, indicative of an explosive process. These findings confirm that the dynamic response of the solar atmosphere is sensitively dependent on the flux of incident electrons as predicted by current hydrodynamical simulations. Title: A non-LTE abundance analysis of the post-AGB star ROA5701 Authors: Thompson, H. M. A.; Keenan, F. P.; Dufton, P. L.; Ryans, R. S. I.; Smoker, J. V. Bibcode: 2006MNRAS.368.1749T Altcode: 2006astro.ph..5223T; 2006MNRAS.tmp..396T An analysis of high-resolution Anglo-Australian Telescope (AAT)/University College London Échelle Spectrograph (UCLÉS) optical spectra for the ultraviolet (UV)-bright star ROA5701 in the globular cluster ω Cen (NGC5139) is performed, using non-local thermodynamic equilibrium (non-LTE) model atmospheres to estimate stellar atmospheric parameters and chemical composition. Abundances are derived for C, N, O, Mg, Si and S, and compared with those found previously by Moehler et al. We find a general metal underabundance relative to young B-type stars, consistent with the average metallicity of the cluster. Our results indicate that ROA5701 has not undergone a gas-dust separation scenario as previously suggested. However, its abundance pattern does imply that ROA5701 has evolved off the asymptotic giant branch (AGB) prior to the onset of the third dredge-up. Title: The effect of dust obscuration in RR Telescopii on optical and IR long-term photometry and Fe II emission lines Authors: Kotnik-Karuza, D.; Friedjung, M.; Whitelock, P. A.; Marang, F.; Exter, K.; Keenan, F. P.; Pollacco, D. L. Bibcode: 2006A&A...452..503K Altcode: 2006astro.ph..3155K Aims.Infrared and optical photometric and spectroscopic observations of the symbiotic nova RR Tel are used to study the effects and properties of dust in symbiotic binaries containing a cool Mira component, as well as showing "obscuration events" of increased absorption, which are typical for such Miras.
Methods: .A set of photometric observations of the symbiotic nova RR Tel in different wavelength bands - visual from 1949 to 2002 and near-infrared ({JHKL}) from 1975 to 2002 - are presented. The variability due to the normal Mira pulsation was removed from the JHKL data, which were then compared with the American Association of Variable Star Observers' ({AAVSO}) visual light curve. The changes of the Fe II emission line fluxes during the 1996-2000 obscuration episode were studied in the optical spectra taken with the Anglo-Australian telescope.
Results: .We discuss the three periods during which the Mira component was heavily obscured by dust as observed in the different wavelength bands. A change in the correlations of J with other infrared magnitudes was observed with the colour becoming redder after JD 2 446 600. Generally, J-K was comparable, while K-L was larger than typical values for single Miras. A distance estimate of 2.5 kpc, based on the IR data, is given. A larger flux decrease for the permitted than for the forbidden Fe II lines, during the obscuration episode studied, has been found. There is no evidence for other correlations with line properties, in particular with wavelength, which suggests obscuration due to separate optically thick clouds in the outer layers.
Title: Opacity in the transition region of cool dwarfs: A powerful diagnostic Authors: Mathioudakis, M.; Christian, D. J.; Bloomfield, D. S.; Keenan, F. P.; Linsky, J. L.; Dupuis, J. Bibcode: 2006ASPC..348..159M Altcode: A detailed study of the C III 1176Å multiplet in active cool stars has shown significant deviations of the line flux from the optically thin approximation. These deviations become more pronounced during flares. Opacity can be used as a powerful diagnostic to estimate path lengths in the transition region. Our analysis reveals that stellar transition regions have very small spatial characteristics typically in the range of 10 - 100 km. These path lengths are in agreement with the small scale structure seen in the solar transition region. Title: Study of X-ray photoionized Fe plasma and comparisons with astrophysical modeling codes Authors: Foord, M. E.; Heeter, R. F.; Chung, H. -K.; van Hoof, P. A. M.; Bailey, J. E.; Cuneo, M. E.; Liedahl, D. A.; Fournier, K. B.; Jonauskas, V.; Kisielius, R.; Ramsbottom, C.; Springer, P. T.; Keenan, F. P.; Rose, S. J.; Goldstein, W. H. Bibcode: 2006JQSRT..99..712F Altcode: The charge state distributions of Fe, Na and F are determined in a photoionized laboratory plasma using high-resolution X-ray spectroscopy. Independent measurements of the density and radiation flux indicate the ionization parameter ξ in the plasma reaches values ξ=20 25ergcms under near steady-state conditions. A curve-of-growth analysis, which includes the effects of velocity gradients in a one-dimensional expanding plasma, fits the observed line opacities. Absorption lines are tabulated in the wavelength region 8 17Å. Initial comparisons with a number of astrophysical X-ray photoionization models show reasonable agreement. Title: Observational Evidence of Gentle Chromospheric Evaporation during the Impulsive Phase of a Solar Flare Authors: Milligan, Ryan O.; Gallagher, Peter T.; Mathioudakis, Mihalis; Keenan, Francis P. Bibcode: 2006ApJ...642L.169M Altcode: 2006astro.ph..3652M Observational evidence of gentle chromospheric evaporation during the impulsive phase of a C9.1 solar flare is presented using data from the Reuven Ramaty High-Energy Solar Spectroscopic Imager and the Coronal Diagnostic Spectrometer on board the Solar and Heliospheric Observatory. Until now, evidence of gentle evaporation has often been reported during the decay phase of solar flares, where thermal conduction is thought to be the driving mechanism. Here we show that the chromospheric response to a low flux of nonthermal electrons (>=5×109 ergs cm-2 s-1) results in plasma upflows of 13+/-16, 16+/-18, and 110+/-58 km s-1 in the cool He I and O V emission lines and the 8 MK Fe XIX line, respectively. These findings, in conjunction with other recently reported work, now confirm that the dynamic response of the solar atmosphere is sensitively dependent on the flux of incident electrons. Title: Electron impact excitation of Fe XVI: radiative and excitation rates Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2006A&A...450.1249A Altcode: Aims.In this paper we report calculations for energy levels, radiative rates, collision strengths, and effective collision strengths for transitions in Fe XVI.
Methods: . For energy levels and radiative rates we have used the General purpose Relativistic Atomic Structure Package (grasp), and for the compuations of collision strengths the Dirac Atomic R-matrix Code (darc) has been adopted.
Results: . Energies for the lowest 39 levels among the n ≤ 7 (ℓ ≤ 4) configurations of Fe XVI are reported. Additionally, radiative rates, oscillator strengths, and line strengths are reported for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions among these levels. Electron impact excitation collision strengths have also been calculated for all 741 transitions among the above 39 levels over a wide energy range up to 220 Ryd. Resonances have been resolved in the threshold region, and effective collision strengths have been obtained over a wide temperature range up to 107 K. Comparisons are made with the available results in the literature, and the accuracy of the present results is assessed.
Title: Sensitive HI Spectra Through the Arms of the SMC Authors: Muller, Erik; Smoker, Jonathan; Keenan, Francis Bibcode: 2006atnf.prop..152M Altcode: We request two complete 12 hour synthesis cycles of (total of ~24 hours) on the ATCA be allocated to obtaining high spatial resolution and sensitive measurements of the HI in the Magellanic Bridge, towards two continuum objects. These resulting data will be of sufficient spatial and velocity resolution to combine with proposed UVES spectroscopic measurements to enable accurate and precise measurements of the relative Ca II K/HI abundance levels in three different parts of the SMC: through two unrelated locations in the 'transverse' arm of the SMC, and one sight line through the 'radial' arm. We will therefore be probing, for the first time, the abundance levels of the kinematically distinct and tidally-generated arms of the SMC. Title: Early-type stars observed in the ESO UVES Paranal Observatory Project - I. Interstellar NaI UV, TiII and CaII K observations* Authors: Hunter, I.; Smoker, J. V.; Keenan, F. P.; Ledoux, C.; Jehin, E.; Cabanac, R.; Melo, C.; Bagnulo, S. Bibcode: 2006MNRAS.367.1478H Altcode: 2006astro.ph..1363H; 2006MNRAS.tmp..277H We present an analysis of interstellar NaI (λair= 3302.37 and 3302.98 Å), TiII(λair= 3383.76 Å) and CaII K (λair= 3933.66 Å) absorption features for 74 sightlines towards O- and B-type stars in the Galactic disc. The data were obtained from the Ultraviolet and Visual Echelle Spectrograph Paranal Observatory Project, at a spectral resolution of 3.75 km s-1 and with mean signal-to-noise ratios per pixel of 260, 300 and 430 for the NaI, TiII and CaII observations, respectively. Interstellar features were detected in all but one of the TiII sightlines and all of the CaII sightlines. The dependence of the column density of these three species with distance, height relative to the Galactic plane, HI column density, reddening and depletion relative to the solar abundance has been investigated. We also examine the accuracy of using the NaI column density as an indicator of that for HI. In general, we find similar strong correlations for both Ti and Ca, and weaker correlations for Na. Our results confirm the general belief that Ti and Ca occur in the same regions of the interstellar medium (ISM) and also that the TiII/CaII ratio is constant over all parameters. We hence conclude that the absorption properties of Ti and Ca are essentially constant under the general ISM conditions of the Galactic disc. Title: An investigation of Fe XV emission lines in solar flare spectra Authors: Keenan, F. P.; Aggarwal, K. M.; Bloomfield, D. S.; Msezane, A. Z.; Widing, K. G. Bibcode: 2006A&A...449.1203K Altcode: 2005astro.ph.12571K Previously, large discrepancies have been found between theory and observation for Fe XV emission line ratios in solar flare spectra covering the 224-327 Å wavelength range, obtained by the Naval Research Laboratory's S082A instrument on board Skylab. These discrepancies have been attributed to either errors in the adopted atomic data or the presence of additional atomic processes not included in the modelling, such as fluorescence. However our analysis of these plus other S082A flare observations (the latter containing Fe XV transitions between 321-482 Å), performed using the most recent Fe XV atomic physics calculations in conjunction with a chianti synthetic flare spectrum, indicate that blending of the lines is primarily responsible for the discrepancies. As a result, most Fe XV lines cannot be employed as electron density diagnostics for solar flares, at least at the spectral resolution of S082A and similar instruments (i.e. 0.1 Å). An exception is the intensity ratio I(3s3p 3P{2}-3p2 3P{1})/I(3s3p 3P{2}-3p2 1D{2}) = I(321.8 Å)/I(327.0 Å), which appears to provide good estimates of the electron density at this spectral resolution. Title: VizieR Online Data Catalog: RR Tel JHKL photometry 1975-2002 (Kotnik-Karuza+, 2006) Authors: Kotnik-Karuza, D.; Friedjung, M.; Whitelock, P. A.; Marang, F.; Exter, K.; Keenan, F. P.; Pollacco, D. L. Bibcode: 2006yCat..34520503K Altcode: The file table1.dat contains a list of JHKL magnitudes monitored from the South African Astronomical Observatory (SAAO) from 1975 to 2002. The JHKL magnitudes are accurate to better than 0.03mag in JHK and 0.05mag at L. Some of the early data, which had been published in Feast et al. (1983MNRAS.202..951F), were subsequently slightly corrected to the SAAO system as defined by Carter (1990MNRAS.242....1C).

(1 data file). Title: RHESSI and SOHO CDS Observations of Explosive Chromospheric Evaporation Authors: Milligan, Ryan O.; Gallagher, Peter T.; Mathioudakis, Mihalis; Bloomfield, D. Shaun; Keenan, Francis P.; Schwartz, Richard A. Bibcode: 2006ApJ...638L.117M Altcode: 2005astro.ph..9664M Simultaneous observations of explosive chromospheric evaporation are presented using data from the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) and the Coronal Diagnostic Spectrometer (CDS) on board the Solar and Heliospheric Observatory. For the first time, cospatial imaging and spectroscopy have been used to observe explosive evaporation within a hard X-ray emitting region. RHESSI X-ray images and spectra were used to determine the flux of nonthermal electrons accelerated during the impulsive phase of an M2.2 flare. When we assumed a thick-target model, the injected electron spectrum was found to have a spectral index of ~7.3, a low-energy cutoff of ~20 keV, and a resulting flux of >=4×1010 ergs cm-2 s-1. The dynamic response of the atmosphere was determined using CDS spectra; we found a mean upflow velocity of 230+/-38 km s-1 in Fe XIX (592.23 Å) and associated downflows of 36+/-16 and 43+/-22 km s-1 at chromospheric and transition region temperatures, respectively, relative to an averaged quiet-Sun spectra. The errors represent a 1 σ dispersion. The properties of the accelerated electron spectrum and the corresponding evaporative velocities were found to be consistent with the predictions of theory. Title: VizieR Online Data Catalog: Fe XVI radiative and excitation rates (Aggarwal+, 2006) Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2006yCat..34501249A Altcode: In this paper we report calculations for energy levels, radiative rates, collision strengths, and effective collision strengths for transitions in Fe XVI.

For energy levels and radiative rates we have used the General purpose Relativistic Atomic Structure Package (GRASP), and for the computations of collision strengths the Dirac Atomic R-matrix Code (DARC) has been adopted.

Energies for the lowest 39 levels among the n<=7 (l<=4) configurations of Fe XVI are reported. Additionally, radiative rates, oscillator strengths, and line strengths are reported for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions among these levels. Electron impact excitation collision strengths have also been calculated for all 741 transitions among the above 39 levels over a wide energy range up to 220 Ryd. Resonances have been resolved in the threshold region, and effective collision strengths have been obtained over a wide temperature range up to 107K. Comparisons are made with the available results in the literature, and the accuracy of the present results is assessed.

(5 data files). Title: Serendipitous Asteroid Lightcurve Survey Using SuperWASP Authors: Parley, N. R.; McBride, N.; Green, S. F.; Haswell, C. A.; Clarkson, W. I.; Christian, D. J.; Collier-Cameron, A.; Evans, N. A.; Fitzsimmons, A.; Hellier, C.; Hodgkin, S. T.; Horne, K.; Irwin, J.; Kane, S. R.; Keenan, F. P.; Lister, T. A.; Norton, A. J.; Osborne, J. P.; Pollacco, D.; Ryans, R.; Skillen, I.; Street, R. A.; West, R. G.; Wheatley, P. J. Bibcode: 2005EM&P...97..261P Altcode: The SuperWASP project is an ultra-wide angle search for extra solar planetary transits. However, it can also serendipitously detect solar system objects, such as asteroids and comets. Each SuperWASP instrument consists of up to eight cameras, combined with high-quality peltier-cooled CCDs, which photometrically survey large numbers of stars in the magnitude range 7 15. Each camera covers a 7.8 × 7.8 degree field of view. Located on La Palma, the SuperWASP-I instrument has been observing the Northern Hemisphere with five cameras since its inauguration in April 2004. The ultra-wide angle field of view gives SuperWASP the possibility of discovering new fast moving (near to Earth) asteroids that could have been missed by other instruments. However, it provides an excellent opportunity to produce a magnitude-limited lightcurve survey of known main belt asteroids. As slow moving asteroids stay within a single SuperWASP field for several weeks, and may be seen in many fields, a survey of all objects brighter than magnitude 15 is possible. This will provide a significant increase in the total number of lightcurves available for statistical studies without the inherent bias against longer periods present in the current data sets. We present the methodology used in the automated collection of asteroid data from SuperWASP and some of the first examples of lightcurves from numbered asteroids. Title: Preliminary Results from Secis Observations of the 2001 Total Solar Eclipse Authors: Katsiyannis, A. C.; Williams, D. R.; Murtagh, F.; McAteer, R. T. J.; Keenan, F. P. Bibcode: 2005ESASP.600E..86K Altcode: 2005ESPM...11...86K; 2005dysu.confE..86K No abstract at ADS Title: First Results from Secis Observations of the 2001 Total Solar Eclipse Authors: Katsiyannis, A. C.; Williams, D. R.; Murtagh, F.; McAteer, R. T. J.; Keenan, F. P. Bibcode: 2005ESASP.596E..45K Altcode: 2005ccmf.confE..45K No abstract at ADS Title: Ca II K observations of QSOs in the line-of-sight to the Magellanic Bridge Authors: Smoker, J. V.; Keenan, F. P.; Thompson, H. M. A.; Brüns, C.; Muller, E.; Lehner, N.; Lee, J. -K.; Hunter, I. Bibcode: 2005A&A...443..525S Altcode: 2005astro.ph.10507S We describe medium-resolution spectroscopic observations taken with the ESO Multi-Mode Instrument (emmi) in the Ca ii K line (λ_air=3933.661 Å) towards 7 QSOs located in the line-of-sight to the Magellanic Bridge. At a spectral resolution R = λ/Δλ = 6000, five of the sightlines have a signal-to-noise (S/N) ratio of 20 or higher. Definite Ca absorption due to Bridge material is detected towards 3 objects, with probable detection towards two other sightlines. Gas-phase Ca ii K Bridge and Milky Way abundances or lower limits for the all sightlines are estimated by the use of Parkes 21-cm H i emission line data. These data only have a spatial resolution of 14 arcmin compared with the optical observations which have milli-arcsecond resolution. With this caveat, for the three objects with sound Ca ii K detections, we find that the ionic abundance of Ca ii K relative to H i, A=log(N(Ca K)/N(H i)) for low-velocity Galactic gas ranges from -8.3 to -8.8 dex, with H i column densities varying from 3-6×1020 cm-2. For Magellanic Bridge gas, the values of A are 0.5 dex higher, ranging from -7.8 to -8.2 dex, with N(H i) = 1{-}5×1020 cm-2. Higher values of A correspond to lower values of N(H i), although numbers are small. For the sightline towards B 0251-675, the Bridge gas has two different velocities, and in only one of these is Ca ii tentatively detected, perhaps indicating gas of a different origin or present-day characteristics (such as dust content), although this conclusion is uncertain and there is the possibility that one of the components could be related to the Magellanic Stream. Higher signal-to-noise Ca ii K data and higher resolution H i data are required to determine whether A changes with N(H i) over the Bridge and if the implied difference in the metalicity of the two Bridge components towards B 0251-675 is real. Title: High-resolution spectroscopic observations of post-asymptotic giant branch candidates from the Edinburgh-Cape Survey Authors: Lynn, B. B.; Keenan, F. P.; Dufton, P. L.; Rolleston, W. R. J.; Smoker, J. V.; Ryans, R. S. I.; Kilkenny, D.; O'Donoghue, D.; Hambly, N.; McGillivray, H. T. Bibcode: 2005MNRAS.363..911L Altcode: 2005MNRAS.tmp..846L High spectral resolution (R~ 40000) and signal-to-noise optical spectra, obtained at the Very Large Telescope (VLT), are presented for three post-asymptotic giant branch (AGB) candidates selected from the Edinburgh-Cape (EC) Faint Blue Object Survey. The stellar atmospheric parameters and chemical compositions, derived using sophisticated non-local thermodynamic equilibrium calculations, reveal that EC 14102-1337 and EC 20068-7324 are both in an evolved post-horizontal branch (HB) evolutionary state. However, EC 11507-2253 is most likely a post-AGB star. Title: Plasma diagnostics of active-region evolution and implications for coronal heating Authors: Milligan, R. O.; Gallagher, P. T.; Mathioudakis, M.; Keenan, F. P.; Bloomfield, D. S. Bibcode: 2005MNRAS.363..259M Altcode: 2005MNRAS.tmp..764M; 2005astro.ph..9219M A detailed study is presented of the decaying solar-active region NOAA 10103 observed with the Coronal Diagnostic Spectrometer (CDS), the Michelson Doppler Imager (MDI) and the Extreme-ultraviolet Imaging Telescope (EIT) onboard the Solar and Heliospheric Observatory (SOHO). Electron-density maps formed using SiX (356.03 Å/347.41 Å) show that the density varies from ~1010cm-3 in the active-region core to ~7 × 108cm-3 at the region boundaries. Over the 5d of observations, the average electron density fell by ~30 per cent. Temperature maps formed using FeXVI (335.41 Å)/FeXIV (334.18 Å) show electron temperatures of ~2.34 × 106 K in the active-region core and ~2.10 × 106 K at the region boundaries. Similarly to the electron density, there was a small decrease in the average electron temperature over the 5-d period. The radiative, conductive and mass-flow losses were calculated and used to determine the resultant heating rate (PH). Radiative losses were found to dominate the active-region cooling process. As the region decayed, the heating rate decreased by almost a factor of 5 between the first and last day of observations. The heating rate was then compared to the total unsigned magnetic flux , yielding a power law of the form PH~Φ0.81+/-0.32tot. This result suggests that waves rather than nanoflares may be the dominant heating mechanism in this active region. Title: Electron impact excitation of Ar XVII Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2005A&A...441..831A Altcode: Energies for the lowest 49 levels among the 1s2 and 1snℓ (n = 2-5) configurations of Ar XVII have been calculated using the grasp code of Dyall et al. (1989, Comput. Phys. Comm., 55, 424). Additionally, radiative rates, oscillator strengths, and line strengths are calculated for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions among these levels. Furthermore, collision strengths have also been calculated for all the 1176 transitions among the above 49 levels using the Dirac Atomic R-matrix Code (DARC) of Norrington & Grant (2005, Comput. Phys. Commun., in preparation), over a wide energy range up to 580 Ryd. Resonances have been resolved in the threshold region, and effective collision strengths have been obtained over a wide temperature range up to log Te = 7.2 K. Comparisons are made with the limited results available in the literature, and the accuracy of the data is assessed. Our energy levels are estimated to be accurate to better than 0.1%, whereas results for other parameters are probably accurate to better than 20%. Title: Fe II emission lines of RR Tel during an obscuration event Authors: Kotnik-Karuza, D.; Friedjung, M.; Exter, K.; Keenan, F. P.; Pollacco, D. L. Bibcode: 2005AIPC..797..577K Altcode: A study of the behaviour of the permitted Fe II and forbidden [Fe II] emission lines during a dust obscuration episode, suggests a larger flux decrease for the permitted than for the forbidden lines. No other correlation with line properties have been found. Possible interpretations are discussed. Title: Effective collision strengths for transitions in Fe X Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2005A&A...439.1215A Altcode: Collision strengths for 4005 transitions among the lowest 90 levels of the (1s^22s^22p^6) 3s^23p^5, 3s3p^6, 3s^23p^43d, 3s3p^53d and 3s^23p^33d2 configurations of Fe X have been calculated using the Dirac Atomic R-matrix Code (DARC) of Norrington & Grant (2005, Comput. Phys. Commun., in preparation), over a wide energy range up to 210 Ryd. Resonances have been resolved in the threshold region, and effective collision strengths have been obtained over a wide temperature range up to 107 K. The present calculations should represent a significant improvement (in both range and accuracy) over the earlier available results of Bhatia & Doschek (1995, At. Data Nucl. Data Tables, 60, 97), Tayal (2001, ApJS, 132, 117) and Pelan & Berrington (2001, A&A, 365, 258). Based on several comparisons, the accuracy of our data is assessed to be better than 20%, for a majority of transitions. Title: An Analytic Geometry-variant Approach to Line Ratio Enhancement above the Optically Thin Limit Authors: Kerr, F. M.; Rose, S. J.; Wark, J. S.; Keenan, F. P. Bibcode: 2005ApJ...629.1091K Altcode: We describe a simple theoretical model to investigate the anomalous effects of opacity on spectral line ratios, as previously studied in elements such as Fe XV and Fe XVII. The model developed is general: it is not specific to a particular atomic system, thus giving applicability to a number of coronal and chromospheric plasmas; furthermore, it may be applied to a variety of astrophysically relevant geometries. The analysis is underpinned by geometrical arguments, and we outline a technique for it to be used as a tool for the explicit diagnosis of plasma geometry in distant astrophysical objects. Title: Modeling X-Ray Photoionized Plasmas Produced at the Sandia Z-Facility Authors: van Hoof, P. A. M.; Foord, M. E.; Heeter, R. F.; Bailey, J. E.; Chung, H. -K.; Cuneo, M. E.; Goldstein, W. H.; Jonauskas, V.; Keenan, F. P.; Kisielius, R.; Liedahl, D. A.; Ramsbottom, C.; Rose, S. J.; Springer, P. T.; Thoe, R. S. Bibcode: 2005Ap&SS.298..147V Altcode: 2005Ap&SS.298..147H In experiments at the high-power Z-facility at Sandia National Laboratory in Albuquerque, New Mexico, we have been able to produce a low density photoionized laboratory plasma of Fe mixed with NaF. The conditions in the experiment allow a meaningful comparison with X-ray emission from astrophysical sources. The charge state distributions of Fe, Na and F are determined in this plasma using high resolution X-ray spectroscopy. Independent measurements of the density and radiation flux indicate unprecedented values for the ionization parameter ξ = 20 25 erg cm s-1 under nearly steady-state conditions. First comparisons of the measured charge state distributions with X-ray photoionization models show reasonable agreement, although many questions remain. Title: Soft X-ray emission lines of Fe XV in spectra of the Sun and Capella Authors: Drake, J. J.; Keenan, F. P.; Chung, S.; Brickhouse, N. S.; Aggarwal, K. M.; Msezane, A. Z.; Ryans, R. S. I.; Bloomfield, D. S. Bibcode: 2005AIPC..774..349D Altcode: Recent calculations of atomic data for Fe XV have been used to generate theoretical line ratios involving n = 3-4 transitions in the soft X-ray spectral region (~52-83 Å) for a wide range of electron temperatures and densities applicable to solar and stellar coronal plasmas. The line ratio calculations are compared with solar flare observations from a rocket-borne spectrograph (XSST) and with a co-added spectra of Capella obtained with the Chandra LETGS, representing the highest signal-to-noise observation achieved for a stellar source in the 30-80 Å soft X-ray region. Results are promising for use of Fe XV as astrophysical plasma diagnostics: Agreement between theory and observation is generally good, after particular account is taken of line blending. The 82.76 Å emission line in the XSST spectrum is identified, for the first time to our knowledge in an astrophysical source, as the 3s3d 3D3-3s4p 3P2 transition of Fe XV. Title: Energy levels and radiative rates for transitions in Ar XIII, Ar XIV and Ar XV Authors: Aggarwal, K. M.; Keenan, F. P.; Nakazaki, S. Bibcode: 2005A&A...436.1141A Altcode: Energies for 524 levels of Ar XIII, 460 levels of Ar XIV and 156 levels of Ar XV have been calculated using the grasp code of Dyall et al. (1989). Additionally, radiative rates, oscillator strengths, and line strengths are calculated for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions among these levels. Comparisons are made with the limited results available in the literature, and the accuracy of the data is assessed. Our energy levels are estimated to be accurate to better than 1%, whereas results for other parameters are probably accurate to better than 20%. Additionally, the level lifetimes derived from our radiative rates are in excellent agreement with measured values. Title: VizieR Online Data Catalog: Electron impact excitation of Ar XVII (Aggarwal+, 2005) Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2005yCat..34410831A Altcode: Energies for the lowest 49 levels among the 1s^2 and 1snl (n=2-5) configurations of Ar XVII have been calculated using the GRASP code of Dyall et al. (1989, Comput. Phys. Commun., 55, 424). Additionally, radiative rates, oscillator strengths, and line strengths are calculated for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions among these levels. Furthermore, collision strengths have also been calculated for all the 1176 transitions among the above 49 levels using the Dirac Atomic R-matrix Code (DARC) of Norrington & Grant (2005, Comput. Phys. Commun., in prep.), over a wide energy range up to 580Ryd. Resonances have been resolved in the threshold region, and effective collision strengths have been obtained over a wide temperature range up to log Te=7.2K. Comparisons are made with the limited results available in the literature, and the accuracy of the data is assessed. Our energy levels are estimated to be accurate to better than 0.1%, whereas results for other parameters are probably accurate to better than 20%.

(8 data files). Title: Fe XI Emission Lines in a High-Resolution Extreme-Ultraviolet Active Region Spectrum Obtained by the Solar Extreme Ultraviolet Research Telescope and Spectrograph Authors: Keenan, F. P.; Aggarwal, K. M.; Ryans, R. S. I.; Milligan, R. O.; Bloomfield, D. S.; Brosius, J. W.; Davila, J. M.; Thomas, R. J. Bibcode: 2005ApJ...624..428K Altcode: 2005astro.ph..4106K New calculations of radiative rates and electron impact excitation cross sections for Fe XI are used to derive emission-line intensity ratios involving 3s23p4-3s23p33d transitions in the 180-223 Å wavelength range. These ratios are subsequently compared with observations of a solar active region obtained during the 1995 flight of the Solar Extreme Ultraviolet Research Telescope and Spectrograph (SERTS). The version of SERTS flown in 1995 incorporated a multilayer grating that enhanced the instrumental sensitivity for features in the ~170-225 Å wavelength range, observed in second order between 340 and 450 Å. This enhancement led to the detection of many emission lines not seen on previous SERTS flights, which were measured with the highest spectral resolution (0.03 Å) ever achieved for spatially resolved active region spectra in this wavelength range. However, even at this high spectral resolution, several of the Fe XI lines are found to be blended, although the sources of the blends are identified in the majority of cases. The most useful Fe XI electron density diagnostic line intensity ratio is I(184.80 Å)/I(188.21 Å). This ratio involves lines close in wavelength and free from blends, and it varies by a factor of 11.7 between Ne=109 and 1011 cm-3 yet shows little temperature sensitivity. An unknown line in the SERTS spectrum at 189.00 Å is found to be due to Fe XI, the first time (to our knowledge) this feature has been identified in the solar spectrum. Similarly, there are new identifications of the Fe XI 192.88, 198.56, and 202.42 Å features, although the latter two are blended with S VIII/Fe XII and Fe XIII, respectively. Title: VizieR Online Data Catalog: Effective collision strengths for Fe X trans. (Aggarwal+, 2005) Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2005yCat..34391215A Altcode: Collision strengths for 4005 transitions among the lowest 90 levels of the (1s22s22p6) 3s23p5, 3s3p6, 3s23p43d, 3s3p53d and 3s23p33d2 configurations of Fe X have been calculated using the Dirac Atomic R-matrix Code (DARC) of Norrington & Grant (2005, Comput. Phys. Commun. , in prep.), over a wide energy range up to 210Ryd. Resonances have been resolved in the threshold region, and effective collision strengths have been obtained over a wide temperature range up to 107K. The present calculations should represent a significant improvement (in both range and accuracy) over the earlier available results of Bhatia & Doschek (1995, At. Data Nucl. Data Tables, 60, 97), Tayal (2001ApJS..132..117T) and Pelan & Berrington (2001A&A...365..258P). Based on several comparisons, the accuracy of our data is assessed to be better than 20%, for a majority of transitions.

(4 data files). Title: Chromospheric Response to Non-Thermal Electrons During Flares Using RHESSI and SOHO/CDS Authors: Milligan, R. O.; Gallagher, P. T.; Mathioudakis, M.; Keenan, F. P. Bibcode: 2005AGUSMSP52A..04M Altcode: Many current solar flare models predict a relationship between the amount of energy deposited in the chromospheric and transition region layers of the solar atmosphere by non-thermal electrons, and the velocity at which this superheated material rises. For the first time, we present findings from simultaneous observations of loop footpoints using RHESSI and SOHO/CDS. RHESSI HXR images and spectra are used to determine the flux of non-thermal electrons using the thick-target bremsstrahlung model, while upflow velocities in the Fe XIX emission line are observed using CDS. Title: The Application Of À Trous Wave Filtering And Monte Carlo Analysis On Secis 2001 Solar Eclipse Observations Authors: Katsiyannis, A. C.; Murtagh, F.; Keenan, F. P. Bibcode: 2005SoPh..228..323K Altcode: 2005astro.ph..4181K Eight thousand images of the solar corona were captured during the June 2001 total solar eclipse. New software for the alignment of the images and an automated technique for detecting intensity oscillations using multi-scale wavelet analysis were developed. Large areas of the images covered by the Moon and the upper corona were scanned for oscillations and the statistical properties of the atmospheric effects were determined. The à Trous wavelet transform was used for noise reduction and Monte Carlo analysis as a significance test of the detections. The effectiveness of those techniques is discussed in detail. Title: Energy levels and transition probabilities for nitrogen-like Fe xx Authors: Jonauskas, V.; Bogdanovich, P.; Keenan, F. P.; Foord, M. E.; Heeter, R. F.; Rose, S. J.; Ferland, G. J.; Kisielius, R.; van Hoof, P. A. M.; Norrington, P. H. Bibcode: 2005A&A...433..745J Altcode: Energies of the 700 lowest levels in ion{Fe}{xx} have been obtained using the multiconfiguration Dirac-Fock method. Configuration interaction method on the basis set of transformed radial orbitals with variable parameters taking into account relativistic corrections in the Breit-Pauli approximation was used to crosscheck our presented results. Transition probabilities, oscillator and line strengths are presented for electric dipole (E1), electric quadrupole (E2) and magnetic dipole (M1) transitions among these levels. The total radiative transition probabilities from each level are also provided. Results are compared with data compiled by NIST and with other theoretical work.

Tables 8 to 10 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/433/745 Tables 1-7 are only available in electronic form at http://www.edpsciences.org Title: AB Dor: Evidence for stellar coronal opacity in Fe XVII Authors: Matranga, M.; Mathioudakis, M.; Kay, H. R. M.; Keenan, F. P. Bibcode: 2005ESASP.560..807M Altcode: 2005csss...13..807M No abstract at ADS Title: Variables in the Pleiades and Hyades from SuperWASP-I commissioning data Authors: Lister, T. A.; Collier Cameron, A.; Christian, D. J.; Clarkson, W. I.; Evans, N.; Fitzsimmons, A.; Haswell, C. A.; Hellier, C.; Hodgkin, S. T.; Horne, K.; Kane, S. R.; Keenan, F. P.; Norton, A. J.; Pollacco, D. L.; Ryans, R.; Skillen, I.; Street, R. A.; West, R. G.; Wheatley, P. J. Bibcode: 2005ESASP.560..763L Altcode: 2005csss...13..763L No abstract at ADS Title: Current status of the SuperWASP project Authors: Christian, D. J.; Pollacco, D. L.; Clarkson, W. I.; Collier Cameron, A.; Evans, N.; Fitzsimmons, A.; Haswell, C. A.; Hellier, C.; Hodgkin, S. T.; Horne, K.; Kane, S. R.; Keenan, F. P.; Lister, T. A.; Norton, A. J.; Ryans, R.; Skillen, I.; Street, R. A.; West, R. G.; Wheatley, P. J. Bibcode: 2005ESASP.560..475C Altcode: 2004astro.ph.11019C; 2005csss...13..475C We present the current status of the SuperWASP project, a Wide Angle Search for Planets. SuperWASP consists of up to 8 individual cameras using ultra-wide field lenses backed by high-quality passively cooled CCDs. Each camera covers 7.8 x 7.8 sq degrees of sky, for nearly 500 sq degrees of sky coverage. SuperWASP I, located in LaPalma, is currently operational with 5 cameras and is conducting a photometric survey of a large numbers of stars in the magnitude range ~7 to 15. The collaboration has developed a custom-built reduction pipeline and aims to achieve better than 1 percent photometric precision. The pipeline will also produce well sampled light curves for all the stars in each field which will be used to detect: planetary transits, optical transients, and track Near-Earth Objects. Status of current observations, and expected rates of extrasolar planetary detections will be presented. The consortium members, institutions, and further details can be found on the web site at: http://www.superwasp.org. Title: Magnetohydrodynamic mode coupling in the quiet-Sun network Authors: Bloomfield, D. S.; McAteer, R. T. J.; Mathioudakis, M.; Williams, D. R.; Keenan, F. P. Bibcode: 2005ESASP.560..449B Altcode: 2005csss...13..449B No abstract at ADS Title: Flare X-Ray Observations of AB Doradus: Evidence of Stellar Coronal Opacity Authors: Matranga, M.; Mathioudakis, M.; Kay, H. R. M.; Keenan, F. P. Bibcode: 2005ApJ...621L.125M Altcode: 2005astro.ph..2063M X-ray spectra of the late-type star AB Dor obtained with the XMM-Newton satellite are analyzed. AB Dor was particularly active during the observations. An emission measure reconstruction technique is employed to analyze flare and quiescent spectra, with emphasis on the Fe XVII 15-17 Å wavelength region. The Fe XVII 16.78 Å/15.01 Å line ratio increases significantly in the hotter flare plasma. This change in the ratio is opposite to the theoretical predictions and is attributed to the scattering of 15.01 Å line photons from the line of sight. The escape probability technique indicates an optical depth of ~0.4 for the 15.01 Å line. During the flare, the electron density is 4.4+2.7-1.6×1010 cm-3, and the fractional Fe abundance is 0.5+/-0.1 of the solar photospheric value. Using these parameters, a path length of ~8000 km is derived. There is no evidence of opacity in the quiescent X-ray spectrum of the star. Title: VizieR Online Data Catalog: Radiative rates in Ar XIII, Ar XIV & Ar XV (Aggarwal+, 2005) Authors: Aggarwal, K. M.; Keenan, F. P.; Nakazaki, S. Bibcode: 2005yCat..34361141A Altcode: Energies for 524 levels of Ar XIII, 460 levels of Ar XIV and 156 levels of Ar X V have been calculated using the GRAS code of Dyall et al. (1989, Comput. Phys. Commun, 55, 424). Additionally, radiative rates, oscillator strengths, and line strengths are calculated for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions among these levels. Comparisons are made with the limited results available in the literature, and the accuracy of the data is assessed. Our energy levels are estimated to be accurate to better than 1%, whereas results for other parameters are probably accurate to better than 20%. Additionally, the level lifetimes derived from our radiative rates are in excellent agreement with measured values.

(12 data files). Title: Electron impact excitation of Al XIII: A relativistic approach Authors: Aggarwal, K. M.; Keenan, F. P.; Rose, S. J. Bibcode: 2005A&A...432.1151A Altcode: Energy levels, radiative rates, collision strengths, and effective collision strengths for all transitions up to and including the n = 5 levels of Al XIII have been computed in the jj coupling scheme including relativistic effects. All partial waves with angular momentum J ≤ 60 have been included, and resonances have been resolved in a fine energy grid in the threshold region. Collision strengths are tabulated at energies above thresholds in the range 170.0 ≤ E ≤ 300.0 Ryd, and results for effective collision strengths, obtained after integrating the collision strengths over a Maxwellian distribution of electron velocities, are tabulated over a wide temperature range of 4.4 ≤ log Te ≤ 6.8 K. The importance of including relativistic effects in a calculation is discussed in comparison with the earlier available non-relativistic results.

Tables 2 4 are available only in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/432/1151 Title: VizieR Online Data Catalog: FeXX energy levels + transition probabilities (Jonauskas+, 2005) Authors: Jonauskas, V.; Bogdanovich, P.; Keenan, F. P.; Foord, E. M.; Heeter, R. F.; Rose, S. J.; Ferland, G. J.; Kisielius, R.; van Hoof, P. A. M.; Norrington, P. H. Bibcode: 2005yCat..34330745J Altcode: Energy levels and the corresponding transition probabilities as well as oscillator strengths and line strengths for allowed (E1) and forbidden (E2, M1) transitions among the lowest 700 levels of nitrogen-like Fe XX are presented. Calculations were performed using the multiconfigurational Dirac-Fock GRASP code.

(4 data files). Title: Observations of Hα Intensity Oscillations in a Flare Ribbon Authors: McAteer, R. T. James; Gallagher, Peter T.; Brown, Daniel S.; Bloomfield, D. Shaun; Moore, Ruth; Williams, David R.; Mathioudakis, Mihalis; Katsiyannis, A.; Keenan, Francis P. Bibcode: 2005ApJ...620.1101M Altcode: High-cadence Hα blue wing observations of a C9.6 solar flare obtained at Big Bear Solar Observatory using the Rapid Dual Imager are presented. Wavelet and time-distance methods were used to study oscillatory power along the ribbon, finding periods of 40-80 s during the impulsive phase of the flare. A parametric study found statistically significant intensity oscillations with amplitudes of 3% of the peak flare amplitude, periods of 69 s (14.5 mHz) and oscillation decay times of 500 s. These measured properties are consistent with the existence of flare-induced acoustic waves within the overlying loops. Title: Emission lines of FeXV in spectra obtained with the Solar Extreme-Ultraviolet Research Telescope and Spectrograph Authors: Keenan, F. P.; Aggarwal, K. M.; Milligan, R. O.; Ryans, R. S. I.; Bloomfield, D. S.; Srigengan, V.; O'Mullane, M. G.; Lawson, K. D.; Msezane, A. Z.; Brosius, J. W.; Davila, J. M.; Thomas, R. J. Bibcode: 2005MNRAS.356.1592K Altcode: 2004MNRAS.tmp..752K Recent R-matrix calculations of electron impact excitation rates in Mg-like FeXV are used to derive theoretical emission-line ratios involving transitions in the 243-418 Åwavelength range. A comparison of these with a data set of solar active region, subflare and off-limb spectra, obtained during rocket flights by the Solar Extreme-Ultraviolet Research Telescope and Spectrograph (SERTS), reveals generally very good agreement between theory and observation, indicating that most of the FeXV emission lines may be employed with confidence as electron density diagnostics. In particular, the 312.55-Åline of FeXV is not significantly blended with a CoXVII transition in active region spectra, as suggested previously, although the latter does make a major contribution in the subflare observations. Most of the FeXV transitions which are blended have had the species responsible clearly identified, although there remain a few instances where this has not been possible. We briefly address the long-standing discrepancy between theory and experiment for the intensity ratio of the 3s21S-3s3p 3P1 intercombination line at 417.25 Åto the 3s21S-3s3p 1P resonance transition at 284.16 Å. Title: Effective collision strengths for transitions in Fe XIII Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2005A&A...429.1117A Altcode: Effective collision strengths for transitions among the lowest 97 fine-structure levels belonging to the (1s22s22p6) 3s23p2, 3s3p3, 3s23p3d, 3p4, 3s3p23d and 3s23d2 configurations of Fe XIII have been calculated using the fully relativistic Dirac Atomic R-matrix Code (DARC) of Norrington & Grant (\cite{Norrington04}). Resonances have been resolved in the threshold region, and results are reported over a wide electron temperature range up to log Te = 6.8 K. Comparisons are made with the earlier available R-matrix results of Gupta & Tayal (\cite{Gupta98}), and the accuracy of the data is assessed.

Tables 2 and 3 are available only in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http :// cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/429/1117 Title: Modeling X-Ray Photoionized Plasmas Produced at the Sandia Z-Facility Authors: Van Hoof, P. A. M.; Foord, M. E.; Heeter, R. F.; Bailey, J. E.; Chung, H. -K.; Cuneo, M. E.; Goldstein, W. H.; Jonauskas, V.; Keenan, F. P.; Kisielius, R.; Liedahl, D. A.; Ramsbottom, C.; Rose, S. J.; Springer, P. T.; Thoe, R. S. Bibcode: 2005hedl.book..147V Altcode: In experiments at the high-power Z-facility at Sandia National Laboratory in Albuquerque, New Mexico, we have been able to produce a low density photoionized laboratory plasma of Fe mixed with NaF. The conditions in the experiment allow a meaningful comparison with X-ray emission from astrophysical sources. The charge state distributions of Fe, Na and F are determined in this plasma using high resolution X-ray spectroscopy. Independent measurements of the density and radiation flux indicate unprecedented values for the ionization parameter ξ = 20-25 erg cm s-1 under nearly steady-state conditions. First comparisons of the measured charge state distributions with X-ray photoionization models show reasonable agreement, although many questions remain. Title: Initial Results from Secis Observations of the 2001 Eclipse Authors: Katsiyannis, A. C.; Williams, D. R.; Murtagh, F.; McAteer, R. T. J.; Keenan, F. P. Bibcode: 2004ESASP.575..410K Altcode: 2004soho...15..410K; 2003astro.ph.11534K SECIS observations of the June 2001 total solar eclipse were taken using an Fe xiv 5303 A filter. Existing software was modified and new code was developed for the reduction and analysis of these data. The observations, data reduction, study of the atmospheric and instrumental effects, together with some preliminary results are discussed. Emphasis is given to the techniques used for the automated alignment of the 8000 images, the application of the a Trous algorithm for noise filtering and the software developed for the automated detection of intensity oscillations using wavelet analysis. In line with findings from the 1999 SECIS total eclipse observations, intensity oscillations with periods in the range of 20-30 s, both inside and just outside coronal loops are also presented. Title: New results about dust in the envelope of the symbiotic nova RR Tel Authors: Kotnik-Karuza, D.; Friedjung, M.; Exter, K.; Keenan, F. P.; Pollacco, D. L.; Whitelock, P. A. Bibcode: 2004ASPC..318..363K Altcode: 2004ssrc.conf..363K We have examined the changes of line fluxes of RR Tel in the optical spectra taken in 2000 compared with the corresponding ones of the spectra taken in 1996. The fading of the lines leading to the apparent decrease of the radius of the line emitting region can be understood as being spurious and explained by increased circumstellar dust absorption in the stellar wind of the mira. This dust obscuration event has given clues about stratification effects in the emitting region. In addition, infrared photometry performed from SAAO shows a change in the nature of colour behaviour. It is not yet clear if that is due to a change in dust properties. Title: Spectroscopy: Spectroscopy of astrophysic al plasmas in the laboratory Authors: Keenan, F. P.; Rose, S. J. Bibcode: 2004A&G....45f..18K Altcode: Most of the matter in the universe is in the form of a plasma. Over the past few years physicists have produced laboratory plasmas that can mimic those observed in astrophysics. The best known is probably the tokamak, which has similar physical conditions and plasma processes to those found in collisionally dominated solar and stellar transition regions and coronae. Spectroscopy of such laboratory plasmas, in particular at ultraviolet and X-ray wavelengths, has greatly aided our understanding of their astrophysical counterparts. More recently, experiments have been performed on the Z Machine at the Sandia National Laboratory in the USA with the aim of creating, for the first time, steady-state photoionization-dominated plasmas that recreate the conditions found in some accretion-powered X-ray sources, such as X-ray binaries. In the future, experiments are envisaged with laser-produced plasmas at AWE Aldermaston that may be able to mimic the steady-state conditions found in high-energy accretion-powered sources, including the central regions of active galaxies. Title: The behaviour of the Fe II emission lines of the symbiotic mira RR Tel during an obscuration event Authors: Friedjung, M.; Kotnik-Karuza, D.; Exter, K.; Keenan, F. P.; Pollacco, D. L. Bibcode: 2004sf2a.conf..289F Altcode: 2004sf2a.confE.311K RR Tel, like other symbiotic miras, is a binary containing a giant, which is a mira variable, and a compact component. According to present day ideas, the latter is a white dwarf, accreting from the mira wind. The wind contains dust; during "obscuration events" absorption due to this dust increases temporarily. At present we are comparing relative fluxes of optical Fe II emission lines at two dates, of which one was during an obscuration event and the other not during such an event, in order to obtain information on the changes in the distribution of dust between the two dates and the physics involved. Title: Wavelet Phase Coherence Analysis: Application to a Quiet-Sun Magnetic Element Authors: Bloomfield, D. Shaun; McAteer, R. T. James; Lites, Bruce W.; Judge, Philip G.; Mathioudakis, Mihalis; Keenan, Francis P. Bibcode: 2004ApJ...617..623B Altcode: A new application of wavelet analysis is presented that utilizes the inherent phase information residing within the complex Morlet transform. The technique is applied to a weak solar magnetic network region, and the temporal variation of phase difference between TRACE 1700 Å and SOHO/SUMER C II 1037 Å intensities is shown. We present, for the first time in an astrophysical setting, the application of wavelet phase coherence, including a comparison between two methods of testing real wavelet phase coherence against that of noise. The example highlights the advantage of wavelet analysis over more classical techniques, such as Fourier analysis, and the effectiveness of the former to identify wave packets of similar frequencies but with differing phase relations is emphasized. Using cotemporal, ground-based Advanced Stokes Polarimeter measurements, changes in the observed phase differences are shown to result from alterations in the magnetic topology. Title: Current Status of the SuperWASP Project Authors: Clarkson, W. I.; Christian, D. C.; Collier-Cameron, A.; Evans, N.; Fitzsimmons, A.; Haswell, C. A.; Hellier, C.; Hodgkin, S. T.; Horne, K. D.; Kane, S. R.; Keenan, F. P.; Lister, T. A.; Norton, A. J.; Pollacco, D. L.; Ryans, R.; Skillen, I.; Street, R. A.; West, R. G.; Wheatley, P. J. Bibcode: 2004AAS...20517101C Altcode: 2005BAAS...37..375C We present the current status of the SuperWASP project, an ultra-wide angle search for exoplanetary transits. Each instrument consists of up to eight cameras backed by high-quality passively-cooled CCDs, to photometrically survey large numbers of stars in the magnitude range 7-15. Each camera covers a largely distinct 7.8x7.8-degree field of view, as a result of which roughly 25,000 stars brighter than 13th magnitude are surveyed per field per camera for exoplanet transit events. Located on La Palma, the SuperWASP-I instrument has been observing the Northern Hemisphere with five cameras since its April 2004 inauguration. The resulting dataset provides an excellent opportunity to evaluate hardware and software performance, to optimise observing efficiency and inform the construction of the Southern-hemisphere SuperWASP-II instrument in 2005.

The collaboration has developed a custom-built reduction pipeline and aims to achive better than 1% photometric precision. Roughly four genuine transiting exoplanetary systems per field per camera will be detected through repeat transit events over the interval in which these systems are visible, though perhaps ten times this number of false-positives will also be observed. By monitoring a large number of fields over its lifetime, SuperWASP will provide ephemerides for roughly 104 systems exhibiting candidate exoplanet transits. These first-alarm ephemerides will be used to perform incremental followup observations of the candidates, separating out the false-positives and constraining the properties of the true exoplanets. The resulting planet harvest will increase the known exoplanet population by roughly an order of magnitude. The pipeline will also produce well-sampled lightcurves for all unblended objects in each field, providing a rich photometric dataset to pursue the secondary science goals of the project, including detection of optical transients and detailed studies of stellar variability at the 1% level.

SuperWASP is a consortium of Queen's University Belfast, The University of Cambridge, the Isaac Newton Group of Telescopes, Keele University, Leicester University, the Open University and St Andrews University. Title: Radiative rates for E1, E2, M1 and M2 transitions in Fe X Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2004A&A...427..763A Altcode: Energies of the 54 levels belonging to the (1s22s22p6) 3s23p5, 3s3p6, 3s23p43d and 3s3p53d configurations of Fe X have been calculated using the GRASP code of Dyall et al. (\cite{Dyall89}). Additionally, radiative rates, oscillator strengths, and line strengths are calculated for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions among these levels. Comparisons are made with results available in the literature, and the accuracy of the data is assessed. Our energy levels are estimated to be accurate to better than 3%, whereas results for other parameters are probably accurate to better than 20%. Additionally, the agreement between measured and calculated lifetimes is better than 10%.

Tables 2 and 3 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/427/763 Title: VizieR Online Data Catalog: Electron impact excitation of Al XIII (Aggarwal+, 2005) Authors: Aggarwal, K. M.; Keenan, F. P.; Rose, S. J. Bibcode: 2004yCat..34321151A Altcode: Energy levels, radiative rates, collision strengths, and effective collision strengths for all transitions up to and including the n=5 levels of Al XIII have been computed in the jj coupling scheme including relativistic effects. All partial waves with angular momentum J<=60 have been included, and resonances have been resolved in a fine energy grid in the threshold region. Collision strengths are tabulated at energies above thresholds in the range 170.0<=E<=300.0Ryd, and results for effective collision strengths, obtained after integrating the collision strengths over a Maxwellian distribution of electron velocities, are tabulated over a wide temperature range of 4.4<=logTe<=6.8K. The importance of including relativistic effects in a calculation is disc ussed in comparison with the earlier available non-relativistic results.

(4 data files). Title: Status of SuperWASP I (La Palma) Authors: Street, R. A.; Christian, D. J.; Clarkson, W. I.; Collier Cameron, A.; Evans, N.; Fitzsimmons, A.; Haswell, C. A.; Hellier, C.; Hodgkin, S. T.; Horne, K.; Kane, S. R.; Keenan, F. P.; Lister, T. A.; Norton, A. J.; Pollacco, D.; Ryans, R.; Skillen, I.; West, R. G.; Wheatley, P. J. Bibcode: 2004AN....325..565S Altcode: SuperWASP is an ultra-wide field (over 300 sq. degrees) photometric survey project designed to monitor stars between 7 - 15 mag to high precision and with high cadence over long (≥2 months) timescales. The primary science goal of this project is the detection of exoplanetary transits, as well as NEOs and optical transients. The resulting photometric catalogue will be made public via a web-based interface. The SuperWASP instrument consists of an array of cameras each with a 7.8° × 7.8° field of view, guided by a robotic fork mount and sited in a fibreglass enclosure at the Observatorio de Roque de los Muchachos (ORM), La Palma, Canary Islands. In this progress report, we describe the specifications of the instrument, its semi-automated operation and pipeline data reduction. Title: Enhancement of Optically Thick to Thin Line Intensities in Solar and Stellar Coronal Plasmas through Radiative Transfer Effects: An Angularly Resolved Study Authors: Kerr, F. M.; Rose, S. J.; Wark, J. S.; Keenan, F. P. Bibcode: 2004ApJ...613L.181K Altcode: An analysis of radiative transfer effects present in the Fe XV ion stage of solar and stellar coronal plasmas provides a general explanation of line radiation intensity enhancement above the optically thin limit. Full linearization radiation transfer is compared with the escape factor method and found to be in good agreement at the lower column densities. An angular study of the enhancement shows that symmetry factors are of great importance. This gives a possible reason for the indeterminate status of opacity in relation to coronal lines of distant stellar sources, where only emission integrated across the whole surface is detected. Title: A Detailed Study of Opacity in the Upper Atmosphere of Proxima Centauri Authors: Christian, D. J.; Mathioudakis, M.; Bloomfield, D. S.; Dupuis, J.; Keenan, F. P. Bibcode: 2004ApJ...612.1140C Altcode: We present far-UV and UV spectroscopic observations of Proxima Centauri obtained as part of our continued investigation into the optically thin approximation assumed for the transition regions of late-type stars. Significant opacity is found in the C III lines during both the quiescent and flaring states of Proxima Cen, with up to 70% of the expected flux being lost in the latter. Our findings cast some doubt on the suitability of the C III λ977 line for estimating the electron density in stellar atmospheres. However, the opacity has no significant effect on the observed line widths. We calculate optical depths for homogeneous and inhomogeneous geometries and estimate an electron density of 6×1010 cm-3 for the transition region using the O IV line ratios at 1400 Å. The combination of electron density and optical depth indicates path lengths as low as ~10 km, which are in excellent agreement with estimates of the small-scale structure seen in the solar transition region. Title: VizieR Online Data Catalog: Fe XIII effective collision strengths (Aggarwal+, 2005) Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2004yCat..34291117A Altcode: Effective collision strengths for transitions among the lowest 97 fine-structure levels belonging to the (1s22s22p6) 3s23p2, 3s3p3, 3s23p3d, 3p4, 3s3p23d and 3s23d2 configurations of Fe XIII have been calculated using the fully relativistic Dirac Atomic R-matrix Code (DARC) of Norrington & Grant (2004, Comput. Phys. Commun. - in prep.). Resonances have been resolved in the threshold region, and results are reported over a wide electron temperature range up to log Te=6.8K. Comparisons are made with the earlier available R-matrix results of Gupta & Tayal (1998ApJ...506..464G), and the accuracy of the data is assessed.

(4 data files). Title: High-resolution spectroscopic observations of B-type stars from the Edinburgh-Cape Survey - III. Completion of a magnitude range limited survey Authors: Lynn, B. B.; Keenan, F. P.; Dufton, P. L.; Kilkenny, D.; Rolleston, W. R. J.; Smoker, J. V.; Ryans, R. S. I.; Hambly, N.; McGillivray, H. T.; O'Donoghue, D. Bibcode: 2004MNRAS.353..633L Altcode: 2004MNRAS.tmp..271L High spectral resolution (R~ 40000) and signal-to-noise ratio observations of five high Galactic latitude early-type stars taken from the Edinburgh-Cape (EC) Faint Blue Object Survey are presented. These were required to complete a magnitude range-limited survey of young B-type objects with 11 < V < 15. Of the five stars, four were rejected on the grounds that they are either subluminous (subdwarf or horizontal branch), were part of a binary system or possessed colours later than the (U-B) =-0.5 cut-off employed. The remaining star in the data set, EC 19596-5356, is found to exhibit normal young B-type stellar properties. A kinematic analysis reveals that an origin in the Galactic disc appears likely for all the stars in the sample. Some statistics are drawn about the number density of young stars in the Galactic halo. Title: Dirac-Fock energy levels and transition probabilities for oxygen-like Fe XIX Authors: Jonauskas, V.; Keenan, F. P.; Foord, M. E.; Heeter, R. F.; Rose, S. J.; Ferland, G. J.; Kisielius, R.; van Hoof, P. A. M.; Norrington, P. H. Bibcode: 2004A&A...424..363J Altcode: Multiconfigurational Dirac-Fock calculations are reported for 656 energy levels and the 214 840 electric dipole (E1), electric quadrupole (E2) and magnetic dipole (M1) transition probabilities in oxygen-like Fe XIX. The spectroscopic notations as well as the total transition probabilities from each energy level are provided. Good agreement is found with data compiled by NIST.

Tables \ref{EnLevels} and \ref{RateLevels} are only available in electronic form at http://www.edpsciences.org

Tables 6 to 8 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/424/363 Title: VizieR Online Data Catalog: Fe XIX transition probabilities (Jonauskas+, 2004) Authors: Jonauskas, V.; Keenan, F. P.; Foord, M. E.; Heeter, R. F.; Rose, S. J.; Ferland, G. J.; Kisielius, R.; van Hoof, P. A. M.; Norrington, P. H. Bibcode: 2004yCat..34240363J Altcode: Energy levels and the corresponding transition probabilities as well oscillator strengths and line strengths for allowed (E1) and forbidden (E2, M1) transitions among the lowest 656 levels of oxygen-like Fe XIX are presented. Calculations were performed using the multiconfigurational Dirac-Fock GRASP code.

(3 data files). Title: CaII K interstellar observations towards early-type disc and halo stars - distances to intermediate- and high-velocity clouds Authors: Smoker, J. V.; Lynn, B. B.; Rolleston, W. R. J.; Kay, H. R. M.; Bajaja, E.; Poppel, W. G. L.; Keenan, F. P.; Kalberla, P. M. W.; Mooney, C. J.; Dufton, P. L.; Ryans, R. S. I. Bibcode: 2004MNRAS.352.1279S Altcode: 2004MNRAS.tmp..169S; 2004astro.ph..6038S We compare existing high spectral resolution (R=λ/Δλ~ 40000) CaII K observations (λair= 3933.66 Å) towards 88 mainly B-type stars, and new observations taken using the Intermediate dispersion Spectrograph and Imaging System (ISIS) on the William Herschel Telescope at R~ 10000 towards three stars taken from the Palomar-Green Survey, with 21-cm HI emission-line profiles, in order to search for optical absorption towards known intermediate- and high-velocity cloud complexes. Given certain assumptions, limits to the gas phase abundance of CaII are estimated for the cloud components. We use the data to derive the following distances from the Galactic plane (z). (i) Tentative lower z-height limits of 2800 and 4100 pc towards complex C using lack of absorption in the spectra of HD341617 and PG0855+294, respectively. (ii) A weak lower z-height of 1400 pc towards complex WA-WB using lack of absorption in EC09470-1433 and a weak lower limit of 2470 pc using lack of absorption in EC09452-1403. (iii) An upper z-height of 2470 pc towards a southern intermediate-velocity cloud (IVC) with vLSR=-55 km s-1 using PG2351+198. (iv) Detection of a possible IVC in CaII absorption at vLSR=+52 km s-1 using EC20104-2944. No associated HI in emission is detected. At this position, normal Galactic rotation predicts velocities of up to ~+25 km s-1. The detection puts an upper z-height of 1860 pc to the cloud. (v) Tentative HI and CaII K detections towards an IVC at ~+70 km s-1 in the direction of high-velocity cloud (HVC) complex WE, sightline EC06387-8045, indicating that the IVC may be at a z-height lower than 1770 pc. (vi) Detection of CaII K absorption in the spectrum of PG0855+294 in the direction of IV20, indicating that this IVC has a z-height smaller than 4100 pc. (vii) A weak lower z-height of 4300 pc towards a small HVC with vLSR=+115 km s-1 at l, b= 200°, + 52°, using lack of absorption in the CaII K spectrum of PG0955+291. Title: VizieR Online Data Catalog: FeX E1, E2, M1 and M2 transitions (Aggarwal+, 2004) Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2004yCat..34270763A Altcode: Energies of the 54 levels belonging to the (1s22s23p5, 3s3p6, 3s23p43d and 3s3p53d configurations of FeX have been calculated using the GRASP code of Dyall et al. (1989, Comput. Phys. Commun, 55, 424). Additionally, radiative rates, oscillator strengths, and line strengths are calculated for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions among these levels. Comparisons are made with results available in the literature, and the accuracy of the data is assessed. Our energy levels are estimated to be accurate to better than 3%, whereas results for other parameters are probably accurate to better than 20%. Additionally, the agreement between measured and calculated lifetimes is better than 10%.

(4 data files). Title: Erratum: ``Propagating Waves and Magnetohydrodynamic Mode Coupling in the Quiet-Sun Network'' (ApJ, 604, 936 [2004]) Authors: Bloomfield, D. Shaun; McAteer, R. T. James; Mathioudakis, Mihalis; Williams, David R.; Keenan, Francis P. Bibcode: 2004ApJ...609..465B Altcode: Proof corrections were not carried correctly to the final printed version of this paper, which resulted in an extra set of overbars appearing in both terms of the denominator of equation (3). The correct form of this equation is:C(Δt,ν)=(Σ[Pλ1(t,ν)-Pλ1(t,ν)][Pλ2(t+Δt,ν)-Pλ2(t+Δt,ν)])/(sqrt(Σ[Pλ1(t,ν)-Pλ1(t,ν)]2Σ[Pλ2(t,ν)-Pλ2(t,ν)]2)). (3)As noted in footnote 3, this correlation equation was stated incorrectly in our previous paper (eq. [4] in R. T. J. McAteer et al., ApJ, 604, 936 [2004]). However, the correct form of equation (3), now given here, was used for the analysis in both papers.

The press sincerely regrets this error. Title: High-resolution spectroscopy of globular cluster post-Asymptotic Giant Branch stars Authors: Mooney, C. J.; Rolleston, W. R. J.; Keenan, F. P.; Dufton, P. L.; Smoker, J. V.; Ryans, R. S. I.; Aller, L. H.; Trundle, C. Bibcode: 2004A&A...419.1123M Altcode: We present model atmosphere analyses of high resolution Keck and VLT optical spectra for three evolved stars in globular clusters, viz. ZNG-1 in M 10, ZNG-1 in M 15 and ZNG-1 in NGC 6712. The derived atmospheric parameters and chemical compositions confirm the programme stars to be in the post-Asymptotic Giant Branch (post-AGB) evolutionary phase. Differential abundance analyses reveal CNO abundance patterns in M 10 ZNG-1, and possibly M 15 ZNG-1, which suggest that both objects may have evolved off the AGB before the third dredge-up occurred. The abundance pattern of these stars is similar to the third class of optically, bright post-AGB objects discussed by van Winckel (\cite{van97}). Furthermore, M 10 ZNG-1 exhibits a large C underabundance (with \bigtriangleup[C/O] ∼ -1.6 dex), typical of other hot post-AGB objects. Differential \bigtriangleup[α/Fe] abundance ratios in both M 10 ZNG-1 and NGC 6712 ZNG-1 are found to be approximately 0.0 dex, with the Fe abundance of the former being in disagreement with the cluster metallicity of M 10. Given that the Fe absorption features in both M 10 ZNG-1 and NGC 6712 ZNG-1 are well observed and reliably modelled, we believe that these differential Fe abundance estimates to be secure. However, our Fe abundance is difficult to explain in terms of previous evolutionary processes that occur on both the Horizontal Branch and the AGB.

Equivalent width data table is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/419/1123 Title: Radiative rates for transitions in Fe XVII Authors: Aggarwal, K. M.; Keenan, F. P.; Kisielius, R. Bibcode: 2004A&A...420..783A Altcode: Energies of the lowest 157 levels belonging to the (1s2) 2s22p6, 2s22p53ℓ, 2s22p54ℓ, 2s22p55ℓ, 2s2p63ℓ, 2s2p64ℓ and 2s2p65ℓ configurations of Fe XVII have been calculated using the GRASP code of Dyall et al. (\cite{Dya89}). Additionally, radiative rates, oscillator strengths, and line strengths are calculated for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions among these levels. Comparisons are made with the results already available in the literature, and the accuracy of the data is assessed. Our energy levels are expected to be accurate to better than 1%, whereas results for other parameters are probably accurate to better than 20%.

Tables 2-5 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/420/783 Title: VizieR Online Data Catalog: Electron impact excitation of Fe XVII (Aggarwal+, 2004) Authors: Aggarwal, K. M.; Keenan, F. P.; Kisielius, R. Bibcode: 2004yCat..34200783A Altcode: Energies of the lowest 157 levels belonging to the (1s2) 2s 22p6, 2s 22p 53l, 2s 22p 54l, 2s 22p 55l, 2s2p 63l, 2s2p 64l and 2s2p 65l configurations of Fe XVII have been calculated using the GRASP code of Dyall et al. (1989, Comput. Phys. Commun., 55, 424). Additionally, radiative rates, oscillator strengths, and line strengths are calculated for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions among these levels. Comparisons are made with the results already available in the literature, and the accuracy of the data is assessed. Our energy levels are expected to be accurate to better than 1%, whereas results for other parameters are probably accurate to better than 20%.

(6 data files). Title: Plasma Diagnostics of Active Region Evolution and Implications for Coronal Heating Authors: Milligan, R. O.; Gallagher, P. T.; Mathioudakis, M.; Bloomfield, D. S.; Keenan, F. P. Bibcode: 2004AAS...204.9803M Altcode: 2004BAAS...36..984M The decaying solar active region NOAA 10103 was observed during 2002 September 10--14 using the Coronal Diagnostic Spectrometer (CDS) onboard the Solar and Heliospheric Observatory (SOHO). Electron density maps were created using the Si X (356Å/347Å) ratio, which show densities of ∼1010cm-3 in the active region core, and ∼7x108cm-3 in the region boundaries. Over the five days of observations, the average electron density fell by approximately a factor of two. Temperature maps were created using the Fe XVI (335.4Å)/Fe XIV (334.2Å) ratio, which show electron temperatures of ∼2.2x106K in the active region core, and ∼2.0x106K in the region boundaries. Similarly to the electron density, the average electron temperature decreased over the five days, but by only ∼3%. The radiative and conductive losses, and resultant heating rate, were then calculated and compared to the total unsigned magnetic flux (Φ tot = ∫ dA |Bz|) from Michelson Doppler Interferometer (MDI) magnetograms. Losses due to radiation were found to exceed conductive losses by a factor of ten. As the region decayed, the heating rate decreased by close to an order of magnitiude between the first and last day of observations. In line with several coronal heating theories, a power-law relationship of the form Ptot} ∼Φ {tot0.95±0.07 was found between the heating rate and the unsigned magnetic flux. This result provides further observational evidence for wave rather than nanoflare heating of solar active regions.

Ryan Milligan would like to thank the Solar Physics Division for being awarded an SPD Studentship. Title: Early-type stars in the Galactic halo from the Palomar-Green survey-III. Completion of a magnitude range limited sample Authors: Lynn, B. B.; Keenan, F. P.; Dufton, P. L.; Saffer, R. A.; Rolleston, W. R. J.; Smoker, J. V. Bibcode: 2004MNRAS.349..821L Altcode: High-resolution (R~ 40000) echelle spectroscopic observations of 13 high-latitude early-type stars are presented. These stars comprise the final part of a complete magnitude range limited sample based on low-resolution spectroscopy of targets drawn from the Palomar-Green survey. The magnitude range under consideration is 13 <=BPG<= 14.6, corresponding to an approximate distance limit for main-sequence B-type objects of 5 <=d<= 40 kpc. Three stars are found to be apparently normal, young stars, based on their positions on the (Teff, log g) diagram, normal abundance patterns and relatively large projected rotational velocities. A further star, PG 1209+263, was found to belong to the chemically peculiar (CP) silicon star class of objects. The remainder are evolved subluminous stars lying on post-horizontal branch (post-HB) tracks, with the exception of PG 2120+062, which appears to be in a post-asymptotic giant branch evolutionary stage. For the young stars in the sample, we have derived distance and age estimates through comparison of the atmospheric parameters with recent theoretical evolutionary models. We discuss formation scenarios by comparing times-of-flight and evolutionary time-scales. It is found that all stars could have formed in the Galactic disc and been ejected from there soon after their birth, with the exception of PG 1209+263. The adopted proper motion is found to be a crucial factor in the kinematical analysis. We also present some number densities for young B-type halo stars, which indicate that they are extremely scarce objects. Title: Propagating Waves and Magnetohydrodynamic Mode Coupling in the Quiet-Sun Network Authors: Bloomfield, D. Shaun; McAteer, R. T. James; Mathioudakis, Mihalis; Williams, David R.; Keenan, Francis P. Bibcode: 2004ApJ...604..936B Altcode: High-cadence multiwavelength optical observations were taken with the Dunn Solar Telescope at the National Solar Observatory, Sacramento Peak, accompanied by Advanced Stokes Polarimeter vector magnetograms. A total of 11 network bright points (NBPs) have been studied at different atmospheric heights using images taken in wave bands centered on Mg I b1 - 0.4 Å, Hα, and Ca II K3. Wavelet analysis was used to study wave packets and identify traveling magnetohydrodynamic waves. Wave speeds were estimated through the temporal cross-correlation of signals, in selected frequency bands of wavelet power, in each wavelength. Four mode-coupling cases were identified, one in each of four of the NBPs, and the variation of the associated Fourier power with height was studied. Three of the detected mode-coupling, transverse-mode frequencies were observed in the 1.2-1.6 mHz range (mean NBP apparent flux density magnitudes over 99-111 Mx cm-2), with the final case showing 2.0-2.2 mHz (with 142 Mx cm-2). Following this, longitudinal-mode frequencies were detected in the range 2.6-3.2 mHz for three of our cases, with 3.9-4.1 mHz for the remaining case. After mode coupling, two cases displayed a decrease in longitudinal-mode Fourier power in the higher chromosphere. Title: Electron impact excitation of Fe XIII Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2004A&A...418..371A Altcode: Energy levels and radiative rates for transitions among the lowest 97 fine-structure levels belonging to the (1s22s22p6) 3s23p2, 3s3p3, 3s23p3d, 3p4, 3s3p23d and 3s23d2 configurations of Fe XIII have been calculated using the fully relativistic GRASP code. Additionally, collision strengths for transitions among these levels have been computed using the Dirac Atomic R-matrix Code (DARC) of Norrington & Grant (\cite{Norrington04}). Radiative rates and oscillator strengths are tabulated for all allowed transitions among the 97 fine-structure levels, while collision strengths are reported for some transitions at a few energies above thresholds. Comparisons are made with the available results, and the accuracy of the data is assessed.

Table 2 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/418/371 Title: Time signatures of impulsively generated coronal fast wave trains Authors: Nakariakov, V. M.; Arber, T. D.; Ault, C. E.; Katsiyannis, A. C.; Williams, D. R.; Keenan, F. P. Bibcode: 2004MNRAS.349..705N Altcode: Impulsively generated short-period fast magneto-acoustic wave trains, guided by solar and stellar coronal loops, are numerically modelled. In the developed stage of the evolution, the wave trains have a characteristic quasi-periodic signature. The quasi-periodicity results from the geometrical dispersion of the guided fast modes, determined by the transverse profile of the loop. A typical feature of the signature is a tadpole wavelet spectrum: a narrow-spectrum tail precedes a broad-band head. The instantaneous period of the oscillations in the wave train decreases gradually with time. The period and the spectral amplitude evolution are shown to be determined by the steepness of the transverse density profile and the density contrast ratio in the loop. The propagating wave trains recently discovered with the Solar Eclipse Coronal Imaging System (SECIS) instrument are noted to have similar wavelet spectral features, which strengthens the interpretation of SECIS results as guided fast wave trains. Title: Improved data for solar flare X-ray spectral analysis Authors: Phillips, K. J. H.; Rainnie, J. A.; Harra, L. K.; Dubau, J.; Keenan, F. P.; Peacock, N. J. Bibcode: 2004A&A...416..765P Altcode: The inclusion of collisional rates for He-like Fe and Ca ions is discussed with reference to the analysis of solar flare Fe XXV and Ca XIX line emission, particularly from the Yohkoh Bragg Crystal Spectrometer (BCS). The new data are a slight improvement on calculations presently used in the BCS analysis software in that the discrepancy in the Fe XXV y and z line intensities (observed larger than predicted) is reduced. Values of electron temperature from satellite-to-resonance line ratios are slightly reduced (by up to 1 MK) for a given observed ratio. The new atomic data will be incorporated in the Yohkoh BCS databases. The data should also be of interest for the analysis of high-resolution, non-solar spectra expected from the Constellation-X and Astro-E space missions. A comparison is made of a tokamak S XV spectrum with a synthetic spectrum using atomic data in the existing software and the agreement is found to be good, so validating these data for particularly high-n satellite wavelengths close to the S XV resonance line. An error in a data file used for analyzing BCS Fe XXVI spectra is corrected, so permitting analysis of these spectra. Title: VizieR Online Data Catalog: Equivalent widths of 3 post-AGB (Mooney+, 2004) Authors: Mooney, C. J.; Rolleston, W. R. J.; Keenan, F. P.; Dufton, P. L.; Smoker, J. V.; Ryans, R. S. I.; Aller, L. H.; Trundle, C. Bibcode: 2004yCat..34191123M Altcode: NGC 6712 ZNG-1 was observed on the 4 July 2000 with the 10m Keck I telescope. M10 ZNG-1 and M15 ZNG-1 were observed during the period 01-03 July 2001 with the 8m VLT KUEYEN telescope.

The table presents absorption line equivalent widths (in m{AA}) for the 3 globular cluster stars: M10 ZNG-1, M15 ZNG-1 and NGC 6712 ZNG-1. The first column lists the species, the second the rest wavelength for the line, and columns 3-5 list the equivalent widths (where measurable). Where 2 wavelengths are given for a single species, the measured line equivalent width is a blend.

(1 data file). Title: Search for 1-10 Hz modulations in coronal emission with SECIS during the August 11, 1999 eclipse Authors: Rudawy, P.; Phillips, K. J. H.; Gallagher, P. T.; Williams, D. R.; Rompolt, B.; Keenan, F. P. Bibcode: 2004A&A...416.1179R Altcode: Results of the search of the periodic changes of the 530.3 nm line intensity emitted by selected structures of the solar corona in the frequency range 1-10 Hz are presented. A set of 12 728 images of the section of the solar corona extending from near the north pole to the south-west were taken simultaneously in the 530.3 nm (``green'') line and white-light with the Solar Eclipse Coronal Imaging System (SECIS) during the 143-seconds-long totality of the 1999 August 11 solar eclipse observed in Shabla, Bulgaria. The time resolution of the collected data is better than 0.05 s and the pixel size is approximately 4 arcsec. Using classical Fourier spectral analysis tools, we investigated temporal changes of the local 530.3 nm coronal line brightness in the frequency range 1-10 Hz of thousands of points within the field of view. The various photometric and instrumental effects have been extensively considered. We did not find any indisputable, statistically significant evidence of periodicities in any of the investigated points (at significance level α=0.05). Title: Relativistic allowed and forbidden transition probabilities for fluorine-like Fe XVIII Authors: Jonauskas, V.; Keenan, F. P.; Foord, M. E.; Heeter, R. F.; Rose, S. J.; van Hoof, P. A. M.; Ferland, G. J.; Aggarwal, K. M.; Kisielius, R.; Norrington, P. H. Bibcode: 2004A&A...416..383J Altcode: Energy levels and the corresponding transition probabilities for allowed and forbidden transitions among the levels of the ground configuration and first 23 excited configurations of fluorine-like Fe XVIII have been calculated using the multiconfigurational Dirac-Fock GRASP code. A total of 379 lowest bound levels of Fe XVIII is presented, and the energy levels are identified in spectroscopic notations. Transition probabilities, oscillator strengths and line strengths for electric dipole (E1), electric quadrupole (E2) and magnetic dipole (M1) transitions among these 379 levels are also presented. The calculated energy levels and transition probabilities are compared with experimental data.

Tables 5 to 8 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/416/383 Title: Ultraviolet Oscillations in the Chromosphere of the Quiet Sun Authors: McAteer, R. T. James; Gallagher, Peter T.; Bloomfield, D. Shaun; Williams, David R.; Mathioudakis, Mihalis; Keenan, Francis P. Bibcode: 2004ApJ...602..436M Altcode: Quiet-Sun oscillations in the four Transition Region and Coronal Explorer (TRACE) ultraviolet passbands centered on 1700, 1600, 1216, and 1550 Å are studied using a wavelet-based technique. Both network and internetwork regions show oscillations with a variety of periods and lifetimes in all passbands. The most frequent network oscillation has a period of 283 s, with a lifetime of 2-3 cycles in all passbands. These oscillations are discussed in terms of upwardly propagating magnetohydrodynamic wave models. The most frequent internetwork oscillation has a period of 252 s, again with a lifetime of 2-3 cycles, in all passbands. The tendency for these oscillations to recur in the same position is discussed in terms of ``persistent flashers.'' The network contains greater oscillatory power than the internetwork at periods longer than 300 s in the low chromosphere. This value is shown to decrease to 250 s in the high chromosphere. The internetwork also displays a larger number of short-lifetime, long-period oscillations than the network, especially in the low chromosphere. Both network and internetwork regions contain a small number of nonrecurring long-lifetime oscillations. Title: VizieR Online Data Catalog: Electron impact excitation of Fe XIII (Aggarwal+, 2004) Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2004yCat..34180371A Altcode: Energy levels and radiative rates for transitions among the lowest 97 fine-structure levels belonging to the (1s22s22p6) 3s23p2, 3s3p3, 3s23p3d , 3p4, 3s3p23d and 3s23d2 configurations of Fe XIII have been calculated using the fully relativistic GRASP code. Additionally, collision strengths for transitions among these levels have been computed using the Dirac Atomic R-matrix Code (DARC) of Norrington & Grant (2004, Comput. Phys. Commun., in prep.). Radiative rates and oscillator strengths are tabulated for all allowed transitions among the 97 fine-structure levels, while collision strengths are reported for some transitions at a few energies above thresholds. Comparisons are made with the available results, and the accuracy of the data is assessed.

(5 data files). Title: A Comparison of Theoretical Si <Emphasis Type="SmallCaps">VIII</Emphasis> Emission Line Ratios with Observations from Serts Authors: Keenan, F. P.; Katsiyannis, A. C.; Ramsbottom, C. A.; Bell, K. L.; Brosius, J. W.; Davila, J. M.; Thomas, R. J. Bibcode: 2004SoPh..219..251K Altcode: Recent R-matrix calculations of electron impact excitation rates in N-like Si VIII are used to derive theoretical emission line intensity ratios involving 2s22p3-2s2p4 transitions in the 216-320 Å wavelength range. A comparison of these with an extensive dataset of solar active region, quiet-Sun, sub-flare and off-limb observations, obtained during rocket flights of the Solar EUV Research Telescope and Spectrograph (SERTS), indicates that the ratio R1= I(216.94 Å)/I(319.84 Å) may provide a usable electron density diagnostic for coronal plasmas. The ratio involves two lines of comparable intensity, and varies by a factor of about 5 over the useful density range of 108-1011 cm−3. However R2= I(276.85 Å)/I(319.84 Å) and R3=I(277.05 Å)/I(319.84 Å) show very poor agreement between theory and observation, due to the severe blending of the 276.85 and 277.05 Å lines with Si VII and Mg VII transitions, respectively, making the ratios unsuitable as density diagnostics. The 314.35 Å feature of Si VIII also appears to be blended, with the other species contributing around 20% to the total line flux. Title: Extreme-Ultraviolet Emission Lines of S X in Solar Flare and Active Region Spectra Authors: Keenan, F. P.; Katsiyannis, A. C.; Widing, K. G. Bibcode: 2004ApJ...601..565K Altcode: R-matrix calculations of electron impact excitation rates in N-like S X are used to derive theoretical emission-line intensity ratios involving 2s22p3-2s2p4 transitions in the 189-265 Å wavelength range. A comparison of these with observational data for solar flares and active regions, obtained with the Naval Research Laboratory's S082A spectrograph on board Skylab and the Solar EUV Rocket Telescope and Spectrograph, reveals that many of the S X lines in the spectra are badly blended with emission features from other species. However, the intensity ratios I(228.70Å)/I(264.24Å) and I(228.70Å)/I(259.49Å) are found to provide useful electron density diagnostics for flares, although the latter cannot be employed for active regions, because of blending of the 259.49 Å line with an unidentified transition in these solar features. Title: Oscillatory Signatures above Quiet Sun Magnetic Elements Authors: Bloomfield, D. S.; McAteer, R. T. J.; Lites, B. W.; Judge, P. G.; Mathioudakis, M.; Keenan, F. P. Bibcode: 2004ESASP.547...51B Altcode: 2004soho...13...51B A new application of wavelet analysis is presented. The data used are part of Joint Observing Proposal 72 between SoHO and TRACE, obtained on 1998 May 16 with accompanying groundbased data taken with the Dunn Solar Telescope at Sacramento Peak, New Mexico. A weak magnetic network region is studied and the temporal variation of phase difference between TRACE 1700 Å and SoHO/SUMER C II intensities is shown. The example clearly highlights the advantages of wavelet analysis over more classical techniques such as Fourier analysis, where the effectiveness of the technique to identify wavepackets with differing phase difference relations is emphasised. Title: An Automated Wavelet Analysis Approach to TRACE Quiet Sun Oscillations Authors: McAteer, R. T. J.; Gallagher, P. T.; Williams, D. R. Williams D. R.; Bloomfield, D. S.; Mathioudakis, M.; Keenan, F. P. Bibcode: 2004ESASP.547..139M Altcode: 2004soho...13..139M An automated wavelet analysis approach to TRACE UV quiet Sun datasets is discussed. Periodicity and lifetime of oscillations present in the network and internetwork are compared and contrasted. This provides a means of extending previous Fourier results into the time-localised domain. The longest lifetime oscillations occur around the acoustic band and the network tends to dominate over the internetwork at periods 4 mins. However, it is shown that the internetwork can dominate over the network at long periods (7 - 20 mins), but only for short lifetimes ( 3 complete oscillations). These results are discussed in terms of chromospheric heating theories. Title: Effect of Dust Obscuration on the Emission Lines of RR Tel Authors: Kotnik-Karuza, D.; Friedjung, M.; Exter, K.; Keenan, F. P.; Pollacco, D. L. Bibcode: 2004IAUS..219..888K Altcode: 2003IAUS..219E..76K We continue our investigation of the emitting region of the symbiotic nova RR Telescopii by analyzing the emission line fluxes from high quality AAT optical spectra obtained in 2000 and comparing these with previous observations. The fading found in the recent spectra suggests increased circumstellar dust absorption in the stellar wind of the mira. Differing absorption of lines formed in different regions provides information on the geometry of the dust regions. The radii of the Fe II emitting region obtained by the SAC method have been corrected for the dust obscuration. Title: Initial Results from SECIS Observations of the 2001 Eclipse Authors: Katsiyannis, A. C.; McAteer, R. T. J.; Williams, D. R.; Gallagher, P. T.; Keenan, F. P. Bibcode: 2004ESASP.547..459K Altcode: 2004astro.ph.11722K; 2004soho...13..459K SECIS observations of the June 2001 total solar eclipse were taken using an Fe XIV 5303 Å filter. Existing software was modified and new code was developed for the reduction and analysis of these data. The observations, data reduction, study of the atmospheric and instrumental effects, together with some preliminary results are discussed. Emphasis is given to the techniques used for the automated alignment of the 8000 images, the application of the `a Trous algorithm for noise filtering and the software developed for the automated detection of intensity oscillations using wavelet analysis. In line with findings from the 1999 SECIS total eclipse observations, intensity oscillations with periods in the range of 20-30 s, both inside and just outside coronal loops are also presented. Title: CaII K interstellar observations towards early-type disc and halo stars Authors: Smoker, J. V.; Rolleston, W. R. J.; Kay, H. R. M.; Kilkenny, D.; Morras, R.; Arnal, M.; Keenan, F. P.; Mooney, C. J.; Dufton, P. L.; Ryans, R. S. I.; Hambly, N. C.; O'Donoghue, D.; McGillivray, H. Bibcode: 2003MNRAS.346..119S Altcode: We present high-resolution (R=λ/Δλ~ 40000) CaII K interstellar observations (λair= 3933.66Å) towards 88 mainly B-type stars, of which 74 are taken from the Edinburgh-Cape or Palomar-Green surveys, and 81 have |b| > 25°. The majority of the data come from previously existing spectroscopy, although also included are 18 new observations of stars with echelle spectra taken with UVES on the Very Large Telescope UT2 (Kueyen). Some 49 of the sample stars have distance estimates above the Galactic plane (|z|) >= 1 kpc, and are thus good probes of the halo interstellar medium. Of the 362 interstellar Ca K components that we detect, 75 (21 per cent) have absolute values of their LSR velocity values exceeding 40 km s-1. In terms of the deviation velocity for the sightlines with distance estimates, 46/273 (17 per cent) of components have velocity values exceeding those predicted by standard Galactic rotation by more than 40 km s-1. Combining this data set with previous observations, we find that the median value of the reduced equivalent width (REW) of stars with |z| >= 1 kpc (EW×sin|b|) is ~115 mÅ (n= 80), similar to that observed in extragalactic sightlines by Bowen. Using data of all z distances, the REW at infinity is found to be ~130 mÅ, with the scaleheight (l) of the CaII K column density distribution being ~800 pc (n= 196) and reduced column density at infinity of log[N(CaII K) cm-2]~12.24. This implies that ~30 per cent of CaII K absorption occurs at distances exceeding ~1 kpc. For nine sightlines with distance exceeding 1 kpc and with a companion object within 5°, we find that all but two have values of CaII reduced equivalent width the same to within ~20 per cent, when the REW of the nearest object is extrapolated to the distance of the further of the pair, and assuming l= 800 pc. For 29 of our sightlines with |z| >= 1 kpc and a HI detection from the Leiden-Dwingeloo survey (beamsize of 0.5°), we find log(N(CaII K)/N(HI)) ranging from -7.4 to -8.4. Values of the CaII K abundance relative to neutral hydrogen (log[N(CaIIK)cm-2]-log[N(HI)cm-2]) are found to be more than ~0.5dex higher in stars with distances exceeding ~100 pc, when compared with the (log[N(CaII K) cm-2]- log[N(Htot) cm-2]) values found in nearby sightlines such as those in Wakker & Mathis (2000). Finally, stellar CaII K equivalent widths of the sample are determined for 26 objects. Title: VizieR Online Data Catalog: Transition probabilities for Fe XVIII (Jonauskas+, 2004) Authors: Jonauskas, V.; Keenan, F. P.; Foord, M. E.; Heeter, R. F.; Rose, S. J.; van Hoof, P. A. M.; Ferland, G. J.; Aggarwal, K. M.; Kisielius, R.; Norrington, P. H. Bibcode: 2003yCat..34160383J Altcode: Energy levels and the corresponding transition probabilities as well oscillator strengths and line strengths for allowed (E1) and forbidden (E2, M1) transitions among the lowest 379 levels of fluorine-like Fe XVIII are presented. Calculations were performed using the multiconfigurational Dirac-Fock GRASP code.

(4 data files). Title: Extreme ultraviolet emission lines of ArXIV in solar active region and flare spectra Authors: Keenan, F. P.; Katsiyannis, A. C.; Reid, R. H. G.; Pradhan, A. K.; Zhang, H. L.; Widing, K. G. Bibcode: 2003MNRAS.346...58K Altcode: New R-matrix calculations of electron impact excitation rates for transitions among the 2s22p, 2s2p2 and 2p3 levels of ArXIV are presented. These data are subsequently used to derive the theoretical electron density diagnostic emission-line intensity ratios R1=I(187.95 Å)/I(194.41 Å) and R2=I(257.40 Å)/I(243.78 Å) for a range of densities (Ne= 109-1013 cm-3) and electron temperatures (Te= 106.3-106.7 K) appropriate to solar transition region and coronal plasmas. A comparison of these diagnostics with observational data for solar active regions and flares, obtained with the Naval Research Laboratory's S082A spectrograph on board Skylab, reveals that the electron densities determined from R1 are in good agreement with those estimated from line ratios in FeXIV or FeXV, which are formed at similar electron temperatures to ArXIV. However, there are large discrepancies between densities inferred from the R2 ratio and those from FeXIV or FeXV, confirming that the ArXIV 243.78- and 257.40-Å lines are badly blended with FeXV 243.79 Å and FeXIV 257.38 Å, respectively. Hence, R2 cannot be employed as a density diagnostic, in contrast to R1, which does provide reliable Ne estimates. Title: Extreme Ultraviolet Emission Lines of ca xv in Solar and Laboratory Spectra Authors: Keenan, F. P.; Aggarwal, K. M.; Katsiyannis, A. C.; Reid, R. H. G. Bibcode: 2003SoPh..217..225K Altcode: New R-matrix calculations of electron impact excitation rates in Ca xv are used to derive theoretical electron density diagnostic emission line intensity ratios involving 2s22p2-2s2p3 transitions, specifically R1=I(208.70 Å)/I(200.98 Å), R2=I(181.91 Å)/I(200.98 Å), and R3=I(215.38 Å)/I(200.98 Å), for a range of electron temperatures (Te=106.4-106.8 K) and densities (Ne=109-1013 cm−3) appropriate to solar coronal plasmas. Electron densities deduced from the observed values of R1, R2, and R3 for several solar flares, measured from spectra obtained with the Naval Research Laboratory's S082A spectrograph on board Skylab, are found to be consistent. In addition, the derived electron densities are in excellent agreement with those determined from line ratios in Ca xvi, which is formed at a similar electron temperature to Ca xv. These results provide some experimental verification for the accuracy of the line ratio calculations, and hence the atomic data on which they are based. A set of eight theoretical Ca xv line ratios involving 2s22p2-2s2p3 transitions in the wavelength range ∼ 140-216 Å are also found to be in good agreement with those measured from spectra of the TEXT tokamak plasma, for which the electron temperature and density have been independently determined. This provides additional support for the accuracy of the theoretical line ratios and atomic data. Title: VizieR Online Data Catalog: Effective collision strengths in Fe XV (Aggarwal+, 2003) Authors: Aggarwal, K. M.; Keenan, F. P.; Msezane, A. Z. Bibcode: 2003yCat..34100349A Altcode: Collision strengths for transitions among the energetically lowest 53 fine-structure levels belonging to the (1s2 2s2 2p6) 3l2, 3l3l', 3s4l and 3p4s configurations of Fe XV are computed, over an electron energy range below 160Ryd, using the Dirac Atomic R-matrix Code (DARC) of Norrington & Grant (2003, Comput. Phys. Commun., in prep.). Effective collision strengths, obtained after integrating the collision strengths over a Maxwellian distribution of electron energies, have also been calculated. These results of effective collision strengths are tabulated for all 1378 inelastic transitions over a wide temperature range of 105 to 107K. Comparisons are also made with other R-matrix calculations and the accuracy of the results is assessed.

(3 data files). Title: Effective collision strengths for transitions in Fe XV. Authors: Aggarwal, K. M.; Keenan, F. P.; Msezane, A. Z. Bibcode: 2003A&A...410..349A Altcode: Collision strengths for transitions among the energetically lowest 53 fine-structure levels belonging to the (1s22s22p6) 3{l}2, 3{l}3{l}', 3s4{l} and 3p4s configurations of Fe XV are computed, over an electron energy range below 160 Ryd, using the Dirac Atomic R-matrix Code (DARC) of Norrington & Grant (\cite{Norrington03}). Effective collision strengths, obtained after integrating the collision strengths over a Maxwellian distribution of electron energies, have also been calculated. These results of effective collision strengths are tabulated for all 1378 inelastic transitions over a wide temperature range of 105 to 107 K. Comparisons are also made with other R-matrix calculations and the accuracy of the results is assessed.

Table 4 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/410/349 Title: VizieR Online Data Catalog: Excitation rates for transitions in Ca XV (Aggarwal+, 2003) Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2003yCat..34070769A Altcode: Collision strengths for transitions among the energetically lowest 46 fine-structure levels belonging to the (1s2) 2s22p2, 2s2p3, 2p4, and 2s22p3l configurations of Ca XV are computed, over a wide electron energy range below 300Ryd, using the Dirac Atomic R-matrix Code (DARC) of Norrington & Grant (2003, Comput. Phys. Comm., in preparation). Resonances in the threshold region have been resolved in a fine energy mesh, and excitation rates are determined over a wide electron temperature range below 107K. The results are compared with those available in the literature, and the accuracy of the data is assessed.

(2 data files). Title: Inner-shell photoexcitation of FeXV and FeXVI Authors: Kisielius, R.; Hibbert, A.; Ferland, G. J.; Foord, M. E.; Rose, S. J.; van Hoof, P. A. M.; Keenan, F. P. Bibcode: 2003MNRAS.344..696K Altcode: The configuration-interaction method as implemented in the computer code CIV3 is used to determine energy levels, electric dipole radiative transition wavelengths, oscillator strengths and transition probabilities for inner-shell excitation of transitions in FeXV and FeXVI. Specifically, transitions are considered of the type 1s22s22p63s2-1s22s22p53l3l'3l'' (l, l' and l''= s, p or d) in FeXV and 1s22s22p63s-1s22s22p53l3l' (l and l'= s, p or d) in FeXVI, using the relativistic Breit-Pauli approach. An assessment of the accuracy of the derived atomic data is performed. Title: Eclipse observations of high-frequency oscillations in active region coronal loops Authors: Katsiyannis, A. C.; Williams, D. R.; McAteer, R. T. J.; Gallagher, P. T.; Keenan, F. P.; Murtagh, F. Bibcode: 2003A&A...406..709K Altcode: 2003astro.ph..5225K One of the mechanisms proposed for heating the corona above solar active regions is the damping of magnetohydrodynamic (MHD) waves. Continuing on previous work, we provide observational evidence for the existence of high-frequency MHD waves in coronal loops observed during the August 1999 total solar eclipse. A wavelet analysis is used to identify twenty 4x4 arcsec2 areas showing intensity oscillations. All detections lie in the frequency range 0.15-0.25 Hz (7-4 s), last for at least 3 periods at a confidence level of more than 99% and arise just outside known coronal loops. This leads us to suggest that they occur in low emission-measure or different temperature loops associated with the active region. Title: Excitation rates for transitions in Ca XV Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2003A&A...407..769A Altcode: Collision strengths for transitions among the energetically lowest 46 fine-structure levels belonging to the (1s2) 2s22p2, 2s2p3, 2p4, and 2s22p3l configurations of Ca XV are computed, over a wide electron energy range below 300 Ryd, using the Dirac Atomic R-matrix Code (DARC) of Norrington & Grant (\cite{Norrington03}). Resonances in the threshold region have been resolved in a fine energy mesh, and excitation rates are determined over a wide electron temperature range below 107 K. The results are compared with those available in the literature, and the accuracy of the data is assessed.

Table \ref{tab3} is also (and Table 4 only) available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/407/769 Title: Emission lines of Na-like ions in spectra obtained with the Solar EUV Research Telescope and Spectrograph (SERTS) Authors: Keenan, F. P.; Katsiyannis, A. C.; Brosius, J. W.; Davila, J. M.; Thomas, R. J. Bibcode: 2003MNRAS.342..513K Altcode: Theoretical emission-line ratios involving transitions in the 236-412 Å wavelength range are presented for the Na-like ions ArVIII, CrXIV, MnXV, FeXVI, CoXVII, NiXVIII and ZnXX. A comparison of these with an extensive data set of the solar active region, quiet-Sun, subflare and off-limb observations, obtained during rocket flights by the Solar EUV Research Telescope and Spectrograph (SERTS), reveals generally very good agreement between theory and experiment. This indicates that most of the Na-like ion lines are reliably detected in the SERTS observations, and hence may be employed with confidence in solar spectral analyses. However, the features in the SERTS spectra at 236.34 and 300.25 Å, originally identified as the NiXVIII 3p 2P3/2-3d 2D3/2 and CrXIV 3p 2P3/2-3d 2D5/2 transitions, respectively, are found to be due to emission lines of ArXIII (236.34 Å) and possibly SV or NiVI (300.25 Å). The CoXVII 3s 2S-3p 2P3/2 line at 312.55 Å is always badly blended with an FeXV feature at the same wavelength, but MnXV 3s 2S-3p 2P1/2 at 384.75 Å may not always be as affected by second-order emission from FeXII 192.37 Å as previously thought. On the other hand, we find that the ZnXX 3s 2S-3p 2P3/2 transition can sometimes make a significant contribution to the ZnXX/FeXIII 256.43-Å blend, and hence care must be taken when using this feature as an FeXIII electron density diagnostic. A line in the SERTS-89 active region spectrum at 265.00 Å has been re-assessed, and we confirm its identification as the FeXVI 3p 2P3/2-3d 2D3/2 transition. Title: Oscillator strengths for transitions in C-like ions between K XIV and Mn XX Authors: Aggarwal, K. M.; Keenan, F. P.; Msezane, A. Z. Bibcode: 2003A&A...401..377A Altcode: Energy levels and oscillator strengths (transition probabilities) have been calculated for transitions among 46 fine-structure levels of the (1s2) 2s22p2, 2s2p3, 2p4, 2s22p3s, 2s22p3p and 2s22p3d configurations of C-like K XIV, Sc XVI, Ti XVII, V XVIII, Cr XIX and Mn XX using the GRASP code. Configuration interaction and relativistic effects have been included while generating the wavefunctions. Calculated values of energy levels agree within 3% with the experimentally compiled results, and the length and velocity forms of oscillator strengths agree within 20% for a majority of allowed transitions.

Tables \ref{tab4} to \ref{tab9} are only available in electronic form at http://www.edpsciences.org Title: Observational Evidence for Mode Coupling in the Chromospheric Network Authors: McAteer, R. T. James; Gallagher, Peter T.; Williams, David R.; Mathioudakis, Mihalis; Bloomfield, D. Shaun; Phillips, Kenneth J. H.; Keenan, Francis P. Bibcode: 2003ApJ...587..806M Altcode: Oscillations in network bright points (NBPs) are studied at a variety of chromospheric heights. In particular, the three-dimensional variation of NBP oscillations is studied using image segmentation and cross-correlation analysis between images taken in light of Ca II K3, Hα core, Mg I b2, and Mg I b1-0.4 Å. Wavelet analysis is used to isolate wave packets in time and to search for height-dependent time delays that result from upward- or downward-directed traveling waves. In each NBP studied, we find evidence for kink-mode waves (1.3, 1.9 mHz), traveling up through the chromosphere and coupling with sausage-mode waves (2.6, 3.8 mHz). This provides a means for depositing energy in the upper chromosphere. We also find evidence for other upward- and downward-propagating waves in the 1.3-4.6 mHz range. Some oscillations do not correspond to traveling waves, and we attribute these to waves generated in neighboring regions. Title: An analysis of the optical spectra of the post-asymptotic giant branch stars LSIV -12 111 and HD 341617 Authors: Ryans, R. S. I.; Dufton, P. L.; Mooney, C. J.; Rolleston, W. R. J.; Keenan, F. P.; Hubeny, I.; Lanz, T. Bibcode: 2003A&A...401.1119R Altcode: High spectral resolution and signal-to-noise observations of the absorption and emission line spectra in two post-asymptotic-giant-branch (PAGB) stellar candidates, LSIV -12 111 and HD 314617 are discussed. The absorption line spectra have been analysed using non-LTE model atmosphere techniques to determine stellar atmospheric parameters and chemical compositions, both in absolute terms and relative to a standard star, HD 13841. The atmospheric parameters differ from previous estimates based on LTE model atmospheres, probably due to non-LTE effects. In turn these imply stellar masses that are generally larger than have been previously estimated. Both PAGB candidates have relative uniform underabundances of metals with mean values of -0.35 dex for LSIV -12 111 and -0.50 dex for HD 314617.

Furthermore, their abundance patterns are remarkably similar to that observed for optically bright, F-type PAGBs. From the emission spectra, the plasma parameters and angular size of the circumstellar material are constrained, and these are consistent with previous estimates and with a PAGB evolutionary stage. Title: Effective collision strengths for transitions in Fe XI Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2003A&A...399..799A Altcode: Collision strengths for transitions among the lowest 48 fine-structure levels belonging to the (1s22s22p6) 3s23p4, 3s3p5, 3s23p33d and 3p6 configurations of Fe XI have been calculated using the Dirac Atomic R-matrix Code (DARC) of Norrington & Grant (2003). Results are tabulated at energies above thresholds in the range 10 <=E <=100 Ry, although resonances have been resolved in a fine energy mesh in the thresholds region. Effective collision strengths, obtained after integrating the collision strengths over a Maxwellian distribution of electron velocities, are also tabulated over a wide electron temperature range below 5x 106 K. Comparisons with other available results are made, and the accuracy of the present data is assessed.

Tables 2 and 3 are only available in electronic form at http://www.edpsciences.org Title: Emission Lines of [Cl II] in the Optical Spectra of Gaseous Nebulae Authors: Keenan, F. P.; Aller, L. H.; Exter, K. M.; Hyung, S.; Pollacco, D. L. Bibcode: 2003ApJ...584..385K Altcode: Recent R-matrix calculations of electron impact excitation rates among the 3s23p4 levels of Cl II are used to derive the nebular emission-line intensity ratios R1=I(6161.8 Å)/I(8578.7 Å) and R2=I(6161.8 Å)/I(9123.6 Å) as a function of electron temperature (Te) and density (Ne). The ratios are found to be very sensitive to changes in Te but not Ne for densities lower than 105 cm-3. Hence, they should, in principle, provide excellent optical Te diagnostics for planetary nebulae. The observed values of R1 and R2 for the planetary nebulae NGC 6741 and IC 5117, measured from spectra obtained with the Hamilton echelle spectrograph on the 3 m Shane Telescope, imply temperatures in excellent agreement with those derived from other diagnostic lines formed in the same region of the nebula as [Cl II]. This provides some observational support for the accuracy of the [Cl II] line ratio calculations and hence the atomic data on which they are based. The [Cl II] 8578.7 and 9123.6 Å lines are identified for the first time (to our knowledge) in a high-resolution spectrum of the symbiotic star RR Telescopii, obtained with the University College London Echelle Spectrograph on the 3.9 m Anglo-Australian Telescope. However, the 6161.8 Å feature is unfortunately too weak to be identified in the RR Telescopii observations, consistent with its predicted line strength. Title: Electron impact excitation of S-like iron Authors: Aggarwal, Kanti M.; Keenan, Francis P. Bibcode: 2003MNRAS.338..412A Altcode: Energy levels and radiative rates for transitions among the lowest 48 fine-structure levels belonging to the (1s22s22p6) 3s23p4, 3s3p5, 3s23p33d and 3p6 configurations of FeXI have been calculated using the fully relativistic GRASP code. Additionally, collision strengths for transitions among these levels have also been computed using the Dirac Atomic R-matrix Code (DARC) of Norrington & Grant. Radiative rates and oscillator strengths are tabulated for all allowed transitions among the 48 fine-structure levels, while collision strengths are reported at three energies above thresholds, i.e. 8, 16 and 24 Ryd for a few representative transitions. Furthermore, excitation rates have been calculated in a wide electron temperature range below 5 × 106 K, and the contribution of resonances has been included in the threshold regions. Comparisons are made with the earlier available theoretical and experimental rates, and it is concluded that the experimental rates are overestimated by up to a factor of 2. Title: Energy Levels, Radiative Rates, and Collision Strengths for Transitions in Fe XVII Authors: Aggarwal, K. M.; Keenan, F. P.; Msezane, A. Z. Bibcode: 2003ApJS..144..169A Altcode: Energy levels and radiative rates have been calculated for fine-structure transitions among the lowest 89 levels of the (1s2) 2s22p6, 2s22p53l, 2s22p54l, 2s2p63l, and 2s2p64l configurations of Fe XVII, using the GRASP code of Dyall et al. Collision strengths have also been calculated, for transitions among the lowest 55 levels, using the recently developed Dirac atomic R-matrix code (DARC) of Norrington & Grant. The results are compared with those available in the literature, and the accuracy of the data is assessed. Title: Si IX Emission Lines in Spectra Obtained with the Solar euv Research Telescope and Spectrograph (Serts) Authors: Keenan, F. P.; Katsiyannis, A. C.; Aggarwal, K. M.; Mathioudakis, M.; Brosius, J. W.; Davila, J. M.; Thomas, R. J. Bibcode: 2003SoPh..212...65K Altcode: Theoretical electron-density-sensitive emission line ratios involving 2s22p2-2s2p3 transitions in Si ix between 223 and 350 Å are presented. A comparison of these with an extensive dataset of solar-active-region, quiet-Sun, subflare and off-limb observations, obtained during rocket flights by the Solar EUV Research Telescope and Spectrograph (SERTS), reveals generally very good agreement between theory and experiment. This provides support for the accuracy of the line-ratio diagnostics, and hence the atomic data on which they are based. In particular, the density-sensitive intensity ratio I(258.10 Å)/I(349.87 Å) offers an especially promising diagnostic for studies of coronal plasmas, as it involves two reasonably strong emission lines and varies by more than an order of magnitude over the useful density range of 109-1011 cm−3. The 2s22p2 1S0-2s2p3 1P1 transition at 259.77 Å is very marginally identified for the first time in the SERTS database, although it has previously been detected in solar flare observations. Title: SuperWASP: Wide Angle Search for Planets Authors: Street, R. A.; Pollaco, D. L.; Fitzsimmons, A.; Keenan, F. P.; Horne, K.; Kane, S.; Collier Cameron, A.; Lister, T. A.; Haswell, C.; Norton, A. J.; Jones, B. W.; Skillen, I.; Hodgkin, S.; Wheatley, P.; West, R.; Brett, D. Bibcode: 2003ASPC..294..405S Altcode: 2002astro.ph..8233S SuperWASP is a fully robotic, ultra-wide angle survey for planetary transits. Currently under construction, it will consist of 5 cameras, each monitoring a 9.5 by 9.5 degree field of view. The Torus mount and enclosure will be fully automated and linked to a built-in weather station. We aim to begin observations at the beginning of 2003. Title: New Results Concerning the Fe II Lines of RR Tel Authors: Kotnik-Karuza, D.; Friedjung, M.; Exter, K.; Keenan, F. P.; Pollacco, D. L. Bibcode: 2003ASPC..303..136K Altcode: 2003ssps.conf..136K No abstract at ADS Title: The distance to high-velocity O VI absorption in the Galactic halo Authors: Keenan, F. Bibcode: 2003fuse.prop.D015K Altcode: Previous FUSE studies have revealed the presence of large amounts of high-velocity (midVLSRmid > 100 kms) hot gas towards Galactic halo sightlines, detected via O VI absorption lines in high-velocity clouds (HVCs). However, these sightlines are all extragalactic, and hence the observations do not provide any insight into a crucial HVC parameter -- the distance. As part of a continuing program to investigate the distribution and origin of hot stars in the Galactic halo, we have obtained high resolution (∼ 0.1Å FWHM) optical echelle spectra of many faint B-type Post-AGB stars at high Galactic latitudes. Detailed model atmosphere analyses of these spectra have allowed us to derive reliable atmospheric parameters, and hence determine stellar distances accurate to ∼ 20%. We have identified a sample of our stars at distances from the Galactic plane (z) of up to 13 kpc, and which lie close in the sky (within 9°) to AGNs with HVC O VI absorption in their sightlines. The detection of HVC O VI absorption in our stellar sample will show that this hot gas lies close to the Galaxy, and hence either originates from the Galaxy (e.g. a Galactic fountain or wind), or arises via some interaction with the Galaxy (e.g. cloud interactions with a Galactic corona). However null detections will also provide useful constraints, indicating that the HVCs are extragalactic in origin, such as intergalactic gas in the Local Group. Title: Multiwavelength observations of the M15 intermediate-velocity cloud Authors: Smoker, J. V.; Haffner, L. M.; Keenan, F. P.; Davies, R. D.; Pollacco, D. Bibcode: 2002MNRAS.337..385S Altcode: 2002astro.ph..6373S We present Westerbork Synthesis Radio Telescope HI images, Lovell telescope multibeam HI wide-field mapping, William Herschel Telescope long-slit echelle CaII observations, Wisconsin Hα Mapper (WHAM) facility images, and IRAS ISSA 60- and 100-1μm co-added images towards the intermediate-velocity cloud (IVC) at +70 km s-1, located in the general direction of the M15 globular cluster. When combined with previously published Arecibo data, the HI gas in the IVC is found to be clumpy, with a peak HI column density of ~1.5 × 1020 cm-2, inferred volume density (assuming spherical symmetry) of ~24 cm-3/D (kpc) and a maximum brightness temperature at a resolution of 81 × 14 arcsec2 of ~14 K. The major axis of this part of the IVC lies approximately parallel to the Galactic plane, as does the low-velocity HI gas and IRAS emission. The HI gas in the cloud is warm, with a minimum value of the full width at half-maximum velocity width of 5 km s-1 corresponding to a kinetic temperature, in the absence of turbulence, of ~540 K. From the HI data, there are indications of two-component velocity structure. Similarly, the CaII spectra, of resolution 7 km s-1, also show tentative evidence of velocity structure, perhaps indicative of cloudlets. Assuming that there are no unresolved narrow-velocity components, the mean values of log10[N(CaII K) cm-2]~ 12.0 and CaII/HI~2.5 × 10-8 are typical of observations of high Galactic latitude clouds. This compares with a value of CaII/HI> 10-6 for IVC absorption towards HD 203664, a halo star of distance 3 kpc, some from the main M15 IVC condensation. The main IVC condensation is detected by WHAM in Hα with central local-standard-of-rest velocities of ~60-70 km s-1, and intensities uncorrected for Galactic extinction of up to 1.3 R, indicating that the gas is partially ionized. The FWHM values of the Hα IVC component, at a resolution of 1°, exceed 30 km s-1. This is some 10 km s-1 larger than the corresponding HI value at a similar resolution, and indicates that the two components may not be mixed. However, the spatial and velocity coincidence of the Hα and HI peaks in emission towards the main IVC component is qualitatively good. If the Hα emission is caused solely by photoionization, the Lyman continuum flux towards the main IVC condensation is ~2.7 × 106 photon cm-2 s-1. There is not a corresponding IVC Hα detection towards the halo star HD 203664 at velocities exceeding ~60 km s-1. Finally, both the 60- and 100-μm IRAS images show spatial coincidence, over a 0.675 × 0.625 deg2 field, with both low- and intermediate-velocity HI gas (previously observed with the Arecibo telescope), indicating that the IVC may contain dust. Both the Hα and tentative IRAS detections discriminate this IVC from high-velocity clouds, although the HI properties do not. When combined with the HI and optical results, these data point to a Galactic origin for at least parts of this IVC. Title: Search for short period coronal plasma oscillations. SECIS results from 1999 and 2001 total eclipses Authors: Rudawy, P.; Phillips, K. J. H.; Read, P.; Gallagher, P. T.; Rompolt, B.; Berlicki, A.; Williams, D.; Keenan, F. P.; Buczylko, A. Bibcode: 2002ESASP.506..967R Altcode: 2002ESPM...10..967R; 2002svco.conf..967R Results of the analysis of the high-cadence observations of the solar corona, taken with the Solar Eclipse Coronal Imaging System instrument during joint British-Polish expeditions during the total solar eclipses of 1999 August 11 in Bulgaria (12768 images) and 2001 June 21 in Zambia (16000 images) are presented. Using data collected during the both solar eclipses we searched for possible periodic changes of the 530.3 nm line intensity emitted by the selected points of the solar corona in the frequency range up to 10 Hz. The time resolution of the collected data is close to 0.05 sec and the pixel size is approximately 4 seconds of arc. The standard photometric processing and correction of the image motions caused by temporal drifts of the instrument pointing were made. Using classical Fourier spectral analysis and wavelet analysis tools we investigated temporal changes of the 530.3 nm coronal line brightness of many thousands of points at various heights and position angles above the solar limb. We did not find any statistically important evidence of periodicity in the frequency range from 1 to 10 Hz in any of the investigated points. Title: High-resolution Keck I spectroscopy of Galactic halo post-asymptotic giant branch stars Authors: Mooney, C. J.; Rolleston, W. R. J.; Keenan, F. P.; Dufton, P. L.; Smoker, J. V.; Ryans, R. S. I.; Aller, L. H. Bibcode: 2002MNRAS.337..851M Altcode: Absolute and differential abundance analyses have been performed from high-resolution, high signal-to-noise ratio optical (Keck I) spectra for three evolved Galactic halo stars, namely PG 1704 + 222, HD 341617 and LS IV -04 01. Their derived atmospheric parameters indicate that all three objects are undergoing a post-asymptotic giant branch (post-AGB) phase of evolution. A differential abundance analysis reveals HD 341617 as having a mild carbon deficiency of 0.74 dex, possibly due to the star having evolved off the AGB before the onset of the third dredge-up. Although such carbon underabundances are typical of hot post-AGB objects, the same trend is not observed in PG 1704 + 222, where the carbon abundance is found to be consistent with those derived for nitrogen and oxygen. Hence, a dredge-up scenario need not be invoked to explain the chemical composition of PG 1704 + 222. For LS IV -04 01 no iron deficiency is apparent relative to magnesium and silicon, and hence a gas-dust separation event in the AGB progenitor need not be invoked for this star. Title: The OIV and SIV intercombination lines in the ultraviolet spectra of astrophysical sources Authors: Keenan, F. P.; Ahmed, S.; Brage, T.; Doyle, J. G.; Espey, B. R.; Exter, K. M.; Hibbert, A.; Keenan, M. T. C.; Madjarska, M. S.; Mathioudakis, M.; Pollacco, D. L. Bibcode: 2002MNRAS.337..901K Altcode: New electron density diagnostic line ratios are presented for the OIV 2s22p 2P-2s2p24P and SIV 3s23p 2P-3s3p24P intercombination lines around 1400Å. A comparison of these with observational data for the symbiotic star RR Telescopii (RR Tel), obtained with the Space Telescope Imaging Spectrograph (STIS), reveals generally very good agreement between theory and observation. However the SIV2P3/2-4P1/2 transition at 1423.824Å is found to be blended with an unknown feature at 1423.774Å. The linewidth for the latter indicates that the feature arises from a species with a large ionization potential. In addition, the SIV2P1/2-4P3/2 transition at 1398.044Å is identified for the first time (to our knowledge) in an astrophysical source other than the Sun, and an improved wavelength of 1397.166 Å is measured for the OIV2P1/2-4P3/2 line. The OIV and SIV line ratios in a sunspot plume spectrum, obtained with the Solar Ultraviolet Measurements of the Emitted Radiation (SUMER) instrument on the Solar and Heliospheric Observatory, are found to be consistent, and remove discrepancies noted in previous comparisons of these two ions. Title: A search for star formation around the Galactic halo B-type star PHL 346 with the 2dF spectrograph Authors: Lynn, B. B.; Dufton, P. L.; Keenan, F. P.; Hambly, N. C.; Irwin, M. J.; Gilmore, G.; Rolleston, W. R. J. Bibcode: 2002MNRAS.336.1287L Altcode: A preliminary search for stars that may have formed coevally with the apparently young halo B-type star PHL 346 has been performed with the 2dF multifibre spectrograph on the Anglo-Australian Telescope (AAT). Candidates were selected for spectroscopy from APM scans of B and R Schmidt plates centred on PHL 346. A total of 476 stars of spectral type A or F were found; radial velocity estimates and more accurate spectral type assignments narrowed the number of possible coeval candidates to 6 A-type and 14 F-type stars. A statistical analysis of these results using a comparison with a control field suggests that the number of A-type or F-type candidate stars around PHL 346 is not unexpected, and that they need not be associated with PHL 346. A number of ways to improve the project are suggested. Title: An observational study of a magneto-acoustic wave in the solar corona Authors: Williams, D. R.; Mathioudakis, M.; Gallagher, P. T.; Phillips, K. J. H.; McAteer, R. T. J.; Keenan, F. P.; Rudawy, P.; Katsiyannis, A. C. Bibcode: 2002MNRAS.336..747W Altcode: The Solar Eclipse Corona Imaging System (SECIS) observed a strong 6-s oscillation in an active region coronal loop, during the 1999 August 11 total solar eclipse. In the present paper we show that this oscillation is associated with a fast-mode magneto-acoustic wave that travels through the loop apex with a velocity of 2100 km s-1. We use near-simultaneous SOHO observations to calculate the parameters of the loop and its surroundings such as density, temperature and their spatial variation. We find that the temporal evolution of the intensity is in agreement with the model of an impulsively generated, fast-mode wave. Title: A search for circumstellar material around B-type stars in the Galactic halo Authors: Magee, H. R. M.; Rolleston, W. R. J.; Dufton, P. L.; Keenan, F. P.; Mooney, C. J. Bibcode: 2002MNRAS.336.1147M Altcode: 19 B-type stars, selected from the Palomar-Green Survey, have been observed at infrared wavelengths to search for possible infrared excesses, as part of an ongoing programme to investigate the nature of early-type stars at high Galactic latitudes. The resulting infrared fluxes, along with Strömgren photometry, are compared with theoretical flux profiles to determine whether any of the targets show evidence of circumstellar material, which may be indicative of post-main-sequence evolution. Eighteen of the targets have flux distributions in good agreement with theoretical predictions. However, one star, PG 2120+062, shows a small near-infrared excess, which may be due either to a cool companion of spectral type F5-F7, or to circumstellar material, indicating that it may be an evolved object such as a post-asymptotic giant branch star, in the transition region between the asymptotic giant branch and planetary nebula phase, with the infrared excess due to recent mass loss during giant branch evolution. Title: VizieR Online Data Catalog: Effective collision strengths for Fe XI trans. (Aggarwal+, 2003) Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2002yCat..33990799A Altcode: Collision strengths for transitions among the lowest 48 fine-structure levels belonging to the (1s22s22p6) 3s23p4, 3s3p5, 3s23p33d and 3p6 configurations of Fe XI have been calculated using the Dirac Atomic R-matrix Code (DARC) of Norrington & Grant (2003, Comput. Phys. Commun., in prep.). Results are tabulated at energies above thresholds in the range 10<=E<=100Ry, although resonances have been resolved in a fine energy mesh in the thresholds region. Effective collision strengths, obtained after integrating the collision strengths over a Maxwellian distribution of electron velocities, are also tabulated over a wide electron temperature range below 5x106K. Comparisons with other available results are made, and the accuracy of the present data is assessed.

(5 data files). Title: Detections of high-frequency oscillations in solar active region coronal loops Authors: Katsiyannis, Athanassios C.; Williams, David R.; McAteer, R. T. James; Gallagher, Peter T.; Mathioudakis, Mihalis; Keenan, Francis P. Bibcode: 2002ESASP.505..441K Altcode: 2002IAUCo.188..441K; 2002solm.conf..441K One of the mechanisms proposed as a possible solution to the Sun's coronal heating problem is the damping of energy carried by magnetohydrodynamic (MHD) waves that are expected to be present in active regions. Continuing previous work on total solar eclipse data, we provide further obervational evidence for the existence of high-frequency MHD waves in coronal loops. Wavelet analysis is used to identify 21 areas of 4×4 arcsec2 with periodic intensity oscillations. The frequency range of these detections was 0.2-0.3 Hz and all last for at least 3 periods at a confidence level of more than 99%. All of the above detections are made just outside known coronal loops, leading us to suggest a possible, unconventional mechanism. Title: Detection of propagating waves throughout the chromosphere in network bright points Authors: McAteer, R. T. James; Gallagher, Peter T.; Williams, David R.; Mathioudakis, Mihalis; Phillips, Kenneth J. H.; Keenan, Francis P. Bibcode: 2002ESASP.505..305M Altcode: 2002IAUCo.188..305M; 2002solm.conf..305M We analysed oscillations in individual Network Bright Points (NBPs) in Ca II K3, Hα core, Mg I b2, and Mg I b1-0.4 Å giving us a range of heights from the upper to the lower chromosphere. Lightcurves, and hence power spectra, were created by isolating distinct regions of the NBP via a simple intensity thresholding technique. Using this technique, it was possible to identify peaks in the power spectra with particular spatial positions within the NBPs. This was extended into the time domain by means of wavelet analysis. We track the temporal evolution of power in particular frequency bands by creating power curves. These are then cross-correlated across all observed wavelengths to search for propagating waves. In particular, long-period waves with periods of 4-15 minutes (1-4 mHz) were found in the central portion of each NBP, indicating that these waves are certainly not acoustic, but possibly due to magneto-acoustic or magneto-gravity wave modes. We note the possible existence of fast-mode MHD waves in the lower chromosphere, coupling and transferring power top higher-frequency slow-mode MHD waves in the upper chromosphere. Title: Macroturbulent and rotational broadening in the spectra of B-type supergiants Authors: Ryans, R. S. I.; Dufton, P. L.; Rolleston, W. R. J.; Lennon, D. J.; Keenan, F. P.; Smoker, J. V.; Lambert, D. L. Bibcode: 2002MNRAS.336..577R Altcode: The absorption-line spectra of early B-type supergiants show significant broadening that implies that an additional broadening mechanism (characterized here as `macroturbulence') is present in addition to rotational broadening. Using high-resolution spectra with signal-to-noise ratios of typically 500, we have attempted to quantify the relative contributions of rotation and macroturbulence, but even with data of this quality significant problems were encountered. However, for all our targets, a model where macroturbulence dominates and rotation is negligible is acceptable; the reverse scenario leads to poor agreement between theory and observation. Additionally, there is marginal evidence for the degree of broadening increasing with line strength, possibly a result of the stronger lines being formed higher in the atmosphere. Acceptable values of the projected rotational velocity are normally less than or equal to 50 km s-1, which may also be a typical upper limit for the rotational velocity. Our best estimates for the projected rotational velocity are typically 10-20 km s-1 and hence compatible with this limit. These values are compared with those predicted by single star evolutionary models, which are initially rapidly rotating. It is concluded that either these models underestimate the rate of rotational breaking or some of the targets may be evolving through a blue loop or are binaries. Title: Observations of a high-frequency, fast-mode wave in a coronal loop Authors: Williams, David R.; Mathioudakis, Mihalis; Gallagher, Peter T.; Phillips, Kenneth J. H.; McAteer, R. T. James; Keenan, Francis P.; Katsiyannis, Athanassios C. Bibcode: 2002ESASP.505..615W Altcode: 2002IAUCo.188..615W; 2002solm.conf..615W The high-cadence Solar Eclipse Corona Imaging System (SECIS) observed a strong 6-second oscillation in an active region coronal loop, during the 1999 August 11 total solar eclipse. In the present paper we show that this oscillation is associated with a fast-mode wave that travels through the loop apex with a velocity of ~2000 km s-1. We use near-simultaneous SoHO/CDS obervations to calculate the parameters of the loop and its surroundings such as density, temperature and their spatial variation. We also calculate radiative losses from the loop in the temperature range 105.8 - 106.4K, and compare these losses with the wave energy density. Although the wave travels a distance greater than λ/4π and therefore meets a necessary criterion for slow dissipation, the dissipation length is well in excess of the loop length. The temporal evolution of the intensity is found to be in agreement with the model of an impulsively generated, fast-mode wave. Title: Opacity in the upper atmosphere of AU Mic Authors: Bloomfield, D. S.; Mathioudakis, M.; Christian, D. J.; Keenan, F. P.; Linsky, J. L. Bibcode: 2002A&A...390..219B Altcode: In this paper we investigate the validity of the optically thin assumption in the transition region of the late-type star AU Mic. We use Far-Ultraviolet Spectroscopic Explorer (FUSE) observations of the C Iii multiplet and O Vi resonance lines, hence yielding information at two different levels within the atmosphere. Significant deviations from the optically thin fluxes are found for C Iii in both quiescent and flare spectra, where only 60% of the flux is actually observed. This could explain the apparent deviation of C Iii observed in emission measure distributions. We utilize escape probabilities for both homogeneous and inhomogeneous geometries and calculate optical depths as high as 10 for the C Iii 1175.71 Åcomponent of the multiplet. Using a lower limit to the electron density (1011 cm-3) we derive an effective thickness of <100 km for the scattering layer. The emission originates from very small and compact regions, consistent with a filling factor of 10-5 derived for the flare plasma. Title: Optical spectroscopy of the M 15 intermediate velocity cloud Authors: Smoker, J. V.; Keenan, F. P.; Lehner, N.; Trundle, C. Bibcode: 2002A&A...387.1057S Altcode: We present echelle spectrograph observations in the Na D lines, at resolutions of 6.2-8.5 km s-1, for 11 stars located in the line-of-sight to the M 15 intermediate velocity cloud (IVC), which has a radial velocity of ~ +70 km s-1 in the Local Standard of Rest. This cloud is a part of IVC Complex gp. The targets range in magnitude from mV=13.3-14.8. Seven of the observed stars are in the M 15 globular cluster, the remaining four being field stars. Three of the observed cluster stars are located near a peak in intensity of the IVC H I column density as observed at a resolution of ~ 1 arcmin. Intermediate velocity gas is detected in absorption towards 7 stars, with equivalent widths in Na D2 ranging from ~ 0.09-0.20 Å, corresponding to log10(NNa cm-2) ~ 11.8-12.5, and Na I/H I column density ratios (neglecting the H II component) ranging from ~ (1-3)x10-8. Over scales ranging from 30 arcsec to 1 arcmin, the Na I column density and the Na I/H I ratio varies by upto 70 per cent and a factor of ~ 2, respectively. Combining the current sightlines with previously obtained Na I data from Kennedy et al. (\cite{Kennedy98}b), the Na I/H I column density ratio over cluster sightlines varies by upto a factor of ~ 25, when using H I data of resolution ~ 2x1 arcmin. One cluster star, M 15 ZNG-1, was also observed in the Ca I (lambdaair =4226.728 Å) and Ca II (lambdaair =3933.663 Å) lines. A column density ratio N(Ca I)/N(Ca II) < 0.03 was found, typical of values seen in the warm ionised interstellar medium. Towards this sightline, the IVC has a Na I/Ca II column density ratio of ~ 0.25, similar to that observed in the local interstellar medium. Finally, we detect tentative evidence for IV absorption in K I (lambdaair =7698.974 Å) towards 3 cluster stars, which have N(K I)/N(H I) ratios of ~ 0.5-3x10-9. Based on observations made with the Apache Point Observatory 3.5-m, USA, Very Large Telescope, Chile, and William Herschel Telescope, La Palma, Spain. Title: Long-Period Chromospheric Oscillations in Network Bright Points Authors: McAteer, R. T. James; Gallagher, Peter T.; Williams, David R.; Mathioudakis, Mihalis; Phillips, Kenneth J. H.; Keenan, Francis P. Bibcode: 2002ApJ...567L.165M Altcode: The spatial variation of chromospheric oscillations in network bright points (NBPs) is studied using high-resolution observations in Ca II K3. Light curves and hence power spectra were created by isolating distinct regions of the NBP via a simple intensity thresholding technique. Using this technique, it was possible to identify peaks in the power spectra with particular spatial positions within the NBPs. In particular, long-period waves with periods of 4-15 minutes (1-4 mHz) were found in the central portions of each NBP, indicating that these waves are certainly not acoustic but possibly due to magnetoacoustic or magnetogravity wave modes. We also show that spatially averaged or low spatial resolution power spectra can lead to an inability to detect such long-period waves. Title: A Comparison of Theoretical mg vi Emission Line Strengths with Active-Region Observations From Serts Authors: Keenan, F. P.; Mathioudakis, M.; Katsiyannis, A. C.; Ramsbottom, C. A.; Bell, K. L.; Thomas, R. J.; Brosius, J. W. Bibcode: 2002SoPh..205..265K Altcode: R-matrix calculations of electron impact excitation rates in N-like Mg vi are used to derive theoretical electron-density-sensitive emission line ratios involving 2s22p3−2s2p4transitions in the 269-403 Å wavelength range. A comparison of these with observations of a solar active region, obtained during the 1989 flight of the Solar EUV Rocket Telescope and Spectrograph (SERTS), reveals good agreement between theory and observation for the 2s22p34S−2s2p44Ptransitions at 399.28, 400.67, and 403.30 Å, and the 2s22p32P−2s2p42Dlines at 387.77 and 387.97 Å. However, intensities for the other lines attributed to Mg vi in this spectrum by various authors do not match the present theoretical predictions. We argue that these discrepancies are not due to errors in the adopted atomic data, as previously suggested, but rather to observational uncertainties or mis-identifications. Some of the features previously identified as Mg vi lines in the SERTS spectrum, such as 291.36 and 293.15 Å, are judged to be noise, while others (including 349.16 Å) appear to be blended. Title: Extreme-Ultraviolet Emission Lines of S XII in Solar Active Region and Flare Spectra Authors: Keenan, F. P.; Katsiyannis, A. C.; Ryans, R. S. I.; Reid, R. H. G.; Zhang, H. L.; Pradhan, A. K.; Widing, K. G. Bibcode: 2002ApJ...566..521K Altcode: New R-matrix calculations of electron impact excitation rates for transitions among the 2s22p, 2s2p2 and 2p3 levels of S XII are presented. These data are subsequently used to derive the theoretical electron density diagnostic emission line intensity ratios R1=I(215.16 Å)/I(299.50 Å), R2=I(218.19 Å)/I(299.50 Å), R3=I(288.40 Å)/I(299.50 Å), and R4=I(221.41 Å)/I(299.50 Å). A comparison of these with observational data for solar active regions and flares, obtained with the Naval Research Laboratory's S082A spectrograph on board Skylab and the Solar EUV Rocket Telescope and Spectrograph (SERTS), reveals that the electron densities determined from R1, R3, and R4 are consistent with each other. In addition, the densities deduced from these ratios are in good agreement with those estimated from diagnostic lines in Fe XIV or Fe XV, which are formed at similar electron temperatures to S XII. However, the R2 ratios in the flare observations imply densities smaller than those from Fe XIV/Fe XV, although the active region measurements do not show such discrepancies, suggesting that the 218.19 Å line may be blended with a transition from a high-temperature ion. An emission feature in the SERTS active region spectrum at 215.29 Å, previously identified as the 2s2p3P2-2s3s3S1 transition in O V, may be due primarily to the S XII 215.16 Å line. Title: Chemical Composition of Globular Cluster and Halo Post-AGB Stars Authors: Mooney, C. J.; Aller, L. H.; Rolleston, W. . R. J.; Dufton, P. L.; Keenan, F. P.; Smoker, J. V.; Pollacco, D. L. Bibcode: 2002RMxAC..12..181M Altcode: We present results of model atmosphere analyses of two post-AGB stars, ZNG-1 in the globular cluster M10 and the halo star PG1704+222. A differential abundance analysis reveals typical post-AGB abundance patterns, both stars being generally metal poor with approximately solar He. Large C depletions, observed in all hot post-AGB objects, are confirmed. The C deficiency may suggest that hot post-AGB stars evolve off the AGB before the third dredge-up begins. However, Fe depletions observed in other similar stars suggest that gas-dust fractionation in the AGB progenitor is responsible for the observed composition of these objects. Title: Emission lines of [K V] in the optical spectra of gaseous nebulae Authors: Keenan, Francis P.; Aller, Lawrence H.; Espey, Brian R.; Exter, Katrina M.; Hyung, Siek; Keenan, Michael T. C.; Pollacco, Don L.; Ryans, Robert S. I. Bibcode: 2002PNAS...99.4152K Altcode: Recent R-matrix calculations of electron impact excitation rates in K V are used to derive the nebular emission line ratio R = I(4122.6 Å)/I(4163.3 Å) as a function of electron density (Ne). This ratio is found to be very sensitive to changes in Ne over the density range 103 to 106 cm-3, but does not vary significantly with electron temperature, and hence in principle should provide an excellent optical Ne diagnostic for the high-excitation zones of nebulae. The observed value of R for the planetary nebula NGC 7027, measured from a spectrum obtained with the Hamilton Echelle spectrograph on the 3-m Shane Telescope, implies a density in excellent agreement with that derived from [Ne IV], formed in the same region of the nebula as [K V]. This observation provides observational support for the accuracy of the theoretical [K V] line ratios, and hence the atomic data on which they are based. However, the analysis of a high-resolution spectrum of the symbiotic star RR Telescopii, obtained with the University College London Echelle Spectrograph on the 3.9-m Anglo-Australian Telescope, reveals that the [K V] 4122.6 Å line in this object is badly blended with Fe II 4122.6Å. Hence, the [K V] diagnostic may not be used for astrophysical sources that show a strong Fe II emission line spectrum. Title: Boron Abundances in B-Type Stars: A Test of Rotational Depletion during Main-Sequence Evolution Authors: Venn, K. A.; Brooks, A. M.; Lambert, David L.; Lemke, M.; Langer, N.; Lennon, D. J.; Keenan, F. P. Bibcode: 2002ApJ...565..571V Altcode: 2001astro.ph..8263V Boron abundances have been derived for seven main-sequence B-type stars from Hubble Space Telescope STIS spectra around the B III λ2066 line. In two stars, boron appears to be undepleted with respect to the presumed initial abundance. In one star, boron is detectable but is clearly depleted. In the other four stars, boron is undetectable, implying depletions of 1-2 dex. Three of these four stars are nitrogen enriched, but the fourth shows no enrichment of nitrogen. Only rotationally induced mixing predicts that boron depletions are unaccompanied by nitrogen enrichments. The inferred rate of boron depletion from our observations is in good agreement with these predictions. Other boron-depleted nitrogen-normal stars are identified from the literature. In addition, several boron-depleted nitrogen-rich stars are identified, and while all fall on the boron-nitrogen trend predicted by rotationally induced mixing, a majority have nitrogen enrichments that are not uniquely explained by rotation. The spectra have also been used to determine iron group (Cr, Mn, Fe, and Ni) abundances. The seven B-type stars have near-solar iron group abundances, as expected for young stars in the solar neighborhood. We have also analyzed the halo B-type star PG 0832+676. We find [Fe/H]=-0.88+/-0.10, and the absence of the B III line gives the upper limit [B/H]<-2.5. These and other published abundances are used to infer the star's evolutionary status as a post-asymptotic giant branch star. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with proposal GO 07400. Title: Flare Temperature from FE XXV and CA XIX: Improved Atomic Data Authors: Phillips, K. J. H.; Rainnie, J. A.; Harra, L. K.; Dubau, J.; Keenan, F. P. Bibcode: 2002mwoc.conf..293P Altcode: For several years flare temperatures and emission measures have been derived from comparison of observed Yohkoh BCS spectra with theoretical spectra derived from atomic parameters based on distorted wave approximation. In the case of Fe XXV and Ca XIX spectra, the main lines used in the determination are dielectronic satellite lines (j or k as appropriate) and the resonance line w. More accurate close-coupling calculations from the R-matrix procedure have been available in unpublished form, and in this work these new atomic data were substituted for the distorted wave data. The intensities of the Fe XXV and Ca XIX lines w, x, y, and z are affected -- all are increased. However, the differences from the previously used atomic data are very slight. We estimate that for a given j/w ratio in Fe XXV, for instance, the temperature estimated from the new atomic data will be about 1MK smaller than from the existing data in the standard Yohkoh software at temperatures of around 20MK. Smaller differences are expected for Ca XIX at typical temperatures of 14MK. The increase in the Fe XXV y and z line intensities tends to reduce a well-known discrepancy in these lines (more evident in the much better resolved SMM BCS spectra) but not by a sufficient amount to explain the discrepancy. Title: Radiation damping effects on L-shell photoionization cross-sections of O-like Fe XIX and N-like recombination rate coefficients for Fe XX Authors: McLaughlin, B. M.; Gorczyca, T. W.; Keenan, F. P.; Bell, K. L. Bibcode: 2001MNRAS.328..442M Altcode: Photoionization cross-sections out of the fine-structure levels (2s22p4 3P2,0,1) of the O-like Fe ion FeXIX have been reinvestigated. Data for photoionization out of each of these fine-structure levels have been obtained, where the calculations have been performed with and without the inclusion of radiation damping on the resonance structure in order to assess the importance of this process. Recombination rate coefficients are determined using the Milne relation, for the case of an electron recombining with N-like Fe ions (FeXX) in the ground state to form O-like Fe (FeXIX) existing in each of the fine-structure ground-state levels. Recombination rates are presented over a temperature range ~4.0<=logTe<=7.0, of importance to the modelling of X-ray emission plasmas. Title: Boron Abundances in Main Sequence B-type Stars: A Test of Rotational Depletion during Main Sequence Evolution Authors: Venn, K. A.; Brooks, A. M.; Lambert, D. L.; Lemke, M.; Langer, N.; Lennon, D. J.; Keenan, F. P. Bibcode: 2001AAS...19913703V Altcode: 2001BAAS...33.1512V Boron abundances have been derived for seven main sequence B-type stars from HST STIS spectra around the BIII 2066 A line. Boron abundances range from normal to severly depleted. One boron depleted star shows no nitrogen enrichment, which is an abundance pattern uniquely predicted from the rotationally-induced mixing models, e.g., Heger and Langer 2000. Other stars show boron depletions that correlate with nitrogen enrichments; this pattern is predicted by rotationally-induced mixing, but also by other theories. The inferred rate of boron depletion (i.e., boron versus age) from our observations is also in good agreement with the predictions. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with proposal GO-7400. Title: HI observations of the high-velocity cloud in the direction of M 92 Authors: Smoker, J. V.; Roger, R. S.; Keenan, F. P.; Davies, R. D.; Lang, R. H.; Bates, B. Bibcode: 2001A&A...380..673S Altcode: We present wide-field neutral hydrogen (H I) Lovell telescope multibeam, and Dominion Radio Astrophysical Observatory H I synthesis observations, of the high velocity cloud (HVC) located in the general direction of the globular cluster M 92. This cloud is part of the larger Complex C and lies at velocities between ~ -80 and -130 km s-1 in the Local Standard of Rest. The Lovell telescope observations, of resolution 12 arcmin spatially and 3.0 km s-1 in velocity, fully sampling a 3.1deg x12.6deg RA-Dec grid, have found that this part of HVC Complex C comprises two main condensations, lying approximately north-south in declination, separated by ~ 2deg and being parallel to the Galactic plane. At this resolution, peak values of the brightness temperature and H I column density of ~ 1.4 K and ~ 5x1019 cm-2 are determined, with relatively high values of the full width half maximum velocity (FWHM) of ~ 22 km s-1 being observed, equivalent to a gas kinetic temperature, in the absence of turbulence and geometric effects of ~ 10 000 K. Each of these properties, as well as the sizes of the clouds, are similar in the two components. The DRAO observations, towards the Northern HVC condensation, are the first high-resolution H I spectra of Complex C. When smoothed to a resolution of 3 arcmin, they identify several H I intensity peaks with column densities in the range 4-7x1019 cm-2. Further smoothing of these data to 6 arcmin resolution tentatively indicates that parts of the HVC consist of two velocity components, of similar brightness temperature, separated by ~ 7 km s-1 in velocity, and with FWHM velocity widths of ~ 5-7km s-1. No IRAS 60 or 100 micron flux is associated with the M 92 HVC. Cloud properties are briefly discussed and compared to previous observations of HVCs. Based on observations made with the Lovell telescope, Jodrell Bank, UK, the Synthesis Telescope at the Dominion Radio Astrophysical Observatory, Canada, and at the Isaac Newton Group of telescopes, La Palma, Spain. Title: Solar coronal observations at high frequencies Authors: Katsiyannis, A. C.; Mathioudakis, M.; Phillips, K. J. H.; Williams, D. R.; Keenan, F. P. Bibcode: 2001astro.ph.11447K Altcode: The Solar Eclipse Coronal Imaging System (SECIS) is a simple and extremely fast, high-resolution imaging instrument designed for studies of the solar corona. Light from the corona (during, for example, a total solar eclipse) is reflected off a heliostat and passes via a Schmidt-Cassegrain telescope and beam splitter to two CCD cameras capable of imaging at 60 frames a second. The cameras are attached via SCSI connections to a purpose-built PC that acts as the data acquisition and storage system. Each optical channel has a different filter allowing observations of the same events in both white light and in the green line (Fe XIV at 5303 A). Wavelet analysis of the stabilized images has revealed high frequency oscillations which may make a significant contribution on the coronal heating process. In this presentation we give an outline of the instrument and its future development. Title: Electron Densities in the Coronae of the Sun and Procyon from Extreme-Ultraviolet Emission Line Ratios in Fe XI Authors: Pinfield, D. J.; Keenan, F. P.; Mathioudakis, M.; Widing, K. G.; Gallagher, P. T.; Gupta, G. P.; Tayal, S. S.; Thomas, R. J.; Brosius, J. W. Bibcode: 2001ApJ...562..566P Altcode: New R-matrix calculations of electron impact excitation rates for Fe XI are used to determine theoretical emission line ratios applicable to solar and stellar coronal observations. These are subsequently compared to solar spectra of the quiet Sun and an active region made by the Solar EUV Rocket Telescope and Spectrograph (SERTS-95), as well as Skylab observations of two flares. Line blending is identified, and electron densities of 109.3, 109.7, >=1010.8, and >=1011.3 cm-3 are found for the quiet Sun, active region, and the two flares, respectively. Observations of the F5 IV-V star Procyon, made with the Extreme Ultraviolet Explorer (EUVE) satellite, are compared and contrasted with the solar observations. It is confirmed that Procyon's average coronal conditions are very similar to those seen in the quiet Sun, with Ne=109.4 cm-3. In addition, although the quiet Sun is the closest solar analog to Procyon, we conclude that Procyon's coronal temperatures are slightly hotter than solar. A filling factor of 25+38-12% was derived for the corona of Procyon. Title: Extreme ultraviolet transitions of FeXXI in solar, stellar and laboratory spectra Authors: Keenan, F. P.; Aggarwal, K. M.; Williams, D. R.; Mathioudakis, M.; Phillips, K. J. H. Bibcode: 2001MNRAS.326.1387K Altcode: Recent <b><sansserif>R</sansserif></b>-matrix calculations of electron impact excitation rates for transitions among the 2s22p2, 2s2p3 and 2p4 levels of FeXXI are used to derive theoretical electron density (Ne) sensitive emission-line ratios involving 2s22p2-2s2p3 transitions in the ~98-146Å wavelength range. A comparison of these with observations from the PLT tokamak plasma, for which the electron density has been independently determined, reveals generally very good agreement between theory and experiment, and in some instances removes discrepancies found previously. The observed FeXXI ratios for a solar flare, obtained with the OSO-5 satellite, imply electron densities which are consistent, with discrepancies that do not exceed 0.2dex. In addition, the derived values of Ne are similar to those estimated for the high-temperature regions of other solar flares. The good agreement between theory and observation, in particular for the tokamak spectra, provides experimental support for the accuracy of the present line-ratio calculations, and hence for the atomic data on which they are based. Title: Oscillator Strengths for Transitions in C-like Ions between F IV and Ar XIII Authors: Aggarwal, K. M.; Keenan, F. P.; Msezane, A. Z. Bibcode: 2001ApJS..136..763A Altcode: Energy levels and oscillator strengths (transition probabilities) have been calculated for the fine-structure transitions among the levels of the (1s2) 2s22p2, 2s2p3, 2p4, 2s22p3s, 2s22p3p, and 2s22p3d configurations of C-like F IV, Na VI, Al VIII, P X, Cl XII, and Ar XIII using the CIV3 program. The extensive configuration interaction and relativistic effects have been included while generating the wavefunctions. Calculated values of energy levels generally agree within 5% with the experimentally compiled results, and the length and velocity forms of oscillator strengths agree within 20% for a majority of allowed transitions. Title: High-frequency oscillations in a solar active region coronal loop Authors: Williams, D. R.; Phillips, K. J. H.; Rudawy, P.; Mathioudakis, M.; Gallagher, P. T.; O'Shea, E.; Keenan, F. P.; Read, P.; Rompolt, B. Bibcode: 2001MNRAS.326..428W Altcode: The Solar Eclipse Corona Imaging System (SECIS) was used to record high-cadence observations of the solar corona during the total solar eclipse of 1999 August 11. During the 2min 23.5s of totality, 6364 images were recorded simultaneously in each of the two channels: a white light channel, and the Fexiv (5303Å) `green line' channel (T~2MK). Here we report initial results from the SECIS experiment, including the discovery of a 6-s intensity oscillation in an active region coronal loop. Title: A detailed abundance analysis of the hot post-AGB star ZNG-1 in M10 Authors: Mooney, C. J.; Rolleston, W. R. J.; Keenan, F. P.; Dufton, P. L.; Pollacco, D. L.; Magee, H. R. Bibcode: 2001MNRAS.326.1101M Altcode: We present a model-atmosphere analysis for the bright (V~13) star ZNG-1, in the globular cluster M10. From high-resolution (R~40000) optical spectra we confirm ZNG-1 to be a post-asymptotic giant branch (post-AGB) star. The derived atmospheric parameters are Teff=26500+/-1000K and logg=3.6+/-0.2dex. A differential abundance analysis reveals a chemical composition typical of hot post-AGB objects, with ZNG-1 being generally metal poor, although helium is approximately solar. The most interesting feature is the large carbon underabundance of more than 1.3dex. This carbon deficiency, along with an observed nitrogen enhancement relative to other elements, may suggest that ZNG-1 evolved off the AGB before the third dredge-up occurred. Also, iron depletions observed in other similar stars suggest that gas-dust fractionation in the AGB progenitor could be responsible for the observed composition of these objects. However, we need not invoke either scenario since the chemical composition of ZNG-1 is in good agreement with abundances found for a Population II star of the same metallicity. Title: The Extreme-Ultraviolet Structure and Properties of a Newly Emerged Active Region Authors: Gallagher, Peter T.; Phillips, Kenneth J. H.; Lee, Jeongwoo; Keenan, Francis P.; Pinfield, David J. Bibcode: 2001ApJ...558..411G Altcode: The structure and properties of a newly emerged solar active region (NOAA Active Region 7985) are discussed using the Coronal Diagnostic Spectrometer (CDS) and the Extreme-Ultraviolet Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory. CDS obtained high-resolution EUV spectra in the 308-381 Å and 513-633 Å wavelength ranges, while EIT recorded full-disk EUV images in the He II (304 Å), Fe IX/X (171 Å), Fe XII (195 Å), and Fe XV (284 Å) bandpasses. Electron density measurements from Si IX, Si X, Fe XII, Fe XIII, and Fe XIV line ratios indicate that the region consists of a central high-density core with peak densities of the order of 1.2×1010 cm-3, which decrease monotonically to ~5.0×108 cm-3 at the active region boundary. The derived electron densities also vary systematically with temperature. Electron pressures as a function of both active region position and temperature were estimated using the derived electron densities and ion formation temperatures, and the constant pressure assumption was found to be an unrealistic simplification. Indeed, the active region is found to have a high-pressure core (1.3×1016 cm-3 K) that falls to 6.0×1014 cm-3 K just outside the region. CDS line ratios from different ionization stages of iron, specifically Fe XVI (335.4 Å) and Fe XIV (334.4 Å), were used to diagnose plasma temperatures within the active region. Using this method, peak temperatures of 2.1×106 K were identified. This is in good agreement with electron temperatures derived using EIT filter ratios and the two-temperature model of Zhang et al. The high-temperature emission is confined to the active region core, while emission from cooler (1-1.6)×106 K lines originates in a system of loops visible in EIT 171 and 195 Å images. Finally, the three-dimensional geometry of the active region is investigated using potential field extrapolations from a Kitt Peak magnetogram. The combination of EUV and magnetic field extrapolations extends the ``core-halo'' picture of active region structure to one in which the core is composed of a number of compact coronal loops that confine the hot, dense, high-pressure core plasma while the halo emission emerges from a system of cooler and more extended loops. Title: Solar coronal observations in high frequencies Authors: Katsiyannis, A. C.; Mathioudakis, M.; Phillips, K. J. H.; Williams, D. R.; Keenan, F. P. Bibcode: 2001hell.confE.174K Altcode: No abstract at ADS Title: X-ray and extreme-ultraviolet emission from the coronae of Capella Authors: Phillips, K. J. H.; Mathioudakis, M.; Huenemoerder, D. P.; Williams, D. R.; Phillips, M. E.; Keenan, F. P. Bibcode: 2001MNRAS.325.1500P Altcode: The primary objective of this work is the analysis and interpretation of coronal observations of Capella obtained in 1999 September with the High Energy Transmission Grating Spectrometer on the Chandra X-ray Observatory and the Extreme Ultraviolet Explorer (EUVE). He-like lines of O (Ovii) are used to derive a density of 1.7×1010cm-3 for the coronae of the binary, consistent with the upper limits derived from Fexxi, Neix and Mgxi line ratios. Previous estimates of the electron density based on Fexxi should be considered as upper limits. We construct emission measure distributions and compare the theoretical and observed spectra to conclude that the coronal material has a temperature distribution that peaks around 4-6MK, implying that the coronae of Capella were significantly cooler than in the previous years. In addition, we present an extended line list with over 100 features in the 5-24Å wavelength range, and find that the X-ray spectrum is very similar to that of a solar flare observed with SMM. The observed to theoretical Fexvii 15.012-Å line intensity reveals that opacity has no significant effect on the line flux. We derive an upper limit to the optical depth, which we combine with the electron density to derive an upper limit of 3000km for the size of the Fexvii emitting region. In the same context, we use the Siiv transition region lines of Capella from HST/Goddard High-Resolution Spectrometer observations to show that opacity can be significant at T=105K, and derive a path-length of ~75km for the transition region. Both the coronal and transition region observations are consistent with very small emitting regions, which could be explained by small loops over the stellar surfaces. Title: Model atmosphere and kinematical analyses of early-type stars from the Edinburgh-Cape Survey Authors: Magee, H. R. M.; Dufton, P. L.; Keenan, F. P.; Rolleston, W. R. J.; Kilkenny, D.; O'Donoghue, D.; Koen, C.; Stobie, R. S. Bibcode: 2001MNRAS.324..747M Altcode: We present high-resolution spectroscopic observations of 21 B-type stars, selected from the Edinburgh-Cape Blue Object Survey. Model atmosphere analyses confirm that 14 of these stars are young, main-sequence B-type objects with Population I chemical compositions. The remaining seven are found to be evolved objects, including subdwarfs, horizontal branch and post-AGB objects. A kinematical analysis shows that all 14 young main-sequence stars could have formed in the disc and subsequently been ejected into the halo. These results are combined with the analysis of a previous subsample of stars taken from the Survey. Of the complete sample, 31 have been found to be young, main-sequence objects, with formation in the disc, and subsequent ejection into the halo, again being found to be a plausible scenario. Title: HST/STIS observations of the high-velocity interstellar cloud HVC 291.2-41.2+80: a warm, mainly ionized high-velocity cloud Authors: Lehner, N.; Keenan, F. P.; Sembach, K. R. Bibcode: 2001MNRAS.323..904L Altcode: We present intermediate-resolution HST/STIS spectra of a high-velocity interstellar cloud (vLSR=+80kms-1) towards DI1388, a young star in the Magellanic Bridge located between the Small and Large Magellanic Clouds. The STIS data have a signal-to-noise ratio (S/N) of 20-45 and a spectral resolution of about 6.5kms-1 (FWHM). The high-velocity cloud absorption is observed in the lines of Cii, Oi, Siii, Siiii, Siiv and Siii. Limits can be placed on the amount of Sii and Feii absorption that is present. An analysis of the relative abundances derived from the observed species, particularly Cii and Oi, suggests that this high-velocity gas is warm (Tk~103-104K) and predominantly ionized. This hypothesis is supported by the presence of absorption produced by highly ionized species, such as Siiv. This sightline also intercepts two other high-velocity clouds that produce weak absorption features at vLSR=+113 and +130kms-1 in the STIS spectra. Title: Line identification in the Ca II K spectral region of sharp-lined B-type stars Authors: Lehner, N.; Trundle, C.; Keenan, F. P.; Sembach, K. R.; Lambert, D. L. Bibcode: 2001A&A...370..996L Altcode: Previous Ca Ii K observations of the B-type star HD 83206 have revealed putative high-velocity interstellar clouds (HVCs) at Local Standard of Rest (LSR) velocities of -80 and -110 kms-1. Similar results were also found for the sightline towards HD 135485. In this article, we show that these absorption lines are in fact due to stellar S Ii features. As the Ca Ii K absorption line in B-type stars is often used to assess the presence and distance of HVCs, we also present a very high quality spectrum of HD 83206 in the Ca Ii K region ( ~ +/- 4 Å or +/- 300 kms-1), so that in the future confusion between stellar lines and HVC features may be avoided. Title: Observations of the Interstellar Medium in the Magellanic Bridge Authors: Lehner, N.; Sembach, K. R.; Dufton, P. L.; Rolleston, W. R. J.; Keenan, F. P. Bibcode: 2001ApJ...551..781L Altcode: 2001astro.ph..1548L We present ultraviolet and optical spectra of DI 1388, a young star in the Magellanic Bridge, a region of gas between the Small and Large Magellanic Clouds. The data have signal-to-noise ratios of 20-45 and a spectral resolution of 6.5 km s-1. Interstellar absorption by the Magellanic Bridge at vLSR~200 km s-1 is visible in the lines of C I, C II, C II*, C IV, N I, O I, Al II, Si II, Si III, Si IV, S II, Ca II, Fe II, and Ni II. The relative gas-phase abundances of C II, N I, O I, Al II, Si II, Fe II, and Ni II with respect to S II are similar to those found in Galactic halo clouds, despite a significantly lower metallicity in the Magellanic Bridge. The higher ionization species in the cloud have a column density ratio N(C+3)/N(Si+3)~1.9, similar to that inferred for collisionally ionized Galactic cloud interfaces at temperatures ~105 K. We identify substructure in the stronger interstellar lines, with a broad component (FWHM~20 km s-1) at ~179 km s-1 and a sharp component (FWHM~11 km s-1) at 198 km s-1. The abundance analysis for these clouds indicates that the feature at 198 km s-1 consists of a low electron density, mainly neutral gas that may be associated with an interface responsible for the highly ionized gas. The 179 km s-1 cloud consists of warmer, lower density gas that is partially ionized. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS5-26555. Title: Hi and optical spectroscopy towards the M15 intermediate-velocity cloud Authors: Smoker, J. V.; Lehner, N.; Keenan, F. P.; Totten, E. J.; Murphy, E.; Sembach, K. R.; Davies, R. D.; Bates, B. Bibcode: 2001MNRAS.322...13S Altcode: 2002astro.ph..4464S We present single-dish Arecibo 21-cm Hi observations, covering a 0.675°×0.625° RA-Dec. grid, of the intermediate-velocity cloud (IVC) centred upon the M15 globular cluster. The velocity and positional structure of the IVC gas at VLSR=70kms-1 are investigated; it is found to be clumpy and has a peak surface density NHi~8×1019cm-2. Additionally, we have performed a long Hi integration towards HD 203664, a Galactic halo star some 3.1° from M15, in which optical IVC absorption has previously been detected. No Hi with a velocity exceeding 60kms-1 was found to a brightness temperature limit of 0.05K. However, additional pointings did detect IVC gas approximately mid-way between HD 203664 and M15. Finally, we present both Arecibo Hi pointings and low-resolution spectra in the Caii H and K lines towards 15 field stars in the general field towards M15, in an attempt to obtain the distance to the IVC. Intermediate-velocity Hi is detected towards seven sightlines. Stellar spectral types are derived for 12 of the sample. Assuming that these stars lie on the main sequence, their distances are estimated to lie in the range 150<=d<=1350pc. No Caii absorption is observed, either because the IVC is further away than ~1350pc or more likely because the gas along these sightlines is of too low a density to be detected by the current observations. Title: Chemical abundances in the inner 5 kpc of the Galactic disk Authors: Smartt, S. J.; Venn, K. A.; Dufton, P. L.; Lennon, D. J.; Rolleston, W. R. J.; Keenan, F. P. Bibcode: 2001A&A...367...86S Altcode: 2000astro.ph..9157S High-resolution, high signal-to-noise spectral data are presented for four young B-type stars lying towards the Galactic Centre. Determination of their atmospheric parameters from their absorption line profiles, and uvby photometric measurement of the continua indicate that they are massive objects lying slightly out of the plane, and were probably born in the disk between 2.5-5 kpc from the Centre. We have carried out a detailed absolute and differential line-by-line abundance analyses of the four stars compared to two stars with very similar atmospheric parameters in the solar neighbourhood. The stars appear to be rich in all the well sampled chemical elements (C, N, Si, Mg, S, Al), except for oxygen. Oxygen abundances derived in the atmospheres of these four stars are very similar to that in the solar neighbourhood. If the photospheric composition of these young stars is reflective of the gaseous ISM in the inner Galaxy, then the values derived for the enhanced metals are in excellent agreement with the extrapolation of the Galactic abundance gradients previously derived by Rolleston et al. (2000) and others. However, the data for oxygen suggests that the inner Galaxy may not be richer than normal in this element, and the physical reasons for such a scenario are unclear. Title: VizieR Online Data Catalog: Chemical abundances of 5 Galactic disk B stars (Smartt+, 2001) Authors: Smartt, S. J.; Venn, K. A.; Dufton, P. L.; Lennon, D. J.; Rolleston, W. R. J.; Keenan, F. P. Bibcode: 2001yCat..33670086S Altcode: High-resolution, high signal-to-noise spectral data are presented for four young B-type stars lying towards the Galactic Centre. Determination of their atmospheric parameters from their absorption line profiles, and uvby photometric measurement of the continua indicate that they are massive objects lying slightly out of the plane, and were probably born in the disk between 2.5-5kpc from the Centre. We have carried out a detailed absolute and differential line-by-line abundance analyses of the four stars compared to two stars with very similar atmospheric parameters in the solar neighbourhood. The stars appear to be rich in all the well sampled chemical elements (C, N, Si, Mg, S, Al), except for oxygen. Oxygen abundances derived in the atmospheres of these four stars are very similar to that in the solar neighbourhood. If the photospheric composition of these young stars is reflective of the gaseous ISM in the inner Galaxy, then the values derived for the enhanced metals are in excellent agreement with the extrapolation of the Galactic abundance gradients previously derived by Rolleston et al. (2000A&A...363..537R) and others. However, the data for oxygen suggests that the inner Galaxy may not be richer than normal in this element, and the physical reasons for such a scenario are unclear. (2 data files). Title: Photoionization and Heating of a Well-characterized Iron Plasma Authors: Foord, M. E.; Heeter, R. F.; Thoe, R. S.; Liedahl, D. A.; Fournier, K. B.; Goldstein, W. H.; Springer, P. T.; Bailey, J. E.; Cuneo, M. E.; Chandler, G. A.; Nash, T. J.; Phillips, M.; Keenan, F.; Rose, S. Bibcode: 2001ASPC..247..117F Altcode: 2001scpp.conf..117F No abstract at ADS Title: Photoionized Plasma Calculations using Laboratory and Astrophysical Models Authors: Phillips, M. E.; Keenan, F. P.; Rose, S. J.; Botha, G. J. J.; Foord, M. E.; Heeter, R. F.; Ferland, G. J. Bibcode: 2001ASPC..247..123P Altcode: 2001scpp.conf..123P No abstract at ADS Title: Cornoal Heating by MHD Waves: Results from the SECIS Instrument during the 1999 Eclipse Authors: Phillip, K. J. H.; Gallagher, P. T.; Williams, D. R.; Keenan, F. P.; Rudawy, P.; Rompolt, B.; Berlicki, A. Bibcode: 2001IAUS..203..467P Altcode: We report on observational evidence for the rôles that small flare-like events and short-period MHD waves play in the heating of the solar corona. In several studies of SOHO and Yohkoh data, we examine the numbers and energies of small events in the EUV and in soft X-rays can account for the necessary energetics of the quiet-Sun corona, finding that EUV events at least might be sufficient to provide the heating, at least in closed-field regions. Results will be summarized in this paper. However, MHD waves may still play an important part, and in a separate investigation we have used fast-cadence imaging of the white-light and green-line corona during the total eclipse of 1999 August 11 to search for short-period modulations. The imaging system is the Solar Eclipse Coronal Imaging System (SECIS), and consists of a pair of CCD cameras and an adapted PC to form images of the corona at a frame rate of 44 s-1. Preliminary analysis of the data suggests the presence of fast changes over the 2-minute-long period of eclipse totality. This paper will also report on the SECIS data. Title: Opacity Effects in the Transition Region of Active Stars (CD-ROM Directory: contribs/williams) Authors: Williams, D. R.; Mathioudakis, M.; McKenny, J.; Keenan, F. P. Bibcode: 2001ASPC..223..889W Altcode: 2001csss...11..889W No abstract at ADS Title: Theoretical emission line ratios for [Fe III] and [Fe VII] applicable to the optical and infrared spectra of gaseous nebulae Authors: Keenan, Francis P.; Aller, Lawrence H.; Ryans, Robert S. I.; Hyung, Siek Bibcode: 2001PNAS...98.9476K Altcode: Recent calculations of electron impact excitation rates and Einstein A-coefficients for transitions among the 3d6 levels of Fe III and among the 3d2 levels of Fe VII are used to derive theoretical emission line ratios applicable to the optical and infrared spectra of gaseous nebulae. Results for [Fe III] are generated for electron temperatures Te = 7,000-20,000 K and densities Ne = 102-108 cm-3, whereas those for [Fe VII] are provided for Te = 10,000-30,000 K and Ne = 102-108 cm-3. The theoretical line ratios are significantly different in some instances from earlier calculations and resolve discrepancies between theory and observation found for the planetary nebulae IC 4997 and NGC 7027. Title: Emission-Line Ratios for [N II] in Gaseous Nebulae and a Comparison between Theory and Observation Authors: Keenan, F. P.; Crawford, F. L.; Feibelman, W. A.; Aller, L. H. Bibcode: 2001ApJS..132..103K Altcode: R-matrix calculations of electron impact excitation rates among the 2s22p2 3P, 1D, 1S, and 2s2p3 5S levels of N II are presented. These results are used in conjunction with other recent calculations of electron impact excitation rates and Einstein A-coefficients for N II to derive the emission-line ratio: ratio diagrams (R1, R2) and (R1, R3), where R1=I(5756.2 Å)/I(6549.9+6585.2 Å), R2=I(2143.5 Å)/I(6549.9+6585.2 Å), and R3=I(2139.7 Å)/I(6549.9+6585.2 Å), for a range of electron temperatures (Te=5000-20,000 K) and electron densities (Ne=102-107 cm-3) appropriate to gaseous nebulae. These diagrams should, in principle, allow the simultaneous determination of Te and Ne from measurements of the [N II] lines in a spectrum. Plasma parameters deduced for a sample of gaseous nebulae, using observational data obtained from ground-based telescopes plus the International Ultraviolet Explorer and Hubble Space Telescope satellites, are found to show generally excellent internal consistency and to be in good agreement with the values of Te and Ne estimated from other line ratios. These results provide observational support for the accuracy of the theoretical ratios and hence the atomic data adopted in their derivation. Theoretical ratios are also presented for the infrared line pair R4=I(122 μm)/I(205 μm), and the usefulness of R4 as an electron density diagnostic is briefly discussed. Title: S xi Emission Lines in Active Region Spectra Obtained with the Solar euv Rocket Telescope and Spectrograph (Serts) Authors: Keenan, F. P.; Pinfield, D. J.; Mathioudakis, M.; Aggarwal, K. M.; Thomas, R. J.; Brosius, J. W. Bibcode: 2000SoPh..197..253K Altcode: Theoretical electron density sensitive emission line ratios involving a total of eleven 2s22p2-2s2p3 transitions in S xi between 187 and 292 Å are presented. A comparison of these with solar active region observations obtained during rocket flights by the Solar EUV Rocket Telescope and Spectrograph (SERTS) reveals generally good agreement between theory and experiment. However, the 186.87 Å line is masked by fairly strong Fe xii emission at the same wavelength, while 239.83 Å is blended with an unknown feature, and 285.58 Å is blended with possibly N iv 285.56 Å. In addition, the 191.23 Å line appears to be more seriously blended with an Fe xiii feature than previously believed. The presence of several new S xi lines is confirmed in the SERTS spectra, at wavelengths of 188.66, 247.14 and 291.59 Å, in excellent agreement with laboratory measurements. In particular, the detection of the 2s22p23P1 -2s2p33P0,1 transitions at 242.91 Å is the first time (to our knowledge) that this feature has been identified in the solar spectrum. The potential usefulness of the S xi line ratios as electron density diagnostics for the solar transition region and corona is briefly discussed. Title: CO and optical observations of the Magellanic Bridge Authors: Smoker, J. V.; Keenan, F. P.; Polatidis, A. G.; Mooney, C. J.; Lehner, N.; Rolleston, W. R. J. Bibcode: 2000A&A...363..451S Altcode: We present 12CO(1-0) molecular line and BV CCD observations towards 0311-7651, a region in the Magellanic Bridge where cold atomic Hydrogen has previously been detected by Kobulnicky & Dickey. Additionally, BV images of a comparison field 1deg to the South were taken. No CO was detected to a limit of ~ 0.06 Kelvin, and the colour-magnitude diagrams show no evidence for a stellar association in either field. Based on observations made with the Danish 1.54-m and SEST telescopes at the European Southern Observatory, La Silla, Chile. Title: A developed stage of Alfvén wave phase mixing Authors: Botha, G. J. J.; Arber, T. D.; Nakariakov, V. M.; Keenan, F. P. Bibcode: 2000A&A...363.1186B Altcode: Alfvén wave phase mixing is an extensively studied mechanism for dissipating wave energy in an inhomogeneous medium. It is common in the vast majority of phase mixing papers to assume that even though short scale lengths and steep gradients develop as a result of phase mixing, nonlinear wave coupling does not occur. However, weakly nonlinear studies have shown that phase mixing generates magnetoacoustic modes. Numerical results are presented which show the nonlinear generation of magnetosonic waves by Alfvén wave phase mixing. The efficiency of the effect is determined by the wave amplitude, the frequency of the Alfvén waves and the gradient in the background Alfvén speed. Weakly nonlinear theory has shown that the amplitude of the fast magnetosonic wave grows linearly in time. The simulations presented in this paper extend this result to later times and show saturation of the fast magnetosonic component at amplitudes much lower than that of the Alfvén wave. For the case where Alfvén waves are driven at the boundary, simulating photospheric footpoint motion, a clear modulation of the saturated amplitude is observed. All the results in this paper are for a low amplitude (<= 0.1), single frequency Alfvén wave and a uniform background magnetic field in a two dimensional domain. For this simplified geometry, and with a monochromatic driver, we concluded that the nonlinear generation of fast modes has little effect on classical phase mixing. Title: Electron density diagnostics for solar ultraviolet lines of O V Authors: O'Shea, E.; O'Neill, T.; Keenan, F. P.; Doyle, J. G. Bibcode: 2000SoPh..196..321O Altcode: We determine the electron densities for a range of solar features using new calculations for the O v line ratio, R=I(λ761.1)/I(λ760.4), in conjunction with observational data obtained with the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) instrument on the Solar and Heliospheric Observatory (SOHO). The densities obtained from this diagnostic are in good agreement with earlier measured values. This provides support for the theoretical diagnostics presented in this paper, and hence the atomic data used in their derivation. We conclude from these results that this particular O v ratio is a useful diagnostic for many types of solar features. Title: Emission lines of O bt III in the optical and ultraviolet spectra { } of planetary nebulae Authors: Crawford, F. L.; Keenan, F. P.; Aggarwal, K. M.; Wickstead, A. W.; Aller, L. H.; Feibelman, W. A. Bibcode: 2000A&A...362..730C Altcode: Recent R-matrix calculations of electron impact excitation rates in O Iii are used to calculate electron temperature and density-dependent emission line ratios R1 = I(4363 Å) / I(4960 Å+ 5007 Å), R2 = I(1661 Å+ 1667 Å) / I(4960 Å+ 5007 Å) and R3 = I(2322 Å) / I(1661 Å+ 1667 Å), for a range of electron temperatures (7500 <= Te <= 30 000 K) and densities (104 <= Ne <= 107 cm-3) applicable to gaseous nebulae. The ratio-ratio diagrams (R1, R2) and (R1, R3) should, in principle, allow the simultaneous determination of Te and Ne from measurements of the O Iii features in a spectrum. Plasma parameters derived for a sample of mid- to high-excitation planetary nebulae from (R1, R2) and (R1, R3) measurements, produced using a combination of ultraviolet spectra obtained with the International Ultraviolet Explorer (IUE) and optical data from a number of observing runs, are found to show excellent internal consistency. They also show, in general, good agreement with the values of Te and Ne estimated from other line ratios in the nebulae, therefore providing observational support for the accuracy of the theoretical ratios and hence the atomic data adopted in their derivation. Title: The Radial and Angular Variation of Electron Density in the Solar Corona. Authors: Gallagher, P. T.; Mathioudakis, M.; Phillips, K. J. H.; Tsinganos, K.; Keenan, F. P. Bibcode: 2000SPD....31.0234G Altcode: 2000BAAS...32.1290G We derive, for the first time, electron densities as a function of both radius (R) and position angle (θ ) for the south-west quadrant of the off-limb corona, using the density-sensitive Si ix (349.9 Å/341.9 Å) and Si x (356.0 Å/347.7 Å) extreme ultraviolet line ratios. The observations were made with the Coronal Diagnostic Spectrometer (cds) on board the Solar and Heliospheric Observatory (soho), over the range 1.00R⊙ < R < 1.20R⊙ and 180° < θ < 270° . Within the south polar coronal hole, the density varies from 2.3 x 108 cm-3 at 1.0R⊙ to 8.3x 107 cm-3 at 1.20R⊙ , while at the equator the density varies from 6.3 x 108 cm-3 at 1.0R⊙ to 1.6x 108 cm-3 at 1.20R⊙ . The density falloff with height is therefore faster in the equatorial region. We also find that electron densities are, on average, a factor of 2.7 larger in the equatorial regions than in the polar coronal hole at a given radial distance. Finally, we find remarkable agreement between our measured densities as a function of radius and position angle and those predicted by a recent analytic MHD model of the solar wind, strongly supporting its basic premises. Title: Extreme ultraviolet emission lines of Nixii in laboratory and solar spectra Authors: Keenan, F. P.; Botha, G. J. J.; Matthews, A.; Lawson, K. D.; Coffey, I. H. Bibcode: 2000MNRAS.318...37K Altcode: Wavelengths for emission lines arising from 3s23p5-3s3p6 and 3s23p5-3s23p43d transitions in Nixii have been measured in extreme ultraviolet spectra of the Joint European Torus (JET) tokamak. The 3s23p5 2P1/2- 3s23p4(3P)3d 2D3/2 line is found to lie at 152.90+/-0.02Å, a significant improvement over the previous experimental determination of 152.95+/-0.5Å. This new wavelength is in good agreement with a solar identification at 152.84+/-0.06Å, confirming the presence of this line in the solar spectrum. The Nixii feature at 152.15Å may be a result only of the 3s23p5 2P3/2- 3s23p4(3P)3d 2D5/2 transition, rather than a blend of this line with 3s23p5 2P3/2- 3s23p4(3P)3d 2P1/2, as previously suggested. Unidentified emission lines at 295.32 and 317.61Å in solar flare spectra from the Skylab mission are tentatively identified as the 3s23p5 2P3/2-3s3p6 2S1/2 and 3s23p5 2P1/2-3s3p6 2S1/2 transitions in Nixii, which have laboratory wavelengths of 295.33 and 317.50Å, respectively. Additional support for these identifications is provided by the line intensity ratio for the solar features, which shows good agreement between theory and observation. Title: K-Shell Photoionization of Fe Authors: McLaughlin, B. M.; Donnelly, D.; Bell, K. L.; Scott, M. P.; Keenan, F. P. Bibcode: 2000adnx.conf...85M Altcode: The status of K-shell photoionization of neutral iron has been reviewed. A comparison with the available experimental data and existing theoretical work is made for this important element. Several anomalies and features are illustrated and future directions of theoretical work are indicated. Title: Radio continuum observations of possible B-type stars in the halo of M 31 Authors: Smoker, J. V.; Keenan, F. P.; Marcha, M. J.; Watson, D.; Irwin, M. J. Bibcode: 2000A&A...361...60S Altcode: We present Very Large Array (VLA) 5 GHz continuum observations of six point sources towards the halo of M 31, which have featureless optical spectra and magnitudes ranging from V=21.5-22.2, in order to determine whether these objects are BL Lacs. No radio emission coincident with the optical positions is detected to a 5sigma noise level of between 0.08 and 0.11 mJy. The resulting upper limits to the two-point radio-to-optical spectral indexes from 5 GHz to 2500 &Aring (alpha_RO ) are less than 0.30 for all of the sample. These observations make it highly likely that these objects are not BL Lacs, and hence strengthens the case that they are normal B-type stars in the halo of M 31. Based on observations taken at the National Radio Observatory which is operated by Associated Universities, Inc., under cooperative agreement with the National Science Foundation, USA Title: Multi-wavelength observations of the 1998 September 27 flare spray Authors: Gallagher, Peter T.; Williams, David R.; Phillips, Kenneth J. H.; Mathioudakis, Mihalis; Smartt, Raymond N.; Keenan, Francis P. Bibcode: 2000SoPh..195..367G Altcode: We report on observations of a large eruptive event associated with a flare that occurred on 27 September 1998 made with the Richard B. Dunn Solar Telescope at Sacramento Peak Observatory (several wave bands including off-line-center Hα), in soft and hard X-rays (GOES and BATSE), and in several TRACE wave bands (including Fe ix/x 171 Å, Fe xii 195 Å, and C iv 1550 Å). The flare initiation is signaled by two Hα foot-point brightenings which are closely followed by a hard X-ray burst and a subsequent gradual increase in other wavelengths. The flare light curves show a complicated, three-component structure which includes two minor maxima before the main GOES class C5.2 peak after which there is a characteristic exponential decline. During the initial stages, a large spray event is observed within seconds of the hard X-ray burst which can be directly associated with a two-ribbon flare in Hα. The emission returns to pre-flare levels after about 35 min, by which time a set of bright post-flare loops have begun to form at temperatures of about 1.0-1.5 MK. Part of the flare plasma also intrudes into the penumbra of a large sunspot, generally a characteristic of very powerful flares, but the flare importance in GOES soft X-rays is in fact relatively modest. Much of the energy appears to be in the form of a second ejection which is observed in optical and ultraviolet bands, traveling out via several magnetic flux tubes from the main flare site (about 60° from Sun center) to beyond the limb. Title: Six emission lines in spectra obtained with the Solar EUV Rocket Telescope and Spectrograph (SERTS) Authors: Keenan, F. P.; O'Shea, E.; Thomas, R. J.; Brosius, J. W.; Katsiyannis, A.; Ryans, R. S. I.; Reid, R. H. G.; Pradhan, A. K.; Zhang, H. L. Bibcode: 2000MNRAS.315..450K Altcode: New R-matrix calculations of electron impact excitation rates for transitions among the 2s22p, 2s2p2 and 2p3 levels of Six are presented. These data are subsequently used, in conjunction with recent estimates for proton excitation rates, to derive theoretical electron density sensitive emission-line ratios involving transitions in the ~253-356Å wavelength range. A comparision of these with observations of a solar active region and subflare, obtained during the 1989 flight of the Solar EUV Rocket Telescope and Spectrograph (SERTS), reveals that the electron densities determined from most of the Six line ratios are consistent with one another for both solar features. In addition, the derived densities are also in good agreement with the values of Ne estimated from diagnostic lines in other species formed at similar electron temperatures to Six, such as Fexii and Fexiii. These results provide observational support for the general accuracy of the adopted atomic data, and hence line ratio calculations, employed in the present analysis. However, we find that the Six 256.32-Å line is blended with the Heii transition at the same wavelength, while the feature at 292.25Å is not due to Six, but currently remains unidentified. The intensity of the 253.81-Å line in the SERTS active region spectrum is about a factor of 3 larger than expected from theory, but the reason for this is unclear, and requires additional observations to explain the discrepancy. Title: Transition region and coronal structuring Authors: O'Shea, E.; Gallagher, P. T.; Mathioudakis, M.; Phillips, K. J. H.; Keenan, F. P.; Katsiyannis, A. C. Bibcode: 2000A&A...358..741O Altcode: In this paper we examine regions of internetwork, network and bright network emission, observed in the quiet Sun with the Coronal Diagnostic Spectrometer (cds) onboard SoHO. The slopes of the emission measure distributions, between 5.4 <= log Te <= 6.0, are found to differ in each region, suggesting the presence of different atmospheric structures. From an analysis of emission area the network is shown to have two populations of structures, a low transition region group and a coronal group. Using mdi magnetograms the bright network emission is shown to originate from regions of strong magnetic field composed of bipolar loops and unipolar funnels, that extend from the low transition region up to the corona. Up to 30% of all radiative losses between 5.7 <= log Te <= 6.3 are found to come from these continuous bright network structures. Cross-sectional areas calculated from redshift values suggest that the area expansion seen in the bright network emission is the result of flux tube expansion into the corona, accompanied by either a downflow or upflow of material. Title: Strömgren uvby photometry of B-type stars from the Palomar-Green Survey Authors: Mooney, C. J.; Rolleston, W. R. J.; Keenan, F. P.; Pinfield, D. J.; Pollacco, D. L.; Dufton, P. L.; Katsiyannis, A. C. Bibcode: 2000A&A...357..553M Altcode: We present Strömgren uvby photometry for a sample of 31 high Galactic latitude stars selected from the Palomar-Green Survey. The data include photometric magnitudes accurate to <= 0.01 mag in most cases, plus colours and the reddening free [c_1] and [u-b] indices, which possess a precision of better than 0.02 and 0.04 mag, respectively. The latter should be suitable for the reliable determination of stellar photometric temperatures. Title: High-resolution optical spectroscopy of the sharp-lined B-type star HD83206 Authors: Lehner, N.; Dufton, P. L.; Lambert, D. L.; Ryans, R. S. I.; Keenan, F. P. Bibcode: 2000MNRAS.314..199L Altcode: Very-high-resolution (R~160000) spectroscopic observations are presented for the early B-type star, HD83206. Because it has very sharp metal lines, this star affords an opportunity to test theories of model atmospheres and line formation. Non-LTE model atmosphere calculations have been used to estimate the atmospheric parameters and absolute metal abundances (C, N, O, Mg and Si); an LTE analysis was also undertaken to investigate the validity of this simpler approach and to estimate an iron abundance. For the non-LTE calculations, there is excellent agreement with observations of the Balmer lines Hα and Hδ and the lines of Siii and Siiii for atmospheric parameters of Teff~=21700+/-600K and logg~=4.00+/-0.15dex. The agreement is less convincing for the LTE calculations, and a higher gravity is deduced. Careful comparison of the metal line profiles with non-LTE calculations implies that the projected rotational and microturbulent velocities have maximum values of ~=5 and ~=2kms-1, respectively. The latter value is smaller than has often been adopted in LTE model atmosphere analyses of main-sequence stars. Non-LTE absolute metal abundances are estimated, and a comparison with those for normal B-type stars (deduced using similar non-LTE techniques) shows no significant differences. A comparison of the abundances deduced using non-LTE and LTE calculations implies systematic differences of 0.1-0.2dex, showing the importance of using a non-LTE approach when accurate absolute abundances are required. Its location in the Hertzsprung-Russell diagram and normal metal abundance lead us to conclude that HD83206 is probably a main-sequence B-type star. As such, it is among the sharpest-lined young B-type star discovered to date. Title: SECIS: The Solar Eclipse Coronal Eclipse Imaging System Authors: Phillips, K. J. H.; Read, P. D.; Gallagher, P. T.; Keenan, F. P.; Rudawy, P.; Rompolt, B.; Berlicki, A.; Buczylko, A.; Diego, F.; Barnsley, R.; Smartt, R. N.; Pasachoff, J. M.; Babcock, B. A. Bibcode: 2000SoPh..193..259P Altcode: The Solar Eclipse Coronal Imaging System (SECIS) is an instrument designed to search for short-period modulations in the solar corona seen either during a total eclipse or with a coronagraph. The CCD cameras used in SECIS have the capability of imaging the corona at a rate of up to 70 frames a second, with the intensities in each pixel digitised in 12-bit levels. The data are captured and stored on a modified PC. With suitable optics it is thus possible to search for fast changes or short-period wave motions in the corona that will have important implications for the coronal heating mechanism. The equipment has been successfully tested using the Evans Solar Facility coronagraph at National Solar Observatory/Sacramento Peak and during the 11 August 1999 eclipse at a site in north-eastern Bulgaria. The instrument is described and preliminary results are outlined. Title: Cross Sections for the K-Shell Photoabsorption of Neutral Iron Authors: Donnelly, D. W.; Bell, K. L.; Scott, M. P.; Keenan, F. P. Bibcode: 2000ApJ...531.1168D Altcode: The Fe I Kα emission lines are observed during solar flares and in the emission spectra of other astrophysical sources, such as active galactic nuclei. This paper presents cross sections for the K-shell photoionization of neutral iron, which are urgently required for the modeling of these astrophysical phenomena. A 16 target-state representation is utilized, where each target state is represented by an extensive configuration-interaction-type wave function. The consequent introduction of electron correlation effects is seen to significantly alter the magnitude of the background cross section in comparison with earlier work, while extensive resonance structure is also resolved near threshold for the first time. Title: VizieR Online Data Catalog: Excitation rate coefficients for O III (Aggarwal+, 1999) Authors: Aggarwal, K. M.; Keenan, F. P. Bibcode: 2000yCat..21230311A Altcode: Collision strengths for fine-structure transitions among the levels of the (1s2) 2s22p2, 2s2p3, 2p4, 2s22p3s, 2s22p3p, and 2s22p3d configurations of O III have been computed over a wide range of energies below 13.0 ryd using the R-matrix program. All partial waves with L{<=}40 have been included to ensure the convergence of results. Excitation rate coefficients, in the form of dimensionless effective collision strengths, have also been computed at temperatures below 200,000 K. The results are compared with available calculations, and accuracy of the data is assessed.

(4 data files). Title: Fe II emission lines as a chronometer for high-redshift quasars Authors: Espey, Brian; Ferland, Gary; Keenan, Francis; Verner, Dima Bibcode: 2000noao.prop..301E Altcode: We have embarked on a project to fully simulate the physical conditions within Fe II-emitting gas, and predict the resulting spectrum. The first steps of generating the initial atomic database, and incorporating it into the photoionization code CLOUDY, are complete. Here we request echelle observations of the symbiotic star RR Telescopii (RR Tel), to combine with HST/STIS data to give the first complete coverage of Fe II emission lines in the 1150-10000 Arange. The Fe II emitting regions in symbiotics have similar physical conditions to those in active galaxies, and hence the RR Tel observations will provide a testbed for our Fe II numerical simulations. Analysis of the RR Tel data using CLOUDY will allow us to check the reliability and completeness of the atomic data and processes considered, to investigate the sensitivity of emission to temperature and density variations, and to assess the importance of blending. Once calibrated against the RR Tel data, we will use our Fe II simulations to deduce iron abundances in high-redshift quasars. This, in conjunction with predictions of stellar evolution and galactic nucleosynthesis, will result in a chronometer measuring the redshift when the universe passed through an age of 1 Gyr, thus constraining several cosmological parameters. Title: Strömgren uvby photometry of hot stars at high galactic latitudes Authors: Mooney, C. J.; Rolleston, W. R. J.; Keenan, F. P.; Pinfield, D. J.; Pollacco, D. L.; Dufton, P. L. Bibcode: 2000LIACo..35..517M Altcode: 2000ghgc.conf..517M No abstract at ADS Title: Identification of the [Al II] Forbidden Line at 2661 Å in the Spectrum of RR Telescopii Authors: Crawford, F. L.; Keenan, F. P.; Mathioudakis, M.; Aggarwal, K. M.; McKenna, F. C.; Feibelman, W. A.; Espey, B. R. Bibcode: 2000ASPC..204..387C Altcode: 2000tiaf.conf..387C No abstract at ADS Title: Nebular and auroral emission lines of [Cl III] in the optical spectra of planetary nebulae Authors: Keenan, Francis P.; Aller, Lawrence H.; Ramsbottom, Catherine A.; Bell, Kenneth L.; Crawford, Fergal L.; Hyung, Siek Bibcode: 2000PNAS...97.4551K Altcode: Electron impact excitation rates in Cl III, recently determined with the R-matrix code, are used to calculate electron temperature (Te) and density (Ne) emission line ratios involving both the nebular (5517.7, 5537.9 A) and auroral (8433.9, 8480.9, 8500.0 A) transitions. A comparison of these results with observational data for a sample of planetary nebulae, obtained with the Hamilton Echelle Spectrograph on the 3-m Shane Telescope, revelas that the R1 = I(5518)/I(5538) intensity ratio provides estimates of Ne in excellent agreement with values derived from other line ratios in the echelle spectra. This agreement indicates that R1 is a reliable density diagnostic for planetary nebulae, and it also provides observational support for the accuracy of the atomic data adopted in the line ratio calculations. However the [Cl III] 8433.9 line is found to be frequently blended with a weak telluric emission feature, although in those instances when the [Cl III] intensity may be reliably measured, it provides accurate determinations of Te when ratioed against the sum of the 5518 and 5538 A line fluxes. Similarly, the 8500.0 A line, previously believed to be free of contamination by the Earth's atmosphere, is also shown to be generally blended with a weak telluric emission feature. The [Cl III] transition at 8480.9 A is found to be blended with the He I 8480.7 A line, except in planetary nebulae that show a relatively weak He I spectrum, where it also provides reliable estimates of Te when ratioed against the nebular lines. Finally, the diagnostic potential of th near-UV [Cl III] lines at 3344 and 3354 A is briefly discussed. Title: The Quiet Sun Atmosphere as Seen by Soho Authors: Phillips, K. J. H.; Gallagher, P. T.; Harra-Murnion, L. K.; Keenan, F. P.; Pres, P. Bibcode: 2000AdSpR..25.1747P Altcode: The recent solar minimum has allowed studies to be made of quiet-Sun structures with SOHO instruments with better resolution than before. This paper reports on the morphology and dynamics of the EUV emission, including the chromospheric and transition-region network and coronal features, and how the photospheric magnetic field and coronal bright points are related Title: Line Identifications and Intensitites for the Optical Spectrum of RR Telescopi between 3180 and 9455 Å Authors: Crawford, F. L.; McKenna, F. C.; Keenan, F. P.; Aller, L. H.; Fiebelman, W. A.; Ryan, S. G. Bibcode: 2000ASPC..204..385C Altcode: 2000tiaf.conf..385C No abstract at ADS Title: Modeling the Warm Ionized Interstellar Medium and Its Impact on Elemental Abundance Studies Authors: Sembach, Kenneth R.; Howk, J. Christopher; Ryans, Robert S. I.; Keenan, Francis P. Bibcode: 2000ApJ...528..310S Altcode: 1999astro.ph..8051S We present model calculations of ionization fractions for elements in the warm (T~104 K), low-density photoionized interstellar medium (WIM) of the Milky Way. We model the WIM as a combination of overlapping low-excitation H II regions having n(H+)/n(H)>~0.8. Our adopted standard model incorporates an intrinsic elemental abundance pattern similar to that found for warm neutral clouds in the Galaxy and includes the effects of interstellar dust grains. The radiation field is characterized by an ionizing spectrum of a star with Teff~35,000 K and an ionization parameter log(q)~-4.0. The emergent emission-line strengths are in agreement with the observed ratios of [S II]/Hα, [N II]/Hα, [S II]/[N II], [O I]/Hα, [O III]/Hα, and He I/Hα in the Galactic WIM. Although the forbidden emission-line intensities depend strongly on the input model parameters, the ionization fractions of the 20 elements studied in this work are robust over a wide range of physical conditions considered in the models. These ionization fractions have direct relevance to absorption-line determinations of the elemental abundances in the warm neutral and ionized gases in the Milky Way and other late-type galaxies. We demonstrate a method for estimating the WIM contributions to the observed column densities of singly and doubly ionized atoms used to derive abundances in the warm neutral gas. We apply this approach to study the gas-phase abundances of the warm interstellar clouds toward the halo star HD 93521. Title: Model atmosphere and kinematical analyses of early-type stars from the Edinburgh-Cape survey Authors: Magee, H. R. M.; Dufton, P. L.; Keenan, F. P.; Rolleston, W. R. J.; Kilkenny, D.; O'Donoghue, D.; Koen, C.; Stobie, R. S. Bibcode: 2000LIACo..35..249M Altcode: 2000ghgc.conf..249M No abstract at ADS Title: HST/STIS Observations of the Interstellar Medium in the Magellanic Bridge Authors: Lehner, N.; Keenan, F. P.; Dufton, P. L.; Sembach, K. R. Bibcode: 2000dhst.conf...56L Altcode: No abstract at ADS Title: SUMER Measurements of Electron Density Enhancements in the Solar Transition Region Authors: Pérez, M. E.; Doyle, J. G.; O'Shea, E.; Keenan, F. Bibcode: 1999ESASP.448..629P Altcode: 1999mfsp.conf..629P; 1999ESPM....9..629P No abstract at ADS Title: Evidence for Non-Maxwellian Electron Energy Distributions in the Solar Transition Region: Si III Line Ratios from SUMER Authors: Pinfield, D. J.; Keenan, F. P.; Mathioudakis, M.; Phillips, K. J. H.; Curdt, W.; Wilhelm, K. Bibcode: 1999ApJ...527.1000P Altcode: Recent calculations of Si III emission-line strengths are compared with SUMER observations from a quiet solar region, a coronal hole, and an active region. Diagnostic line ratios are used to derive Te and Ne for the emitting plasma in each region, and good agreement between theory and observations is found. A major enhancement in the intensity of the 1313 Å emission line is observed, as well as some evidence of a small decrease in the temperature of maximum ionization fraction, as one moves from the coronal hole to the active region. Possible explanations for these effects are discussed, and it is concluded that they may be caused by the presence of nonthermal electrons in the transition region. Title: Optical observations of three Galactic halo stars: evidence for cloudlets in intermediate- and high-velocity interstellar clouds Authors: Lehner, N.; Sembach, K. R.; Lambert, D. L.; Ryans, R. S. I.; Keenan, F. P. Bibcode: 1999A&A...352..257L Altcode: Very high resolution (R ~ 160000) absorption line measurements of the interstellar Ca Ii K and Na I D lines and medium resolution (R ~ 50000) measurements of the interstellar Ti Ii (3384 Ä) line towards three Galactic halo stars are presented. The data have signal-to-noise ratios of ~ 90-240. The sightlines studied clearly show several intermediate-high velocity interstellar clouds with local standard of rest velocities in the range ~ - 40 to -110 \km. Two different methods have been used to analyze these data. Line profile fitting allows us to model multiple components for the different high-velocity clouds separated by only a few km. The close proximity of the lines in velocity space indicates that the cloudlets are related. Conversion of the absorption profiles to apparent optical depth profiles also allows us to examine the column densities and their ratios as a function of velocity. Variations in N(ion {Ca}{ii})/N(ion {Na}i), N(ion {Ca}{ii})/N(ion {Ti}{ii}) and N(ion {Ti}{ii})/N(ion {Na}i) with cloud velocity are discussed. Title: Temporal variability in the electron density at the solar transition region Authors: Pérez, M. E.; Doyle, J. G.; O'Shea, E.; Keenan, F. P. Bibcode: 1999A&A...351.1139P Altcode: The electron density as measured in the transition region of a coronal hole, a `quiet' Sun region at disk center plus an active region shows variations of up to a factor of two at T_e ~ 1.5 105 K, lasting at most only a few minutes. There is remarkable agreement between the number of such variations, their temporal variability and duration in the coronal hole and `quiet' Sun datasets, consistent with an earlier bright point study. There appears to be evidence of super-granular cells, with the increases in electron density occurring along the network boundaries. At some locations, periodicities of between 8 and 16 min are visible in the electron density variations. We associate these variations with the sites of explosive events. Title: The effects of opacity in the transition region of YZ CMi Authors: Mathioudakis, M.; McKenny, J.; Keenan, F. P.; Williams, D. R.; Phillips, K. J. H. Bibcode: 1999A&A...351L..23M Altcode: It has generally been assumed that the emission from the upper atmosphere of late-type stars is optically thin. In the present paper we use the Si IV and C IV resonance lines to investigate this assumption for the active dMe star YZ CMi. The significant deviations of the line ratios from their optically thin values, demonstrate that opacity can be quite important particularly in the case of stellar flares. These deviations are combined with a method of escape probabilities to derive optical depths of approximately unity for the lines under consideration. We demonstrate that, if the electron density in the atmosphere is known, opacity can provide important information on the linear dimensions of the scattering layer. Using this technique, we have estimated path lengths of a few kilometers for one of the flares under consideration. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. Title: Line identifications and intensities for the optical spectrum of RR Telescopii between 3180 and 9455 Å Authors: Crawford, F. L.; McKenna, F. C.; Keenan, F. P.; Aller, L. H.; Feibelman, W. A.; Ryan, S. G. Bibcode: 1999A&AS..139..135C Altcode: The symbiotic nova RR Telescopii has been observed with the 3.9 m telescope at the Anglo-Australian Observatory (AAO), using the University College London Echelle Spectrograph (UCLES) in conjunction with a Tek CCD. It displays a rich emission line spectrum, ranging in excitation from N I to [Ni Viii]. We present a list of 811 measured lines, with their suggested identifications and absolute line intensities, covering a wavelength range from 3180 Å to 9455 Å. The absolute line intensities have been derived by comparing the high resolution data with a flux-calibrated low resolution spectrum taken with the Australian National University 2.3 m telescope. All of the lines have been successfully identified. Comparing our results with those of previous studies indicates that the RR Tel system is advancing towards higher degrees of ionisation.

Tables 2 and 3 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html Title: A New Study of the Quiet Sun Authors: O'Shea, E.; Gallagher, P. T.; Mathioudakis, M.; Phillips, K. J. H.; Keenan, F. P. Bibcode: 1999ESASP.446..519O Altcode: 1999soho....8..519O In this paper we present results of an emission measure analysis performed on regions of cell, network and bright network emission which were observed in the quiet Sun at Sun centre with the Coronal Diagnostic Spectrometer (CDS) on board SOHO. Seperate emission from the three regions was obtained by a method of image segmentation using a histogram modification technique. From the averaged emission it was possible to produce emission measures over a broad temperature range. These emission measures were then used to produce estimates of radiative and conductive losses in the three regions considered. Using a magnetogram obtained from the MDI instrument on SOHO we show that the bright network emission originates from bipolar magnetic loops and from what appear to be monopole regions, which could be the remains of footpoints of larger loops. The bright network emission shows significantly higher mean magnetic field strength as well as significantly larger radiative energy losses than either of the other two regions. We find some evidence suggesting the presence of cool loops. The process of image segmentation also enabled us to obtain the relative areas of the cell, network and bright network emission as a function of temperature. We found that only the bright network emission showed an expansion in area with temperature and therefore height. Fitting this area curve with the functional form suggested by Rabin (1991),i.e A(T)/A(Th) = [1 + (Gamma2 - 1)(T/Th)nu]1/2/Gamma , for the cross-sectional area of a flux tube, we obtain a value of Gamma=7.1 and nu=2.5 for the constriction and shape factors respectively. Title: The Radial and Angular Variation of the Electron Density in the Solar Corona Authors: Gallagher, P. T.; Mathioudakis, M.; Keenan, F. P.; Phillips, K. J. H.; Tsinganos, K. Bibcode: 1999ApJ...524L.133G Altcode: We derive, for the first time, electron densities as a function of both radius (R) and position angle (θ) for the southwest quadrant of the off-limb corona, using the density-sensitive Si IX λ349.9/λ341.9 and Si X λ356.0/λ347.7 extreme-ultraviolet line ratios. The observations were made with the coronal diagnostic spectrometer on board the Solar and Heliospheric Observatory over the ranges of 1.00 Rsolar<R<1.20 Rsolar and 180deg<θ<270deg. Within the south polar coronal hole, the density varies from 2.3×108 cm-3 at 1.0 Rsolar to 8.3×107 cm-3 at 1.20 Rsolar, while at the equator, the density varies from 6.3×108 cm-3 at 1.0 Rsolar to 1.6×108 cm-3 at 1.20 Rsolar. The density falloff with height is therefore faster in the equatorial region. We also find that electron densities are, on average, a factor of 2.7 larger in the equatorial regions than in the polar coronal hole at a given radial distance. Finally, we find remarkable agreement between our measured densities as a function of radius and position angle and those predicted by a recent analytic MHD model of the solar wind, strongly supporting its basic premises. Title: [Alii] in the ultraviolet spectrum of the symbiotic star RR Telescopii Authors: Keenan, F. P.; Espey, B. R.; Mathioudakis, M.; Aggarwal, K. M.; Crawford, F. L.; Feibelman, W. A.; McKenna, F. C. Bibcode: 1999MNRAS.309..195K Altcode: An inspection of a GHRS/HST spectrum of the symbiotic star RR Telescopii reveals the presence of the [Alii] 3s^2 ^1S - 3s3p ^3P_2 line at a vacuum wavelength of 2661.06+/-0.08Å, 8.89+/-0.08Å away from the Alii] 3s^2 ^1S - 3s3p ^3P_1 intercombination transition at 2669.95Å, in good agreement with the theoretical prediction of Δλ=8.80Å. We also find that the Alii] line profile is asymmetric, showing a strong low-density component with a weak high-density wing, redshifted by 30kms^-1, in agreement with the findings of Schild & Schmid, which were based on optical observations. Our measurement of the emission-line ratio RI(2661.06Å)/I(2669.95Å)=0.027+/-0.003 implies logN_e=5.8+/-0.2, in good agreement with the densities found from other ions, such as Siiii. These results provide strong evidence that we have detected the [Alii] line, the first time (to our knowledge) that this feature has been reliably identified in an astrophysical or laboratory spectrum. Title: Fexiixii emission lines in solar active regions observed by the RES-C spectroheliograph on the CORONAS-I mission Authors: Zhitnik, I. A.; Kuzin, S. V.; Urnov, A. M.; Keenan, F. P.; Pinfield, D. J. Bibcode: 1999MNRAS.308..228Z Altcode: Theoretical line intensity ratios involving Fexii transitions in the 186-201Å wavelength range are compared with observational data for five solar active regions, obtained by the RES-C spectroheliograph on the CORONAS-I mission. Generally good agreement is found between theory and observation, hence resolving discrepancies previously found in the comparison of calculations with active region and subflare spectra from the Solar EUV Rocket Telescope and Spectrograph (SERTS). However, the Fexii 190.06- and 201.12-Å lines are blended with Fex 190.04Å and Fexiii 201.13Å, respectively. In addition, a weak feature at ~197Å, tentatively identified as Fexii 196.87Å, does not appear to be due to this ion. Title: Photoionization cross sections for Fe XVI and Fe XVII recombination rate coefficients Authors: Donnelly, D.; Bell, K. L.; Darlington, W. G. V.; Reid, R. H. G.; Keenan, F. P. Bibcode: 1999A&A...349..996D Altcode: The Breit-Pauli R-matrix codes are utilized in a detailed study of the photoionization of the ground state of Fe XVI (2s(22p^63s) (2S_{1/2}) ). High resolution total and partial cross sections are obtained using 37 Jpi configuration interaction type wavefunctions to represent the residual ion, Fe XVII, after 3s, 2p and 2s photoionization. For the total cross section, the work of Verner et al. and previous Opacity Project calculations are in fair agreement with the present results, while relativistic effects are seen to have a noticeable but not an overly significant effect on the background cross section. The derived partial cross sections are used in a calculation of rates for the recombination of states of Fe XVII to the ground state of Fe XVI. Title: Effective collision strengths for forbidden transitions among the 3s23p3 fine-structure levels of CL IIIIII Authors: Ramsbottom, C. A.; Bell, K. L.; Keenan, F. P. Bibcode: 1999MNRAS.307..669R Altcode: Effective collision strengths for the 10 astrophysically important fine-structure forbidden transitions among the ^4S^o, ^2D^o and ^2P^o levels in the 3s^23p^3 configuration of Cliii are presented. The calculation employs the multichannel R-matrix method to compute the electron-impact excitation collision strengths in a close-coupling expansion, which incorporates the lowest 23 LS target eigenstates of Cliii. These states are formed from the 3s^23p^3, 3s3p^4, 3s^23p^23d and 3s^23p^24s configurations. The Maxwellian-averaged effective collision strengths are presented graphically for all 10 fine-structure transitions over a wide range of electron temperatures appropriate for astrophysical applications [logT(K)=3.3-logT(K)=5.9]. Comparisons are made with the earlier seven-state close-coupling calculation of Butler & Zeippen, and in general excellent agreement is found in the low-temperature region where a comparison is possible [logT(K)=3.3-logT(K)=4.7]. However, discrepancies of up to 30 per cent are found to occur for the forbidden transitions which involve the ^4S^o ground state level, particularly for the lowest temperatures considered. At the higher temperatures, the present data are the only reliable results currently available. Title: Transient events in the EUV transition region and chromosphere Authors: Gallagher, P. T.; Phillips, K. J. H.; Harra-Murnion, L. K.; Baudin, F.; Keenan, F. P. Bibcode: 1999A&A...348..251G Altcode: Rapid time cadence observations of the quiet Sun extreme ultraviolet emission, observed by the cds instrument on soho, are discussed. Numerous transient brightenings are observed in network features in both a transition region line (O V 629.73 Ä) and a chromospheric line (He I 584.33 Ä), indicating a dynamic coupling between the chromospheric and transition region network. Their durations are between 80 and 200 s and dimensions 6 000-10 000 km. A wavelet analysis reveals a tendency for semi-periodic behaviour, with excess power at a frequency of about 4 mHz. The variations are much less evident in the internetwork or cell regions, although they are again semi-periodic. Relative line-of-sight velocities have also been derived from the data, the cds spectral resolution allowing a precision of between 4.7 and 6 km s(-1) . There is a clear association of brightenings in the network with downflows of ~ 13 km s(-1) at 250 000 K with some events having velocities of up to ~ 20 km s(-1) , these being measured relative to the average quiet Sun emission. Within the internetwork, we also find a weak correlation between events seen in the He I (584.33 Ä) and the O V (629.73 Ä) lines. In this case, the events have a smaller size (<= 2 000 km), amplitude (both in terms of their intensity and velocity), and also show a higher frequency of about 6 mHz. The apparent differing properties of network and internetwork events implies that both these regions are heated by two distinct mechanisms. In the case of the internetwork, these results further confirm that acoustic waves propagating up from the photosphere and forming shocks in the overlying atmosphere are the most likely heating mechanism. For the network, it is apparent that the heating required must be in excess of that supplied by acoustic shocks. Our view is that the network events are produced by nanoflare-like magnetic reconnections in the corona, or possibly excitation due to a spicule-type event in which there is a repeated rebound. Title: L-shell photoionization cross-sections for FeXIXXIX and FeXXXX recombination rate coefficients Authors: Donnelly, D.; Bell, K. L.; Keenan, F. P. Bibcode: 1999MNRAS.307..595D Altcode: High-quality atomic data concerning the interaction of photons with highly ionized ions of iron are an essential requirement in the modelling of X-ray emission from astrophysical plasmas. Consequently a detailed study of the photoionization of the ground-state fine-structure levels (2s^22p^4 ^3P_2,0,1) of FeXIX has been undertaken, and a set of high-resolution cross-sections for photoionization of each of these levels obtained. We have considered both the total and partial cross-section cases, with the latter restricted to those instances where the residual ion is left in one of the energetically lowest 23 Jpi (12 LSpi) states of FeXX. The calculation was performed by applying the Breit-Pauli R-matrix codes using a sophisticated representation of these 23 target-states. This approach allows for the possibility of fine-structure splitting in both thresholds and resonances, as well as incorporating any coupling between target-states with different LS symmetries through the inclusion of the spin-orbit operator. A significant amount of such coupling is discovered in the present investigation, and is responsible for a background cross-section whose magnitude is lower than that determined in previous LS-coupling calculations by more than a factor of 2. Extensive resonance structure is also resolved, including shape resonances in the 133 -> 148Ryd photon energy region. Such structure has not been resolved in any previous investigation and is of extreme importance in the modelling of X-ray emission plasmas. Using the derived photoionization cross-section data, recombination rate coefficients are calculated using the Milne relation, for the case of an electron recombining with FeXX in the ground state to form FeXIX existing in each of the fine-structure ground-state levels. These recombination rates are summarized over a temperature range of 50 000 to 10^7K. To supplement these data further we also present a set of energy levels and oscillator strengths for FeXX. Title: Electron densities above a polar coronal hole based on improved SI IX density diagnostics Authors: Doyle, J. G.; Keenan, F. P.; Ryans, R. S. I.; Aggarwal, K. M.; Fludra, A. Bibcode: 1999SoPh..188...73D Altcode: Using new close-coupling excitation rates for the C-like ion Si ix, density-diagnostic ratios based on Si ix lines have been re-evaluated and applied to a sequence of CDS observations taken above a polar coronal hole. The derived electron densities are in excellent agreement with previous values of Neestimated from the N-like ion Si viii for another coronal hole. The confirmed trend is for a fall-off of one order of magnitude within the first 0.3 R⊙above the limb. These densities are well fitted with an analytic formula for the density profile out to at least 8 R⊙, by which stage the electron density has fallen to ∼4×103 cm−3, from 1.5×108 cm−3at 1.0 R⊙. Title: HR 1099 - A multi-wavelength study of a short period RS CVn binary Authors: Mathioudakis, Mihalis; Christian, Damian; Keenan, Francis Bibcode: 1999noao.prop...50M Altcode: The launch of AXAF in the summer of 1999 will open a new era in the study of stellar coronae. The active RS CVn binary HR 1099 is one of the AXAF primary calibration targets that will be observed in the first 3-4 months of the mission. We propose to carry out a ground based spectroscopic study of HR 1099. With the combination of optical and X- ray observations we will be able to : (i) Study the effects of rotational modulation in photospheric (TiO bands), chromospheric (H(alpha), Ca II H& K) and coronal lines (e.g. Fe XVII) (ii) Carry out a near simultaneous estimate of photospheric and coronal abundances (iii) Investigate whether the absorption features that cross the H(alpha) profile are due to cool hydrogen prominences or mass transfer between the components of the binary. The requested observing time will allow us to cover ~ 3 rotational revolutions with an ~ 80% phase coverage. Title: Source Tracing of Archeological Copper Smelting Ore by In Situ Isotopic Measurements by Laser Ablation Inductively Coupled Plasma Mass Spectrometry Using Quadrupole and Multicollector Techniques Authors: Young, S. M. M.; Horn, I.; Miller, D.; Cantle, J.; Keenan, F.; Bowen, I. Bibcode: 1999nag..conf.7662Y Altcode: No abstract at ADS Title: The Search for Extraterrestrial Intelligence (SETI) Authors: Keenan, F. P.; Phillips, M. E.; Rose, S. J.; Burgess, D. D. Bibcode: 1999IrAJ...26...87K Altcode: A brief review is presented of the hypotheses inherent in searches for extraterrestrial intelligence (SETI). Some of the problems associated with such work at radio wavelengths are discussed, such as the optimal choice of a search frequency. It is shown that pulsed laser signals sent from an extraterrestrial civilisation should be observed to be brighter than the parent star, even when conservative estimates are adopted for the laser energy generation and detector time resolution. This is still the case when the energy output from the parent star is summed over all wavelengths. As a result, optical SETI programmes may be more attractive than their radio counterparts. Title: Early-type stars in the Galactic halo from the Palomar-Green Survey II: A sample of distant, apparently young Population I stars Authors: Rolleston, W. R. J.; Hambly, N. C.; Keenan, F. P.; Dufton, P. L.; Saffer, R. A. Bibcode: 1999A&A...347...69R Altcode: We present échelle (R ~ 40 000) spectroscopic observations for a sample of apparently normal, high Galactic latitude, early-type stars drawn from the Palomar-Green Survey. The metal-line spectra show evidence for rotational velocity broadening with values of vsin i<=300 km s(-1) . In conjunction with Kurucz model atmospheres, we derive stellar photospheric abundances that are consistent with a Population i chemical composition; differential abundances with respect to Galactic disk Population i stars indicate no abundance differences outside the estimated errors. From a comparison of the derived atmospheric parameters with recent theoretical evolutionary models, we derive distance and age estimates for individual stars. Using kinematical considerations, we conclude that all these objects are `runaway' stars, formed in the Galactic disk and subsequently ejected, possibly by supernovae explosions or dynamical interactions. Tables 4 and 5 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html Title: VizieR Online Data Catalog: The Optical Spectrum of RR Tel (Crawford+ 1999) Authors: Crawford, F. L.; McKenna, F. C.; Keenan, F. P.; Aller, L. H.; Feibelman, W. A.; Ryan, S. G. Bibcode: 1999yCat..41390135C Altcode: The symbiotic nova RR Telescopii has been observed with the 3.9 m telescope at the Anglo-Australian Observatory (AAO), using the University College London Echelle Spectrograph (UCLES) in conjunction with a Tek CCD. It displays a rich emission line spectrum, ranging in excitation from NI to NiVIII. We present a list of 811 measured lines, with their suggested identifications and absolute line intensities, covering a wavelength range from 3180 to 9455 A. The absolute line intensities have been derived by comparing the high resolution data with a flux-calibrated low resolution spectrum taken with the Australian National University 2.3 m telescope. All of the lines have been successfully identified. Comparing our results with those of previous studies indicates that the RR Tel system is advancing towards higher degrees of ionisation. (2 data files). Title: Excitation Rate Coefficients for Fine-Structure Transitions in O III Authors: Aggarwal, Kanti M.; Keenan, Francis P. Bibcode: 1999ApJS..123..311A Altcode: Collision strengths for fine-structure transitions among the levels of the (1s2) 2s22p2, 2s2p3, 2p4, 2s22p3s, 2s22p3p, and 2s22p3d configurations of O III have been computed over a wide range of energies below 13.0 ryd using the R-matrix program. All partial waves with L<=40 have been included to ensure the convergence of results. Excitation rate coefficients, in the form of dimensionless effective collision strengths, have also been computed at temperatures below 200,000 K. The results are compared with available calculations, and accuracy of the data is assessed. Title: The interstellar medium near to and beyond the Galactic Center Authors: Keenan, Francis Bibcode: 1999hst..prop.8096K Altcode: 1999hst..prop.4430K We have recently identified a B-type supergiant, LS 4825, which lies on the far side of the Galaxy, at a Galactocentric distance of R_G = 12 kpc, and whose sightline passes within 1 kpc of the Galactic Center. Optical ionCa2 and ionNa1 interstellar observations of LS 4825 reveal a miriad of intermediate and high velocity clouds, several of which arise from gas near to and beyond the Galactic Center. We now propose to obtain medium resolution STIS spectra, primarily to observe the ultraviolet interstellar lines towards LS 4825. These data will allow us to determine the abundances of important elements such as Mg, Si, S, Cr, Mn, Fe, and Zn {and possibly C, N, and O} in interstellar gas as a function of Galactocentric distance, from the Solar position all the way in to the Galactic Center and beyond, which is vital for testing the competing models for the chemical evolution of our Galaxy. A secondary aim of the STIS observations will be to study the ultraviolet stellar absorption lines in LS 4825, which will provide reliable element abundances for this star, and hence the chemical composition of the interstellar medium at R_G = 12 kpc on the far side of the Galaxy. This will be compared with results at R_G = 12 kpc on the near side, to investigate the azimuthal dependence of the Galactic abundance gradient. Title: Low Resolution Optical Spectroscopy of The M15 High Velocity Interstellar Cloud Authors: Smoker, J. V.; Lehner, N.; Keenan, F. P.; Totten, E. J. Bibcode: 1999IrAJ...26..105S Altcode: We present low resolution optical spectra of 16 field stars in the CaII H and K lines towards the high velocity cloud (HVC) at V=+80 kms-1, observed in the direction of the M15 globular cluster. Stellar spectral types and distances are estimated for 12 of the sample. Null detections of HVC CaII absorption in the spectra, combined with an upper limit to the HVC distance from observations of the Galactic halo star HD 203664, tentatively imply that the HVC lies in the distance range 400 <= d <= 3200 pc. Title: Fe II emission lines as a chronometer for high-redshift quasars Authors: Keenan, Francis Bibcode: 1999hst..prop.8098K Altcode: 1999hst..prop.4432K We request STIS observations of the symbiotic nova RR-TEL to give complete coverage of FeII emission lines in the 1150- 9800 Angstrom wavelength range. We have embarked on a long- term program to fully simulate the physical conditions within FeII-emitting gas, and predict the resulting spectrum. The first steps of generating the initial atomic database and incorporating it into the photoionization code Cloudy, are complete. Analysis of the FeII lines from RR-TEL using Cloudy will allow us to check the r eliability and completeness of the atomic data and processes considered, to investigate the sensitivity of emission to temperature and density variations, and to assess the importance of blending. Although emission lines from FeII are observed from a wide variety of astronomical objects, including protostellar disks, novae, supernovae, and quasars, these lines have been notoriously difficult to interpret because of the great complexity of the FeII energy level structure. We no w have the tools to quantify the abundances in these objects and, once calibrated against the RR-TEL data, we will apply the same technique to deduce iron abundances from FeII emission in high-redshift quasars. This, in conjunction with predictions of ste llar evolution and galactic nucleosynthesis, will result in a chronometer measuring the redshift when the universe passed through an age of 1 Gyr, thus constraining several cosmological parameters. Title: Book Review: The sun in eclipse / Springer, 1997 & 1998 Authors: Gallagher, P. T.; Keenan, F. P.; Phillips, K. J. H.; Read, P. D.; Rudawy, P.; Mpolt, B. Ro Bibcode: 1999IrAJ...26..115G Altcode: The Solar Eclipse Coronal Imaging System (SECIS) is an instrument designed to search for short-period modulations in the solar corona seen either during a total eclipse or with a coronagraph. The CCD cameras used in SECIS have the capability of imaging a selected portion of the corona at a rate of 50 frames per second, with the intensities in each pixel digitised in 12-bit levels. The data are captured and stored on a modified PC. It will thus be possible to search for fast changes or short-period wave motions in the corona that will have important implications for the coronal heating mechanism. Tests have been carried out during the 1998 total solar eclipse visible in Guadeloupe (French West Indies) and with the Evans Solar Facility coronagraph at the National Solar Observatory, Sacramento Peak, with scientifically useful results obtained from the latter. Title: Electron temperature diagnostics for the quiet Sun using SI BT IV lines Authors: Ahmed, S.; Pinfield, D. J.; Mathioudakis, M.; Keenan, F. P.; Phillips, K. J. H.; Curdt, W. Bibcode: 1999A&A...346L..69A Altcode: We compare SUMER observations of six Si riptsize IV emission lines detected at the quiet Sun disk centre with recent theoretical line ratio calculations. Good agreement is found between theory and observation for ratios involving the 1394, 1403 and 818 Ä line intensities. This agreement supports the theoretical prediction that the temperature where Si riptsize IV has its maximum ionisation fraction in ionisation equilibrium is T_max =~ 10(4.8) K, as well as showing that Lyman continuum absorption does not significantly effect line intensities for transitions with wavelengths below 912 Ä. We find that the 815, 1122 and 1128 Ä lines are blended by approximately 30, 55 and 45%, respectively, in the SUMER transitions. Title: NE VII emission lines in the solar EUV spectrum Authors: McKeown, M.; Keenan, F. P.; Ramsbottom, C. A.; Bell, K. L.; Ryans, R. S. I.; Reid, R. H. G. Bibcode: 1999SoPh..186..231M Altcode: Recent calculations of electron and proton impact excitation rates in Ne vii are used to calculate theoretical emission line ratios involving both Δn=0 (2-2) and Δn=1 (2-3) transitions in the ∼ 97-895 Å wavelength range. A comparison of these with existing solar observations, obtained by instruments on rocket flights and on the Skylab mission, reveals generally good agreement between theory and observation. This provides experimental support for the accuracy of the atomic data adopted in the line ratio calculations, and implies that the latter may be applied with confidence to the analysis of solar and stellar spectra from current and future satellite missions. Title: Proton impact excitation of the 1s(2) 2s(2) 2p(2) (3) P fine-structure transitions in carbon-like ions Authors: Ryans, R. S. I.; Foster-Woods, V. J.; Reid, R. H. G.; Keenan, F. P. Bibcode: 1999A&A...345..663R Altcode: We present new cross sections and thermally averaged excitation rate coefficients for proton impact excitation of the 1s(2) 2s(2) 2p(2) (3) P fine-structure transitions for ions in the carbon isoelectronic sequence. These data have been calculated using a close-coupled impact parameter method that incorporates the effects of higher lying levels of the triplet 2s2p(3) configuration. We find that the inclusion of these additional states leads to significant reductions in excitation rates for high-Z ions. Title: High-resolution stellar and interstellar spectra of HD 100340 Authors: Ryans, R. S. I.; Keenan, F. P.; Rolleston, W. R. J.; Sembach, K. R.; Davies, R. D. Bibcode: 1999MNRAS.304..947R Altcode: We present new, high-resolution, high signal-to-noise ratio, optical and 21-cm HI observations of the faint blue halo star HD 100340. A differential abundance analysis with respect to the Galactic disc star HR 2387 shows no significant peculiarities. We find that HD 100340 lies at a distance of 3 kpc, and a kinematical analysis strongly supports a `runaway star' origin. We also present improved cloud models for three intermediate velocity clouds seen in Ca II K or H I towards HD 100340. Title: VizieR Online Data Catalog: Abundances of halo early-type stars (Rolleston+, 1999) Authors: Rolleston, W. R. J.; Hambly, N. C.; Keenan, F. P.; Dufton, P. L.; Saffer, R. A. Bibcode: 1999yCat..33470069R Altcode: We present echelle (R~40,000) spectroscopic observations for a sample of apparently normal, high Galactic latitude, early-type stars drawn from the Palomar-Green Survey. The metal-line spectra show evidence for rotational velocity broadening with values of vsini<=300km/s. In conjunction with Kurucz model atmospheres, we derive stellar photospheric abundances that are consistent with a Population I chemical composition; differential abundances with respect to Galactic disk Population I stars indicate no abundance differences outside the estimated errors. From a comparison of the derived atmospheric parameters with recent theoretical evolutionary models, we derive distance and age estimates for individual stars. Using kinematical considerations, we conclude that all these objects are `runaway' stars, formed in the Galactic disk and subsequently ejected, possibly by supernovae explosions or dynamical interactions. (2 data files). Title: Soft X-ray emission lines of Ni XVIII in the solar spectrum Authors: Keenan, F. P.; Mathioudakis, M.; Pinfield, D. J.; Brown, W. A.; Bruner, M. E. Bibcode: 1999SoPh..185..289K Altcode: R-matrix calculations of electron impact excitation rates in Ni xviii are used to derive theoretical electron-temperature-sensitive emission line ratios involving 3s−4p,3p−4d,3p −4s, and 3d−4f transitions in the 41-53 Å wavelength range. A comparison of these with solar flare observations from a rocket-borne X-ray spectrograph (XSST) reveals generally excellent agreement between theory and experiment (within the experimental and theoretical uncertainties), which provides support for the atomic data adopted in the analysis. However the 3s 2S−4p 2P1/2 line of Ni xviii at 41.22 Å appears to be blended with the Fe xix 13.74 Å feature observed by XSST in third order. In addition, the measured Ni xviii intensity ratio I(3p 2P3/2− 4s 2S)/I(3p 2P1/2−4s 2S)=I(51.02 Å)/I(50.26 Å)=0.56, a factor of ∼3.8 smaller than the theoretical (temperature and density-insensitive) value of 2.1. The reason for this discrepancy is currently unexplained, but is unlikely to be due to blending of the 50.26 Å line, as the intensity of this feature is consistent with that expected from the other Ni xviii lines in the XSST spectrum. Future observations of the Ni xviii lines by the Advanced X-ray Astrophysics Facility (AXAF) should allow this problem to be resolved, and may also permit the use of the lines as electron-temperature diagnostics. Title: Emission lines of [O II] in the optical and ultraviolet spectra of planetary nebulae Authors: Keenan, F. P.; Aller, L. H.; Bell, K. L.; Crawford, F. L.; Feibelman, W. A.; Hyung, S.; McKenna, F. C.; McLaughlin, B. M. Bibcode: 1999MNRAS.304...27K Altcode: Recent R-matrix calculations of electron impact excitation rates in O II are used to calculate the emission-line ratio-ratio diagrams (R_1, R_2), (R_1, R_3) and (R_1, R_4), where R_1 = I(3729 A)/I(3726 A), R_2 = I(7320 A)/I(3726 + 3729 A), R_3 = I(7330 A)/I(3726 + 3729 A) and R_4 = I(2470 A)/I(3726 + 3729 A), for a range of electron temperatures (T_e = 7500-20 000 K) and electron densities (N_e = 10^1.5-10^5 cm^-3) appropriate to planetary nebulae. These diagrams should, in principle, allow the simultaneous determination of T_e and N_e from measurements of the [O II] emission lines in a spectrum. Plasma parameters deduced for a sample of planetary nebulae, using observational data obtained with the IUE satellite and the Hamilton Echelle spectrograph on the 3-m Shane Telescope at the Lick Observatory, are found to show excellent internal consistency, and to be in generally good agreement with the values of T_e and N_e estimated from other line ratios in the echelle spectra. These results provide observational support for the accuracy of the theoretical ratios, and hence the atomic data adopted in their derivation. Title: Quiet Sun Bright Point Dynamics and Energetics as seen by SOHO and Yohkoh Authors: Gallagher, P.; Keenan, F.; Phillips, K.; Prés, P.; Harra-Murnion, L. Bibcode: 1999ASPC..183..405G Altcode: 1999hrsp.conf..405G No abstract at ADS Title: The Intersteliar Medium in the Magellanic Bridge Authors: Lehner, N.; Keenan, F. P.; Smoker, J. V.; Dufton, P. L.; Rolleston, W. R. J.; McKenna, F. C.; Sembach, K. R.; Tohline, J. E.; White, G.; Stanimirovic, S. Bibcode: 1999IAUS..190..501L Altcode: 1998IAUS..190E.167L We present high resolution ultraviolet (HST/STIS) and H I 21 cm (ATCA) observations of the interstellar lines towards DI 1388, a B-type star in the Bridge of gas between the Small and Large Magellanic Clouds (SMC, LMC). Our observations provide a unique opportunity to investigate the velocity structure, elemental abundances, and physical conditions within the Bridge gas, which until this time has remained unexplored. We compare the results obtained with information for the LMC and SMC, to test the theory that the Bridge gas originated in the SMC. The presence of young B-type stars in the Bridge implies ongoing star formation, and our observations allow us to investigate the mechanisms responsible for creating stars in this gas, and to determine whether they are similar to the processes inferred for high velocity clouds within our Galaxy. Title: Cross Sections and Rate Coefficients for Excitation of the 1s22s22p2 3PJ --> 1s22s22p2 3PJ' Fine-Structure Transition in Carbon-like Ions by Heavy Particle Impact Authors: Ryans, R. S. I.; Foster-Woods, V. J.; Keenan, F. P.; Reid, R. H. G. Bibcode: 1999ADNDT..73....1R Altcode: We have calculated cross sections for excitation of the fine-structure transitions in carbon-like ions by proton, deuteron, triton, and α-particle impact via a close-coupled impact-parameter method. This technique includes the effects of dipole coupling to the nearby triplet 2s2p3 configuration by means of a polarization potential. We consider the ions N II, O III, Ne V, Mg VII, Si IX, S XI, Ar XIII, Ca XV, Ti XVII, Cr XIX, Fe XXI, and Ni XXIII. Excitation rate coefficients have also been calculated for a range of temperatures. Title: High-velocity interstellar clouds towards the M 15 globular cluster. I. Low resolution optical data Authors: Lehner, N.; Rolleston, W. R. J.; Ryans, R. S. I.; Keenan, F. P.; Bates, B.; Pollacco, D. L.; Sembach, K. R. Bibcode: 1999A&AS..134..257L Altcode: We present low resolution interstellar spectra of the Ca Ii K and Na I D lines towards 12 stars in the M 15 globular cluster. These sightlines are used to study the small scale structure of the interstellar medium, over scales of a few arcseconds to a few arcminutes. A high-velocity cloud is detected in the Ca Ii and Na I lines at a LSR velocity of approximately ~ 70 km s(-1) . Tentative velocity and equivalent width variations are observed on scales of a few arcseconds; however, higher resolution data are necessary to quantify the magnitude of these variations. We discuss these observations and their importance for future studies of this high velocity gas at high spectral resolution. Title: Photoionization cross sections for Fe XVIII Authors: Donnelly, D.; Bell, K. L.; Keenan, F. P. Bibcode: 1998A&AS..133..249D Altcode: A sophisticated R-matrix calculation is performed for the photoionization of the fine-structure levels of the ground state of Fe XVIII. High resolution total and partial cross sections are obtained with the later restricted to the cases of the Fe XVIII ion being left in one of the fine-structure levels corresponding to the energetically lowest 11 LS states of Fe XIX after ionization. Both sets of cross sections are obtained using the Breit-Pauli R-matrix approximation which allows for the possibility of fine structure splitting in both resonances and thresholds. We find extensive resonance structure in the 99 to 113 Ryd photon energy range, a high percentage of which arises from 2p photoionization leaving the ion in the 2s(2) 2p(4) (3) P_2 state while the background cross section is constructed almost exclusively of 2p and 2s photoionization with the former dominant in both photoionization cases. Relativistic effects are found to be important in obtaining accurate threshold positions as well as being responsible for a significant drop in the background cross section in comparison with various calculations done in LS coupling. We believe that this is the first relativistic calculation for this ion. Title: The O V 1213.9 Angstroms forbidden line in the quiet Sun Authors: Pinfield, D. J.; Mathioudakis, M.; Keenan, F. P.; Phillips, K. J. H.; Curdt, W. Bibcode: 1998A&A...340L..15P Altcode: We present the first unambiguous detection of the O v 1213.9 Angstrom (2s(2) (1) S_0 -> 2s2p (3) P_2) forbidden line in the solar spectrum, using observations obtained with the SUMER instrument on board SOHO. The wavelength separation of the forbidden to the (2s(2) (1) S_0 -> 2s2p (3) P_1) intercombination line at 1218.35 Angstroms is 4.5+/-0.1 Angstroms in excellent agreement with theoretical predictions. The observed line ratio, combined with the latest calculations, allows us to derive an electron density of log {N_e/cm(-3}) = 8.5 +/- 0.15 for the quiet Sun. However, the O v 1213.9 Angstroms line was not detected in the HST spectra of Procyon and we can only place a lower limit of log {N_e/cm(-3}) >= 7.8 to the electron density in this object. Title: Rotational velocities of B-type stars from the Edinburgh-Cape survey Authors: Magee, H. R. M.; Dufton, P. L.; Keenan, F. P.; Rolleston, W. R. J.; Kilkenny, D.; O'Donoghue, D.; Koen, C.; Stobie, R. S.; Peterson, R. C. Bibcode: 1998A&A...338...85M Altcode: The projected rotational velocity distribution for a sample of 34 high Galactic latitude B-type stars from the Edinburgh-Cape Faint Blue Object Survey is presented to investigate the evolutionary status of the group as a whole. Statistical analyses of the distribution show it to be similar to that expected if the sample contained mainly normal Population i early B-type stars, although a contamination of up to 20 % by evolved stars cannot be ruled out. This implies that a large fraction of the sample consists of normal Population i B-type stars similar to those found in the Galactic disk. Possible mechanisms explaining the presence of these stars in the halo are briefly discussed. Title: The solar transition region: a time-varying interface between the chromosphere and corona? Authors: O'Shea, E.; Doyle, J. G.; Keenan, F. P. Bibcode: 1998A&A...338.1102O Altcode: Using joint observations taken with the CDS and SUMER instruments onboard SOHO, we re-examine the solar transition region in an attempt to determine whether it is de-coupled from the over-lying coronal region. Line ratios calculated from temporal series observations of O iv and Fe xiii spectral lines were converted to electron density, and hence electron pressure using theoretical line ratios. Little or no evidence was found to support the constant electron density assumption, and instead a constant electron pressure is found between the transition region and corona. This lends support to the idea that the transition region is a time varying interface between the chromosphere and corona, and is not formed in unresolved fine-structures that are disconnected from the corona. Title: K-shell photoejection cross section for neutral iron Authors: Black, G. M.; Donnelly, D.; Bell, K. L.; Scott, M. P.; Keenan, F. P. Bibcode: 1998A&A...337L..21B Altcode: This Letter presents the first ab initio calculation, using the R-matrix method, of the cross section for photoejection of a K-shell electron from neutral iron. A 9-state target state approximation is employed, and the results are compared with recent theoretical values, namely the Hartree-Dirac-Slater method data of Verner and co-workers (1993, 1995). At the highest photon energy considered (640 Ryd), agreement is excellent. However, with decreasing photon energy the two calculations diverge, and the behaviour of the present cross section near threshold shows a rapid rise from threshold in contrast to earlier work for which the behaviour of the cross section as a function of photon energy is approximately linear. Title: Proton impact excitation of the 1s(2) 2s2p (3) P fine-structure transitions in the Be-like ions C iii, N iv, and O V Authors: Ryans, R. S. I.; Foster-Woods, V. J.; Reid, R. H. G.; Keenan, F. P.; Copeland, F. Bibcode: 1998A&A...336..393R Altcode: Cross sections and thermally averaged excitation rate coefficients are presented for proton impact excitations of the 1s(2) 2s2p (3) P fine-structure transitions in the Be-like ions C iii, N iv, and O v. The cross sections were calculated using a close-coupled impact parameter method that has been modified to include the higher lying levels of the triplet states of the 2p(2) , 2s3s, and 2s3d configurations. Excitation rate coefficients have been calculated using these cross-sections for a wide range of temperatures. Title: Extreme-Ultraviolet Transitions of Ca XVI in Solar Flare and Laboratory Spectra Authors: Keenan, F. P.; Pinfield, D. J.; Woods, V. J.; Reid, R. H. G.; Conlon, E. S.; Pradhan, A. K.; Zhang, H. L.; Widing, K. G. Bibcode: 1998ApJ...503..953K Altcode: New R-matrix calculations of electron impact excitation rates for transitions among the 2s22p, 2s2p2, and 2p3 levels of Ca XVI are presented. These data are subsequently used, in conjunction with recent estimates for proton excitation rates, to derive theoretical electron density sensitive emission-line ratios involving 2s22p-2s2p2 transitions in the ~155-225 Å wavelength range. A comparison of these with observational data for solar flares, obtained with the Naval Research Laboratory's S082A spectrograph on board Skylab, reveals excellent agreement between theory and observation. In addition, the theoretical ratios compare favorably with those measured from the TEXT tokamak plasma, for which the electron temperature and density have been independently determined. This provides experimental support for the accuracy of the atomic data, and hence line ratio calculations, employed in the present analysis. Title: Radio HI and optical absorption-line spectra of an intermediate-velocity cloud in the general direction of the M15 globular cluster Authors: Kennedy, D. C.; Bates, B.; Keenan, F. P.; Kemp, S. N.; Ryans, R. S. I.; Davies, R. D.; Sembach, K. R. Bibcode: 1998MNRAS.297..849K Altcode: Using HI spectra obtained with the Lovell telescope (FWHM ~ 12 arcmin) we present maps showing the HI distribution and velocity structure of an intermediate-velocity cloud (IVC; v_LSR~70 km s^-1) which is observed in the general direction of the globular cluster M15. The gas is shown to be clumpy in nature and we examine its position and velocity structure. The IVC is detected in absorption in the CaII K line towards five cluster stars in intermediate resolution spectra obtained with ISIS/WHT and in high resolution UES/WHT NaI D line spectra of two cluster stars (II-75; IV-38). The clumpy nature of the gas is indicated by the NaI and KI spectra obtained in the II-75 and IV-38 sightlines, which have angular separation ~ 3.5 arcmin. The IVC is detected in KI in the higher column density II-75 sightline; this appears to be the first detection of IVC or HVC gas in KI. The IVC gas towards M15 has a similar velocity to that observed towards HD 203664, some 3.1 deg away from the cluster. Similarities in the IVC gas velocity suggest a gas structure that extends across both sightlines, although gas column densities are considerably higher towards M15. For a common feature, this would place the M15 IVC at a height above the Galactic plane (z-distance) of <~1.5 kpc based on the Little et al. estimate of the HD 203664 distance. From the fine-scale structure and column density observations, estimates are made of the space density of the small-scale concentrations. However, these remain uncertain and the present observations emphasize the need for higher spatial and spectral resolution studies to provide firmer estimates of cloud properties. We report also on a radio HI and CaII line survey towards a sample of 24 stars over a wider field. This was carried out in an attempt to detect any wider distribution of the IVC gas and to place better limits on its distance. Although these observations are of sufficient spectral quality, no new optical detections are reported. Title: Properties of the quiet Sun EUV network Authors: Gallagher, P. T.; Phillips, K. J. H.; Harra-Murnion, L. K.; Keenan, F. P. Bibcode: 1998A&A...335..733G Altcode: Observations of the quiet Sun network in a small region at Sun centre taken with the Coronal Diagnostic Spectrometer (CDS) on board SOHO are reported for EUV lines with T_e between ~ 10(4) and 10(6) K. The changing structure of the network in the upper chromosphere, transition region, up to the corona was examined using intensity distributions which were decomposed into two normal components using a mixture-modelling technique. This enabled areas of high and low intensities to be separated, and hence averaged network properties including area, intensity, contrast, and fractal dimension to be derived as a function of ion temperature. The network area and emission were found to be more concentrated in the transition region than in the chromosphere and in the corona, although the results for the chromospheric He lines appear to be affected by resonance scattering. At ~ 10(6) K, the area and emission of bright structures dramatically increase, partly due to the appearance of small coronal loops. There is also a discrete change in the fractal dimension at coronal temperatures, signifying a change from network to simpler coronal structures. Furthermore, the contrast of bright to dark regions is at a maximum for T_e ~ 2.5x 10(5) K and falls to its lowest values for coronal temperatures. The properties of several individual network structures were found to follow the same general behaviour as in the statistical analysis. Our results including physical dimensions are broadly consistent with the transition region model of Gabriel, although we cannot exclude the existence of low-lying loops as in the model of Dowdy et al. Title: Beta Cephei type variability in the ultraviolet spectrum and radial velocity of PHL 346 Authors: Dufton, P. L.; Keenan, F. P.; Kilkenny, D.; O'Donoghue, D.; Parker, Q. A.; van Wyk, F.; van Leeuwen, F. Bibcode: 1998MNRAS.297..565D Altcode: International Ultraviolet Explorer low-resolution and optical moderate-resolution spectra are presented for the high galactic latitude beta Cephei type star, PHL 346. Variability is identified in both the ultraviolet flux and the radial velocity with periods and phases consistent with those previously deduced from optical photometry. The similarity of both the flux and the radial velocity amplitude to those previously reported for the beta Cephei variable, gamma Pegasus, is striking and provides evidence for PHL 346 being a young core hydrogen burning star. A distance estimate for PHL 346 of approximately 7 kpc (corresponding to a z-distance of approximately 6 kpc) is obtained by scaling the distance of gamma Pegasus obtained from Hipparcos observations. Title: Photoionisation cross sections for Fe XVII Authors: Leo, P. J.; Bell, K. L.; Keenan, F. P. Bibcode: 1998A&A...333..385L Altcode: This paper reports the first close-coupling photoionisation calculation of Fe XVII, and provides accurate total and partial cross sections for photon energies up to 450 Ryd. The total and first partial photoionisation cross sections, the latter obtained when the Fe XVIII ion is left in the 2s(22p^5;^2P^o) ground state, are dominated by resonance structure for photon energies in the range from threshold to excitation of the first excited state (2s2p(6;^2S) ) of Fe XVIII. This is the first time that such structure has been determined. The background cross section is found to be in good agreement (to within 10%) with the results of Verner and co-workers for the total cross section, and for the partial cross sections corresponding to 2p and 2s photoejection, respectively. Title: Emission lines of [NeIV] in the optical and ultraviolet spectra of gaseous nebulae Authors: Keenan, F. P.; Aller, L. H.; Bell, K. L.; Espey, B. R.; Feibelman, W. A.; Hyung, S.; McKenna, F. C.; Ramsbottom, C. A. Bibcode: 1998MNRAS.295..683K Altcode: Recent R-matrix calculations of electron impact excitation rates in Ne IV are used to calculate emission line ratio-ratio diagrams involving both the ultraviolet (1602, 2422 and 2424 A) and optical (4714, 4716, 4724 and 4726 A) [Ne IV] transitions, for a range of electron temperatures (T_e=10 000-30 000 K) and electron densities (N_e=10^2-10^6.5 cm^-3) appropriate to gaseous nebulae. These diagrams should, in principle, allow the simultaneous determination of T_e and N_e from measurements of the [Ne IV] lines in a spectrum. Plasma parameters deduced for a sample of high-excitation planetary nebulae, using a combination of observational data obtained with the IUE satellite and the Hamilton Echelle Spectrograph (HES) on the 3-m Shane Telescope at the Lick Observatory, are found to show generally excellent internal consistency. In addition, they are in good agreement with the values of T_e and N_e estimated from other high-excitation line ratios in the HES spectra, and by previous authors using infrared and ultraviolet transitions in [O IV] and [Ne V]. These results provide observational support for the accuracy of the theoretical [Ne IV] ratios, and hence the atomic data adopted in their derivation. An inspection of IUE and GHRS/HST spectra of the symbiotic stars Z And and RR Tel reveals asymmetries in the line profile of the [Ne IV] 2s^22p^3 ^4S-2s^22p^3 ^2P_1/2, 3/2 doublet at 1602 A, hence allowing the measurement of the wavelength separation of the ^4S-^2P_1/2 and ^4S-^2P_3/2 components. The separation is found to be 0.21+/-0.02 A, in good agreement with the theoretical estimate of 0.16+/-0.03 A this is the first time (to our knowledge) that this quantity has been experimentally determined. Title: Effective Collision Strengths for Fine-Structure Transitions from the 3s23p5 2P Ground State of Chlorine-like Ni XII Authors: Matthews, A.; Ramsbottom, C. A.; Bell, K. L.; Keenan, F. P. Bibcode: 1998ApJ...492..415M Altcode: The R-matrix method is used to compute electron impact collision strengths for transitions in Ni XII from its ground-state fine-structure levels. Sophisticated configuration-interaction wave functions are used to represent the 14 lowest LS target states employed in the R-matrix expansion. By transforming the LS-coupled reactance matrices, and by assuming a Maxwellian velocity distribution for the incident electrons, the effective collision strengths are calculated for the 3s23p52Po1/2-3s23p52Po3/2 transition within the ground state and from both these fine-structure levels to the 29 excited levels arising from states obtained from 3s3p6 and 3s23p43d configurations. Effective collision strengths, obtained in the temperature range log Te = 3.2-6.6 (K), are expected to have an accuracy of better than 20%. Title: CDS observations of the quiet Sun EUV network Authors: Gallagher, P. T.; Phillips, K. J. H.; Harra-Murnion, L. K.; Keenan, F. P. Bibcode: 1998ESASP.421..365G Altcode: 1998sjcp.conf..365G No abstract at ADS Title: Effective collision strengths for fine-structure forbidden transitions among the 2s^22p^3 levels of Neiv Authors: Ramsbottom, C. A.; Bell, K. L.; Keenan, F. P. Bibcode: 1998MNRAS.293..233R Altcode: Effective collision strengths for electron-impact excitation of the N-like ion Neiv are calculated in the close-coupling approximation using the multichannel R-matrix method. Specific attention is given to the 10 astrophysically important fine-structure forbidden transitions among the ^4S^o, ^2D^o and ^2P^o levels in the 2s^22p^3 ground-state configuration. The expansion of the total wavefunction incorporates the lowest 11 LS eigenstates of Neiv, consisting of eight n=2 terms with configurations 2s^22p^3, 2s2p^4 and 2p^5, together with three n=3 states of configuration 2s^22p^23s. We present in graphical form the effective collision strengths obtained by thermally averaging the collision strengths over a Maxwellian distribution of velocities, for all 10 fine-structure transitions, over the range of electron temperatures log T(K) = 3.6 to log T(K) = 6.1 (the range appropriate for astrophysical applications). Comparisons are made with the earlier, less sophisticated close-coupling calculation of Giles, and excellent agreement is found in the limited temperature region where a comparison is possible [log T(K) = 3.7 to log T(K) = 4.3]. At higher temperatures the present data are the only reliable results currently available. Title: Fe XVIII Emission Lines in Solar X-Ray Spectra Authors: Warren, G. A.; Keenan, F. P.; Greer, C. J.; Phillips, K. J.; Bruner, M. E. Bibcode: 1998smc..conf.....W Altcode: We have calculated intensity ratios for emission lines of Fe XVIII in the 19-94A wavelength range at electron temperatures characteristic of the solar corona, Te = 2-10 x 10 to the 6th power K. Our model ion includes data for transitions among the 2s22p5, 2s2p6, 2s22p43l, and 2s2p53l (l = s, p, and d) states. Test calculations that omit the 2s2p53l levels show that cascades from these are important. We compare our results with observed ratios determined from four solar X-ray instruments, a rocket-borne spectrograph, and spectrometers on the P78-1, OV1-17 and Solar Maximum Mission (SMM) satellites. In addition, we have generated synthetic spectra which we compare directly with flare observations from SMM. Agreement between theory and observation is generally quite good, with differences that are mostly less than 30%, providing limited support for the accuracy of the atomic physics data used in our calculations. However, large discrepancies are found for ratios involving the 2s22p5 2P3/2-2s2p6 2S line at 93.84A, which currently remain unexplained. Our analysis indicates that the Fe XVIII feature at 15.83A is the 2s22p5 2P3/2-2s22p4(3P)3s4 P3/2 transition, rather than 2s22p5 2P3/2-2s22p4(3P)3s 2P3/2, as suggested by some authors. Title: Effective Collision Strengths for Electron-Impact Excitation of Ni XII Authors: Matthews, A.; Ramsbottom, C. A.; Bell, K. L.; Keenan, F. P. Bibcode: 1998ADNDT..70...41M Altcode: Effective collision strengths computed by the R-matrix method are presented for the electron-impact excitation of Cl-like Ni XII. The total wave function used in the close-coupling expansion includes the lowest 14 target states of Ni XII, arising from the 3s23p5, 3s3p6and 3s23p43dconfigurations. These 14LStarget states corresponds to 31j-resolved fine-structure levels, connected by 465 independent transitions. Effective collision strengths for all possible transitions, calculated by averaging the electron collision strengths over a Maxwellian distribution of electron velocities, are tabulated over the electron temperature range logT(K) = 5.5 to logT(K) = 6.6. This range includes the temperatures of particular interest for many astrophysical applications. Title: The Structural Variability of the Solar EUV Network Authors: Gallagher, P. T.; Phillips, K. J. H.; Harra-Murnion, L. K.; Keenan, F. P. Bibcode: 1998ASPC..154..612G Altcode: 1998csss...10..612G Observations of the quiet Sun with the Coronal Diagnostic Spectrometer (CDS) on board the Solar and Heliospheric Observatory (SOHO) are reported for the upper chromosphere, transition region, and corona. The changing structure of the EUV network is examined over a temperature range of 1.5 x 10^4 K to 1.2 x 10^6 K using a variety of properties of the characteristic intensity distributions. The distribution of intensity in small (4 x 4 arcmins^2) areas of the quiet Sun at Sun centre has been examined. These distributions were found to consist of both a low intensity core distribution combined with an extended tail associated with the transition region EUV network. Network properties such as relative area, emission, contrast, and fractal dimension have been derived by fitting two Gaussians (one representing the cell distribution, the other the network) to each frequency histogram and then using the cross-over point of the two Gaussians as a boundary point between the two components. The integrity of the network displays a well defined relationship with temperature showing a noticeable structural enhancement in the temperature range 1.1 x 10^5 K to 2.5 x 10^5 K together with a dramatic change in integrity at coronal (>= 10^6 K) temperatures. Title: Proton-Impact Excitation Data of Relevance to the SOHO Mission Authors: Foster-Woods, V. J.; Copeland, F.; Reid, R. H. G.; Keenan, F. P. Bibcode: 1998ASPC..154..608F Altcode: 1998csss...10..608F Calculations of proton-impact fine-structure excitation of ions have been compiled and assessed, listing references and accuracies for individual transitions for each isoelectronic sequence. We present here a summary of that compilation, which was carried out in line with the recent exercise for the electron-impact excitation data for the SOHO mission. We also report on new data for several B-like, Be-like and C-like ions, calculated by the close-coupled impact-parameter method modified to include higher states by means of a polarization potential. Title: Cross Sections and Rate Coefficients for Excitation of the 1s22s2p 3PoJ --> 1s22s2p 3PoJ' Fine-Structure Transitions in Beryllium-like Ions by Heavy Particle Impact Authors: Ryans, R. S. I.; Foster-Woods, V. J.; Copeland, F.; Keenan, F. P.; Matthews, A.; Reid, R. H. G. Bibcode: 1998ADNDT..70..179R Altcode: Cross sections for excitation of the 1s22s2p3PoJ→ 1s22s2p3PoJ‧fine-structure transitions in beryllium-like ions by proton, deuteron, triton, and α-particle impact have been calculated using a close-coupled impact-parameter method. This technique includes the effects of dipole coupling to the nearby triplet 2p2, 2s3s, and 2s3dconfigurations by means of a polarization potential. We consider the ions C III, N IV, O V, Ne VII, Mg IX, Al X, Si XI, S XIII, Ar XV, Ca XVII, Ti XIX, Cr XXI, Fe XXIII, and Ni XXV. Excitation rate coefficients have also been calculated from the cross sections for a range of temperatures. Title: Hubble Space Telescope Observations of an Intermediate-High Velocity Cloud in the Low Galactic Halo Authors: Sembach, K. R.; Keenan, F.; Ryans, Robert Bibcode: 1997AAS...191.5113S Altcode: 1997BAAS...29.1297S For many years it has been realized that the existence of intermediate and high velocity clouds in the Milky Way can provide information about the nature of the gaseous halo that surrounds our Galaxy. Despite this realization, there is still very little known about the chemical compositions, physical properties, and origins of most interstellar clouds that fall into these categories. Furthermore, the relationships (or lack thereof) between intermediate velocity and high velocity clouds themselves are poorly defined, though at least in some cases it does appear that the intermediate velocity clouds may be more confined to the Galactic plane than their higher velocity counterparts. Those clouds that have velocities near the arbitrary velocity cutoff to be considered high velocity (|v| ~ 100 km/s) are particularly worthy of study, since they may contain clues to help distinguish between the competing physical processes responsible for separating (or linking) clouds in these two velocity regimes. Using the Goddard High Resolution Spectrograph aboard the Hubble Space Telescope, we have obtained high quality spectra (S/N > 50, R ~ 20,000-85,000) of a large number of atomic transitions observable in the intermediate-high velocity cloud in the direction of HD 203664 (l = 61.9, b = -27.5). This cloud has a velocity (LSR) of about +80 km/s and displays absorption in a wide range of ionization stages. Much of the observed absorption may arise in an envelope of gas that extends across the face of the globular cluster M 15, located ~ 3 degrees away from the sight line. In this poster, we provide comparisons of the various ionization stages observed and their velocity distributions, information about the chemical and physical properties of the cloud, and some comments about the possible origins of such clouds. Title: The calculation of photoionization of highly-ionized iron using R-matrix theory. Authors: Black, G.; Rose, S. J.; Bell, K. L.; Keenan, F. P. Bibcode: 1997JQSRT..58..491B Altcode: Results of recent R-matrix calculations on the photoionization cross-sections for Fe XXIII and Fe XXIV are presented. These, unlike previous calculations, predict large resonance structure. Title: A Large-Scale Spectroscopic Survey of Early-Type Stars at High Galactic Latitudes Authors: Saffer, Rex A.; Keenan, F. P.; Hambly, N. C.; Dufton, P. L.; Liebert, James Bibcode: 1997ApJ...491..172S Altcode: We present new model atmosphere analyses of optical spectroscopy of a large sample of B-type stellar candidates. Of a total of 298 objects, the largest sample of its kind to date, 205 were drawn from the Palomar Green Survey of high Galactic latitude ultraviolet-excess stellar objects and comprise a complete magnitude-limited sample. Effective temperatures, surface gravities, and helium abundances for the hot subdwarf (high-gravity) component of the sample are derived from a detailed line profile analysis of the hydrogen and helium absorption lines in intermediate-resolution (3-5 Å FWHM) optical spectra. A separate analysis of the lower gravity component is made using a newly calculated grid of synthetic spectra. Additional estimates of the effective temperatures are made from wide- and intermediate-band photometry taken from the literature. We are currently undertaking two follow-up programs. (1) Detailed abundance analyses of high-resolution echelle spectra of the lower gravity component of the survey using modern model atmosphere and synthetic spectrum techniques will differentiate between massive Population I main-sequence B stars and low-mass, lower luminosity Population II blue horizontal branch stars and post-asymptotic giant branch stars. (2) The derived atmospheric parameters for the higher gravity component, the field extended horizontal branch stars, will be combined with radial velocity measurements to determine their spatial and kinematic distributions, which will distinguish between competing evolutionary scenarios for this hot, evolved stellar population.

Observations obtained, in part, at the Multiple Mirror Telescope Observatory (MMTO), operated jointly by the University of Arizona and the Smithsonian Institution. Title: LS 4825: A Blue Supergiant on the Far Side of the Galaxy Authors: Ryans, R. S. I.; Dufton, P. L.; Keenan, F. P.; Smartt, S. J.; Sembach, K. R.; Lennon, D. J.; Venn, K. A. Bibcode: 1997ApJ...490..267R Altcode: We present high-resolution spectroscopic observations of LS 4825, a V = 12 B-type star in the Galactic center direction. On the basis of its stellar and interstellar spectra, we infer that it is likely to be a young supergiant at a distance of 21 +/- 5 kpc, and hence lying on the far side of the Galaxy. Adopting this hypothesis, a differential abundance analysis shows LS 4825 to have a chemical composition that is consistent with local B-type supergiants. These observations therefore represent the first detailed investigation of a star on the far side of the Galactic center. We trace multiple interstellar components in Ca II K and Na I D spectra, with velocities -206 <= vlsr <= +93 km s-1. We consider the likely origin of this gas and find that some components appear to trace matter lying close to the Galactic center. We discuss the possible use of such sight lines in furthering our understanding both of the nature of gas around the Galactic center and of the abundance gradient of the Galaxy.

Based in part upon observations made at the European Southern Observatory, La Silla, Chile. Title: Nebular and Auroral Emission Lines of [Ar IV] in the Optical Spectra of Planetary Nebulae Authors: Keenan, F. P.; McKenna, F. C.; Bell, K. L.; Ramsbottom, C. A.; Wickstead, A. W.; Aller, L. H.; Hyung, S. Bibcode: 1997ApJ...487..457K Altcode: Recent R-matrix calculations of electron impact excitation rates in Ar IV are used to calculate the emission-line ratio: ratio diagrams (R1, R2), (R1, R3), and (R1, R4), where R1 = I(4711 Å)/I(4740 Å), R2 = I(7238 Å)/I(4711 + 4740 Å), R3 = I(7263 Å)/I(4711 + 4740 Å), and R4 = I(7171 Å)/I(4711 + 4740 Å), for a range of electron temperatures (Te = 5000-20,000 K) and electron densities (Ne = 10-106 cm-3) appropriate to gaseous nebulae. These diagrams should, in principle, allow the simultaneous determination of Te and Ne from measurements of the [Ar IV] lines in a spectrum. Plasma parameters deduced for a sample of planetary nebulae from (R1, R3) and (R1, R4), using observational date obtained with the Hamilton echelle spectrograph on the 3 m Shane Telescope at the Lick Observatory, are found to show excellent internal consistency and to be in generally good agreement with the values of Te and Ne estimated from other line ratios in the echelle spectra. These results provide observational support for the accuracy of the theoretical ratios and, hence, the atomic data adopted in their derivation. In addition, they imply that the 7171 Å line is not as seriously affected by telluric absorption as previously thought. However, the observed values of R2 are mostly larger than the theoretical high-temperature and density limit, which is due to blending of the Ar IV 7237.54 Å line with the strong C II transition at 7236 Å. Title: [O V] in the Ultraviolet Spectra of Gaseous Nebulae Authors: McKenna, F. C.; Keenan, F. P.; Aller, L. H.; Hyung, S.; Feibelman, W. A.; Berrington, K. A.; Fleming, J.; Hibbert, A. Bibcode: 1997ApJ...486..571M Altcode: Theoretical O V electron-density-sensitive emission line ratios for R = I(2s2 1S0 - 2s2p 3P2)/I(2s2 1S0 - 2s2p 3P1) are presented. Inspection of Goddard High Resolution Spectrograph Hubble Space Telescope spectra of RR Tel reveals the presence of the [O V] 2s2 1S - 2s2p 3P2 line at 1213.80 Å, which is 4.62 +/- 0.12 Å away from the 2s2 1S - 2s2p 3P2 intercombination transition at 1218.42 Å, in good agreement with the theoretical prediction of Δλ = 4.54 Å. The resultant value of R = 0.82 +/- 0.11 implies a logarithmic electron density, log Ne, of 5.2 +/- 0.2 cm-3, in good agreement with that found from other ions with high electron temperature, such as Ne VI, which also provides support for the identification. Title: High-resolution spectroscopic observations of B-type stars from the Edinburgh-Cape survey Authors: Rolleston, W. R. J.; Hambly, N. C.; Dufton, P. L.; Keenan, F. P.; Little, J. E.; Kilkenny, D.; O'Donoghue, D.; Koen, C.; Stobie, R. S. Bibcode: 1997MNRAS.290..422R Altcode: High-resolution spectroscopy has been obtained for 25 high-latitude stars identified from the Edinburgh-Cape faint blue object survey as having B-type spectra. Five objects are found to be subluminous (subdwarf or horizontal branch), chemically peculiar, or later than B-type. We present model atmosphere analyses for the other 20 objects, and conclude that 17 stars exhibit stellar properties typical of young B-type dwarfs. Photospheric abundances determined for a subset of stars were also found to be consistent with a Population I composition. Furthermore, we believe EC 05229-6058 to be an evolved object currently on the post-asymptotic giant branch phase, whilst EC 20411-2704 and 11074-2912 are consistent with being zero-age horizontal branch and post-blue horizontal branch objects respectively. A kinematic analysis of the normal stars implies that all could have formed in, and have been subsequently ejected from, the Galactic disc. Title: Star-forming Processes Far from the Galactic Disk: Inoperative or Indolent Where Operative Authors: Christodoulou, Dimitris M.; Tohline, Joel E.; Keenan, Francis P. Bibcode: 1997ApJ...486..810C Altcode: Highly supersonic collisions between gaseous clouds may effectively trigger star formation in the disk of our Galaxy, but not in the diffuse environment of the Galactic halo. This is because the observed high-velocity clouds (HVCs) are not dominated by collisions: the characteristic time between cloudlet collisions inside an HVC at an assumed distance of 10 kpc is at least 1 Gyr for collective encounters and at least 10 Gyr if a particular cloudlet is considered. In agreement with this result, we also estimate that the observed cloudlets contain smaller masses than the nonmagnetic Jeans mass that signals favorable conditions for gravitational collapse and further fragmentation in the isothermal regime. The diffuse environment observed around the Magellanic Clouds (MCs) is more difficult to understand than HVCs. Six sparse blue associations and two young B-type stars have been observed in the H I bridge between the MCs, while no stars exist in the H I cloud complexes that make up the Magellanic Stream. We discuss the conditions under which spatially sporadic star formation took place in the Magellanic Bridge during the past 16-25 Myr and the reasons for the complete absence of star formation in the Stream during its entire lifetime. We also estimate the angular resolutions that need to be achieved by follow-up radio observations of these regions that could detect cold cloudlets embedded in the gas. Title: Optical and HI studies of high- and intermediate-velocity gas towards Complex A Authors: Ryans, R. S. I.; Keenan, F. P.; Sembach, K. R.; Davies, R. D. Bibcode: 1997MNRAS.289..986R Altcode: We present high-resolution optical and 21-cm Hi spectra of seven early-type stellar sightlines towards the high-velocity cloud Complex A, at distances of up to 4.6 kpc from the Galactic plane. We do not optically detect the -160 kms^-1 interstellar gas associated with Complex A, and so are unable to establish limits on its distance. However, we do detect gas associated with the Low Latitude Intermediate Velocity Arch, placing it at z<0.9kpc, and also establish distance limits (z<=1.2-3.3kpc) on several other intermediate- and high-velocity clouds in this region that have not been catalogued previously. Title: FeXVII X-ray lines in solar coronal and laboratory plasmas. Authors: Phillips, K. J. H.; Greer, C. J.; Bhatia, A. K.; Coffey, I. H.; Barnsley, R.; Keenan, F. P. Bibcode: 1997A&A...324..381P Altcode: Theoretical intensities of the Fe XVII X-ray lines due to transitions 2p^6^-2p^5^3d (near 15Å) and 2p^6^-2p^5^3s (near 17Å) are presented, and compared with solar flare and active region spectra. The ratio of the 15Å lines to the 17Å lines is a function of temperature T_e_, but for solar spectra this is not of practical use because of the resonance scattering of the intense 15.015Å line. Instead we use the ratio of a nearby Fe XVIII line to obtain T_e_. We find very satisfactory correspondence between solar spectra and synthetic spectra based on calculated line intensities with appropriately chosen T_e_ apart from the 15.015Å line, which is sometimes less intense than its theoretical value, apparently owing to resonance scattering. Spectra emitted by DITE and JET tokamak plasmas with measured T_e_ and N_e_ are also considered. A predicted density variation of the ratio of the Fe XVII lines at 17.051Å and 17.096 Å is confirmed, and using Abel inversion techniques applied to a sequence of DITE spectra with different radial distances good agreement is found between the theoretical temperature variation of the I(15.015Å)/I(16.776Å) line ratio and that derived from these spectra. We conclude that our calculated Fe XVII line intensities are very reliable and may therefore be used in future analysis. Title: Early-Type Stars in the Galactic Halo from the Palomar-Green Survey. I. A Sample of Evolved, Low-Mass Stars Authors: Hambly, N. C.; Rolleston, W. R. J.; Keenan, F. P.; Dufton, P. L.; Saffer, R. A. Bibcode: 1997ApJS..111..419H Altcode: We present high-resolution spectroscopic observations of early-type stars drawn from a complete sample based on low-resolution spectroscopy of targets from the Palomar-Green Survey by Green, Schmidt, & Liebert. Qualitatively, the metal-line spectra are sharp and are therefore indicative of extremely low projected rotational velocities. Hence the objects are characterized as members of an old, evolved population (for example, blue horizontal branch or post-asymptotic giant branch). By careful choice of Population I, Galactic disk B stars, we have computed differential abundances between the targets and their main-sequence analogs. The CNO abundances from model-atmosphere analyses suggest the presence of nucleosynthesis dredge-up products in the stellar photospheres. With one exception, the stars all have [Fe/H] abundances consistent with their progenitor objects being metal deficient. Some conclusions are drawn as to the previous evolution (red giant branch, horizontal branch, or asymptotic giant branch) of the stars. Title: The Ar/Ca relative abundance in solar coronal plasma. Authors: Young, P. R.; Mason, H. E.; Keenan, F. P.; Widing, K. G. Bibcode: 1997A&A...323..243Y Altcode: The relative abundances of elements with low and high first ionisation potentials (FIP) is a subject of much recent debate. In situ measurements of the solar wind reveal a clear pattern of low FIP enhancement that has been followed up with various spectroscopic measurements of the solar corona. Argon is unique amongst the more abundant high FIP elements in retaining several of its electrons at the high temperatures seen in flares. This allows emission lines of different ions to be compared with more confidence than for, say, hydrogen-like high FIP ions such as OVIII and NeX. In this paper we look at emission lines of the boron-like ion ArXIV; in particular, the optical line at 4412Å, seen in eclipse observations, is compared to the CaXIII 4086Å and CaXV 5445Å & 5694Å lines to yield an Ar/Ca abundance of 0.85+/- 0.20. In the extreme ultra-violet (EUV), the ArXIV lines at 187.94Å and 194.41Å can be compared with CaXIV 193.87 Å - flare data from Skylab giving values of 1.10+/-0.25 and 0.55+/-0.21. Analysis of previous work indicates a photospheric Ar/Ca abundance of 1.31+/-0.30, hence supporting the conclusion that elements with high FIP have lower coronal abundances. Title: Nonthermal Velocities in the Solar Transition Zone and Corona Authors: Doyle, J. G.; O'Shea, E.; Erdélyi, R.; Dere, K. P.; Socker, D. G.; Keenan, F. P. Bibcode: 1997SoPh..173..243D Altcode: Nonthermal velocities are presented for spectral lines covering the temperature range 10 4-10 6 K, measured from high-spectral-resolution data for several solar features observed at the limb by the high resolution telescope and spectrograph (HRTS), including a coronal hole, `quiescent regions' and several small-scale active regions. These results are compared with predictions based on acoustic waves and heating via Alfvén waves. It is likely that more than one mechanism is operating simultaneously, in particular, resonant Alfvén wave heating, which is very sensitive to background plasma motions. Title: Heavy particle excitation of the fine-structure transitions within the 2s2p^2^4P multiplet in boron-like ions Authors: Foster, V. J.; Reid, R. H. G.; Keenan, F. P. Bibcode: 1997MNRAS.288..973F Altcode: Cross-sections are presented for proton-impact excitation of the fine-structure transitions within the 2s2p^2 ^4P multiplet in Cii, Niii and Oiv. These have been calculated using the close-coupled impact parameter method modified to include the 2p^3 ^4S^o states by means of a polarization potential. Excitation rate coefficients have been derived from the cross-sections for a wide range of temperatures. Title: Spectroscopy of the interstellar medium in the Magellanic Bridge Authors: Keenan, Francis Bibcode: 1997hst..prop.7511K Altcode: Our optical observations of two B-type stars in the Magellanic Bridge, a region of material between the Large and Small Magellanic Clouds {LMC, SMC}, reveal strong interstellar Ca II K absorption arising from the Bridge gas. We now propose to obtain medium resolution STIS spectra of the ultraviolet interstellar lines toward both of the stars. The proposed observations will provide an opportunity to investigate the physical conditions within the Bridge gas, and to determine the chemical composition of important elements such as C, N, O, Mg, Si, S, and Fe. These abundances will be compared with those found for the LMC and SMC, which will allow us to investigate if the Bridge gas originated in the SMC, as current theory suggests. The presence of young B-type stars in the Bridge implies that star formation is still occurring in this region. It has been suggested that the formation mechanism is similar to that believed to be responsible for some of the young B-type stars found in the halo of our Galaxy, namely collisions between cloudlets within high-velocity clouds {HVCs}. To investigate this, we will compare our derived physical conditions for the Bridge gas with those found for halo HVCs. We will also search for cloudlet structure in the Bridge gas, through the identification of multicomponents in the interstellar line profiles; such cloudlets have already been found by us in an HVC. Title: The distance to Complex M and the Intermediate Velocity Arch Authors: Ryans, R. S. I.; Keenan, F. P.; Sembach, K. R.; Davies, R. D. Bibcode: 1997MNRAS.289...83R Altcode: The Intermediate Velocity Arch is an association of Hi clouds lying within the broad limits l~110 deg-210 deg,b~50 deg-80 deg. We use high-resolution optical, and single-dish 21-cm, observations of 10 early-type halo star sightlines in this region to establish distance limits (0.4<=z<=3.5kpc) for seven IVCs that are part of the Arch. We re-examine a previous determination of upper and lower distance limits on the IVC Complex M using the closely aligned halo stars BD+382182 and HD93521. Our Hi spectra show no evidence of emission from Complex M, leading us to conclude that, while an upper distance limit of z<=3.5 kpc may be established, no useful lower distance determination can be made. Our new Hi observations allow new limits to be established on the metallicity of Complex M, and show C, O and Si variations with respect to solar abundances in the range +/-0.3 dex. Title: Photoionisation cross-sections for Fe XXIII and Fe XXIV. Authors: Black, G. M.; Bell, K. L.; Keenan, F. P. Bibcode: 1997A&A...322..359B Altcode: Photoionisation of Fe XXIII and Fe XXIV is investigated using the R-matrix method, with particular attention being given to photoejection of the 1s K-shell electron. In both cases, good agreement (to within 5%) is found with earlier calculations of the background cross-section. However, the present work is the first to determine resonance structure just below and above the 1s photoejection threshold energy. Title: Emission Lines of NI XVIII in the Solar EUV Spectrum Authors: Keenan, F. P.; Foster, V. J.; Mohan, M.; Widing, K. G. Bibcode: 1997SoPh..171..337K Altcode: Using electron excitation rates calculated with the R-matrix code, theoretical Nixviii electron-temperature-sensitive emission line ratios are presented for R1 = I(220.41 Å)/I(320.56 Å) , R2 = I(233.79 Å)/I(320.56 Å) , and R3 = I(220.41 Å)/I(292.00 Å) . A comparison of these with observational data for two solar flares, obtained by the Naval Research Laboratory's S082A slitless spectrograph on board Skylab, reveals good agreement between theory and observation for R1 and R2 in two spectra, which provides limited support for the accuracy of the atomic data adopted in the analysis. However, several of the measured ratios are much larger than theory predicts, which is probably due mainly to saturation of the strong 292.00 and 320.56 Å lines on the photographic film used to record the S082A data. A comparison of our line ratio calculations with active region observations made by the Solar EUV Rocket Telescope and Spectrograph (SERTS) indicate that a feature at 236.335 Å, identified as the Nixviii 3p2P3/2 - 3d2D3/2 transition in the SERTS data, is actually the Arxiii 2s22p23P0 - 2s2p33D1 line. The potential usefulness of the Nixviii line ratios as electron temperature diagnostics for the solar corona is briefy discussed. Title: The Optical Spectral Line List of RR Telescopii Authors: McKenna, F. C.; Keenan, F. P.; Hambly, N. C.; Allende Prieto, C.; Rolleston, W. R. J.; Aller, L. H.; Feibelman, W. A. Bibcode: 1997ApJS..109..225M Altcode: The symbiotic nova RR Telescopii has been observed with the 1.5 m telescope of the Cerro Tololo Inter-American Observatory (CTIO), using the 1.5 m bench-mounted echelle spectrograph in conjunction with a Tektronix CCD. It displays a rich emission-line spectrum, ranging in excitation from O I to [Ni VIII]. We present a list of 491 measured lines, with their suggested identifications, covering a wavelength range from 3430 to 9320 Å. Of these, only nine are unidentified, and 70 lines are cataloged that were not given in the original line list of Thackeray. Absolute line intensities are also given, which have been derived by comparing the high-resolution data with a flux-calibrated low-resolution spectrum taken with the Cassegrain spectrograph on the 1.0 m telescope at CTIO. Title: F XVIII Emission Lines in Solar X-Ray Spectra Authors: Warren, G. A.; Keenan, F. P.; Greer, C. J.; Phillips, K. J. H.; Bruner, M. E.; Brown, W. A.; McKenzie, D. L. Bibcode: 1997SoPh..171...93W Altcode: We have calculated intensity ratios for emission lines of Fexviii in the 13-94 Å wavelength range at electron temperatures characteristic of the solar corona, Te = 2-10 x 106 K. Our model ion includes data for transitions among the 2s22p5 , 2s2p6, 2s22p43l, and 2s2p53l (l = s, p, and d) states. Test calculations which omit the 2s2p53l levels show that cascades from these are important. We compare our results with observed ratios determined from four solar X-ray instruments, a rocket-borne spectrograph, and spectrometers on the P78-1, OV1-17 and Solar Maximum Mission (SMM) satellites. In addition, we have generated synthetic spectra which we compare directly with flare observations from SMM. Agreement between theory and observation is generally quite good, with differences that are mostly less than 30%, providing limited support for the accuracy of the atomic physics data used in our calculations. However, large discrepancies are found for ratios involving the 2s22p52P3/2- 2s2p62S line at 93.84 Å, which currently remain unexplained. Our analysis indicates that the FeXVIII feature at 15.83 Å is the 2s22p52P3/2 - 2s22p4(3P)3s 4P3/2 transition, rather than 2s22p52P3/2 - 2s22p4(3P)3s 2P3/2, as suggested by some authors. Title: M VIII Diagnostic Line Ratios in SKYLAB Solar Observations Authors: Foster, V. J.; Keenan, F. P.; Reid, R. H. G.; Doyle, J. G.; Zhang, H. L.; Pradhan, A. K.; Widing, K. G. Bibcode: 1997SoPh..170..217F Altcode: Recent calculations of Mgviii electron and proton impact excitations rates are used to derive theoretical electron temperature (Te)- and density (Ne)-sensitive emission line ratios involving transitions in the 315-782 Å wavelength range. Some of these ratios are presented in the form of ratio-ratio diagrams, which should in principle allow both Ne and Te to be deduced. These results are compared with solar observational data from Skylab, but agreement between theory and observation is very poor, probably due to blending. Title: Oscillator Strengths for Transitions in Ca XV and Fe XXI Authors: Aggarwal, K. M.; Hibbert, A.; Keenan, F. P.; Norrington, P. H. Bibcode: 1997ApJS..108..575A Altcode: Energy levels and oscillator strengths (transition rates) have been calculated for the fine-structure transitions among the levels of the (1s2) 2s22p2, 2s2p3, 2p4, 2s22p3s, 2s22p3p, and 2s22p3d configurations of Ca XV and Fe XXI using the CIV3 and GRASP programs. The results are compared with the recently available theoretical values from the SuperStructure program. The differences among the various calculations are discussed, and the accuracy of the results is assessed. Title: Observations of Ob-Type Stars in the Halos of Galaxies Authors: Keenan, F. P. Bibcode: 1997fbs..conf..199K Altcode: 1997LDP....22..199K No abstract at ADS Title: Oscillator Strengths for Transitions in O III Authors: Aggarwal, K. M.; Hibbert, A.; Keenan, F. P. Bibcode: 1997ApJS..108..393A Altcode: Energy levels and oscillator strengths have been calculated for the fine-structure transitions among the levels of the (1s2) 2s22p2, 2s2p3, 2p4, 2s22p3s, 2s22p3p, and 2s22p3d configurations of O III using the CIV3 program. The extensive configuration interaction and relativistic effects have been included while generating the wave functions. The results are compared with other recent theoretical estimates, and their accuracy is assessed. Title: Time Series Photometric and Spectroscopic Observations of the β Cephei Halo Star PHL 346 Authors: Dufton, P. L.; Keenan, F. P.; Kilkenny, D. Bibcode: 1997fbs..conf..389D Altcode: 1997LDP....22..389D No abstract at ADS Title: High Resolution Spectroscopic Observations of B-Type Stars from the Edinburgh-Cape Survey Authors: Rolleston, W. R. J.; Dufton, P. L.; Keenan, F. P.; Little, J. E.; Hambly, N. C.; Kilkenny, D.; Koen, C.; Stobie, R. S.; O'Donoghue, D. Bibcode: 1997fbs..conf..367R Altcode: 1997LDP....22..367R No abstract at ADS Title: Abundance analyses of a sample of five faint blue stars in the galactic halo. Authors: Kendall, T. R.; Dufton, P. L.; Keenan, F. P.; Beers, T. C.; Hambly, N. C. Bibcode: 1997A&A...317...82K Altcode: High resolution optical spectra of five faint high galactic latitude B-type stars, identified from a magnitude limited survey, have been analysed using LTE model atmosphere calculations. All targets have small projected rotational velocities (<=30km/s) and hence may be evolved objects. This is supported by their chemical compositions, which indicate that they are old Population II stars; two stars also show enhanced nitrogen abundances probably due to the mixing of nuclear processed material to their surfaces. Their atmospheric parameters are consistent with a post-Asymptotic Giant Branch evolutionary status, although two targets may have evolved directly off the horizontal branch. Title: The identification of the O V forbidden line in the ultraviolet spectrum of gaseous nebulae Authors: McKenna, F. C.; Keenan, F. P.; Aller, L. H.; Hyung, S.; Feibelman, W. A.; Berrington, K. A.; Fleming, J. Bibcode: 1997IAUS..180..259M Altcode: No abstract at ADS Title: Radio HI and optical absorption-line studies of interstellar gas Authors: Bates, B.; Shaw, C. R.; Kemp, S. N.; Keenan, F. P.; Davies, R. D.; Roger, R. S. Bibcode: 1997hsra.book..101B Altcode: No abstract at ADS Title: S II emission lines in Planetary Nebulae Authors: McKenna, F. C.; Keenan, F. P.; Aller, L. H.; Hyung, S.; Bell, K. L.; Ramsbottom, C. A. Bibcode: 1997IAUS..180..258M Altcode: No abstract at ADS Title: Effective collision strengths for fine-structure forbidden transitions among the 3s^23p^3 levels of AR IV Authors: Ramsbottom, C. A.; Bell, K. L.; Keenan, F. P. Bibcode: 1997MNRAS.284..754R Altcode: The multichannel R-matrix method is used to compute electron impact excitation collision strengths in Ar iv for all fine-structure transitions among the ^4S^o, ^2D^o and ^2P^o levels in the 3s^23p^3 ground configuration. Included in the expansion of the total wavefunction are the lowest 13 LS target eigenstates of Ar iv formed from the 3s^23p^3, 3s3p^4 and 3s^23p^23d configurations. The effective collision strengths, obtained by averaging the electron collision strengths over a Maxwellian distribution of electron velocities, are presented for all 10 fine-structure transitions over a wide range of electron temperatures of astrophysical interest (T_e=2000-100 000K). Comparisons are made with an earlier 7-state close-coupling calculation by Zeippen, Butler & Le Bourlot, and significant differences are found to occur for many of the forbidden transitions considered, in particular those involving the ^4S^o ground state, where discrepancies of up to a factor of 3 are found in the low-temperature region. Title: CDS Observations of the Quiet Sun EUV Network Authors: Gallagher, P. T.; Phillips, K. J. H.; Harra-Murnion, L. K.; Keenan, F. P. Bibcode: 1997ESASP.404..395G Altcode: 1997cswn.conf..395G No abstract at ADS Title: Cross Sections and Rate Coefficients for Excitation within the 1s22s22p 2P and 1s22s2p2 4P Multiplets in Boron-like Ions C II-Ni XXIV by Heavy Particle Impact Authors: Foster, V. J.; Keenan, F. P.; Reid, R. H. G. Bibcode: 1997ADNDT..67...99F Altcode: Cross sections for excitation of the fine-structure transitions within the 1s22s22p2Poand 1s22s2p2 4Pemultiplets in boron-like ions by proton, deuteron, triton, and α-particle impact have been calculated using a close-coupled impact-parameter method, which includes the effects of dipole coupling to nearby configurations by means of a polarization potential. The ions considered are C II, N III, O IV, Ne VI, Mg VIII, Al IX, Si X, S XII, Ar XIV, Ca XVI, Ti XVIII, Cr XX, Mn XXI, Fe XXII, Co XXIII, and Ni XXIV. Excitation rate coefficients have been calculated from the cross sections for a wide range of temperatures. Title: On the Variability of Forming Stars in the Galactic Halo and in the Gas around the Magellanic Clouds Authors: Christodoulou, Dimitris M.; Tohline, Joel E.; Keenan, Francis P. Bibcode: 1997fbs..conf..105C Altcode: 1997LDP....22..105C No abstract at ADS Title: A Large Scale Spectroscopic Survey of Early-Type Stars at High Galactic Latitudes Authors: Saffer, Rex A.; Keenan, F. P.; Hambly, N. C.; Dufton, P. I.; Liebert, James W. Bibcode: 1997fbs..conf...97S Altcode: 1997LDP....22...97S No abstract at ADS Title: Assessment of Proton-Impact Excitation Rate-Coefficient Data of Relevance to the SOHO Mission Authors: Copeland, F.; Reid, R. H. G.; Keenan, F. P. Bibcode: 1997ADNDT..67..179C Altcode: Calculations of proton-impact fine-structure excitation of the Be- to Cl-like ions for elements from C to Ni are compiled and assessed, in line with the exercise recently carried out for electron-impact excitation data relevant to the analysis of experiments on the Solar and Heliospheric Observatory (SOHO) spacecraft and published in this journal [Vol.57,Nos. 1/2 (1994)]. References for individual transitions are presented in tabular form for each isoelectronic sequence considered, together with their estimated relative accuracy. Title: Evolved Stars in the Halo of Our Galaxy from the Palomar-Green Survey Authors: Rolleston, W. R. J.; Keenan, F. P.; Dufton, P. L.; Hambly, N. C.; Saffer, R. Bibcode: 1997fbs..conf..363R Altcode: 1997LDP....22..363R No abstract at ADS Title: Fe XVII X-ray lines in solar coronal plasmas Authors: Phillips, K. J. H.; Greer, C. J.; Bhatia, A. K.; Coffey, I. H.; Barnsley, R.; Keenan, F. P. Bibcode: 1997AdSpR..20.2267P Altcode: Calculated intensities of the Fe xvii X-ray lines due to transitions 2p^6 - 2p^53d lines (near 15 A˚) and 2p^6 - 2p^53s lines (near 17 A˚) are compared with measured line intensities in solar and tokamak spectra. For the solar spectra, temperature T_e is obtained from the ratio of the Fe xvii 16.776 A˚ line to a nearby Fe xviii line. We find excellent agreement for all the major Fe xvii line features in the 15-17 A˚ region except the Fe xvii 15.015 A˚ line, the observed flux of which is less than the theoretical by a factor f. We find that f strongly depends on the heliocentric angle theta of the emitting region, being smallest (0.2) when the region is nearest Sun centre, but nearly 1 near the limb. Attributing this to resonance scattering, we are able to deduce the path length and electron density from the observations. Possible application to stellar active regions is given. Title: Fe X Emission Lines in Solar and Stellar Spectra Authors: Foster, V. J.; Mathioudakis, M.; Keenan, F. P.; Drake, J. J.; Widing, K. G. Bibcode: 1996ApJ...473..560F Altcode: Theoretical electron density sensitive emission line ratios involving Fe X 3s23p5-3s23p43d transitions in the 170-190 Å wavelength range are compared with observational data for a solar active region and flares, obtained during the Skylab mission, and Cen and Procyon observations from the Extreme Ultraviolet Explorer (EUVE) satellite. Electron densities derived from the majority of the ratios are consistent for the events but are in poor agreement with the values of Ne estimated from diagnostic lines in other species observed in the spectra, casting doubt on the accuracy of the theoretical line ratio calculations and, hence, the atomic data of Mohan et al. used in their derivation. At low Ne, the present ratios are significantly different from those of Young et al., while the latter imply densities that are in somewhat better agreement with densities derived from other diagnostics. This would appear to indicate that the electron impact excitation rates of Bhatia & Doschek adopted by Young et al. are to be preferred over the Mohan et al. results. Title: The Structure and Properties of an Intermediate-Velocity Cloud in the Direction of the Globular Cluster M13 Authors: Shaw, C. R.; Bates, B.; Kemp, S. N.; Keenan, F. P.; Davies, R. D.; Roger, R. S. Bibcode: 1996ApJ...473..849S Altcode: A study of an intermediate-velocity cloud (IVC; VLSR ≍ -70 km s-1) detected in the foreground of the globular cluster M13 has been made using H I spectra obtained with the Lovell Telescope, Jodrell Bank (FWHP beamwidth 12') and H I spectral maps derived from Dominion Radio Astrophysical Observatory Synthesis Telescope observations (FWHP synthesised beamwidth ≍2'.8 x 2.'0). The radio data complement the optical absorption line spectroscopy of M13 cluster stars reported by Bates et al. The H I data obtained with the Lovell Telescope show extended emission from a broad-velocity component (FWHM 30 km s-1) of H I column density≥ 7 x 1O18. Two cloudlets are revealed in the H I observations lying on either side of M13 and having a two-component structure; the broad component (FWHM ≍ 32 km s-1) has an H I column density of 5 x 1O19 cm-2, while the narrow component (FWHM ≍ 8 km s-1) has a column density of ≍6 x 1O18 cm-2 as seen in the Synthesis Telescope observations. The cloudlets have an angular size ≍2' and are only partially resolved in the synthesis telescope data. Fine-scale gas structure is also evident from the cluster star spectroscopy with variations in Na I column density of a factor of ≥10 observed across the several arcminutes of the cluster face; there is also evidence for structure on an angular scale of several arcseconds. A column density ratio Na I/H I≍ 4 × 10-8 is measured for a cloudlet in the foreground of the cluster near the strongest Na I detection. Estimates are made of cloudlet gas density that are comparable with those reported for high-velocity cloud (HVC) concentrations. However, the present observations emphasize further the need for higher spatial resolution H I studies to provide firmer estimates of cloud properties. Title: Fe XXI Emission Line Ratios as Electron Temperature Diagnostics for the Coronae of Cool Stars Authors: Keenan, F. P.; Foster, V. J.; Aggarwal, K. M.; Widing, K. G. Bibcode: 1996SoPh..169...47K Altcode: Theoretical Fe XXI electron temperature and density sensitive emission line ratios are presented for R1 = I(2s22p23P1 - 2s2p35S)/I(2s22p23P0 - 2s22p23P1) and R2 = T(2s22p23P1 - 2s2p21S)/T(2s22p23P0 - 2s22p23P1).

Title: UHRF observations of the interstellar medium towards two stars in the Galactic Halo. Authors: Ryans, R. S. I.; Sembach, K. R.; Keenan, F. P. Bibcode: 1996A&A...314..609R Altcode: We present interstellar Na I and Ca II spectra of the halo stars HD 18100 and HD 203664, obtained with the Ultra-High Resolution Facility on the Anglo-Australian Telescope. These observations have spectral resolutions R=~210,000 and signal-to-noise ratios in the range 20-75. We find multiple absorbing components along both sightlines and resolve the velocity structure within the high velocity cloud toward HD 203664. We discuss these spectra and their use in future Hubble Space Telescope studies of HD 18100 and HD 203664. Title: Active Region Electron Density and Dimensions from Fe XVII X-Ray Lines Authors: Phillips, K. J. H.; Greer, C. J.; Bhatia, A. K.; Keenan, F. P. Bibcode: 1996ApJ...469L..57P Altcode: The Fe XVII 2p6 1S0--2p53d 1P1 X-ray line at 15.015 A is resonance-scattered in solar active region and flare spectra, as has been deduced by comparing theoretical intensities of lines in the Fe XVII 2p6--2p53l (l = s, d) arrays with intensities observed by the flat crystal spectrometer (FCS) on the Solar Maximum Mission. We show that the amount of resonance scattering is strongly dependent on the heliocentric distance of the emitting plasma, disk regions showing much larger scattering than limb regions. Average values for electron density Ne and path length l can be derived for various heliocentric distances using the X-ray line intensities. We find Ne ~ 109 cm-3 and l ~ 100,000 km (region on the disk) to Ne ~ 1011 cm-3 and l ~ 1000 km (region on the limb) for active region AR 4787, as it rotated across the solar disk to the limb. These lengths appear to be consistent with FCS images. We note, from our findings, that the approximate extent of stellar X-ray active regions could be determined, if high-resolution Fe XVII or equivalent observations were available. Title: Auroral and nebular emission lines of [SII] in the optical spectra of planetary nebulae Authors: Keenan, F. P.; Aller, L. H.; Bell, K. L.; Hyung, S.; McKenna, F. C.; Ramsbottom, C. A. Bibcode: 1996MNRAS.281.1073K Altcode: R-matrix calculations of electron impact excitation rates among the 3s^23p^3 levels of SII are presented, which are found to be up to a factor ~2 different from those of Cai & Pradhan. The present results are subsequently used to calculate emission-line ratio-ratio diagrams involving the 4068-, 4076-, 6717- and 6730-A transitions, for a range of electron temperatures (T_e=5000-20000 K) and electron densities (N_e=10-10^5 cm^-3) appropriate to gaseous nebulae. These diagrams should, in principle, allow the simultaneous determination of T_e and N_e from measurements of the [SII] lines in a spectrum. Plasma parameters deduced for a sample of planetary nebulae, using observational data obtained with the Hamilton Echelle spectrograph on the 3-m Shane Telescope at Lick Observatory, are found to show excellent internal consistency, and to be in generally good agreement with the values of T_e and N_e estimated from other line ratios in the echelle spectra. These results provide observational support for the accuracy of the theoretical ratios, and hence the atomic data adopted in their derivation. Title: High-Resolution Optical Spectroscopy of PG 0832+676: A Sharp-lined, Evolved Low-Mass Star Authors: Hambly, N. C.; Keenan, F. P.; Dufton, P. L.; Brown, P. J. F.; Saffer, R. A.; Peterson, R. C. Bibcode: 1996ApJ...466.1018H Altcode: We present high-resolution spectroscopic observations of the faint, hot star PG 0832+676, identified in a previous paper as an extremely distant young B-type object. A differential abundance analysis with respect to the Galactic B-type star HR 1886 shows near normal helium, nitrogen, and oxygen abundances while there is a systematic depletion of ∼0.4 dex in the abundances of other elements. Furthermore, our new high-resolution observations show this object to be extremely sharp lined (v sin i ∼ 1 km s-1), and we therefore conclude that the star is an old, evolved low-mass star, either in the postasymptotic giant branch phase or more probably evolving off the blue horizontal branch. We suggest that such sharp-lined spectra from hot stars provide a unique and critical test for model atmospheric analyses, particularly with respect to the micro turbulent velocity parameter. Title: [N II] and [O III] Mean Electron Temperatures in Planetary Nebulae Authors: McKenna, F. C.; Keenan, F. P.; Kaler, J. B.; Wickstead, A. W.; Bell, K. L.; Aggarwal, K. M. Bibcode: 1996PASP..108..610M Altcode: Mean electron tempertures for 106 planetary nebulae are presented, which have been derived using calculations of the values of electron temperature-sensitive line ratios involving forbidden transitions among the 2s^2 2p^2 3P, 1D, and 1S levels of N+ and O++, based on new electron impact rates and transition probabilities. Comparison of these results with values of T_e[N II] and T_e[O III] determined previously by Kaler reveal that the present electron temperatures are systematically lower for both ions, and that this discrepancy is correlated with the electron density in the nebula. It is also shown that the average difference tween T_e[N II] and T_e[O III] in a planetary nebula is somewhat smaller than that derived by Kaler, with the present results implying that the N II and O III temperatures disagree on average by 2070 K as opposed to the 2210 K average found by Kaler. (SECTION: Interstellar Medium and Nebulae) Title: New Line Identifications in the Optical Spectrum of the Slow Nova RR Telescopii Authors: McKenna, F. C.; Keenan, F. P.; Hambly, N. C.; Allende Prieto, C.; Aller, L. H.; Feibelman, W. A. Bibcode: 1996IrAJ...23..157M Altcode: The symbiotic nova RR~Telescopii has been observed with the 1.5m telescope of the Cerro Tololo Inter-American Observatory (CTIO), using the 1.5m Bench-Mounted Echelle Spectrograph (BME) in conjunction with a Tek CCD. It displays a rich emission line spectrum, ranging in excitation from O I to [Ni VIII]. The result is a list of 483 measured lines, with their suggested identifications, covering a range from 3430 A to 9320 A. Of these, only nine are unidentified, and 70 lines are catalogued that were not given in the original line list of Thackeray. We have also obtained absolute line intensities, which have been derived by comparing the high-resolution data with a flux calibrated low-resolution spectrum taken with the Cassegrain Spectrograph on the 1.0m at the CTIO. Title: NE V and NE VI Lines in the Ultraviolet Spectrum of the Symbiotic Star RR Telescopii Authors: Espey, B.; Keenan, F. P.; McKenna, F. C.; Feibelman, W. A.; Aggarwal, K. M. Bibcode: 1996ApJ...465..965E Altcode: New theoretical Ne VI] electron density-sensitive ratios are presented for the intercombination transitions R1 = I(1006.1 Å)/I(999.6 Å) and R2 = 1(1010.6 Å)/I(999.6 Å). Temperature-sensitive ratios are also given for the Ne V] ratio R = 1(1137.0 Å)/I(1574.8 Å). We discuss the potential usefulness of these line ratios for studying hot gas and apply them to the case of the symbiotic system RR Telescopii. Using far-UV data that has recently been acquired with the Hopkins Ultraviolet Telescope, we conclude that the Ne V and Ne VI emission in RR Tel is due to photoionization, with the temperature and density of the emitting region being approximately Te ≃ 18,000 K and Ne ≃ 106 cm-3, respectively. These results are similar to those estimated using other high ionization line diagnostics of the nebular material, such as O V I(1371 Å)/I(1644 Å) and Ne IV] I(1602 Å)/I(2423 Å). Although these Ne V] and Ne VI] lines have been used as diagnostics for solar physics, we believe that this is the first instance in which they have been applied to another astrophysical object. Title: Proton impact excitation of the ground state fine-structure transition in C II, N III and O IV. Authors: Foster, V. J.; Keenan, F. P.; Reid, R. H. G. Bibcode: 1996A&A...308.1009F Altcode: Cross sections and thermally averaged excitation rate coefficients are presented for proton impact excitation of the ground 1s^2^2s^2^2p ^2^P_1/2_-1s^2^2s^2^2p ^2^P_3/2_ transition, in C II, N III and O IV. Cross sections were calculated using the close-coupled impact parameter method which has been modified to include the higher lying levels of the doublet states of the 2s2p^2^ configuration by means of a polarization potential. Excitation rate coefficients, calculated over a wide range of temperatures, are also presented and compared with previous results. Title: Helium like sulphur X-ray emission in solar flares and laboratory plasmas. Authors: Harra-Murnion, L. K.; Phillips, K. J. H.; Lemen, J. R.; Zarro, D. M.; Greer, C. J.; Foster, V. J.; Barnsley, R.; Coffey, I. H.; Dubau, J.; Keenan, F. P.; Fludra, A.; Rachlew-Kaellne, E.; Watanabe, T.; Wilson, M. Bibcode: 1996A&A...308..670H Altcode: Theoretical X-ray spectra of He-like sulphur (S xv) derived from the General Relativistic Atomic Structure Package, the Dirac R-matrix code and other calculations are compared to laboratory spectra obtained from the Alcator C tokamak and JET, and solar flare spectra obtained from the Yohkoh Bragg Crystal Spectrometer (BCS) and with the SMM Flat Crystal Spectrometer. The spectra depend on electron temperature and electron density for plasma densities greater than 10^14^ cm^-3^. The fits of the derived synthetic spectra to the laboratory spectra at measured density and temperature are in fair agreement. Very good agreement can be achieved with the solar flare spectra, which are in general consistent with the S xv low-density limit, by adjusting temperature. Thus, S xv line spectra can be used to determine the temperatures of relatively weak flares for which diagnostics from higher-temperature ions are unavailable. Using the synthetic spectra, a search for density effects in Yohkoh BCS data at the time of compact flares was made. None was found, so that it can be deduced that for such flares the electron density is less than 10^14^cm^-3^. Density estimates are made from emission measures and image sizes using Yohkoh Soft X-ray Telescope data. Research has been carried out with the results of laboratory spectra which indicate a variation of the I_x_/I_y_ line intensity ratio across the tokamak minor radius. We have studied various flares which occur at different locations across the solar disk to determine if the same effect exists on the Sun. Title: A Search for Star Formation around the Galactic Halo B-type Star PHL 346 Authors: Totten, E.; Wood, K. D.; Keenan, F. P.; Dufton, P. L.; Kilkenny, D.; Miller, L.; Hambly, N. C.; Gilmore, G.; Irwin, M. J. Bibcode: 1996ASPC...92..196T Altcode: 1996fogh.conf..196T A search is presented for stars that may have formed coevally with the apparently young halo star PHL 346. Candidates were selected for spectroscopy from UBR Schmidt Telescope plates scanned with the COSMOS facility at the Royal Observatory, Edinburgh. Spectroscopic observations at 3.5 Angstroms resolution were made of 72 field stars using the 1.9m telescope at the South Africa Astronomical Observatory; 16 A- and B-type stars were found, one of which had the appropriate spectral type and radial velocity to be associated with PHL 346. Further photometry and spectroscopy confirmed this identification. The remaining low gravity early-type stars have a mean LSR radial velocity of --75 kms(-1) , consistent with a non-rotating halo population. Title: Spectroscopic Diagnostics Applicable to the UV and EUV Spectra of Astrophysical Sources Authors: Keenan, F. P. Bibcode: 1996SSRv...75..537K Altcode: A bibliography is provided of the most reliable emission and absorption line ratio diagnostic calculations currently available for application to the spectra of astrophysical sources in the UV and EUV wavelength region (50 3000 Å). References are listed containing diagnostics for species in the Li through P isoelectronic sequences, as well as the iron ions Fe ii-Fe xxiii and nickel ions Ni xvii-Ni xxv. Also given is the wavelength range for which diagnostic calculations are presented in each reference, along with the type of diagnostic considered. These include, for example, emission line ratios for determining electron temperatures and densities, and absorption line diagnostics for evaluating hydrogen densities. Title: Atomic data for the X-ray lines of iron. Authors: Black, G.; Bell, K. L.; Keenan, F. P. Bibcode: 1996rftu.proc..671B Altcode: Iron is an astrophysically abundant element, and the X-ray lines of iron and its ions (especially the K lines in some cases) are important sources of information on the structure of and processes in and around certain astronomical objects. To interpret these lines one needs accurate atomic data about the atoms and ions from which they arise: photoionisation cross-sections are one of the most important sources of such information. This paper presents the results of R-matrix calculations on the photoionisation cross-section of Fe XXIV (total, 1s photoejection and partial cross-sections), which is the start of a series of such calculations on the ions of iron. Title: FeXII emission lines in spectra obtained with the Solar EUV Rocket Telescope and Spectrograph (SERTS) Authors: Keenan, F. P.; Thomas, R. J.; Neupert, W. M.; Foster, V. J.; Brown, P. J. F.; Tayal, S. S. Bibcode: 1996MNRAS.278..773K Altcode: Many intensity ratios involving FeXII 3s^23p^3-3s3p^4 and 3s^23p^3-3s^23p^23d transitions in the 186-383A wavelength range are known to be sensitive to electron density. We compare calculations for these lines with observations of a solar active region and of a subflare obtained during the 1989 flight of the Solar EUV Rocket Telescope and Spectrograph (SERTS). Electron densities derived from the majority of such ratios are consistent with one another for both solar features, and are also in good agreement with the values of N_e estimated from diagnostic lines in other species formed at similar electron temperatures to FeXII, such as FeXIII and FeXIV. These results provide observational support for the general accuracy of the diagnostic calculations, and imply that they may be applied to future observations planned with the Coronal Diagnostic Spectrometer on the SOHO mission. In addition, our analysis indicates that the line at 283.70A in the active region data is the 3s^23p^3 ^2D_3/2-3s3p^4 2P_1/2 transition in FeXII, the first time (to the best of our knowledge) that this line has been identified in the solar spectrum. Five of the line ratios considered are predicted to be relatively insensitive to the adopted electron temperature and density, and the good agreement found between theory and observation for three of these provides evidence for the reliability of the SERTS instrument calibration. However, for one of the remaining ratios the large discrepancies between theory and observation cannot be attributed to blending, and may be due to errors in the adopted atomic data. Title: EUV emission lines of O IV observed in solar spectra by the S-055 instrument on Skylab. Authors: O'Shea, E.; Foster, V. J.; Keenan, F. P.; Doyle, J. G.; Reid, R. H. G.; Zhang, H. L.; Pradhan, A. K. Bibcode: 1996A&A...306..621O Altcode: Recent calculations of electron and proton impact excitation rates in O IV are used to derive the intensity ratios of lines in the ~340-1350A wavelength range as a function of electron temperature (T_e_) and density (N_e_). These results are presented in the form of ratio-ratio diagrams, which should in principle allow both N_e_ and T_e_ to be deduced for the O IV line emitting region of a plasma. Electron temperatures derived from ratio-ratio diagrams involving the 790A/554A ratio, in conjunction with observational data for several solar features obtained with the Harvard S-055 spectrometer on board Skylab, are found to be in reasonable agreement with the value of T_e_ expected from ionization equilibrium calculations. This provides some support for the theoretical diagnostics presented in this paper, and hence the atomic data used in their derivation. However other temperature and density sensitive ratios involving the O IV multiplets at 609A, 625A and 787A could not be used to derive plasma parameters from the ratio-ratio diagrams, due to blending with lines of Mg X and S V. Title: On the nature of the high-latitude B-type star CPD-61 deg455 Authors: Hambly, N. C.; Dufton, P. L.; Keenan, F. P.; Lumsden, S. L. Bibcode: 1996MNRAS.278..811H Altcode: High-resolution, high-signal-to-noise optical and near-infrared spectra, along with lower resolution infrared spectra, of the high-latitude, faint B-type star CPD-61 deg455 have been obtained using the 3.9-m Anglo-Australian Telescope. Using LTE model atmosphere codes to compute optical absorption profiles in the hot star, we find atmospheric parameters of T_eff=25000k and logg~3.6 furthermore, the abundance pattern of metals as measured differentially with respect to the Galactic disc B-type star xi^1CMa is not that expected for a normal young object. We show that the previous interpretation of this object as a composite consisting of a B-type star with a possible early K-type giant secondary is consistent with the near-infrared and infrared data. We hypothesize that CPD-61 deg455 is in fact an evolved, post-asymptotic giant branch (post-AGB) star in a binary system, and is possibly a hotter analogue of the binary systems containing younger, cooler post-AGB stars discussed by van Winckel, Waelkens & Waters. Title: A search for star formation around the Galactic halo B-type star PHL 346. Authors: Hambly, N. C.; Wood, K. D.; Keenan, F. P.; Kilkenny, D.; Dufton, P. L.; Miller, L.; Gilmore, G.; Irwin, M. J.; Totten, E. J. Bibcode: 1996A&A...306..119H Altcode: A search is presented for stars that may have formed coevally with the apparently young halo star PHL 346. Candidates were selected for spectroscopy from UBR Schmidt Telescope plates in U.K. Schmidt Telescope survey field 603 scanned with the COSMOS facility at the Royal Observatory, Edinburgh. Spectroscopic observations at ~3.5A resolution were made of 72 field stars using the 1.9m telescope at the South African Astronomical Observatory; 16 A- and B-type stars were found, one of which had the appropriate spectral type and radial velocity to be associated with PHL 346. Further photometry and spectroscopy confirmed this identification. The remaining low gravity early-type stars have a mean LSR radial velocity of -75km/s, consistent with a non-rotating halo Population. Title: On IV diagnostic line ratios in solar EUV spectra. Authors: Foster, V. J.; O'Shea, E.; Keenan, F. P.; Doyle, J. G.; Reid, R. H. G.; Zhang, H. L.; Pradhan, A. K. Bibcode: 1996uxsa.conf..425F Altcode: 1996uxsa.coll..425F Recent calculations of electron and proton impact excitation rates in O IV are used to derive the intensity ratios of lines in the ≡340 - 1350 Å wavelength range as a function of electron temperature (Te) and density (Ne). These results are presented in the form of ratio-ratio diagrams, which should in principle allow both Ne and Te to be deduced for the O IV line emitting region of a plasma. Electron temperatures derived from ratio-ratio diagrams involving the 790 Å/554 Å ratio, in conjunction with observational data for several solar features obtained with the Harvard S-055 spectrometer on board Skylab, are found to be in reasonable agreement with the value of Te expected from ionization equilibrium calculations. This provides some support for the theoretical diagnostics presented in this paper, and hence the atomic data used in their derivation. Title: Nonthermal velocities in the solar transition and coronal region observed with the high-resolution telescope and spectrograph Authors: O'Shea, E.; Doyle, J. G.; Dere, K. P.; Keenan, F. P. Bibcode: 1996ASPC..109..145O Altcode: 1996csss....9..145O No abstract at ADS Title: Fe XVII X-Ray Lines in Solar Coronal Plasmas Authors: Greer, C. J.; Phillips, K. J. H.; Bhatia, A. K.; Keenan, F. P. Bibcode: 1996ASPC..111..125G Altcode: 1997ASPC..111..125G Calculated intensities of the Fe XVII X-ray lines in the 15 - 17 Å wavelength range are compared with measured line intensities in solar spectra. The intensity ratio of the Fe XVII 16.776 Å line to any one of several nearby Fe XVIII 2p5-2p43s transitions is suitable for determining temperature. Using this ratio, and comparing theory and observed solar spectra, excellent agreement is found for all the major Fe XVII and Fe XVIII features in this region, apart from the Fe XVII 15.015 Å line, which is resonance scattered in solar active region and flare spectra. The observed flux of this line is less than the theoretical value by a factor R2 which varies between 0.2 and 0.9. The relation of R2 to the heliographic position and shape of the emitting feature is examined. Title: Solar EUV Rocket Telescope and Spectrograph (SERTS) Observations of Fe XII Emission Lines Authors: Keenan, F. P.; Thomas, R. J.; Neupert, W. M.; Foster, V. J.; Greer, C. J.; Tayal, S. S. Bibcode: 1996aeu..conf..531K Altcode: 1996IAUCo.152..531K No abstract at ADS Title: Fe XIII Emission Lines Observed by EUVE and the S082A Instrument On-Board SKYLAB Authors: Keenan, F. P.; Drake, J. J.; Foster, V. J.; Greer, C. J.; Tayal, S. S.; Widing, K. C. Bibcode: 1996aeu..conf..525K Altcode: 1996IAUCo.152..525K No abstract at ADS Title: Cl XV and Cl XVI in the jet and COMPASS-D tokamaks. Authors: Coffey, I. H.; Barnsley, R.; Keenan, F. P.; Melnick, I.; McGinnity, P.; O'Mullane, M. G.; Peacock, N. J. Bibcode: 1996uxsa.conf..431C Altcode: 1996uxsa.coll..431C Studies of the soft X-ray emission spectrum of He-like Cl XVI and its associated Li-like Cl XV satellites from the JET (Joint European Torus) and COMPASS-D tokamaks are reported. Title: A differential abundance analysis of the early-type halo star PHL 346 Authors: Ryans, R. S. I.; Hambly, N. C.; Dufton, P. L.; Keenan, F. P. Bibcode: 1996MNRAS.278..132R Altcode: A differential abundance analysis is presented of the faint halo star PHL 346 with respect to gammaPegasus, based on high-resolution optical spectra. PHL 346 is found to have absolute abundances consistent with Population I values, and a differential analysis also shows no significant peculiarities. The evolutionary status and kinematics of PHL 346 are considered, and we conclude that while formation in the halo remains a likely origin, it is also possible that PHL 346 could have been ejected from the disc. Title: Helium-like sulfur emission in solar flares and laboratory plasmas. Authors: Harra-Murnion, L. K.; Phillips, K. J. H.; Lemen, J. R.; Zarro, D. M.; Greer, C. J.; Foster, V. J.; Barnsley, R.; Coffey, I. H.; Dubau, J. D.; Keenan, F. P.; Fludra, A.; Rachlew-Källne, E.; Watanabe, T.; Wilson, M. Bibcode: 1996uxsa.conf..417H Altcode: 1996uxsa.coll..417H Theoretical X-ray spectra of S XV derived from the General Relativistic Structure Package, the Dirac R-matrix code and other calculations are compared to laboratory spectra obtained from the Alcator C tokamak and JET, and solar flare spectra obtained from the Yohkoh Bragg Crystal Spectrometer (BCS) and with the SMM Flat Crystal Spectrometer. The spectra depend on electron temperature and, electron density for plasma densities greater than 1014cm-3. The fits of the derived synthetic spectra to the laboratory spectra at measured density and temperature are in fair agreement. Very good agreement can be achieved with the solar flare spectra, which are in general consistent with the S XV low-density limit, by adjusting temperature. Thus, S XV line spectra can be used to determine the temperatures of relatively weak flares for which diagnostics from higher-temperature ions are unavailable. Title: Excitation of boron-like ions by heavy particle impact. Authors: Foster, V. J.; Reid, R. H. G.; Keenan, F. P. Bibcode: 1996uxsa.conf..421F Altcode: 1996uxsa.coll..421F Cross sections and rate coefficients for the excitation of the 2s22p 2P1/2 - 2s22p 2P3/2 and 2s2p2 4PJ - 2s2p2 4PJ, transitions in boron-like ions by proton, deuteron, triton and α-particle impact have been calcualted suing the close-coupled impact parameter method, with a number of ions between C II and Pb LXXVIII being considered. Cross sections were calculated for a range of impact energies, with higher lying states being included by means of a polarization potential. There are major differences between the authors' results and previous calculations, due mainly to the emission of higher lying state in the latter. Excitation rate coefficients have been calculated from the cross sections for a wide range of temperatures. In this paper results are presented for a few of the ions considered. Title: Fine-structure population ratios for the 3P ground state of N II. Authors: McKenna, F. C.; Keenan, F. P.; Foster, V. J.; Jenkins, E. B.; Bell, K. L.; Stafford, R. P. Bibcode: 1996uxsa.conf..499M Altcode: 1996uxsa.coll..499M R-matrix calculations of electron impact excitation rates for the 2s22p2 3PJ - 2s22p2 3PJ, fine-structure transitions in N II are used to derive the electron density (ne) and temperature (Te) sensitive population ratios f1 = n(3P1)/n(3P) and f2 = n(3P2)/n(3P) for a range of ne and Te appropriate to H II regions. Title: Line Ratio Diagnostics Applicable to Astronomical Spectra in the 50-3000 Angstrom Wavelength Region Authors: Keenan, F. P. Bibcode: 1996aeu..conf..595K Altcode: 1996IAUCo.152..595K No abstract at ADS Title: SKYLAB Observations of Temperature and Density Sensitive Emission Line Ratios in NE VI Authors: Greer, C. J.; Foster, V. J.; Keenan, F. P.; Reid, R. H. G.; Doyle, J. G.; Zhang, H. L.; Pradhan, A. K. Bibcode: 1996aeu..conf..537G Altcode: 1996IAUCo.152..537G No abstract at ADS Title: Ar XVII and Ar XVIII in the JET tokamak. Authors: McGinnity, P.; Barnsley, R.; Coffey, I. H.; Keenan, F. P.; O'Mullane, M. G.; Peacock, N. J. Bibcode: 1996uxsa.conf..447M Altcode: 1996uxsa.coll..447M Observations of H-like Ar XVIII and He like Ar XVII and its associated Li-like satellite spectra have been made on the JET tokamak. G, α and β intensity ratios have been derived from recently calculated atomic data and, after extensive transport modelling to account for diffusive effects in the plasma, compared with measured values. The measured G-ratio disagrees with the calculated ratio and with a previously published ratio and some possible reasons are given. The α and β ratios show the expected temperature and density sensitivity respectively. Title: Extreme Ultraviolet Emission Lines of Fe XIII in Solar and Stellar Spectra Authors: Keenan, F. P.; Foster, V. J.; Drake, J. J.; Tayal, S. S.; Widing, K. G. Bibcode: 1995ApJ...453..906K Altcode: Recent R-matrix calculations of electron impact excitation rates for Fe XIII are used to derive the theoretical electron density sensitive emission line ratios R1 = I(3s23p2 1D-3s3p3 1D)/I(3s23p2 3P2-3s3p3 3P2) = I(318.12 Å)/I(320.80 Å) and R2 = I(3s23p2 1D-3s3p3 1P)/I(3s22p2 3P2-3s3p3 3S) = 1(256.42 Å)/I(251.95 Å), which are found to be up to 70% different from earlier diagnostics. A comparison of the current line ratios with both solar flare and active region observations, obtained by the Naval Research Laboratory's S082A spectrograph on board Skylab, reveals generally good agreement between densities deduced from Fe XIII and those estimated from diagnostic line ratios in species formed at similar temperatures, such as I(219.12 Å)/I(211.32 Å) in Fe XIV. This provides experimental support for the accuracy of the line ratio calculations, and hence the atomic data adopted in their derivation. In Extreme Ultraviolet Explorer satellite (EUVE) spectra the Fe XIII emission lines are found to be severely blended. However, an analysis of these lines measured in the spectra of Procyon and α Cen demonstrates that they still allow very approximate values of the electron density to be inferred. Moreover, it should be possible to increase the accuracy of the measured line fluxes, and hence of the inferred densities, if longer exposures of the stars concerned can be obtained. Title: The OV 1371.29A/1218.35A emission-line ratio in solar and stellar spectra Authors: Keenan, F. P.; Brekke, P.; Byrne, P. B.; Greer, C. J. Bibcode: 1995MNRAS.276..915K Altcode: New calculations of the theoretical electron-density-sensitive emission-line ratio R=I(2s2p ^1P-2p^2 ^1D)/I(2s^2 ^1S-2s2p ^3P_1)=I(1371.29A)/I(1218.35A) in OV are presented, which are significantly different from those deduced previously, principally due to the adoption of improved atomic data in the present analysis. Electron densities estimated from the current diagnostics, in conjunction with observed values of R measured from solar spectra obtained by the S082B spectrograph on board Skylab and by the High Resolution Telescope and Spectrograph (HRTS) on board a sounding rocket flight, are found to be in good agreement with densities determined from line ratios in species formed at similar electron temperatures to OV, such as OIV and NIV. These results provide experimental support for the accuracy of the diagnostic calculations presented in this paper, and hence the atomic data used in their derivation. The observed value of R for the M0Ve flare star AU Mic, determined from observations made by the Goddard High Resolution Spectrometer on board the Hubble Space Telescope, is within 4 per cent of the expected low-density limit, implying that logN_e<=10.4 for the OV emitting region of the AU Mic atmosphere. This is similar to density estimates made for AU Mic using other methods. Title: Emission Line Ratios for SI XI Applicable to CDS/SUMER Observations from SOHO Authors: Keenan, F. P.; Greer, C. J.; Foster, V. J.; Widing, K. G. Bibcode: 1995SoPh..161..159K Altcode: Calculations of electron temperature (Te) and density (Ne) sensitive line ratios in SiXI involving transitions in the ∼ 358-604 å wavelength range are presented. These are shown in the form of ratio-ratio diagrams, which should in principle allow bothNe andTe to be deduced for the SiXI line-emitting region of a plasma. However a comparison of these with observational data for two solar flares, obtained with the Naval Research Laboratory's S082A spectrograph on boardSkylab, reveals that the experimental ratios are much larger than expected from theory, which is probably due to the SiXI lines in the S082A spectra being blended with transitions from species including NeV, FeXI, and FeXII. Possible future applications of the SiXI results to spectral data from the Coronal Diagnostic Spectrometer on the Solar and Heliospheric Observatory are briefly discussed. Title: A Photometric and Spectroscopic Survey for Young Stars in the Halo of M31 Authors: Hambly, N. C.; Fitzsimmons, A.; Keenan, F. P.; Dufton, P. L.; Brown, P. J. F.; Irwin, M. J.; Rolleston, W. R. J. Bibcode: 1995ApJ...448..628H Altcode: We have obtained UBV CCD photometry of a 0.5 deg2 field toward the halo of M31 (the Andromeda Galaxy), using the 2.5 m Isaac Newton Telescope on La Palma. These observations have allowed us to identify nine blue stellar objects, with (U - B) < - 0.4 and (B - V) < 0.0, in the magnitude range B = 21.5-22.5, typical of main-sequence early B-type stars at the distance of Andromeda. Hence these objects may be normal Population I stars at large distances (>3 kpc) from the plane of M31. Follow-up low-resolution spectra of these objects obtained with the William Herschel Telescope, also on La Palma, do not have the requisite signal-to-noise ratios for a definitive conclusion regarding their nature, although one source appears to be a degenerate star in the halo of our Galaxy and has thus been eliminated from the candidate list. Positive identification of Balmer absorption features in the stellar spectra at the known radial velocity shift of the Andromeda system would provide very strong evidence for the general existence of normal B-type stars in the halos of spiral galaxies. Title: Theoretical emission line intensity ratios for NE ^44^Sc VI compared to EUV solar observations. Authors: Keenan, F. P.; Foster, V. J.; Reid, R. H. G.; Doyle, J. G.; Zhang, H. L.; Pradhan, A. K. Bibcode: 1995A&A...300..534K Altcode: Recent calculations of electron and proton impact excitation rates in Ne ^44^Sc VI are used to derive the intensity ratios of lines in the ~402-1006A wavelength range as a function of electron temperature (T_e_) and density (N_e_). These results are presented in the form of ratio-ratio diagrams, which should in principle allow both N_e_ and T_e_ to be deduced for the Ne ^44^Sc VI line emitting region of a plasma. Electron temperatures and densities derived from ratio-ratio diagrams involving the 562.7, 997.4, 999.6 and 1006.1A lines, in conjunction with observational data for a sunspot obtained with the Harvard S-055 spectrometer on board Skylab, are found to be compatible, and in good agreement with plasma parameters determined using other methods. This provides some support for the diagnostic calculations presented in this paper, and hence the atomic data used in their derivation. However agreement between theory and observation is very poor for other Ne ^44^Sc VI lines in the sunspot spectrum, and for most transitions observed in S-055 active region and flare data, which is probably due to blending with lines from N ^44^Sc III, Mg ^44^Sc VI and Mg ^44^Sc VII. Title: Observations of an intermediate velocity cloud in the direction of the globular cluster M13. Authors: Shaw, C. R.; Bates, B.; Kemp, S. N.; Keenan, F. P.; Davies, R. D.; Roger, R. S. Bibcode: 1995JRASC..89..178S Altcode: No abstract at ADS Title: A 325 Square Degree Survey of B-Type Stars at High Galactic Latitudes Authors: Little, J. E.; Dufton, P. L.; Keenan, F. P.; Hambly, N. C.; Conlon, E. S.; Brown, P. J. F.; Miller, L. Bibcode: 1995ApJ...447..783L Altcode: Final results from model atmosphere analyses of all blue stars in a ∼325 square degree region of the Galactic halo are presented. A kinematic analysis reveals the presence of one star which cannot have been ejected from the disk according to contemporary theories. Ten other objects have, however, evolutionary times consistent with classification as disk runaway stars. Our results therefore imply the existence of some 200 stars in the Galaxy unexplainable in terms of disk ejection models, and set a lower limit of 10,000 runaway halo B-type stars. Title: Properties of the High-Velocity Cloud Towards HD 203664 Authors: Keenan, Francis Bibcode: 1995hst..prop.5883K Altcode: 1995hst..prop.2356K We will obtain high- and intermediate-resolution GHRS spectra of the +70 km/sec HVC seen toward HD 203664 in optical and radio spectra. The observations will provide a unique opportunity to quantify the ionization structure of a HVC and accurately determine the chemical abundances of important elements such as C, N, O, Mg, Si, S, Cr, Mn, Fe, and Zn in high velocity interstellar material. Our high spectral resolution optical data suggest that substructure may exist within the HVC which, if confirmed, would support the possibility that early-type stars at large distances from the Galactic plane are formed through star formation induced by collisions between cloudlets within HVCs. We will test this hypothesis on the HD 203664 HVC with high S/N absorption line measurements made by the GHRS in its highest resolution mode. By combining a supporting set of optical and radio data with the ultraviolet observations, we will study the velocity structure of the HVC, morphology, distance, and physical conditions of this HVC in greater detail than has been possible for any other high velocity cloud in the sky. Title: The O IV and S IV Intercombination Lines in Solar and Stellar Ultraviolet Spectra Authors: Cook, J. W.; Keenan, F. P.; Dufton, P. L.; Kingston, A. E.; Pradhan, A. K.; Zhang, H. L.; Doyle, J. G.; Hayes, M. A. Bibcode: 1995ApJ...444..936C Altcode: New calculations of O IV electron density diagnostic emission-line ratios involving the 1399.8, 1401.2, 1404.8, and 14076.4 A transitions are presented. A comparison of these calculations with observational data from a quiet solar region, a sunspot, and an active region obtained with the High Resolution Telescope and Spectrograph (HRTS), two flares observed with the SO82B spectrograph on board Skylab, and Hubble Space Telescope (HST) observations by the Goddard High Resolution Spectrograph (GHRS) of Capella, gives good results using the ratio R1 = I(1407.4 A)/I(1401.2 A). However, the electron density obtained using the ratio R2 = I(1407.4 A)/I(1404.8 A) is often an order of magnitude smaller. The O IV 1404.8 A line is blended with the S IV 1404.8 A line, and we investigate whether this ratio may still be used as a density diagnostic if the S IV 1406.1 A line intensity is used to correct for the presence of S IV 1404.8 A, using previous S IV calculations by Dufton et al. We still find systematic differences compared to density determinations from line ratios that do not involve the O IV 1404.8 A line, which we suggest are due to errors in earlier theoretical calculations of the S IV atomic data, and also possibly to previously unconsidered fluorescent pumping of the upper level of the S IV 1404.8 A transition. Title: Optical and H i Observations of the Low-Velocity and Intermediate-Velocity Gas toward the Globular Cluster M13 Authors: Bates, B.; Shaw, C. R.; Kemp, S. N.; Keenan, F. P.; Davies, R. D. Bibcode: 1995ApJ...444..672B Altcode: High-resolution spectra of interstellar lines toward 11 stars in the globular cluster M13 and toward three foreground stars which lie within 3 deg from the cluster are reported. The optical spectra are compared with an H I profile of the gas recorded in the direction of the cluster. The principal interstellar components have LSR radial velocities centered near +10 km/s and -4km/s, but there is a considerable variation in the velocities and the column densities of both components across the face of the cluster. The positive velocity gas has a high Na I/H I column density ratio, and it lies beyond the foreground stars at a distance approximately greater than 200 pc; this gas may be associated with the receding part of the Hercules shell discussed in detail by Lilienthal et al. The negative velocity gas is detected toward the foreground stars, and the observed Na I/Ca II ratios suggest an association with gas at the approaching side of the Hercules shell. Gas at a velocity approximately equal -80 km/s has been previously reported in H I emission in the M13 direction and in UV spectra of the post-AGB cluster star, Barnard 29. This intermediate-velocity clouds in the lower halo. We discuss also evidence for the detection of this gas in Na I and show that it is most likely located at a distance. Title: Forbidden Lines of [O I] in the High-Resolution Optical Spectra of Planetary Nebulae Authors: Keenan, F. P.; Aller, L. H.; Hyung, S.; Brown, P. J. F. Bibcode: 1995PASP..107..148K Altcode: Electron impact excitation rates for transitions in O I, calculated with the R-matrix code, are used to derive the electron temperature sensitive emission line ratio R = I(2s^2p^4 1D - 2s^2 2p^4 1S)/I(2s^2 2p^4 3P_1,2 - 2x^2 2p^4 1D) = I(5577 A)/I(6300 + 6365 A), for a range of electron temperatures (T_e = 5000 - 20000 K) and d 2ensities (n_e = 10^4 - 10^6 cm^-3) applicable to planetary nebulae. Experimental values of R for a number of planetaries have been measured from high resolution (~0.6 A FWHM) spectra obtained with the Hamilton Echelle spectrograph on the 3 m telescope at the Lick Observatory. These measurements should be particularly reliable, as the sample of planetaries was restricted to those with large enough radial velocities for the nebular [O I] 5577 A emission to be red- or blue-shifted from the atmospheric airglow feature by a sufficient amount for the former to be reliably determined. Electron temperatures deduced from the observed values of R are generally in good agreement with those derived from T_e sensitive line ratios in other species, providing observational support for the accuracy of the atomic data adopted in the calculations. (SECTION: Interstellar Medium and Nebulae) Title: High-resolution optical observations of two early-type stars towards the high-velocity cloud Complex M Authors: Keenan, F. P.; Shaw, C. R.; Bates, B.; Dufton, P. L.; Kemp, S. N. Bibcode: 1995MNRAS.272..599K Altcode: High-resolution optical spectra of the early-type stars HD 93521 and BD +38 deg2182, which lie only 27 arcmin apart on the sky in the direction of the high-velocity cloud (HVC) Complex M, reveal the presence of weak HVC absorption in the Ca K line towards BD +38 deg2182, with a velocity of V_LSR=-96.0+/-1.5 km s^-1 and an equivalent width W_lambda=11+/-2 mA. However, the HVC is not detected either in the Na D line for BD +38 deg2182 or in the Ca K and Na D lines towards HD 93521. These observations, combined with revised stellar distance estimates, imply that the HVC is at a distance from the Galactic plane of 1.8<=z<=4.6 kpc. The Ca/H abundance in the HVC is found to be at least ~=2 per cent of the solar value, consistent with the material being returning condensations from a Galactic fountain flow. Title: N IV Emission Lines in the Ultraviolet Spectra of Gaseous Nebulae Authors: Keenan, F. P.; Ramsbottom, C. A.; Bell, K. L.; Berrington, K. A.; Hibbert, A.; Feibelman, W. A.; Blair, W. P. Bibcode: 1995ApJ...438..500K Altcode: Theoretical electron density sensitive emission-line ratios, determined using electron impact excitation rates calculated with the R-matrix code, are presented for R = I(2s2 (1)S-2s2p 3P2)/I(2s2 (1)S-2s2p 3P1 = 1(1483 A)/I(1486 A) in N IV. These are found to be up to an order of magnitude different from those deduced by previous authors, principally due to the inclusion of excitation rates for transitions among the 2s2p (3)p fine-structure levels. The observed values of R for several planetary nebulae, symbiotic stars and the Cygnus Loop supernova remnant, measured from spectra obtained with the International Ultraviolet Explorer (IUE) satellite and the Hopkins Ultraviolet Explorer (HUT), lead to electron densities which are in excellent agreement with those deduced from line ratios in other species. This provides observational support for the accuracy of the atomic data adopted in the present calculations. Title: Observations of a possible companion to the high-latitude B-type star PG 0832+676. Authors: Hambly, N. C.; Keenan, F. P.; Dufton, P. L.; Brown, P. J. F.; Irwin, M. J.; Fitzsimmons, A. Bibcode: 1994MNRAS.271..729H Altcode: We present photometric and spectroscopic observations of a faint star 4 arcsec away from the apparently normal, young early B-type star PG 0832+676, which was previously identified as being approximately 18 kpc above the Galactic plane. The differential radial velocity of the two is found to be consistent with zero within the measurement errors, suggesting physical association; however, the other available evidence implies that the companion is a low-luminosity, metal-deficient early G-type star. The implications of these data for the evolutionary status and Galactic z-distance of PG 0832+676 are discussed, and we conclude that this is a chance alignment of two unrelated objects. Key words: stars: early-type - stars: individual: PG 0832+676. Title: Book-Review - Hot Stars in the Galactic Halo Authors: Adelman, S. J.; Upgren, A. R.; Adelman, C. J.; Keenan, F. P. Bibcode: 1994Ap&SS.222..269A Altcode: No abstract at ADS Title: Book reviews Authors: Burgess, D.; Kahn, F. D.; Dyson, John; Roche, Patrick; Priest, E. R.; Budding, Edwin; Keenan, F. P. Bibcode: 1994Ap&SS.222..263B Altcode: No abstract at ADS Title: Cross Sections and Excitation Rate Coefficients for the 2s22p52P3/2-2s22p52P1/2 Transition in Fluorine-Like Ions by p,d,t and α Impact Authors: Foster, V. J.; Keenan, F. P.; Reid, R. H. G. Bibcode: 1994ADNDT..58..227F Altcode: Cross sections and rate coefficients for excitation of the 2s22p52P3/2-2s22p52P1/2 transition in fluorine-like ions by proton, deuteron, triton, and α-particle impact have been calculated using the close-coupled impact parameter method. The ions considered are Ne II, S VIII, Ti XIV, Ni XX, Zn XXII, Ge XXIV, Se XXVI, Kr XXVIII, Mo XXXIV, Ag XXXIX, and Pb LXXIV. Cross sections were calculated for a range of impact energies, and the 2s2p62S State was included by means of a polarization potential. Excitation rate coefficients have been calculated from the cross sections for a wide range of temperatures. Title: Optical observations of the hot post-asymptotic giant branch star, HD 177566. Authors: Kendall, T. R.; Brown, P. J. F.; Conlon, E. S.; Dufton, P. L.; Keenan, F. P. Bibcode: 1994A&A...291..851K Altcode: An LTE model atmosphere analysis of optical and ultra-violet spectra is presented for a hot high galactic latitude star, HD 177566, previously identified as a post-asymptotic giant branch candidate from its ultra-violet spectrum. The derived atmospheric parameters and chemical composition confirm that HD 177566 is a low mass (M=~0.55Msun_) post-AGB star; a general heavy element underabundance of approximately -1.3 dex is found. The possibility that it is the central star of a young, compact planetary nebula is briefly discussed. Title: CA X Line Ratios in Solar Flares Authors: Keenan, F. P.; Foster, V. J.; Roche, I. J.; Mohan, M.; Widing, K. G. Bibcode: 1994SoPh..154..309K Altcode: Theoretical Ca X electron temperature sensitive emission line ratios, derived using electron excitation rates interpolated from accurateR-matrix calculations, are presented forR1 =I(419.74 å)/I(574.02 å,),R2 =I(411.65 å)/I(574.02 å),R3 =I(419.74 å)/I(557.75 å), andR4 =I(411.65 å)/I(557.75 å). A comparison of these with observational data for three solar flares, obtained by the Naval Research Laboratory's S082A slitless spectrograph on boardSkylab, reveals good agreement between theory and observation forR1 andR3 in one event, which provides limited support for the accuracy of the atomic data adopted in the analysis. However, in the other flares the observed values ofR1 -R4 are much larger than the theoretical high-temperature limits, which is probably due to blending of the 419.74 å line with CIV 419.71 å, and 411.65 å with possibly CIII 411.70 å. Title: Relative Emission-Line Strengths for the 146 and 63 Micron Transitions in O i and a Comparison with Far-Infrared Observations of Photodissociation Regions Authors: Keenan, F. P.; Conlon, E. S.; Rubin, R. H. Bibcode: 1994ApJ...434..811K Altcode: Theoretical O I density-sensitive emission-line ratios R = I(2s2)(2p4)(3P0)-((2s2)(2p4)(3P1))/I((2s2)(2p4)(3P1)-(2s2)(2p4)(3P2)) = I(146 micrometers)/I(63 micrometers) are presented for a range of temperatures (T = 100-10,000 K), neutral hydrogen densities (NH = 10-2 to 107/cu cm) and radiation fields (G0 = 1-106) applicable to both photodissociation regions (PDRs) and H II regions and the diffuse ionized medium (DIM). The observed values of R for several PDRs, measured from far-infrared spectra obtained with the Kuiper Airborne Observatory (KAO), imply hydrogen densities which are in good agreement with those determined using other methods. This provides observational support for the validity of the theoretical O I line ratios, and hence the atomic data used in their derivation. Title: Abundance analysis of the hot post-AGB star Barnard 29. Authors: Conlon, E. S.; Dufton, P. L.; Keenan, F. P. Bibcode: 1994A&A...290..897C Altcode: We present a model atmosphere analysis for the relatively bright (V~13) globular cluster post-AGB star, Barnard 29, using IUE and high resolution (0.06A FWHM) optical spectra. The derived atmospheric parameters are T_eff_=20000+/-1000K and logg=3.0+/-0.1dex, which imply a current mass of ~0.55Msun_. The chemical composition provides important constraints on the post-AGB evolutionary stage. We find an overall metal deficiency of 1.46+/-0.11dex, which is compatible with the mean [Fe/H] obtained from previous M13 studies. The most interesting feature is the severe carbon deficiency of more than 2.0dex which has also been observed in a number of high latitude B-type low gravity stars. Hence the present results supports the recent classification of these objects as hot post-AGB stars. Relative to the overall metallicity, the observed carbon deficiency of Barnard 29 coupled with a significant nitrogen overabundance indicates that this star has left the AGB before the third dredge-up has occurred. The implications for AGB and post-AGB evolution are briefly discussed. Title: Optical and UV spectroscopy towards stars in the direction of the Cohen high-velocity H I stream. Authors: Kemp, S. N.; Bates, B.; Dufton, P. L.; Keenan, F. P.; Montgomery, A. S. Bibcode: 1994MNRAS.270..597K Altcode: We present high-resolution, high signal-to-noise ratio optical spectra and UV spectra obtained with lUE for several stars that lie within and adjacent to the Cohen high- velocity (Hv) stream, which is considered by Cohen to lie within 300 pc. From spectral classifications, published photometry and LTE model atmosphere analysis of our stellar spectra, the programme stars are shown to lie at distances from 50 to at least 600 pc. On the basis of the H I column densities for the HV stream, it is expected that gas at corresponding velocity should be observed in Na I and Ca ii in our high- quality spectra, but no such detections are made. Low-velocity (LV) filament gas, which is spatially coincident with the Hv stream in the directions studied, is detected, and is shown to lie within 160 pc. The observations suggest that the HV stream lies beyond our programme stars. Alternatively, if the stream is closer and lies at a similar distance to the LV filament, then possible explanations for the non-detection are (i) the HV gas is depleted in the species observed (for example, for Ca lithe depletion would be significantly greater than the average Ca ii depletion observed for HVCs), (ii) the Na and Ca in the gas is mostly in the form of Na ii and Ca iii, and (iii) the gas is very clumpy on a fine scale. In the last context, our observations of the LV filament also indicate a clumpy distribution for this gas. Key words: stars: distances - ISM: clouds - ISM: structure - radio lines: ISM - ultraviolet: ISM. Title: Ultraviolet FeIII lines in the spectra of high galactic latitude early-type stars Authors: Kendall, T. R.; Conlon, E. S.; Dufton, P. L.; Keenan, F. P. Bibcode: 1994A&A...290..563K Altcode: Using high resolution spectral data from the International Ultraviolet Explorer satellite, we present qualitative and quantitative comparisons of blends of Fe III absorption lines in the region 1890A<=λ<=1930A for a sample of fifteen high latitude B-type and standard stars. Standard and halo stars were matched in effective temperature and surface gravity using Stroemgren [c_1_] and Hβ photometry, and LTE model atmosphere codes were used to investigate whether they had similar iron abundances. We conclude that while most of the halo stars have Population I iron abundances and may be young objects, one star, HD 177566, has significant iron and silicon depletions and is most probably an old, evolved star. In view of the coincidence of the atmospheric parameters of this star with those of young B-type stars, we consider a post-AGB evolutionary status to be likely for HD 177566. Title: The Determination of Electron Densities in the Solar Atmosphere from the 1718.56 Angstrom /1486.51 Angstrom Emission-Line Ratio in N IV Authors: Keenan, F. P.; Harra, L. K.; Doschek, G. A.; Cook, J. W. Bibcode: 1994ApJ...432..806K Altcode: The theoretical electron density sensitive emission-line ratio R = I(1718.56 a)/I(1486.51 A) in N IV is presented for a range of Ne(approximately equals 1010 - 1012/cu cm) applicable to higher density solar plasmas, such as active regions. A comparison of these calculations with the observed values of R of several solar features obtained with the Naval Research Laboratory's S082B spectrograph on board Skylab reveals general agreement between theory and observation at pointings just above the limb, where line blends with N IV 1718.56 A should be insignificant, which provides experimental support for the accuracy of the line ratio calculations. Title: The distance to HVC complex M. Authors: Shaw, C. R.; Keenan, F. P.; Bates, B.; Dufton, P. L. Bibcode: 1994IEEES...3....8S Altcode: No abstract at ADS Title: Fe XVI Line Ratios in the Sun Authors: Keenan, F. P.; Conlon, E. S.; Foster, V. J.; Tayal, S. S.; Widing, K. G. Bibcode: 1994ApJ...432..809K Altcode: Recent R-matrix calculations of electron impact excitation rates in Fe XVI are used to derive the emission-line ratios R1 = I(251.07 A)/I(335.40 A), R2 = I(262.98 A)/I(335.40 A), and R3 = I(265.00 A)/I(335.40 A). A comparison of these with solar observational data obtained by the Naval Research Laboratory's S082A slitless spectrograph on board Skylab reveals generally good agreement between theory and observation, which provides experimental support for the accuracy of the atomic data adopted in the analysis. However, several of the measured ratios are much larger than theory predicts, which is probably due to saturation of the strong 335.40 A line on the photographic film used to record the S082A data. The potential usefulness of R1, R2, and R3 as electron temperature diagnostics for the solar corona is briefly discussed. Title: Book Review: Luminous high-latitude stars / Astronomical Society of the Pacific, 1993 Authors: Keenan, F. Bibcode: 1994Obs...114..182K Altcode: 1994Obs...114..182S No abstract at ADS Title: Coronal Electron Density Diagnostic from Fe XII Authors: Cook, J. W.; Keenan, F. P.; Harra, L. K.; Tayal, S. S. Bibcode: 1994ApJ...429..924C Altcode: We present observations of the forbidden coronal lines Fe XII 1242 A and 1349 A from active regions and from two flares, obtained by the SO82B slit spectrograph onboard Skylab. The line intensity ratio R = I(1242 A)/I(1349 A) is sensitive to electron density. We have calculated this ratio using recent atomic data, and obtained coronal electron densities at T = 1.5 x 106 K for our observations. We find a range in Ne of (0.5 to 7.2) x 109/cm-3 for active regions, which is in good agreement with previous results from other diagnostic ratios in this temperature range, and of approximately (0.9 to 12) x 109/cm-3 (or higher) for flares, which is generally low compared to previous flare results. The flare values employ particularly weak 1349 A observations and may not be reliable. From an observation of an active region just inside the solar limb, giving the best coverage in our data of both line profiles, we find a line width (FWHM) for both lines of 0.20 A, which corresponds to a nonthermal velocity of 18 km/sec. Title: High-resolution spectroscopy of two young stars between the Magellanic Clouds Authors: Hambly, N. C.; Dufton, P. L.; Keenan, F. P.; Rolleston, W. R. J.; Howarth, I. D.; Irwin, M. J. Bibcode: 1994A&A...285..716H Altcode: High-resolution echelle spectra of one main sequence B-type star and one B-type supergiant in the Bridge between the Magellanic Clouds have been obtained using the 3.9-m Anglo-Australian Telescope. These spectra have been analyzed in conjunction with IUE low-resolution observations by using ATLAS9 LTE model atmosphere techniques, to derive the stellar atmospheric parameters and photospheric chemical compositions; the latter should reflect that of the current interstellar medium within the Bridge. From a differential analysis performed relative to the Galactic B-type stars τ Sco and 67 Oph, the stars appear to have a mild helium deficiency of 0.1-0.2 dex, and a general heavy element depletion of at least -0.5 dex for one star, and as much as -1.0 dex for the other. These chemical compositions thus reflect those of SMC rather than LMC stars while the evolutionary status of these objects implies significant star formation is currently underway in the region. Title: SI XIII Emission Lines in Solar Flare X-Ray Spectra Obtained with the P78-1 Satellite Authors: Keenan, F. P.; McKenzie, D. L.; Phillips, K. J. H.; Conlon, E. S. Bibcode: 1994ApJ...426..454K Altcode: 1994STIN...9529279K Theoretical Si XIII electron-temperature-sensitive emission-line ratios, which include satellite-line contributions to the intensities of the forbidden (f) (1s2)(1S) goes to (1s2s)(3S), intercombination (i) (1s2(1S) goes to (1s2p)(3P1,2), and resonance (r) (1s2)(1S) goes to (1s2p)(1P) transitions, are presented for G = (I(f) + I(r), R = I(f)/I(i), R1 = I((1s2)(1S) goes to (1s3p)(1P))/I(r). These ratios are significantly different from those calculated assuming that satellites do not contribute to f, i, and r, and, in addition, are more temperature-sensitive over the range log Te = 6.4-7.4. Electron temperatures deduced using the new diagnostics in conjunction with observed values of G, R1, and R2 from solar-flare spectra obtained by the SOLEX spectrometers aboard the P78-1 satellite are found to be generally consistent. This provides support for the validity of the theoretical R1 and R2 diagnostics and also resolves discrepancies noted previously when the line ratios were compared with observations from the Solar Maximum Mission spectrometers. The R ratio, which is in the low-density limit under solar flare conditions, is found not to be a useful Te diagnostic when satellite contributions to f and i are included in the theoretical line ratios. However, the observed values of R from the SOLEX spectra are in good agreement with theoretical predictions, which provides additional support for the accuracy of the line-ratio calculations. Title: Optical and H i Observations of High-Velocity Gas toward HD 203664 Authors: Little, J. E.; Dufton, P. L.; Keenan, F. P.; Conlon, E. S.; Davies, R. D. Bibcode: 1994ApJ...427..267L Altcode: High-resolution optical stellar and interstellar observations toward the halo star HD 203664 and six surrounding early-type stars have been combined with a 21 cm mapping of the region to investigate a 70 km s-1 between 200 and 1500 pc; upper limits to temperature and velocity dispersion of 4600 K and 2.2 km s-1 have been estimated; and a column density ratio N(Na II)/N (Ca II) approx. equal to 0.32 has been deduced. These parameters are consistent with the material being shocked gas, possibly arising from an old supernova remnant. The N(Na I)/N(H I) and N(Ca II)/N(H I) ratios are anomalously large by factors of approximately 20 and 100, respectively, with respect to normal diffuse gas; several scenarios are presented as possible explanations of this phenomenon. Title: The Fe XIV Spectrum: Predicted Line Intensities and Solar Identifications Authors: Bhatia, A. K.; Kastner, S. O.; Keenan, F. P.; Conlon, E. S.; Widing, K. G. Bibcode: 1994ApJ...427..497B Altcode: Level populations and line intensities have been calculated in a 40-level model of Fe XIV which includes the configuations 3p3 and 3s3p3d. The results have been compared against intensities of weaker, unidentified, or tentatively classified lines in published solar line lists including a recent Goddard Space Flight Center/Solar Extreme Ultraviolet Telescope and Spectrograph (GSFC/SERTS) high-resolution list, and in presently measured archival Naval Research Laboratory (NRL)/S082A active region spectra. Seven new lines are identified as Fe XIV transitions; five other observed, unidentified lines are considered to be Fe XIV transitions on the basis of wavelength coincidence, but require further observations to obtain photometric intensities for verification; one line at 216.93 A is shown to be due to some other ion than Fe XIV. In addition, a unique forbidden infrared (approx. equal to 1.25 micrometer(s)) line originating in the high metastable level 3s3p3d(F9/2-4) is found to have an unusual intensity dependence on electron density. Title: Heavy-particle excitation of fluorinelike Fe xviii Authors: Foster, V. J.; Keenan, F. P.; Reid, R. H. G. Bibcode: 1994PhRvA..49.3092F Altcode: Cross sections and rate coefficients for excitation of the 2s22p5 2P3/2-2s22p5 2P1/2 transition in fluorinelike Fe xviii by proton (p), deuteron (d), triton (t), and α-particle (α) impact have been calculated using the close-coupled impact-parameter method. These data, in conjunction with R-matrix calculations of electron-impact excitation rates, are used to derive the theoretical emission line ratio R=I(2s22p5 2P3/2-2s22p5 2P1/2)/I(2s22p5 2P3/2-2s2p6 2S1/2)=I(974.8 Å)/I(93.4 Å) as a function of electron and heavy-particle number density, and electron and ion temperature, for values applicable to tokamak plasmas. A comparison of our results with observations of R from the JIPP T-II-U tokamak at the Institute of Plasma Physics, Nagoya, Japan, for which the plasma parameters have been independently determined, reveals excellent agreement between theory and experiment, with discrepancies of typically <=10%. This provides observational support for the accuracy of the atomic data adopted in the line ratio calculations. Title: The Allowed Lines of O IV near 1340 Angstrom in High Electron Density Solar Flares Authors: Cook, J. W.; Keenan, F. P.; Bhatia, A. K. Bibcode: 1994ApJ...425..861C Altcode: Intersystem lines of O IV near 1400 A have long been used as electron density diagnostics for solar plasmas at temperatures of around 160,000 K. In addition, however, several allowed lines of O IV near 1340 A should become visible in conditions of high plasma electron number density (greater than 1012/cu cm), such as during a solar flare. We present observations of the 1340 A and 1400 A regions of the solar spectrum for two solar flares, obtained by the SO82B spectrograph on board Skylab. We examine three candidate lines for allowed O IV in the flare spectra which occur at the correct wavelengths, but show that two of these are actually blends dominated by resonantly excited molecular lines of H2. The third candidate line, at 1343.51 A, we identify as the O IV allowd line. We present the density and temperature sensitivity of the ratio of allowed and intersystem O IV lines R = I(1343.51 A)/I(1407.39 A). The 1343.51 A line is clearly present in the first solar flare spectrum, and the ratio value implies an electron density of log Ne = 12.6. The second flare has a much weaker 1343.51 A profile, but again the ratio value implies a high electron density. Both these electron density values are in good agreement with estimates for each flare from independent diagnostic ratios. The simple presence alone of a clearly observed O IV 1343.51 A emission line implies an electron density greater than 1012/cu cm. Title: A Search for Beta-Cephei Type Variability in a Sample of Intermediate Galactic Latitude to High Galactic Latitude B-Type Stars Authors: Hambly, N. C.; Kilkenny, D.; Keenan, F. P.; van Wyk, F.; Marang, F.; Roberts, G.; Dufton, P. L. Bibcode: 1994MNRAS.267.1103H Altcode: We have photometrically monitored nine intermediate- to high-Galactic-latitude B-type stars for β Cephei-type variability. One star, HD 204076, shows a clearly sinusoidal variation with an amplitude of 0.015 mag and a period of a few hours, typical of β Cephei stars. One other (HD 206144) is possibly a longer term variable at the 2 per cent level, while two objects, HD 219188 and HD 118246, may be variable at a smaller amplitude of < 0.0t mag. The remaining five stars show no signs of any periodic changes above 0.0t mag and are therefore unlikely to belong to the β Cephei class of variable. Title: Theoretical Emission Line Strengths for OV Compared to Extreme Ultraviolet Solar Observations Authors: Keenan, F. P.; Warren, G. A.; Doyle, J. G.; Berrington, K. A.; Kingston, A. E. Bibcode: 1994SoPh..150...61K Altcode: Recent R-matrix calculations of electron impact excitation rates in OV are used to derive the emission line intensity ratios (in energy units) R1 = I(2s2p3P - 2p23P)/I(2s21S0 - 2s2p1P1 = I(761.1 A)/I(629.7 A), R2 = I(2s21S0 - 2s2p3P1/I(2s21S0 - 2s2p1P1 = I(1218.4 A)/I(629.7 A), and R3 = I(2s2p1)P1 - 2p21S0/I(2s21S0 - 2s2p1P1) = I(774.5 A)/I(629.7 A) as a function of electron temperature (Te) and density (Ne). These results are presented as plots of R1 vsR2, andR1 vsR3, which should allowboth Ne andTe to be deduced for the OV line emitting region of a plasma. Electron densities derived from the (R1,R2) and (R1,R3) diagrams in conjunction with observational data for several solar features obtained with the Harvard S-055 spectrometer on boardSkylab are found to be compatible, and in good agreement with values ofNe estimated from line ratios in species formed at similar electron temperatures to OV. In addition, values ofTe determined from (R1,R2) and (R1,R3) are generally close to that expected theoretically. These results provide experimental support for the accuracy of the diagnostic calculations presented in this paper, and hence the atomic data used in their derivation. Title: N III Intercombination Lines in the IUE Spectra of Gaseous Nebulae Authors: Keenan, F. P.; Dufton, P. L.; Feibelman, W. A.; Bell, K. L.; Hibbert, A.; Stafford, R. P. Bibcode: 1994ApJ...423..882K Altcode: Theoretical N III electron density-sensitive emission-line ratios involving intercombination transitions, derived using recent calculations of electron impact excitation rates and oscillator strengths, are presented for R1 = I(1754.0 Å)/I(1749.7 Å), R2 = I(1752.2 Å)/I(1749.7 Å), R3 = I(1748.6 Å)/I(1749.7 Å), and R4 = I(1746.8 Å)/I(1749.7 Å). The observed values of R1, R2, and R3 for several gaseous nebulae, measured from high-resolution spectra obtained with the International Ultraviolet Explorer (IUE) satellite, imply electron densities that are compatible. However, values of Ne derived from the R4 ratio are up to several orders of magnitude smaller than those deduced from R1, R2, and R3, which is probably due to the N III 1746.8 Å line being blended with Fe II 1746.8 Å. The electron densities deduced from the N III diagnostics are, in some objects, much larger than those estimated from line ratios in nebular ions such as O III, but are in good agreement with values deduced from the chromospheric C II intercombination transitions at ∼2325 Å. These results suggest that in these nebulae the N III emission may also be chromospheric in origin. Title: Mgix Emission Lines in an Active Region Spectrum Obtained with the Solar Extreme Ultraviolet Rocket Telescope and Spectrograph / SERTS Authors: Keenan, F. P.; Conlon, E. S.; Thomas, R. J.; Neupert, W. M. Bibcode: 1994SoPh..149..301K Altcode: Theoretical electron-temperature-sensitive MgIX emission line ratios are presented forRI =I(443.96 å)/I(368.06 å),R2 =I(439.17 å)/I(368.06 å),R3 =I(443.37 å)/I(368.06 å),R4 =I(441.22 å)/I(368.06 å), andR5 =I(448.28 å)/I(368.06 å). A comparison of these with observational data for a solar active region, obtained during a rocket flight by the Solar EUV Rocket Telescope and Spectrograph (SERTS), reveals excellent agreement between theory and observation forR1 throughR4, with discrepancies that average only 9%. This provides experimental support for the accuracy of the atomic data adopted in the line ratio calculations, and also resolves discrepancies found previously when the theoretical results were compared with solar data from the S082A instrument on boardSkylab. However in the case ofR5, the theoretical and observed ratios differ by almost a factor of 2. This may be due to the measured intensity of the 448.28 å line being seriously affected by instrumental effects, as it lies very close to the long wavelength edge of the SERTS spectral coverage (235.46−448.76 å). Title: NE VI Line Ratios in the Sun Authors: Keenan, F. P.; Conlon, E. S.; Warren, G. A.; Pradhan, A. K.; Zhang, H. L.; Sampson, D. H.; Widing, K. G. Bibcode: 1994ApJ...421..851K Altcode: Recent calculations of electron impact excitation rates for Ne VI are used to derive theoretical electron density sensitive emission line ratios involving transitions in the wavelength range 399-563 A. Electron densities deduced from the observed line ratios for solar flares, obtained with the Naval Research Laboratory's SO82A slitless spectrograph on-board Skylab, are in excellent internal agreement and, furthermore, compare favorably with densities estimated from line ratios in O V and Ne VII, which are formed at similar electron temperatures to Ne VI. These results provide experimental support for the accuracy of the atomic data adopted in the analysis. Title: Emission Line Ratios for Fexxi Applicable to the Extreme Ultraviolet Spectra of Solar Flares Authors: Keenan, F. P.; Conlon, E. S.; Warren, G. A.; Aggarwal, K. M. Bibcode: 1994SoPh..149..129K Altcode: Electron impact excitation rates for FeXXI, calculated with theR-matrix code, are used to determine theoretical electron density sensitive emission line ratios involving transitions in the 121-146 å wavelength range. The observed ratios for a solar flare, obtained with a grazing spectrometer on board the OSO-5 satellite, imply electron densities which are consistent, with discrepancies that do not exceed 0.3 dex. In addition, the derived values ofNe are similar to those estimated for the high temperature regions of other solar flares. This provides experimental support for the accuracy of the atomic data adopted in the line ratio calculations. Title: Alix Emission Line Ratios in Solar Flares Observed with the S:082A Spectrograph on Board SKYLAB Authors: Keenan, F. P.; Conlon, E. S.; Bowden, D. A.; Dwidvedi, B. N.; Widing, K. G. Bibcode: 1994SoPh..149..137K Altcode: Theoretical electron-density-sensitive emission line ratios in B-like AIIX are presented forR =I(385.01 å)/I(392.42 å). A comparison of these with high spectral resolution solar flare data, obtained with the S082A slitless spectrograph on boardSkylab, reveals agreement between theory and observation for those spectra that were observed during the later stages of the flares. These results provide experimental support for the accuracy of the line-ratio calculations, and also resolves discrepancies found previously when the theoretical results were compared with solar observations from the S-055 instrument on boardSkylab. However, the agreement between theory and observation for a spectrum obtained during the early stages of a flare is very poor, which probably indicates that the 392.42 å line is blended with a transition arising from a species formed at a very high electron temperature. Title: UBV CCD Photometry of the Halo of M31 Authors: Fitzsimmons, A. P.; Keenan, F. P.; Dufton, P. L.; Little, J. E.; Irwin, M. J. Bibcode: 1994hsgh.conf..326F Altcode: No abstract at ADS Title: Interstellar Detection of the Intersystem Line SI ii] lambda 2335 toward zeta Ophiuchi Authors: Cardelli, Jason A.; Sofia, Ulysses J.; Savage, Blair D.; Keenan, Francis P.; Dufton, Philip L. Bibcode: 1994ApJ...420L..29C Altcode: We report on the detection of the weak intersystem transistion of Si II lambda 2335 A in the sight line toward zeta Oph using the Ech-B mode (3.5 km/s resolution) of the Goddard High Resolution Spectrograph. The high-quality spectrum is characterized by an empirically measured signal-to-noise of 450, in excellent agreement with that expected from photon-statistics. The measured equivalent width of the Si II line is Wlambda = 0.48 +/- 0.12 mA. Using the new experimental f-value of Calamai, Smith, and Bergeson, we find a Si II column density of 2.34 (+/- 0.58) x 1015 atoms/sq cm and (Si/H)zeta Oph = 1.78 (+/- 0.44) x 10-6 for the principal absorbing component(s) at vsun approx. = -15 km/s. Analysis of the Si II lambda 1808 absorption over the same velocity range using the new experimental f-value of Bergeson & Lawler yields a column density (corrected for saturation) that is consistent within the weak line errors and confirms the relative accuracies of these new f-values. Furthermore, these results indicate that accurate abundances can now be derived for Si II, particularly from the weak Si II lambda 2335 A since it is free of saturation effects. For the zeta Oph vsun approx. = -15 km/s component(s), we find that greater than 95% of the available cosmic abundance (i.e. the 1989 meteoritic abundances of Anders & Grevesse) of Mg, Fe, and Si is 'missing' from the gas phase and is presumably locked up in the dust. These elements are present in the dust grains in ratios of Fe/Si approximately equals 0.9 and Mg/Si approximately equals 1.1, consistent with the ratio of their cosmic abundances. These ratios are in sharp contrast to more diffuse clouds like those seen toward the high-latitude halo star HD 93521 where in the dust Fe/Si approximately equals 1.8 and Mg/Si approximately equals 2.1. Title: Theoretical Line Ratios for Carbon Like Ar XIII and a Comparison with XUV Observations of Solar Flares Authors: Foster, V. J.; Keenan, F. P.; Conlon, E. S.; Aggarwal, K. M.; Widing, K. G. Bibcode: 1994emsp.conf...73F Altcode: No abstract at ADS Title: A 300 Square Degree Survey of Young Stars at High Galactic Latitudes Authors: Eamon Little, J.; Dufton, P. L.; Keenan, F. P.; Hambly, N. C.; Conlon, E. S.; Miller, L. Bibcode: 1994hsgh.conf...79E Altcode: No abstract at ADS Title: Calculated He-Like Argon Line Intensities and Comparison with Solar Flare Spectra from the FCS Instrument on the Solar Maximum Mission Authors: Harra, L. K.; Phillips, K. J. H.; Keenan, F. P.; Zarro, D. M.; Wilson, M. Bibcode: 1994emsp.conf...77H Altcode: No abstract at ADS Title: The Allowed Lines of O IV Near 1340 Angstroms in High Electron Density Solar Flares Authors: Cook, J. W.; Keenan, F. P.; Bhatia, A. K. Bibcode: 1993AAS...183.6805C Altcode: 1993BAAS...25.1396C Intersystem lines of O IV near 1400 Angstroms have long been used as electron density diagnostics for solar plasmas at temperatures of around 160,000 K. In addition, however, several allowed lines of O IV near 1340 Angstroms should become visible in conditions of high plasma electron number density (Ne > 10(12) cm(-3) ), such as during a solar flare. We present observations of the 1340 Angstroms and 1400 Angstroms regions of the solar spectrum for two solar flares, obtained by the S082B spectrograph on board Skylab. We examine three candidate lines for allowed O IV in the flare spectra which occur at the correct wavelengths, but show that two of these are actually blends dominated by resonantly excited molecular lines of H2. The third candidate line, at 1343.51 Angstroms, we identify as the O IV allowed line. We present the density and temperature sensitivity of the ratio of allowed and intersystem O IV lines R = I(1343.51 Angstroms)/I(1407.39 Angstroms). The 1343.51 Angstroms line is clearly present in the first solar flare spectrum, and the ratio value implies an electron density of log Ne = 12.6. The second flare has a much weaker 1343.51 Angstroms profile, but again the ratio value implies a high electron density. Both these electron density values are in good agreement with estimates for each flare from independent diagnostic ratios. The simple presence alone of a clearly observed O IV 1343.51 Angstroms emission line implies an electron density greater than 10(12) cm(-3) . Title: Helium-like Argon Line Emission in Solar Flares Authors: Phillips, K. J. H.; Harra, L. K.; Keenan, F. P.; Zarro, D. M.; Wilson, M. Bibcode: 1993ApJ...419..426P Altcode: Theoretical X-ray spectra of Ar XVII lines and Ar XVI satellites at ∼4 Å, derived from R-matrix code and other calculations, are compared with solar-flare observations obtained with the SMM Flat Crystal Spectrometer. There is good agreement between the observed line features and those in the theoretical spectra, and the comparison leads to best-fit values of electron temperature for the observed solar flares. We present wavelengths for the Ar XVII and some Ar XVI lines, measured from the observed spectra, which have better precision than previous values. In addition, the coronal Ar/S abundance is determined from the relative intensities of Ar XVII lines to those of nearby S XV transitions, and the value of this ratio is discussed in the light of previous work. Title: Model Atmosphere and Kinematical Analyses of Early-Type, High Galactic Latitude Stellar Candidates from the UKST UBVRI Survey Authors: Hambly, N. C.; Conlon, E. S.; Dufton, P. L.; Keenan, F. P.; Little, J. E.; Miller, L. Bibcode: 1993ApJ...417..706H Altcode: From the UKST UBVRI survey, six high Galactic latitude stars have been previously identified which may be young hydrogen-burning objects. Using high-dispersion optical spectra, model atmosphere analyses are presented for these targets. Two have normal or nearly normal Population I chemical compositions, one appears to be subluminous while the remaining three are possibly normal late B-type stars. A kinematic analysis indicates that one star having normal parameters is an excellent candidate for formation in the halo, having an evolutionary age an order of magnitude less than the time required for it to attain its current position following ejection from the Galactic disk. A preliminary analysis implies that there may currently be a few thousand normal B-type stars in the Galactic halo with z-distances from the plane of the Galaxy in the range 3 < Ζ < 22 kpc. Title: The nature of the high latitude B-type binary, SU Piscium. Authors: Dufton, P. L.; Holmgren, D.; Conlon, E. S.; Keenan, F. P. Bibcode: 1993A&A...278...68D Altcode: A spectroscopic orbit is presented for the early-type eclipsing binary star SU Psc and minimum masses of approximately 11 solar mass are deduced for both components. Photometric colors and intermediate dispersion spectra are used to deduce a composite spectral type for this system. The relative strengths of the hydrogen lines in the two components implies a magnitude difference of Delta B approximates to 1.0 and allows spectral types of B3III and B5III to be estimated for the primary and secondary stars, respectively. The SU Psc system would therefore appear to consist of a pair of normal young hydrogen burning B-type stars; their high galactic latitude (b approximates to 48 deg) would then imply that they are at a distance of more than 3 kpc from the galactic plane. Evolutionary ages of approximately 107 years for both components are smaller than the estimated time (approximates to 4 x 107 years) for the system to have been moved from the galactic disk to its current position. However given the uncertainties, these estimates are still consistent with SU Psc having been ejected from the galactic plane, possibly via dynamical interactions in a young open cluster. Title: Electron Density Diagnostics for Gaseous Nebulae Involving the O IV Intercombination Lines near 1400 Angstrom Authors: Keenan, F. P.; Conlon, E. S.; Bowden, D. A.; Feibelman, W. A.; Pradhan, A. K. Bibcode: 1993ApJS...88..169K Altcode: The Bloom and Pradhan (1992) results on the excitation rates for transitions in O IV matrix are used to derive emission-line ratios near 1400 A, applicable to gaseous nebulae. The results are compared with the values measured from high-resolution spectra obtained by the IUE satellite. Title: S XI Line Ratios in the Sun Authors: Keenan, F. P.; Foster, V. J.; Conlon, E. S.; Aggarwal, K. M.; Widing, K. G. Bibcode: 1993ApJ...413..826K Altcode: Recently, Conlon et al. (1992) used Aggarwal's (1986) R-matrix calculations of electron excitation rates for Si IX, Ca XV, and Fe XXI to interpolate atomic data for other C-like ions, including S XI. Here, the results of Conlon et al. are used to derive diagnostic line ratios for S XI, and the ratios are compared with solar flare observational data obtained with the S082A instrument aboard Skylab. The experimental ratios are generally much larger than those predicted by theory, probably because of blending of the S XI 215.97 A line with Ni XVII 215.91 A and S XI 190.37 A with an unidentified feature at a coincident wavelength. These observations indicate that photoexcitation of S XI by Fe XII 191.26 A is probably not an important process in the solar atmosphere under flare conditions. Title: Emission line ratios for C III in the sun Authors: Keenan, F. P.; Warren, G. A. Bibcode: 1993SoPh..146...19K Altcode: Theoretical electron-density-sensitive C III emission line ratios are presented forR1 =I(2s2p3P − 2p23P)/I(2s2p1P − 2p21S) =I(1176 Å)/I(1247 Å),R2 =I(2s2p3P − 2p23P)/I(2s21S − 2s2p3P1) =I(1176 Å)/I(1908 Å), andR3 =I(2s2p1P − 2p21S)/I(2s21S − 2s2p3P1) =I(1247 Å)/I(1908 Å). These are significantly different from those deduced previously, principally due to the adoption of improved electron impact excitation rates in the present analysis. Electron densities deduced from the present theoretical line ratios, in conjunction with observed values ofR1,R2, andR3 measured from solar spectra obtained by the Naval Research Laboratory's S082B instrument on boardSkylab, are found to be generally compatible. In contrast, previous diagnostic calculations imply electron densities fromR1,R2, andR3 that differ by up to two orders of magnitude. These results provide observational support for the accuracy of the atomic physics adopted in the present calculations, and the methods employed in the derivation of the theoretical line ratios. Title: A Search for Young Stars in the Halo of M31 Authors: McCausland, R. J. H.; Conlon, E. S.; Dufton, P. L.; Fitzsimmons, A.; Irwin, M. J.; Keenan, F. P. Bibcode: 1993ApJ...411..650M Altcode: Previous studies have identified young hot stars that appear to have been formed in the halo of our Galaxy. Here we present preliminary results of a spectroscopic search for similar objects in the halo of M31. Radial velocities have been measured for 23 apparently blue objects (selected from APM measurements of Schmidt plates) in a magnitude range B_v_ ~ 17-21. For one of these targets, AND 0029+413, the radial velocity suggests that the object is gravitationally bound to M31 and hence that it may be in its halo. However, recent CCD photometry for this object indicates that it is redder than implied by the original photographic observations. A number of possible scenarios are presented to explain this object, including one consistent with it being a young star in the halo of M31. Title: Ar XIII line ratios in solar flares Authors: Keenan, F. P.; Conlon, E. S.; Foster, V. J.; Aggarwal, K. M.; Widing, K. G. Bibcode: 1993SoPh..145..291K Altcode: Theoretical ArXIII electron-density-sensitive emission line ratios, derived using electron impact excitation rates interpolated from accurateR-matrix calculations, are presented forR1 =I(242.22 å)/I(236.27 å),R2 =I(210.46 å)/I(236.27 å), andR3 =I(248.68 å)/I(236.27 å). Electron densities deduced from the observed values ofR1,R2, andR3 for solar flares obtained with the NRL S082A slitless spectrograph on boardSkylab are in excellent agreement, and furthermore compare favorably with those determined from line ratios in CaXV, which is formed at a similar electron temperature to that of ArXIII. These results provide experimental support for the accuracy of the atomic data adopted in the analysis, as well as for the techniques used to calculate the line ratios. Title: Fe III Emission Lines in the Optical Spectrum of the Planetary Nebula IC 4997 Authors: Keenan, F. P.; Aller, L. H.; Hyung, S.; Conlon, E. S.; Warren, G. A. Bibcode: 1993ApJ...410..430K Altcode: Relative populations for the 17 fine-structure levels in the 5D, 3P, 3H, 3F, and 3G states of the 3d6 configuration in Fe III, calculated using electron impact excitation rates derived with the R-matrix code, are used to derive theoretical electron temperature and density sensitive emission-line ratios applicable to the spectra of astronomical objects in the 4607-5412 A wavelength range. A comparison of these with high spectral resolution observational data for the PN IC 4997 reveals generally good agreement between theory and observation. This provides experimental support for the accuracy of the theoretical ratios and illustrates their usefulness in determining plasma parameters for the Fe III-emitting region of a gaseous nebula. Title: The Ratio of Optical-to-Infrared Emission Line Strengths in AR III as Electron Density Diagnostics for Planetary Nebulae Authors: Keenan, F. P.; Conlon, E. S. Bibcode: 1993ApJ...410..426K Altcode: The Johnson and Kingston (1990) results are used to derive theoretical line ratios for Ar III, and these are compared with optical and infrared observations of planetary nebulae. It is shown that this approach makes it possible to investigate the accuracy of the atomic data and evaluate the potential usefulness of optical/infrared line ratios in Ar III as electron density diagnostics. Title: Infrared observations of possible hot post-asymptotic giant branch stars. Authors: Conlon, E. S.; Dufton, P. L.; Keenan, F. P.; McCausland, R. J. H.; Little, J. E. Bibcode: 1993A&A...272..243C Altcode: Infrared photometry of seventeen high latitude early-type stars, that have either been identified as post-AGB objects or are post-AGB candidates, has been obtained at JHKL and nbM wavelengths. This has been combined with optical and IRAS observations, and compared with LTE model atmosphere fluxes; infrared excesses are found for five stars. Of the known post-AGB stars, only the highest mass objects reveal an infrared excess, suggesting a correlation between the presence of circumstellar material and mass. This may be explained in terms of the very different transition times for high and low mass post-AGB stars from the AGB to becoming a planetary nebula. Title: LSIV -12 degrees 111: A Candidate Halo Proto--Planetary Nebula Authors: Conlon, E. S.; Dufton, P. L.; McCausland, R. J. H.; Keenan, F. P. Bibcode: 1993ApJ...408..593C Altcode: We report on multiwavelength observations of LSIV -12 deg 111, which may be an emerging halo planetary nebula. This object was previously classified as a young emission-line B-type star, but a model atmosphere abundance analysis of high-resolution optical spectra has revealed it to be an evolved object, probably in the postasymptotic giant branch (AGB) evolutionary phase. The presence of an infrared excess and low-excitation nebular emission lines implies that the central star may just have started to photoionize the circumstellar material ejected during the AGB phase. In this paper we discuss the nebular and dust properties of LSIV -12 deg 111 and redetermine some metal abundances for the central star. These are used to constrain the evolutionary status of this unusual object. Title: A Comparison of Theoretical CIV Emission Line Strengths with Active Region Observations Obtained with the Solar Extreme Ultraviolet Rocket Telescope and Spectrograph / SERTS Authors: Keenan, F. P.; Thomas, R. J.; Neupert, W. M.; Conlon, E. S.; Burke, V. M. Bibcode: 1993SoPh..144...69K Altcode: Theoretical line ratios involving 2s2S - 3p2P, 2p2P - 3s2S, and 2p2S - 3d2D transitions inCIV between 312 and 420 Å are presented. A comparison of these with solar active region observational data obtained during a rocket flight by the Solar EUV Rocket Telescope and Spectrograph (SERTS) reveals good agreement between theory and experiment, with discrepancies that average only 22%. This provides experimental support for the accuracy of the atomic data adopted in the line ratio calculations, and also resolves discrepancies found previously when the theoretical results were compared with solar data from the S082A instrument on boardSkylab. The potential usefulness of theCIV line ratios as electron temperature diagnostics for the solar transition region is briefly discussed. Title: Identification of the Fe XV 3 s3p 1P--3p 2 1S Line in Solar Flare Spectra and Its Use as an Electron Density Diagnostic Authors: Keenan, F. P.; Dufton, P. L.; Conlon, E. S.; Foster, V. J.; Kingston, A. E.; Widing, K. G. Bibcode: 1993ApJ...405..798K Altcode: We have examined EUV spectra of solar flares and measured the intensities of the 324.97 A and 323.57 A emission lines relative to that of the Fe XV 3s3p 3P2-3p2 3P1 transition at 321.76 A. A comparison of these line ratios with theoretical predictions indicates that the Fe XV 3s3p 1P-3p2 1S transition is the line observed at 324.97 A, rather than the feature at 323.57 A as previously suggested. In addition, we show that the I(324.97 A)/I(321.76 A) intensity ratio is an excellent electron density diagnostic for the Fe XV emitting region of the solar atmosphere. The relative intensities of other Fe XV lines in the 290-330 A wavelength region of the S082A spectra are also analyzed and briefly discussed. Title: Three stars at high galactic latitudes with peculiar helium abundances. Authors: Dufton, P. L.; Conlon, E. S.; Keenan, F. P.; McCausland, R. J. H.; Holmgren, D. E. Bibcode: 1993A&A...269..201D Altcode: High resolution optical observations have been obtained for three high Galactic latitude hot stars (CD-43 14300 deg, PHL 382, and Feige 56) which have abnormal helium spectra. An LTE model atmosphere analysis indicates that CD-43 14300 deg is probably an intermediate helium star with relatively normal metal abundances, while PHL 382 and Feige 56 are helium weak stars with silicon and magnesium underabundances. A kinematic analysis implies that Feige 56 could have been ejected from the Galactic plane; for the other two stars, the analysis is ambiguous but favors them having been formed away from the Galactic plane. The identification of such objects provides additional evidence for the existence of young hot stars at large distances from the Galactic plane. Title: Theoretical Emission-Line Strengths for Fe XXIII and a Comparison with Solar Observational Data Authors: Keenan, F. P.; Conlon, E. S.; Warren, G. A.; Boone, A. W.; Norrington, P. H. Bibcode: 1993ApJ...406..350K Altcode: Electron impact excitation rates, calculated with a relativistic version of the R-matrix code, are presented for all transitions among the 2s2, 2s2p, and 2p2 levels of Fe XXIII. These data are used to derive theoretical T(e) sensitive emission-line ratios involving Fe XXIII transitions in the 132-1100 A wavelength range. A comparison of our theoretical results for the ratio R1 = I(2s2 1S-2s2p 1P)/I(2s2 1 1S-2s2p 3Pi) = I(132.81 A)/I(263.79 A) with the observed value for a solar flare, obtained with the Goddard Space Flight Center's grating spectrometer on the OSO 5 satellite, reveals good agreement between theory and observation. This provides some experimental support for the accuracy of the atomic data adopted in the line ratio calculations. Title: An abundance and kinematic analysis from high dispersion spectroscopy of early-type, high galactic latitude stellar candidates from the UKST UBVRI survey. Authors: Hambly, N. C.; Conlon, E. S.; Dufton, P. L.; Keenan, F. P.; McCausland, R. J. H. Bibcode: 1993WFINw...3...18H Altcode: The authors have identified four excellent young, high galactic latitude candidates from the UKST UBVRI survey by model atmospheric analysis from high resolution spectra. Title: Proton and Heavy Particle Excitation of the 2s22p5 2P{3/2} - 2s22p5 2P½ Transition in Fluorine-Like Zn XXII, Kr XXVIII and Mo XXXIV Authors: Reid, R.; Foster, V.; Keenan, F. Bibcode: 1993uxrs.conf..154R Altcode: No abstract at ADS Title: C IV emission lines in an active region spectrum obtained with SERTS. Authors: Keenan, F. P.; Thomas, R. J.; Neupert, W. M.; Conlon, E. S.; Burke, V. M. Bibcode: 1993uxrs.conf..337K Altcode: 1993uxsa.conf..337K Theoretical line ratios involving 2s 2S-3p 2P, 2p 2P-3s 2S and 2p 2S-3d 2D transitions in C IV between 312 and 420 Å are presented. A comparison of these with observations of a solar active region obtained during a rocket flight by the Solar EUV Rocket Telescope and Spectrograph (SERTS) reveals good agreement between theory and experiment, with discrepancies that average only 19%. This provides experimental support for the accuracy of the atomic data adopted in the line ratio calculations, and also resolves discrepancies found previously when the theoretical results were compared with solar data from the S082A instrument on board Skylab. The potential usefulness of the C IV line ratios as electron temperature diagnostics for the solar transition region is briefly discussed. Title: Preliminary Results of Two Spectroscopic Surveys to Investigate Star Formation in the Galactic Halo Authors: Conlon, E. S.; Little, J. E.; Dufton, P. L.; Keenan, F. P.; McCausland, R. J. H.; Holmgren, D.; Kilkenny, D.; Stobie, R. S.; Miller, L. Bibcode: 1993ASPC...45..375C Altcode: 1993lhls.work..375C No abstract at ADS Title: Abundance Analyses of Hot Post-Agb Stars at High Galactic Latitude Authors: Conlon, E. S.; McCausland, R. J. H.; Dufton, P. L.; Keenan, F. P. Bibcode: 1993ASPC...45..146C Altcode: 1993lhls.work..146C No abstract at ADS Title: Electron density diagnostics applicable to IUE spectra of gaseous nebulae. Authors: Keenan, F. P.; Feibelman, W. A.; Harra, L. K.; Conlon, E. S.; Aggarwal, K. M. Bibcode: 1993uxrs.conf..341K Altcode: 1993uxsa.conf..341K Observed values of the emission line ratios R = I(3s2 1S - 3s3p 3P2)/ I(3s2 1S - 3s3p 3P1) = I(2660 Å)/I(2669 Å) in Al II, R1 = I(2s2 1S - 2s2p 3P2)/ I(2s2 1S - 2s2p 3P1) = I(1907 Å)/I(1909 Å) in C III, and R2 = I(3s2 1S - 3s3p 3P2)/ I(3s2 1S - 3s3p 3P1) = I(1883 Å)/I(1892 Å) in Si III, measured from high resolution spectra obtained with the International Ultraviolet Explorer (IUE) satellite, are presented for several planetary nebulae and symbiotic stars. Electron densities deduced from these ratios in conjunction with new theoretical R, R1 and R2 diagnostics (which are significantly different from those calculated by previous authors), are found to be compatible, and are also in good agreement with those derived from line ratios in other species. This provides observational support for the accuracy of the atomic data adopted in the line ratio calculations. Title: Ar XVII X-ray lines emitted by solar flares. Authors: Phillips, K. J. H.; Keenan, F. P.; Harra, L. K.; McCann, S. M. Bibcode: 1993uxrs.conf..579P Altcode: 1993uxsa.conf..579P Recent calculations of electron impact excitation rates in helium-like argon (Ar XVII) have been used to derive emission line intensities for the resonance (1s2 1S0 - 1s2p 1P1), intercombination (1s2 1S0 - 1s2p 3P1,2) and forbidden (1s2 1S0 - 1s2s 3S1) lines that appear in the X-ray region (≍4 Å). These have been combined with calculations of nearby dielectronic satellites of Ar XVI to synthesize spectra that can be compared with observations. The synthetic spectra are sensitive to electron temperature Te but not electron density unless extremely large (>1014cm-3). Comparisons have been made using observations taken during solar flares with the Flat Crystal Spectrometer (part of the X-ray Polychromator) on Solar Maximum Mission and with spectra from the Alcator tokamak. The observed spectra show good agreement with the theoretical spectra, and demonstrate the feasibility of using Ar XVII line ratios for determining Te. Title: Diffusion Effects on Diagnostic X-Ray Emission Line Ratio Measurements in Laboratory Plasmas Authors: Coffey, I.; Barnsley, R.; Hughes, I.; Keenan, F.; Lawson, K.; Peacock, N. Bibcode: 1993uxrs.conf..533C Altcode: No abstract at ADS Title: Line ratio diagnostics for astrophysical plasmas. Authors: Keenan, F. P. Bibcode: 1993uxrs.conf...44K Altcode: 1993uxsa.conf...44K In this paper the conditions under which emission (or absorption) line intensity ratios are sensitive to variations in the physical conditions of a plasma, such as electron temperature and density, are discussed. More importantly, a bibliography is provided of the most reliable line ratio diagnostic calculations currently available for application to the IR, optical, UV and X-ray spectra of a wide range of astrophysical sources. These include the solar chromosphere, transition region and corona, late-type stellar atmospheres, gaseous nebulae (such as H II regions and planetary nebulae), active galactic nuclei, supernova remnants and the interstellar medium. Title: LSIV 12 degree 111 - A Newly Emerging Halo Planetary Nebula Authors: Conlon, E. S.; Dufton, P. L.; Keenan, F. P.; McCausland, R. J. H. Bibcode: 1993IAUS..155..356C Altcode: No abstract at ADS Title: The determination of solar coronal electron temperatures from Mg XI emission lines in SMM-FCS spectra of flares and active regions. Authors: Harra, L. K.; Phillips, K. J. H.; Keenan, F. P.; Conlon, E. S.; Kingston, A. E. Bibcode: 1993uxrs.conf..551H Altcode: 1993uxsa.conf..551H Recent atomic physics calculations for Mg XI are used to derive the electron temperature sensitive emission line ratios G = [I(1s2 1S - 1s2s 3S) + I(1s2 1S - 1s2p 3P1,2)]/ I(1s2 1S - 1s2p 1P), R1 = I(1s2 1S - 1s3p 1P)/ I(1s2 1S - 1s2p 1P), and R2 = I(1s2 1S - 1s4p 1P)/ I(1s2 1S - 1s2p 1P), which are found to be significantly different from earlier results. Values of Te deduced from G, R1 and R2 ratios measured from solar flare and active region spectra obtained with the Flat Crystal Spectrometer (FCS) on board the Solar Maximum Mission (SMM) satellite are consistent. This provides support both for the validity of the theoretical G, R1 and R2 diagnostics, and for the FCS calibration curve in the wavelength region covering the Mg XI transitions, 7.472-9.314 Å. Title: Solar O IV and S IV lines from the High Resolution Telescope and Spectrograph (HRTS) and the S082B spectrograph on board Skylab. Authors: Keenan, F. P.; Cook, J. W.; Doyle, J. G.; Dufton, P. L.; Hayes, M. A.; Kingston, A. E. Bibcode: 1993uxrs.conf..345K Altcode: 1993uxsa.conf..345K A comparison of theoretical O IV electron density diagnostics with observational data from a quiet solar region, a sunspot and an active region obtained with the High Resolution Telescope and Spectrograph (HRTS), and a flare observed with the S082B instrument on board Skylab, reveals that the O IV 1404.8 Å line is not only blended with the S IV 1404.8 Å transition, but also with an unknown feature that contributes a significant amount to the blend. It is therefore suggested that line ratios which include the O IV 1404.8 Å transition should not be employed as density diagnostics. Title: EUV lines of Mg IX as ne-diagnostics for high density flares. Authors: Harra, L. K.; Keenan, F. P.; Widing, K. G.; Conlon, E. S. Bibcode: 1993uxrs.conf..320H Altcode: 1993uxsa.conf..320H Theoretical Mg IX electron density sensitive emission line ratios, derived using electron impact excitation rates interpolated from accurate R-matrix calculations, are presented for R1 = I(443.97 Å)/I(368.07 Å), R2 = I(439.17 Å)/I(368.07 Å), R3 = I(443.40 Å)/I(368.07 Å) and R4 = I(441.20 Å)/I(368.07 Å). A comparison of these with observational data for solar flares, obtained with the Naval Research Laboratory's S082A spectrograph on board Skylab, reveals excellent agreement between theory and observation for R1 and R2, which confirms the usefulness of these ratios as Ne-diagnostics for solar flares, as well as providing experimental support for the accuracy of the atomic data adopted in the line ratio calculations. However the observed values of both R3 and R4 generally imply unrealistically high electron densities, which is probably due to blending in the 443.40 and 441.20 Å lines, possibly with Ar IV 443.44 Å and Mg VI/Mg VII 441.22 Å, respectively. Title: Helium-like Ne IX in the JET tokamak. Authors: Coffey, I. H.; Barnsley, R.; Keenan, F. P.; Lawson, K. D.; Peacock, N. J. Bibcode: 1993uxrs.conf..537C Altcode: 1993uxsa.conf..537C New calculations are presented of the electron density sensitive emission line ratio R = I(1s2 1S0 - 1s2s 3S1)/ I(1s2 1S0 - 1s2p 3P1,2), and the electron temperature sensitive emission line ratios G = [I(1s2 1S0 - 1s2s 3S1) + (1s2 1S0 - 1s2p 3P1,2)]/ I(1s2 1S0 - 1s2p 1P1) and R1 = I(1s2 1S0 - 1s3p 1P1)/ I(1s2 1S0 - 1s2p 1P1). They are compared with measured ratios from the JET (Joint European Torus) plasma where the electron temperature and density have been determined by independent means. Consideration is given to diffusion effects which cause a departure from coronal equilibrium conditions, resulting in significant changes to the G ratio. These measurements are made in the absence of blending with Fe XVIII, Fe XIX and Na X lines which are sources of error in solar measurements. Good agreement with theory is found, with discrepancies of typically less than 10%. This implies that the theoretical results may be applied to the analysis of remote plasma sources for which no independent electron density and temperature estimates exist, such as solar flares and active regions. Title: Energy levels and oscillator strengths for transitions in helium-like Fe XXV and Ni XXVII. Authors: Harra, L. K.; Boone, A. W.; Norrington, P. H.; Keenan, F. P.; Kingston, A. E. Bibcode: 1993uxrs.conf..122H Altcode: 1993uxsa.conf..122H Configuration interaction (CI) wavefunctions are used to calculate energy levels and oscillator strengths for all significant electric dipole (E1), electric quadrupole (E2), magnetic dipole (M1) and magnetic quadrupole (M2) transitions among the 1s2, 1s2l and 1s3l states of He-like Fe XXV and Ni XXVII. Accurate wavefunctions are also obtained using the fully relativistic MCDF method and similarly employed to calculate these same energy levels and oscillator strenths. Derived energy levels are compared to each other and with previous results, and indicate that the MCDF method gives data which are closer to the experimental energies. The calculated CI and MCDF A-values are found to be in good agreement, but differ significantly in some cases from these and previous authors. Title: Star formation in the galactic halo. Authors: Keenan, F. P. Bibcode: 1992QJRAS..33..325K Altcode: No abstract at ADS Title: Extreme Ultraviolet Line Ratios for CA XV Applicable to Solar Flare Spectra Authors: Keenan, F. P.; Conlon, E. S.; Foster, V. J.; Aggarwal, K. M.; Widing, K. G. Bibcode: 1992ApJ...401..411K Altcode: New R-matrix calculations of electron impact excitation rates in Ca XV are used to derive theoretical electron density diagonstic emission-line ratios involving 2s2 2p2 - 2s 2p3 transitions in the wavelength range 180-215 A. A comparison of these with observational data for solar flares obtained with the Naval Research Laboratory's S082A spectrograph on board Skylab reveals excellent agreement between theory and observation, as does a comparison with line ratio measurements from the TEXT tokamak plasma, for which the electron temperature and density have been independently determined. This provides experimental support for the accuracy of the atomic data, and hence line ratio calculations, employed in the present analysis. Title: Electron density diagnostics for gaseous nebulae involving the O 4 intercombination lines near 1400 A Authors: Keenan, F. P.; Conlon, E. S.; Bowden, D. A.; Feibelman, W. A.; Pradhan, Anil K. Bibcode: 1992STIN...9314762K Altcode: Theoretical O IV electron density sensitive emission line ratios, determined using electron impact excitation rates calculated with the R-matrix code, are presented for R1 = I(1407.4 A)/I(1401.2 A), R2 = I(1404.8 A)/I(1401.2A), R3 = I(1399.8 A)/(1401.2 A), and R4 = I(1397.2 A)/I(1401.2 A). The observed values of R1-R4, measured from high resolution spectra obtained with the International Ultraviolet Explorer (IUE) satellite, lead to electron densities that are compatible, and which are also in good agreement with those deduced from line ratios in other species. This provides observational support for the accuracy of the atomic data adopted in the present calculations. Title: The Origin of Distant B-Type Stars in the Galactic Halo Authors: Conlon, E. S.; Dufton, P. L.; Keenan, F. P.; McCausland, R. J. H.; Holmgren, D. Bibcode: 1992ApJ...400..273C Altcode: Model atmosphere analyses of seven high-latitude faint blue stars reveal them to be normal Population I objects at typical z-distances of 4 kpc or more. A comparison of the stellar ages with the time that would be required to reach their present locations following ejection from the disk shows that the four objects, PB 5418, TS 195, TS 308, and PHL 2018 could have formed in the disk. The most likely ejection mechanism appears to be close gravitational encounters within stellar clusters, in agreement with previous results (Conlon et al., 1990). The kinematics of the remaining three stars (SB 357, BD - 15 deg 115, and BD - 2 deg 3766) are further investigated, together with those of five high-latitude B-type stars that appear to have formed in the halo, to establish if disk ejection is possible. For three stars (SB 357, PG 0832 + 676, and BD - 15 deg 115), star formation in the halo is the only feasible explanation. Title: Low-dispersion spectroscopy of blue stars from UK Schmidt Telescope UBVRI survey. Authors: Holmgren, D. E.; McCausland, R. J. H.; Dufton, P. L.; Keenan, F. P.; Kilkenny, D. Bibcode: 1992MNRAS.258..521H Altcode: We present analyses of SAAO low-dispersion spectra and COSMOS photographic photometry of 49 B-type stellar candidates selected from the United Kingdom Schmidt Telescope UBVRI survey. Four of the stars are possibly normal B-type stars at large z-distances from the galactic plane. For these objects, we present approximate atmospheric parameters based on a comparison of the stellar H-gamma lines with theoretical profiles, and spectral types based on MK classification and the Johnson Q parameter. Spectral types are also provided for the remaining stars, which are OB-type subdwarfs. Title: A recalculation of the line emissivities for the strongest UV and extreme-UV lines in the 400-2800 A wavelength range Authors: Doyle, J. G.; Keenan, F. P. Bibcode: 1992A&A...264..173D Altcode: Using the most recent atomic data we re-calculate line emissivities for the strongest transitions in the 400-2800 A region. These line emissivities may be used to construct emission measure curves for either observed ultraviolet/extreme ultraviolet solar features or ultraviolet observations of stellar sources. The new tables contain several lines not in the original Raymond and Doyle tables. Title: X-Ray Emission-Line Ratios in MG XI as Electron Temperature Diagnostics for Solar Flares and Active Regions Authors: Keenan, F. P.; Phillips, K. J. H.; Harra, L. K.; Conlon, E. S.; Kingston, A. E. Bibcode: 1992ApJ...393..815K Altcode: Electron temperature-sensitive emission-line ratios are derived via electron impact excitation rates for transitions in helium-like Mg XI, calculated with the R-matrix code. These ratios are found to be significantly different from earlier diagnostic calculations of Keenan et al. (1984, 1991), and lead to electron temperature estimates up to a factor of about 1.6 larger. Values of Te deduced from R1 and R2 ratios measured from solar flare and active region spectra obtained with the FCS on board the SMM satellite are consistent and in good agreement with temperatures estimated from the observed G ratios for these solar features. This provides support both for the validity of the theoretical R1 and R2 diagnostics, and for the FCS calibration curve in the wavelength region covering the Mg XI transitions 7.472-9.314 A. Title: Hot Post--Asymptotic Giant Branch Stars at High Galactic Latitudes Authors: McCausland, R. J. H.; Conlon, E. S.; Dufton, P. L.; Keenan, F. P. Bibcode: 1992ApJ...394..298M Altcode: Model atmosphere analyses are presented for high-resolution spectra of four stars at high Galactic latitudes. Although their derived atmospheric parameters are consistent with their previous classification as early B-type stars, their chemical compositions are significantly different from those expected for Population I objects. However both the chemical compositions and atmospheric parameters appear to be consistent with a post-asymptotic giant branch evolutionary status. Title: AI II as an electron density diagnostic for the upper chromosphere/lower transition region in late-type stars. Authors: Doyle, J. G.; Keenan, F. P.; Harra, L. K.; Aggarwal, K. M.; Tayal, S. S. Bibcode: 1992A&A...261..285D Altcode: The ratio of the Al II resonance line 3s2 1S-3sp 1P1 at 1670 A to the inter-system line 3s2 1S-3s3p 3P1 at 2669 A is a useful electron density diagnostic for N(e) greater than 10 exp 10/cu cm. However, it is also sensitive to the adopted electron temperature, and, in fact, should be a useful electron temperature diagnostic when Ne is not greater than 10 exp 9/cu cm. In particular, we present observational data for the RS CVn star II Peg and show that this ratio implies an electron pressure substantially less than that implied from other diagnostic line ratios but in good agreement with the pressure derived from the C III 1176/C III 1908 ratio. We suggest additional observational and theoretical work that may be required. Title: Improved Calculations for the C III lambda lambda 1907,1909 and SI III lambda lambda 1883,1892 Electron Density Sensitive Emission-Line Ratios, and a Comparison with IUE Observations Authors: Keenan, F. P.; Feibelman, W. A.; Berrington, K. A. Bibcode: 1992ApJ...389..443K Altcode: Atomic data are used in conjunction with the statistical equilibrium code of Dufton (1977) to calculate relative C III and Si III level populations, and hence emission-line strengths for a range of electron temperatures and densities. It is assumed that photoexcitation and deexcitaton rates are negligible in comparison with the corresponding collisional rates, that ionization to and recombination from other ionic levels are slow compared with bound-bound rates, and that all transitions are optically thin. The observed values of R1 and R2 for several planetary nebulae and a symbiotic star, measured from high-resolution spectra obtained with the IUE satellite, lead to electron densities that are compatible, and are also in good agreement with those deduced from line ratios in other species. Title: NE V Line Ratios in the EUV Spectra of Solar Flares Authors: Keenan, F. P.; Conlon, E. S.; Harra, L. K.; Aggarwal, K. M.; Widing, K. G. Bibcode: 1992ApJ...389..440K Altcode: Theoretical line ratios involving 2s22p2-2s2p3 transitions in Ne V between 359 and 572 A are presented. A comparison of these with solar-flare observational data from the spectrograph on board Skylab reveals excellent agreement between theory and experiment, with discrepancies that average only 8 percent. This provides experimental support for the accuracy of the atomic data adopted in the line-ratio calculations, and in addition resolves discrepancies between theory and observations previously found for this species. The potential usefulness of the Ne V line ratios as electron temperature diagnostics for the solar transition region is briefly discussed. Title: The Oscillator Strength of the SI II 3s 23p 2P--3 s3p 2 2D Multiplet and the Interstellar Abundance of Silicon Authors: Dufton, P. L.; Keenan, F. P.; Hibbert, A.; Ojha, P. C.; Stafford, R. P. Bibcode: 1992ApJ...387..414D Altcode: Spontaneous radiative rates, calculated using sophisticated configuration interaction wavefunctions, are presented for Si II resonance transitions in the 3s23p 2Pj-3s3p2 2Dj multiplet. For the J = 1/2 to J' = 3/2 transition, an oscillator strength of 0.0020 (with an estimated uncertainty of 25%) is deduced. This value is significantly lower than those found in some previous studies; the reasons for this and in particular the crucial role of the energy splitting of the 3s3P2 2D and 3s23d 2D levels are investigated. The implication of these new atomic data for gas phase silicon abundances in the interstellar medium is briefly discussed. Title: Solar SI II Line Ratios from the High-Resolution Telescope and Spectrograph Authors: Keenan, F. P.; Cook, J. W.; Dufton, P. L.; Kingston, A. E. Bibcode: 1992ApJ...387..726K Altcode: Theoretical emission-line ratios involving multiplets near 1262, 1306, and 1530 A are derived on the basis of new calculations of electron-impact excitation rates for allowed transition in Si II. A comparison of these line ratios with observational data from a quiet solar region, a sunspot, and an active region, obtained with the HIRTS on board a sounding rocket flight reveals that the 1530-A multiplet is optically thick, which is consistent with a calculation of the optical depth of these lines through a model atmosphere. The 1262- and 1306-A multiplets appear to be effectively optically thin. The average discrepancy between the theoretical and observed ratios is about 40 percent, which may not be significant, since the estimated uncertainties in both the calculated and experimental data are approximately 30 percent. Title: MG IX Line Ratios in the Sun Authors: Keenan, F. P.; Conlon, E. S.; Harra, L. K.; Widing, K. G. Bibcode: 1992ApJ...386..371K Altcode: Attention is given to theoretical Mg IX electron density sensitive emission-line ratios derived using electron impact excitation rates interpolated from accurate R-matrix calculations, which are presented for R1 = I(443.97 A)/I(368.07 A), R2 = I(439.17 A)/I(368.07 A), R3 = I(368.07 A)/I(443.07 A), and R4 = I(441.20 A)/I(368.07 A). A comparison of these with observational data for solar flares on board Skylab reveals excellent agreement between theory and observation for R1 and R2, which confirms the usefulness of these ratios as Ne-diagnostics for solar flares, as well as providing experimental support for the accuracy of the atomic data adopted in the line ratio calculations. The observed values of both R3 and R4 generally imply unrealistically high electron densities, which is argued to be due to blending in the 443.40- and 441.20-A lines, probably with Ar IV 443.44 A and Mg VI/Mg VII 441.22 A, respectively. Title: AL II Emission-Line Strengths in Low-Density Astrophysical Plasmas Authors: Keenan, F. P.; Harra, L. K.; Aggarwal, K. M.; Feibelman, W. A. Bibcode: 1992ApJ...385..375K Altcode: Theoretical values of the emission-line ratio R are derived for the transitions 3s2 1S-3s3p 3P2 and 3s2 1S-3s3p 3P1 in Al II, at 2660 and 2669 A, respectively. These ratios are compared with IUE observations of the planetary nebula NGC 7027 and the symbiotic star RR Tel, to illustrate the usefulness of the R as an electron density diagnostics. A value of R = 0.72 was deduced for NGC 7027, which implies log Ne = 4.2 for Te = 14,000 K. This is consistent with densities deduced earlier for this planetary nebula. Title: Fe XVIII Emission-Line Intensities in the Sun Authors: McKenzie, D. L.; Keenan, F. P.; McCann, S. M.; Berrington, K. A.; Hibbert, A.; Mohan, M. Bibcode: 1992ApJ...385..378M Altcode: Recently calculated electron-impact excitation rates among the 2s2 2p5, 2s2p6, and 2s2 2p4nl levels of Fe XVIII are used to derive theoretical emission-line ratios applicable to solar X-ray spectra. Oscillator strengths for all levels with n of less than or equal to 3 are used to take cascade involving the levels fully into account. Overall, the agreement between the theory and spectra measured by crystal spectrometers aboard the OV 1-17, P78-1, and SMM satellites is good. The effects of cascade from levels for which n is at least 4 are small, at least for the strongest lines. The labor required to take into account these higher levels is not justified by the current discrepancies between theory and observation. Title: Level Populations for Fe III Applicable to Astrophysical Plasmas and a Comparison with Planetary Nebula Observations Authors: Keenan, F. P.; Berrington, K. A.; Burke, P. G.; Zeippen, C. J.; Le Dourneuf, M.; Clegg, R. E. S. Bibcode: 1992ApJ...384..385K Altcode: Recent R-matrix calculations of electron impact excitation rates in Fe III, which are significantly different from the earlier results of Garstang, Robb, & Rountree, are used to derive relative populations for the 17 fine-structure levels in the 5D, 3P, 3H, 3F, and 3G states of the 3d6 configuration. Populations are presented for a wide range of electron temperatures (Te = 5000-20,000 K) and densities (Ne = 102-109 cm-3) applicable to astrophysical plasmas. A comparison of theoretical emission-line ratios generated using these results with observational data for the planetary nebulae DDDM-1, Vy 2-2, and NGC 7027 reveals general agreement between theory and observation, with discrepancies that average only 10%. In addition, the present calculations remove the disagreement found between theory and observation for the I(4881 Å)/I(4658 Å) line intensity ratio in DDDM-1 when the theoretical ratios of Garstang et al. are adopted, which provides experimental support for the accuracy of the current results. Title: C IV Line Ratios in the Sun Authors: Keenan, F. P.; Conlon, E. S.; Harra, L. K.; Burke, V. M.; Widing, K. G. Bibcode: 1992ApJ...385..381K Altcode: Theoretical electron temperature-sensitive emission-line ratios are calculated with R-matrix analysis of electron-impact excitation rates for transitions in C IV. Two of the emission-line ratios are found to agree with observational data on the sun taken with a slitless spectrograph aboard Skylab, and the two remaining lines have inaccuracies that can be attributed to blending of the 312.43 A line. The agreement between the observational and analytical data lends credence to the accuracy of the atomic data used in the analysis. Title: X-ray emission-line ratios in He-like ions as electron-temperature diagnostics for solar flares and active regions (abstract) Authors: Harra, L. K.; Phillips, K. J. H.; Keenan, F. P.; Bromage, B. J. I.; McCann, S. M. Bibcode: 1992sccw.conf..144H Altcode: No abstract at ADS Title: Spectroscopic Line Diagnostics (abstract) Authors: Keenan, F. P. Bibcode: 1992sccw.conf..143K Altcode: No abstract at ADS Title: The origin of distant B-type stars in the galactic halo Authors: Conlon, E. S.; McCausland, R. J. H.; Dufton, P. L.; Keenan, F. P.; Holmgren, D. E. Bibcode: 1992LNP...401...37C Altcode: 1992aets.conf...37C Using model atmosphere analyses of high resolution optical spectra, we have identified a group of young B-type stars at large distances from the galactic plane. A study of the kinematics and evolutionary ages of these objects reveals two groups of stars: those that could have formed in the disc and travelled to their present locations in their lifetimes and those that could not. The kinematics of the first group are in agreement with results from N-body simulations of dynamical ejection from young galactic star clusters. For the stars that could not have formed in the disc, star formation in the halo via collisions within intermediate and high velocity clouds appears the most likely explanation. Title: The determination of accurate cosmic abundances from B-type stellar spectra Authors: Brown, P. J. F.; Dufton, P. L.; Keenan, F. P.; Holmgren, D. E.; Warren, G. A. Bibcode: 1992LNP...401...33B Altcode: 1992aets.conf...33B We have obtained high-resolution, high-signal-to noise observations of weak A II and O II absorption lines formed in the atmospheres of main-sequence early-type stars. The observed line strengths have been combined with equally well determined oscillator strengths, in an analysis which used both LTE and non-LTE model atmosphere techniques. Cosmic argon and oxygen abundances (on a logarithmic scale with hydrogen = 12) of [A] = 6.49 and [O] 8.93 have been determined; these should have an accuracy of ±0.05 dex. Title: Blue post-asymptotic giant branch stars at high galactic latitude Authors: McCausland, R. J. H.; Conlon, E. S.; Dufton, P. L.; Keenan, F. P. Bibcode: 1992LNP...401..301M Altcode: 1992aets.conf..301M Model atmosphere analyses are presented for high resolution spectra of six stars at high galactic latitude. Although their derived atmospheric parameters are consistent with their previous classification as early B-type stars, their metal abundances are significantly different from those expected for Population I objects. However both their chemical composition and atmospheric parameters appear consistent with a Post Asymptotic Giant Branch evolutionary status. Additional evidence for this hypothesis is present in the spectra of one star (LS IV-12° 111), where its higher effective temperature is sufficient to excite emission lines from the surrounding nebula. Title: The SI II intercombination multiplet in late-type stars. Authors: Dufton, P. L.; Keenan, F. P.; Hibbert, A.; Stafford, R. P.; Byrne, P. B.; Agnew, D. Bibcode: 1991MNRAS.253..474D Altcode: New atomic data are used to calculate the relative intensities of transitions within the Si II 3s(2)3p(2)P-3s3p(2) 4P intercombination multiplet for plasma parameters appropriate to late-type stellar atmospheres. These ratios are found to be significantly different from those of Dufton and Kingston, (1991), principally due to changes in the radiative rates. A comparison with line ratios for the sun (from Skylab S082B spectra) and late-type stars (from IUE data) indicates that although the new theoretical line ratios are in better agreement with observation, significant discrepancies still exist. Possible explanations for these discrepancies are briefly discussed. Title: The Ratio of Optical to Near Infrared Emission Line Strengths in SII as Electron Density Diagnostics for Planetary Nebulae Authors: Keenan, F. P. Bibcode: 1991Ap&SS.186..277K Altcode: EinsteinA-coefficients for transitions in Sii, calculated with the atomic structure package CIV3, are used to derive the electron density sensitive emission line ratio {{R_1 = I(3s^2 3p^3 {}^2D_{{5 {/ {5 2}} 2}} - 3s^2 3p^3 {}^2P_{{3 {/ {3 2}} . 2}} )} {/ {{R_1 = I(3s^2 3p^3 {}^2D_{{5 {/ {5 2}} . 2}} - 3s^2 3p^3 {}^2P_{{3 {/ {3 2}} 2}} )} {I(3s^2 3p^3 {}^4S_{{3 {/ {3 2}} right. 2}} - 3s^2 3p^3 {}^2D_{{3 {/{3 2}} 2}, {5 {/ {5 2}} 2}} ) = }}} {I(3s^2 3p^3 {}^4S_{{3 {/ {3 2}} 2}} - 3s^2 3p^3 {}^2D_{{3 {/ {3 2}} 2}, {5 {/ {5 2}} 2}} ) = }} \ {{ = I(10320{Å})} {/ {{ = I(10320{Å})} {I(6717 + 6730{Å})}}} {I(6717 + 6730{Å})}} \ for a range of electron temperatures (T e =5000 20000K) and densities (N e =102 105 cm -3) applicable to planetary nebulae. Electron densities deduced from the observed values ofR 1 in several planetaries are in excellent agreement with those derived fromN e -sensitive line ratios in other species, which provides observational support for the accuracy of the atomic data adopted in the calculations. Title: Effective collision strengths among fine-structure levels of CA XV: erratum Authors: Aggarwal, K. M.; Berrington, K. A.; Keenan, F. P. Bibcode: 1991ApJS...77..441A Altcode: An error has been found in the calculation of Aggarwal et al. made in 1990, due to a mistake in the term coupling coefficients used to transform the collision strengths to intermediate coupling. The 190 fine-structure transitions among the 1s(2)2s(2)2p(2), 1s(2)2s2p(3), and 1s(2)2p(4) configurations of Ca XV are therefore corrected and retabulated. Major differences between the R-matrix calculation of Aggarwal et al. and the distorted wave method of Dere et al. have now been resolved though minor differences still remain. The effective collision strengths obtained after averaging the collision strengths over a Maxwellian distribution of electron velocities are also presented in the temperature range below 10 exp 7 K. Title: Improved Line Ratio Calculations Involving Delta N = 1 (2--3) Transitions in O V and a Reanalysis of SKYLAB Observations of Solar Flares Authors: Keenan, F. P.; Dufton, P. L.; Harra, L. K.; Conlon, E. S.; Berrington, K. A.; Kingston, A. E.; Widing, K. G. Bibcode: 1991ApJ...382..349K Altcode: R-matrix calculations of electron-impact-excitation rates in O V are used to rederive theoretical electron-density diagnostic emission-line ratios involving transitions between the n = 2 and 3 levels, which includes lines at 192.80, 192.90, 215.10, 215.25, 220.35, and 248.46 A. A comparison of these diagnostics with observational data for two solar flares obtained with the spectrograph on board Skylab reveals better agreement between theory and observation than was found previously. This provides experimental support for the improved accuracy of the atomic data employed in the present analysis. Title: A comparison of theoretical Fe xii emission line strengths with EUV observations of a solar active region Authors: Keenan, F. P.; Doyle, J. G.; Tayal, S. S.; Henry, R. J. W. Bibcode: 1991SoPh..135..353K Altcode: New theoretical electron-density-sensitive Fe XII emission line ratios R1 = I(3s23p34S3/2 - 3s3p44P5/2)/I(3s23p32P3/2 - 3s3p4D5/2 and R2 = I(3s23p32P3/2 - 3s3p42D5/2)/I(3s23p34S3/2 - 3s3p2P3/2) are derived using R-matrix electron impact excitation rate calculations. We have identified the FeXII and transitions in an active region spectrum obtained with the Harvard S-055 spectrometer on board Skylab at wavelengths of 364.0, 382.8, 1241.7, and 1349.4 Å, respectively. Electron densities determined from the observed values of R1 (log Ne ≃ 11.0) and R2(log Ne ≃ 11.4) are significantly larger than the typical active region measurements, but are similar to those derived from some active region spectra observed with the Skylab 2082A instrument, which provides observational support for the atomic data adopted in the line ratio calculations, and also for the identification of the Fe XII transitions in the S-055 spectrum. However the observed value of R3 = I(1349.4 Å)/I(1241.7 Å) is approximately a factor of two larger than one would expect from theory which, considering that the 1349.4 Å line lies at the edge of the S-055 wavelength coverage, may reflect errors in the instrument efficiency curve. Another possibility is that the 1349.4 Å transition is blended, probably with Si II 1350.1 Å. Title: Heliumlike Mg xi in the divertor-injected tokamak experiment Authors: Keenan, F. P.; McCann, S. M.; Kingston, A. E.; Barnsley, R.; Dunn, J.; Peacock, N. J. Bibcode: 1991PhRvA..44.3831K Altcode: Electron-impact excitation rates for transitions in heliumlike Mg xi, calculated with the R-matrix code, are used to derive the electron-density-sensitive emission line ratio R (=f/i) and temperature-sensitive ratio G [=(f+i)/r], where f is the forbidden 1s2 1S-1s2s 3S transition, i the intercombination 1s2 1S-1s2p 3P1,2 lines, and r the resonance 1s2 1S-1s2p 1P transition. A comparison of these with R and G ratios determined from x-ray spectra of the divertor-injected tokamak experiment reveals excellent agreement between theory and observation, with discrepancies of typically 3% and 9% in R and G, respectively. These discrepancies correspond to variations in Ne and Te of approximately 0.1 and 0.15 dex, respectively, and hence it should be possible to use the theoretical results to derive plasma parameters to this level of accuracy for remote sources for which no independent electron temperature and density estimates exist, such as solar flares. Title: The 3s 23p 2 P--3s3p 2 4P Intercombination Lines of Fe XIV in the Sun Authors: Keenan, F. P.; Dufton, P. L.; Conlon, E. S.; Boylan, M. B.; Kingston, A. E.; Widing, K. G. Bibcode: 1991ApJ...379..406K Altcode: The EUV spectra of solar flares obtained with the Naval Research Laboratory's S082A slitless spectrograph on board Skylab were examined, and the five components of the Fe XIV 3s2 3p 2P-3s3p2 4P intercombination multiplet were previsionally identified. A comparison of the observed Fe XIV line intensities with theoretical predictions reveals good agreement between theory and experiment, which tends to confirm the identifications and those made previously by Trabert, et al. (1987). The potential usefulness of the lines as electron density diagnostics is briefly discussed. Title: IUE Observations of Early-Type Stars at High Galactic Latitudes Authors: Quin, D. A.; Brown, P. J. F.; Conlon, E. S.; Dufton, P. L.; Keenan, F. P. Bibcode: 1991ApJ...375..342Q Altcode: High- and low-resolution IUE spectra of 14 apparently normal high-Galactic latitude B-type stars, together with visual fluxes determined from Stroemgren four-color photometry, are compared with theoretical spectra deduced from LTE model atmosphere calculations. Ten of the program stars have normal flux distributions, with only four of the stars exhibiting UV flux deficiency. For the latter, PHL 346 has been identified as a beta Cepheid variable, SB 357 is a Be-type star, and the ultraviolet flux deficiency for HD 214080 can be removed by increasing the E(B-V) from 0.09 to 0.12. In the case of HD 100340, the four-color photometry is inconsistent with the ultraviolet flux distribution, but this inconsistency vanishes when UBV photometry is employed in the analysis, implying that the uvby measurements may be in error. The normal flux distributions found for the program star provide support for their being Population I objects in the Galactic halo. Title: On the nature of HD 93521, a high galactic latitude O-star. Authors: Lennon, D. J.; Dufton, P. L.; Keenan, F. P.; Holmgren, D. E. Bibcode: 1991A&A...246..175L Altcode: Classical non-LTE model atmosphere techniques are used to analyze a high signal-to-noise, high-resolution spectrum of HD 93521 in the wavelength region 4070-4510 A. Abundances of nitrogen, oxygen, magnesium, and silicon were all found to be approximately solar. Attempts to fit the UV continuum flux with model fluxes imply a UV deficiency relative to the V-band. The present results are consistent with HD 93521 being a Population I late O-type shell star. It is inferred that the overabundance of helium is the result of turbulent diffusion, induced by the star's large rotational velocity, mixing CNO-cycled material into its atmosphere. It is suggested that HD 93521 is evolving on a track intermediate between homogeneous and normal evolutionary tracks and may exhibit moderate changes in CNO surface abundances which are masked by the star's large projected rotational velocity of 400 km/s. Title: Fe XIV Line Ratios in the Sun Authors: Keenan, F. P.; Dufton, P. L.; Boylan, M. B.; Kingston, A. E.; Widing, K. G. Bibcode: 1991ApJ...373..695K Altcode: Recent R-matrix calculations of electron-impact excitation rates for Fe XIV are used to derive theoretical electron density-sensitive emission-line ratios involving transitions in the wavelength range 211-274 A. Electron densities deduced from the observed line ratios for solar flares and active regions, obtained with the Naval Research Laboratory's SO82A slitless spectrograph on board Skylab, are in excellent internal agreement and, furthermore, compare favorably with densities determined independently from line ratios in Fe XII and Fe XIII. These results provide experimental support for the accuracy of the atomic data adopted in the analysis, as well as for the techniques used to calculate the line ratios. Title: NE V in Planetary Nebulae Authors: Keenan, F. P.; Burke, V. M.; Aggarwal, K. M. Bibcode: 1991ApJ...371..636K Altcode: The improved atomic data of Lennon and Burke (1991) are used there to rederive Ne V diagnostic line ratios applicable to PNe for a range of electron temperatures and densities. These results are found to be somewhat different from those determined when the earlier R-matrix atomic data of Baluja et al. (1980) and Aggarwal (1983) are used in the line ratio calculations. It is shown that it is unwise to use R1 or R3 alone as a temperature or density diagnostic, unless the density or temperature of the Ne V emitting region of the plasma has been independently determined. However, reliable estimates of both Ne and Te may be found when R1 and R3 are used together, while R2 may be used by itself as an accurate Ne diagnostic. Title: Radio and optical observations of high- and intermediate-velocity gas in the nearby interstellar medium. Authors: Bates, B.; Catney, M. G.; Gilheany, S.; Keenan, F. P.; Davies, R. D.; Hummel, E. Bibcode: 1991MNRAS.249..282B Altcode: Using observations at the 21-cm wavelength obtained with the Lovell Telescope the authors report on the detection of a weak H I emission feature at a velocity +100 km s-1 LSR and of column density log N(H I) = 18.5±0.2) towards the star 4 Lac. The feature corresponds in velocity with a high-velocity gas component which the authors have observed in several UV resonance lines in IUE spectra of this star. The component gas temperature which is derived from radio, optical and UV spectra lies in the range 5000 to 9000K and the line-of-sight column thickness is estimated to be less than 10 pc. The relationship between this observed feature and the widely distributed High-Velocity Clouds (HVCs) is considered briefly. H I components are detected also at intermediate velocities (between -20 and +25 km s-1) which vary significantly on an angular scale ≍0°1. Towards the star 4 Lac, components are observed in Na I within the same velocity range. If, as the authors suggest, the H I and Na I components correspond, then the intermediate-velocity gas lies in the foreground to the star and the observed spatial variations occur on a scale ⪉2 pc. Title: Infrared observations of high galactic latitude early-type stars. Authors: Fitzsimmons, A.; Keenan, F. P.; Conlon, E. S.; Dufton, P. L.; Williams, P. M. Bibcode: 1991MNRAS.249..336F Altcode: Infrared photometry of four relatively faint (8.5 ≤ V ≤ 11.0) early-type stars at high galactic latitude has been made in the J, H, K, L' and narrow-band M wavelengths. This has been combined with previously published ultraviolet and visible observations to enable a comparison with LTE model atmosphere fluxes. The results imply that at least three of the stars are normal main-sequence B-stars at large distances from the galactic plane. Title: Fe XII Line Ratios in Solar Flares Authors: Tayal, S. S.; Henry, Ronald J. W.; Keenan, F. P.; McCann, S. M.; Widing, K. G. Bibcode: 1991ApJ...369..567T Altcode: Relative level populations and the density-sensitive emission-line ratios R1 = I(186.87 A)/I(193.51 A), R2 = I(196.64 A)/I(193.51 A), and R3 = I(191.05 A/I(193.51 A) are derived using the recent R-matrix calculations of electron impact excitation rates for Fe XII over a wide range of electron densities (10 to the 9th - 10 to the 12th/cu cm) and at an electron temperature of 1.5 x 10 to the 6th K. These results are applied to solar active region and flare spectra obtained by the Naval Research Laboratory's S082A slitless spectrograph on board Skylab. Excellent agreement is found with observations. The electron densities deduced from Fe XII line ratios are also in agreement with those determined from Fe XIII and Fe XIV. Title: Theoretical Emission Line Strengths for Nevii Compared to Extreme Ultraviolet Solar Observations Authors: Keenan, F. P. Bibcode: 1991SoPh..131..291K Altcode: Theoretical electron-temperature-sensitive Ne VII emission line ratios, calculated using accurate R-matrix electron impact excitation rates, are presented for R1 = I(895.2 Å)/I(465.2 Å), R2 = I(561.7 Å)/I(465.2 Å) and R3 = I(564.5 Å)/I(465.2 Å). A comparison of these with observational data for several solar features obtained with the Harvard S-055 spectrometer on board Skylab reveals good agreement between theory and experiment. This provides observational support for the accuracy of the atomic physics adopted in the calculations, and the methods employed in the derivation of the theoretical diagnostics. Title: Two early-type POST AGB stars at high galactic latitudes. Authors: Conlon, E. S.; Dufton, P. L.; Keenan, F. P.; McCausland, R. J. H. Bibcode: 1991MNRAS.248..820C Altcode: Two high galactic latitude B-type stars, PHL 1580 and PHL 174, originally identified as distant early-type objects from low-resolution spectroscopy and photometry are re-analyzed using high-resolution spectra. The results of LTE and non-LTE model atmosphere analyses reveal general metal underabundances relative to solar values of typically 0.6 and 1.0 dex for PHL 1580 and PHL 174, respectively. For both stars carbon is significantly more underabundant. The anomalous compositions are compatible with those of other high galactic latitude post-AGB objects, while the derived atmospheric parameters are coincident with post-AGB evolutionary tracks. Thus it appears that PHL 1580 and PHL 174 are low-mass post-AGB objects at an evolutionary stage intermediate between those of the A-, F- and G-type objects and planetary nebulae previously identified. The severe carbon deficiency may be evidence that both objects left the AGB before the products of the CNO bi-cycle were mixed to the stellar surface. Title: Relative Populations for Levels in the 3d 2 Ground Configuration of Fe VII Authors: Keenan, F. P.; Norrington, P. H. Bibcode: 1991ApJ...368..486K Altcode: R-matrix calculations of electron impact exxcitation rates in Fe VII are used to derive relative populations for all levels in the 3d2 ground configuration. Results are presented for a wide range of electron temperatures and densities applicable to astrophysical plasmas. The calculations are used in conjunction with observed emission-line ratios for the planetary nebula NGC 7027 to derive the electron temperature of the Fe VII-emitting region, which is found to be in good agreement with the values of Te deduced from other highly ionized species in the planetary. Title: Electron density diagnostics for Ti XIV in high temperature plasmas Authors: Keenan, F. P.; Hibbert, A.; Reid, R. H. G.; Mohan, M.; Baluja, K. L. Bibcode: 1991PhyS...43..147K Altcode: Recent R-matrix calculations of electron excitation rates for transitions in Ti XIV are used to derive two different theoretical emission-line ratios as a function of the electron density values from 10 to the 10 to 10 to the 14/cu cm. The density values are applicable to astrophysical and tokamak plasmas. The results are found to be significantly different from those deduced if the distorted-wave electron rates of Bhatia et al. (1985) are adopted in the calculations. The results also lead to electron density estimates between a factor of 1.6 larger and 30 percent smaller for electron temperatures in the 1.5-6 x 10 to the 6 K range. Title: The Determination of Element Abundances in the Solar Neighborhood from B-Type Stellar Spectra. II. Non--LTE Calculations for AR II Authors: Holmgren, D. E.; Brown, P. J. F.; Dufton, P. L.; Keenan, F. P. Bibcode: 1990ApJ...364..657H Altcode: Non-LTE radiative transfer calculations for argon are presented for models with effective temperatures in the range 17,500-30,000 K and a logarithmic argon abundance of 6.50 on the scale log (H) = 12. These are used to analyze high-resolution and signal-to-noise observations of weak Ar II lines in the spectra of B-type stars. A mean argon abundance of 6.50 + or - 0.05 dex is found, providing a reliable estimate of the current cosmic argon abundance in the solar neighborhood. Title: The 1 1S--n 1P/1 1S--2 1P Emission-Line Ratios in SI XIII as Electron Temperature Diagnostics for Solar Flares and Active Regions Authors: Keenan, F. P.; McCann, S. M.; Phillips, K. J. H. Bibcode: 1990ApJ...363..310K Altcode: Theoretical Si XIII emission-line ratios R1, R2, and R3 are presented as a function of electron temperature. These ratios are found to be more electron temperature sensitive than the commonly used diagnostic for He-like ions (G), with, for example, R1, R2, and R3 varying by factors of approximately 6, 12, and 17 between log Te = 6.2 and 7.2, while G only changes by a factor of 1.8. In addition, R1, R2, and R3 are less dependent on whether or not the Si XIII-emitting plasma is in ionization equilibrium. Electron temperatures deduced using the observed values of R1, R2, and R3 from OV 1-17 and OSO 8 satellite spectra of solar flares and active regions are in good agreement and, in general, compared favorably with those determined from G. However, in the case of measurements made with the Flat Crystal Spectrometer on board the Solar Maximum Mission satellite there are large discrepancies between theory and observation. Possible explanations for these are briefly discussed. Title: NE VII Line Ratios in the Sun Authors: Keenan, F. P.; McCann, S. M.; Widing, K. G. Bibcode: 1990ApJ...363..315K Altcode: Theoretical Ne VII electron density sensitive emission-line ratios, derived using electron impact excitation rates calculated with the R-matrix code, are presented for R1 = I(561.7 A)/I(465.2 A) and R2 = I(561.4 A)/I(465.2 A). A comparison of these with observational data for solar flares, obtained with the Naval Research Laboratory's S082A spectrograph on board Skylab, reveals excellent agreement between theory and observation, which confirms the usefulness of R1 and R2 as Ne diagnostics for solar flares, as well as providing experimental support for the accuracy of the atomic data adopted in the line ratio calculations. Title: The runaway nature of distant early-type stars in the galactic halo. Authors: Conlon, E. S.; Dufton, P. L.; Keenan, F. P.; Leonard, P. J. T. Bibcode: 1990A&A...236..357C Altcode: The kinematics of a sample of 32 distant halo B-stars with masses in the range 3-21 solar masses are investigated using the current 'runaway star' hypotheses to establish if they belong to this group of stars. Whether postmass transfer secondaries in evolved massive close binaries can be normal low mass B-stars is discussed, but support for this idea is not found. Thus it appears that the lower mass stars could not have been ejected out of the disk as a result of supernova explosions in massive close binaries, while the higher mass objects do not in general reveal a binary nature as expected from this theory. The results of recent N-body simulations of the purely dynamical ejection of runaway stars from young galactic star clusters are in excellent agreement with the observations. Thus it appears that these halo stars are the most distant subgroup of OB runaways produced by cluster ejection yet observed. Title: Determination of Cosmic Abundances Authors: Keenan, F. P. Bibcode: 1990IrAJ...19..158K Altcode: Accurate contemporary cosmic abundances are derived using weak stellar absorption lines observed in the spectra of main sequence early-type stars. Initially, weak lines of argon are observed by comparing measured stellar Stromgren colors, beta indices, and Ar II equivalent widths with those predicted by local thermodynamic equilibrium model atmosphere codes. A mean abundance of 6.49 + or - 0.04 dex is obtained, and this value is considered to represent an accurate assessment of the current cosmic abundance value of argon in the solar neighborhood. This result is compared with those of experiments, and it is pointed out that the error estimate in this study is 12 percent or less. Title: IUE, optical and radio observations of high-velocity gas components in the nearby interstellar medium Authors: Gilheany, S.; Bates, B.; Catney, G.; Keenan, F. P.; Davies, R. D. Bibcode: 1990ESASP.310..489G Altcode: 1990eaia.conf..489G No abstract at ADS Title: A Comparison of Theoretical SV Emission Line Strengths with Extreme Ultraviolet Observations of a Sunspot Authors: Keenan, F. P.; Doyle, J. G. Bibcode: 1990SoPh..128..345K Altcode: 1990IAUCo.121P.345K Electron impact excitation rates for transitions in the S v ion, calculated with theR-matrix code, are used to derive the electron temperature sensitive emission line ratiosR1 =I(854.8 Å)/I(786.9 Å),R2 =I(852.2 Å)/I(786.9 Å),R3 =I(849.2 Å)/I(786.9 Å), andR4 =I(1199.1 Å)/I(786.9 Å), which are found to be significantly different from previous estimates. A comparison of the present results with observational data for a sunspot obtained with the Harvard S-055 spectrometer on boardSkylab reveals generally good agreement between theory and experiment, except in the case ofR1, which is probably due to blending in the 854.8 Å feature. The possible effects of Lyman continuum absorption on the observed line ratios is briefly discussed. Title: Solar chlorine abundance from an X-ray flare spectrum Authors: Phillips, K. J. H.; Keenan, F. P. Bibcode: 1990MNRAS.245P...4P Altcode: The solar coronal chlorine abundance is estimated from a weak X-ray line seen during a flare. The line intensity is compared with a nearby sulfur line with very similar contribution function. The chlorine abundance obtained is very similar to the only other positive determination for the sun, from HCl lines in a sunspot spectrum. Title: High Resoltuion Interstellar and Stellar Line Profiles of the Stars in the Globular Cluster M22 Authors: Bates, B.; Catney, M. G.; Keenan, F. P. Bibcode: 1990MNRAS.245..238B Altcode: High-resolution (∼5 km s-1 FWHM) spectra have been obtained for stars in the globular cluster M22 using the University College London echelle spectrograph (UCLES) at the coudé focus of the AAT. The prime objective was a study of the fine-scale spatial structure of the line-of-sight gas through observations of the Na D lines. Essentially the gas towards the cluster at distance ∼ 6 kpc is concentrated in two components at the approximate velocities (LSR) of + 6 and + 37 km s-1. The lower velocity material is likely to be part of a nearby H I cloud, first mapped in the radio region, in which case the spatial sampling in the present study has a scale < 0.3 pc. The higher velocity gas varies from a single component to a multiple component structure over the angular extent of the cluster. The distance to this material is less certain but it may be associated with the Sagittarius arm. New observations are presented also for the stellar Hα and Na D lines. Time variability of Hα emission and Na D line asymmetry are detected for two stars. The present data are in qualitative agreement with models for mass loss occurring in expanding, circumstellar envelopes. Title: N IV line ratios in the Sun Authors: Keenan, F. P. Bibcode: 1990SoPh..126..311K Altcode: Theoretical NIV emission line ratios, which incorporate several improvements over previous estimates, are presented for R1 = I(923.2 Å)/I(765.1 Å) and R2 = I(1718.6 Å)/I(1486.5 Å), which are electron density and temperature sensitive, respectively. A comparison of R1 with observational data for several solar features obtained with the Harvard S-055 spectrometer on board Skylab reveals generally good agreement between theory and observation, except for the quiet Sun, which is probably due to the 923.2 Å line being blended with an FeIII transition in this instance. The observed value of R2, determined from a quiet-Sun spectrum obtained by the S082-B spectrograph on board Skylab, implies an electron temperature in excellent agreement with that of maximum NIV fractional abundance in ionisation equilibrium, which provides observational support for the accuracy of the diagnostic calculations. Title: Interspecies Emission-Line Ratios as Electron Density Diagnostics for Late-Type Stellar Atmospheres Authors: Keenan, F. P.; Dufton, P. L.; Kingston, A. E. Bibcode: 1990ApJ...353..636K Altcode: Electron-impact excitation rates for transitions in S IV, Al III, and N IV, determined with the R-matrix code, are used to calculate relative level populations for electron temperatures log Te = 4.4 - 5.4 and densities Ne between 10 to the 8th and 10 to the 12th/cu cm. These data are combined with similar results for C III and O III to derive emission-line ratios which should be useful as electron-density diagnostics when applied to the UV spectra of late-type stellar atmospheres. Title: Effective Collision Strengths among Fine-Structure Levels of CA XV Authors: Aggarwal, K. M.; Berrington, K. A.; Keenan, F. P. Bibcode: 1990ApJS...72..815A Altcode: The R-matrix program is used to calculate collision strengths Omega for 190 fine-structure transitions among the 1s2 2s2 2p2, 1s2 2s 2p3, and 1s2 2p4 configurations of Ca XV in the energy range of 0-100 Ry. Relativistic effects are included in the computations of Omega through term coupling coefficients. The effective collision strengths Tau, obtained by averaging Omega over a Maxwellian distribution of electron velocities, are listed for all transitions in the temperature range of 10 to the 6th to 10 to the 7th K. The effects on the calculated Omega and Tau values of term coupling and configuration-interaction in the target are examined, and the importance of including relativistic effects is noted, particularly for spin and parity changing transitions at the higher energies and temperatures. Title: The Ratio of Optical to Infrared Emission-Line Strengths in O III as Electron Temperature Diagnostics for Planetary Nebulae Authors: Keenan, F. P.; Aggarwal, K. M. Bibcode: 1990ApJ...350..262K Altcode: Electron impact excitation rates for transitions in O III, calculated with the R-matrix code, are used to derive electron temperature diagnostics involving the ratio of optical (4363, 4959, 5007 A) to infrared (52, 88 microns) emission-line strengths, for a range of Ne( = 0.01-0.0001/cu cm) and Te( = 6000-20,000 K) applicable to planetary nebulae. Temperatures deduced from the observed values of these ratios for several planetaries show good internal agreement and are also similar to those estimated from the I(7135 A)/I(5192 A) ratio in Ar III, which provides observational support for the accuracy of the theoretical O III diagnostics. Title: Determination of stellar and interstellar abundances from weak absorption lines Authors: Keenan, F. P.; Brown, P. J. F.; Dufton, P. L.; Holmgren, D. E. Bibcode: 1990asos.conf...44K Altcode: No abstract at ADS Title: The Determination of Element Abundances in the Solar Neighborhood from B-Type Stellar Spectra. I. Argon Authors: Keenan, F. P.; Bates, B.; Dufton, P. L.; Holmgren, D. E.; Gilheany, S. Bibcode: 1990ApJ...348..322K Altcode: The coude spectrograph and CCD camera on the coude feed telescope at the Kitt Peak National Observatory, have been used to obtain high-resolution (0.09 A FWHM), high signal-to-noise (200) observations of weak A II absorption lines formed in the atmospheres of main-sequence early-type stars. These have been analyzed using LTE model atmosphere techniques to derive a mean argon-to-hydrogen abundance ratio of 6.49, which is believed to be accurate to + or - 0.1 dex. As the stellar atmospheres should be uncontaminated by the products of interior reactions, this abundance should be that of the interstellar medium from which the stars formed some 1-10 million yrs ago, and hence reflects the current chemical composition of the solar neighborhood. The result is compatible with that of Veck and Parkinson (1981). Title: High-velocity gas components towards 4 Lac. Authors: Bates, B.; Catney, M. G.; Keenan, F. P. Bibcode: 1990MNRAS.242..267B Altcode: A comparison of IUE ultraviolet spectra of the star 4 Lac with observations of a suitable comparison star have confirmed the presence of 'high-velocity gas components' in the former which are redshifted by a velocity about 100 km/s from the low-velocity interstellar gas. In addition to providing an unambiguous identification of the species which show high-velocity components, the new data yield improved values for equivalent widths. The derived column densities, element depletions and ionization balances all lie within the range of values obtained from the UV spectroscopy of old supernova remnants. Firmer predictions of the gas electron and hydrogen densities may be possible from observations of fine structure levels in species such as C II and Si II although, as is shown, these will require substantial IUE exposure times even for the brighter stars. Title: An investigation of oscillator strength calculations for interstellarlines of CL I. Authors: Keenan, F. P.; Dufton, P. L. Bibcode: 1990MNRAS.242P..52K Altcode: Recent oscillator strength calculations for the 1088.062, 1097.369 and 1347.240 A interstellar lines of Cl I by Ojha and Hibbert (1990) are found to be incompatible with high quality Copernicus observations. Possible explanations are discussed, including severe blending in the observational data, and misidentification of the 1088.062 and 1097.369 A transitions. Until these discrepancies are resolved, column densities deduced from these two transitions should be treated with caution. Title: The Fe xii 195.1 Å/1242 Å emission line ratio in the solar corona Authors: Keenan, F. P.; Tayal, S. S.; Henry, R. J. W. Bibcode: 1990SoPh..125...61K Altcode: Recent R-matrix calculations of electron impact excitation rates in Fe XII are used to derive the theoretical emission line ratio R1 = I(195.1 Å)/I(1242 Å), which is potentially a useful electron density diagnostic for the solar inner corona (r ≤ 1.05 61-01). These results are found to be significantly different from the earlier estimates of Withbroe and Raymond (1984), but are in good agreement with the observed values of R1, for the quiet Sun and an active region. Adoption of the R-matrix atomic data for the 1242 Å line in the coronal iron abundance determination removes an existing discrepancy between results derived from the EUV transition and other iron lines in the solar XUV spectrum. The R-matrix calculations confirm the prediction of Withbroe and Raymond that the earlier discrepancies in R1 and the iron abundance were due to the 1242 Å line excitation rates being underestimated by a factor of ~2. Withbroe and Raymond's paper is, therefore, an excellent example of how astronomical observations can be used to accurately predict atomic physics data. Title: Peculiar and normal early-type stars in the galactic halo. Authors: Conlon, E. S.; Brown, P. J. F.; Dufton, P. L.; Keenan, F. P. Bibcode: 1989A&A...224...65C Altcode: High resolution optical spectra of eight high latitude blue stars have been obtained. Three of the sample are identified as subdwarfs. The remaining five are analyzed for atmospheric parameters and metal and He abundances using model atmosphere techniques. Four of the sample appear to be normal B type stars 2 kpc or more from the plane. With a logarithmic surface gravity estimated to be 4.6 + or - 0.3 dex, PB 166 could be either a main sequence, horizontal branch or cool subdwarf. The nature of this star is discussed in view of its approximately normal Population I chemical composition. Title: Use of Al xii and Mg xi lines as solar plasma diagnostics Authors: Bromage, B. J. I.; Phillips, K. J. H.; Keenan, F. P.; McCann, S. M. Bibcode: 1989SoPh..124..289B Altcode: We present three sets of observations of n = 1 to n = 2 lines due to helium-like aluminium (AlXII), made during two solar flares (25 August, 1980 and 19 October, 1986), using the X-Ray Polychromator on the SMM satellite. The observed temperature-sensitive line ratio G is shown to be consistent with the close-coupling calculations of Keenan and McCann (1987), although the ratio R, which is both temperature and density-sensitive for lower-Z elements, is not sufficiently well determined from these data to say more than that the observed values of R are not inconsistent with the theoretical calculations. This region of the spectrum also includes the helium-like magnesium (Mgxi) 11S - 31P line, and it is shown that the ratio of this line to the AlXII resonance (11S - 21P) line is a more sensitive indicator of electron temperature than are the AlXIIG and R ratios. We demonstrate that the three ratios may be used together in order to derive values of emission measure, electron temperature and electron density during these flares. Title: On III Line Ratios in the Sun Authors: Keenan, F. P.; Aggarwal, K. M. Bibcode: 1989ApJ...344..522K Altcode: The R-matrix code is used to calculated electron impact excitation rates for transitions in O III. The calculated rates are used to determine the theoretical electron sensitive emission-line ratios R(1) and R(2). The ratios are up to a factor of 2 smaller than those of Bhatia et al. (1982). The results are compared with solar observations from Skylab, showing good agreement. Title: Electron Density Diagnostics of Fe XII in the Solar Plasma Authors: Tayal, S. S.; Henry, Ronald J. W.; Keenan, F. P.; McCann, S. M.; Widing, K. G. Bibcode: 1989ApJ...343.1004T Altcode: Density-sensitive emission-line ratios R1 = I(338.27 A)/I(364.47 A) and R2 = I(338.27 A)/I(352.10 A) are calculated for Fe XII using new electron collisional excitation rates which are substantially larger than those previously published. Electron densities deduced from the values of R1 and R2 for solar active regions and flares obtained by the NRL S082A slitless spectrograph on Skylab are in good agreement. Title: On III electron temperatures in planetary nebulae. Authors: Keenan, F. P.; Aggarwal, K. M. Bibcode: 1989JApA...10..147K Altcode: The electron-temperature-sensitive emission-line ratio I(2s2 2p2 1D - 2s2 2p2 1S)/I(2s2 2p2 3P1,2 - 2s2 2p2 1D) = I(4363 A)/I(4959 + 5007 A) has been determined based upon relative level populations for O III obtained using impact excitation rates calculated with the R-matrix code. Results are presented for a temperature range which is applicable to planetary nebulae. Electron temperatures derived from the observed R values of several planetary nebulae agree well with those determined from electron-temperature-sensitive line ratios is such other species as (semiforbidden C III)/C II, forbidden N II, and forbidden Ar II. Title: Solar SI III Line Ratios from the High-Resolution Telescope and Spectrograph on Board Spacelab 2: The Effects of Non-Maxwellian Electron Distribution Function Authors: Keenan, F. P.; Cook, J. W.; Dufton, P. L.; Kingston, A. E. Bibcode: 1989ApJ...340.1135K Altcode: Electron impact excitation rates for transitions in Si III, incorporating the effects of non-Maxwellian electron velocity distribution functions (EVDFs), are presented for a range of electron temperatures appropriate to the solar transition region. A comparison of theoretical line ratios with observational data for a quiet solar region, a sunspot, and an active region obtained with the high-resolution telescope and spectrograph (HRTS) on board Spacelab 2 indicates that non-Maxwellian EVDFs may exist in the transition region. Non-Maxwellian effects appear to be larger for the sunspot than for the quiet sun, implying that the temperature gradient may be greater in the former. Title: Fine-Structure Population Ratios for the 3P Ground States of C i Authors: Keenan, F. P. Bibcode: 1989ApJ...339..591K Altcode: Results of recent R-matrix calculations of electron impact excitation rates for the 2s2 2p2 3Pj-2s2 2p2 3Pj, fine-structure transition in C I are used to derive density sensitive population ratios n(3P1)/n(3Po) and n(3P2)/n(3Po) for a range of temperatures and electron and neutral hydrogen densities. The present data differ appreciably from those of Smeding and Pottasch (1979) and illustrate the importance of adopting accurate electron excitation rates in population ratio calculations, even in the case of neutrals. Title: Electron density and temperature-sensitive x-ray-emission-line ratios for heliumlike Si xiii in the DITE tokamak Authors: Keenan, F. P.; McCann, S. M.; Barnsley, R.; Dunn, J.; Evans, K. D.; Peacock, N. J. Bibcode: 1989PhRvA..39.4092K Altcode: Analyses of such remote X-ray sources as solar flares, for which no independent electron density and temperature estimates exist, may be undertaken in light of the present derivation of the electron density-sensitive emission line ratio R and the temperature-sensitive ratio G from calculations of the electron-impact excitation rates in He-like Si XIII atoms. These results are compared with R and G values obtained from X-ray spectra of the divertor-injected tokamak experiment; good agreement is obtained between theory and experiment, thereby supporting the accuracy of the atomic data used in the line-ratio calculations. Title: PG 0832+676: an Apparently Normal B1 V Star 18 Kiloparsecs above the Galactic Plane Authors: Brown, Paul J. F.; Dufton, Philip L.; Keenan, Francis P.; Boksenberg, Alec; King, David L.; Pettini, Max Bibcode: 1989ApJ...339..397B Altcode: Stellar equivalent widths and line profiles, measured from optical spectra obtained with the 5 m Hale telescope and the 2.5 m Isaac Newton telescope, are used in conjunction with model atmosphere calculations to determine the atmospheric parameters and chemical composition of the faint, blue, high-galactic latitude star PG 0832 + 676. The effective temperature (Teff = 25,000 K), surface gravity (log g = 3.9), and abundances of He, C, N, O, Mg, Al, and Si are similar to those of Population I OB-type stars, from which it is concluded that PG 0832 + 676 is a normal star at a distance from the galactic plane of about 18 kpc. The star's kinematics and evolutionary age suggest that it formed in the halo, possibly from galactic fountain material. Title: A comparison of theoretical line strengths for the 2s22p2 − 2s2p3 transitions in Ne V with solar data Authors: Keenan, F. P.; Aggarwal, K. M. Bibcode: 1989SoPh..122....1K Altcode: Results are presented for several theoretical line ratios in Nev involving transitions between multiplets in the 2s22p2 and 2s2p3 configurations. A comparison of these with solar data from the S082A and S-055 instruments on board Skylab reveals generally good agreement between theory and experiment, especially in the case of the high-resolution (S082A) observations. However the 2s22p21D − 2s2p31P (365.6 Å) and 2s22p23P − 2s2p33S (359 Å) lines appear to be blended, possibly with transitions in Fex and FeXI/FeXIII, respectively. We note that the intensity ratio I(365.6 Å)/I(416.2 Å) should be a valuable calibration check for a high-resolution extreme ultraviolet instrument in the spectral range 360-420 Å. Title: A Comparison of Theoretical OIII Line Strengths with Extreme Ultraviolet Solar Observations from the S082A Instrument of Board SKYLAB Authors: Keenan, F. P.; McCann, S. M.; Aggarwal, K. M.; Widing, K. G. Bibcode: 1989SoPh..122....7K Altcode: Relative level populations in OIII, determined using R-matrix calculations of electron impact excitation rates, are used to derive the theoretical emission line ratios R1 = I(525.80 Å)/I(599.62 Å), R2 = I(507.41 Å)/I(599.62 Å), R3 = I(507.71 Å)/I(599.62 Å), and R4 = I(508.18 Å)/I(599.62 Å). Electron temperatures deduced from the observed values of these ratios for several solar features obtained with the NRL S082A slitless spectrograph on board Skylab are in good agreement, and also compare favourably with that of maximum OIII fractional abundance in ionisation equilibrium, logTmax = 4.96. These results provide experimental support for the accuracy of the atomic data adopted in the line ratio calculations. Title: Si III electron temperature diagnostics for the solar transition region Authors: Keenan, F. P.; Dufton, P. L.; Kingston, A. E. Bibcode: 1989SoPh..123...33K Altcode: R-matrix calculations of electron impact excitation rates for transitions in Si III are used to derive the electron-density-sensitive emission line ratios R1 = I(1113.2 Å)/I(1206.3 Å), R2 = I(1298.9 Å)/I(1206.3 Å), and R3 = I(1296.7 Å)/I(1206.3 Å). A comparison of these with observational data for several solar features obtained with the Harvard S-055 spectrometer on board Skylab reveals that theory and experiment are compatible if the electron temperature of the Si III emitting region of the solar atmosphere is log Te= 4.5, but not if log Te= 4.7. The implication of the choice of a lower temperature on the electron energy distribution function is also briefly discussed. Title: Argon XV Line Ratios in the Sun Authors: Keenan, F. P.; Widing, K. G.; McCann, S. M. Bibcode: 1989ApJ...338..563K Altcode: Theoretical Ar XV emission-line ratios are presented for R1 = I(2s2p 1P-2s2 1S)/I(2s2p 3P1-2s2 1S) = I(221.12 A)/I(423.98 A) and R2 = I(2s2p 1P-2s2 1S)/I(2p2 3P2-2s2p 3P2) = I(221.12 A)/I(266.23 A), which are electron temperature and density sensitive, respectively. A comparison of these with observational data for solar flares obtained with the NRL S082A slitless spectrograph on board Skylab reveals that there is good agreement between theory and observation for R1, which provides experimental support for the accuracy of the atomic data adopted in the analysis. However the observed values of R2 all lie below the theoretical high-density limit, which may be due to blending of the 266.23 A transition with an unidentified line. Title: Low Resolution Observations of Faint Early-Type Halo Stars Authors: Keenan, F. Bibcode: 1989iue..prop.3616K Altcode: No abstract at ADS Title: B star 18 kpc above the Galactic plane. Authors: Keenan, F.; Dufton, P.; Brown, P. Bibcode: 1989Gemin..23....1K Altcode: No abstract at ADS Title: A Search for Beta Cephei Authors: Keenan, F. Bibcode: 1989iue..prop.3611K Altcode: No abstract at ADS Title: Flare activity on UV Ceti : visible and IUE observations. Authors: Phillips, K. J. H.; Bromage, G. E.; Dufton, P. L.; Keenan, F. P.; Kingston, A. E. Bibcode: 1988MNRAS.235..573P Altcode: Simultaneous far-ultraviolet (IUE) spectroscopy and optical photometry and spectrophotometry of a flare on UV Ceti are reported. The flare reached ΔU = 2 mag but showed only modest enhancements in the IUE spectra. The optical spectrophotometry indicated broadened Balmer line profiles during the flare, with Hβ and Hγ clearly showing red wings (≡100 km s-1). The results are compared with other IUE and optical observations of UV Ceti, and their solar analogues. Title: The O III 52mu.m/88mu.m emission-line ratio in planetary nebulae. Authors: Keenan, F. P.; Aggarwal, K. M. Bibcode: 1988JApA....9..237K Altcode: R-matrix calculations of electron impact excitation rates in O III are used to derive the electron-density-sensitive emission-line ratio R for a range of electron temperatures (Te = 5000 - 20,000K) and densities (Ne = 10 - 105cm-3) applicable to planetary nebulae. Electron densities deduced from the observed values of R in several planetary nebulae are in excellent agreement with those deduced from Cl III and Ar IV, which provides support for the accuracy of the atomic data adopted in the calculations. Title: Population Ratios for the Fine-Structure Ground State of O i Applicable to the Interstellar Medium Authors: Keenan, F. P.; Berrington, K. A. Bibcode: 1988ApJ...333..806K Altcode: Recent R-matrix calculations of electron excitation rates among the 2s22p4 3P fine-structure levels in O I are used to derive density-sensitive population ratios n(3P1)/n(3P2) and n(3P0)/n(3P2) for the ranges of electron and neutral hydrogen densities (ne = 10-2 - 103cm-3; nH = 0 - 1000 cm-3) applicable to H I and H II regions. The results differ significantly from those of Smeding and Pottasch and will lead to electron density estimates between 30% and a factor of 2 smaller. Title: Fine-Structure Populations for the 6D Ground State of Fe II Authors: Keenan, F. P.; Hibbert, A.; Burke, P. G.; Berrington, K. A. Bibcode: 1988ApJ...332..539K Altcode: In this paper, recent R-matrix calculations of electron impact excitation rates in Fe II are used to estimate relative level populations for the 3d6 4s 6D ground state applicable to astrophysical plasmas. The results are found to be up to a factor of two different from the earlier calculations of Nussbaumer and Story (1980). Effective collision strengths for transitions among the 3d6 4s 6D and 3d7 4F levels in Fe II are also given. Title: Theoretical Si iv line ratios compared to extreme ultraviolet solar observations Authors: Keenan, F. P.; Doyle, J. G. Bibcode: 1988SoPh..115..229K Altcode: New theoretical electron temperature sensitive emission line ratios in SiIV involving the 3d2D − 3p2P and 4s2S − 3p2P multiplets at ∼1125 and 816 Å, respectively, are derived using recent R-matrix electron excitation rate calculations. A comparison of these with observational data for a solar active region at the limb obtained with the Harvard S-055 spectrometer on board Skylab reveals that there is good agreement between theory and observation for ratios that include the 2D3/2, 5/2 − 2P3/2 transition at 1128.3 Å. This is in contrast to the findings of Keenan, Dufton, and Kingston (1986) and provides support for the atomic data adopted in the calculations. However, the 2D3/2 − 2P1/2 line at 1122.5 Å appears to be severely blended, as suggested previously by Burton and Ridgeley (1970) and Feldman and Doschek (1977), as it leads to electron temperature estimates that differ significantly from that expected in ionisation equilibrium. The fact that the I(1122.5 Å)/I(1128.3 Å) intensity ratios determined from several flare spectra are closer to theory than that for the active region indicates that the blending is probably due to species with relatively low ionization potentials, as noted by Flower and Nussbaumer (1975). Electron temperatures deduced for a sunspot are much lower than that predicted from ionisation balance calculations, in agreement with earlier results, and imply that a cooling flow may be present. Title: S vi line ratios in the Sun Authors: Keenan, F. P. Bibcode: 1988SoPh..116..279K Altcode: R-matrix calculations of electron impact excitation rates in S VI are used to determine the theoretical temperature sensitive emission line ratios and which are found to be up to 30% larger than the earlier results of Flower and Nussbaumer. A comparison of the present data with solar observations from the Harvard S-055 spectrometer on board Skylab implies that the 944.5 Å transition may be blended with lines from species with relatively low ionization potentials, in contrast to the findings of Flower and Nussbaumer. The 712.8 Å transition may also be similarly blended. Title: Comparison of Theoretical AR XV Line Strengths with SKYLAB XUV Observations of Solar Flares Authors: McCann, S. M.; Keenan, F. P.; Widing, K. G. Bibcode: 1988IrAJ...18..267M Altcode: The UV emission of the six energetically lowest LS states of AR XV has been observed in high-temperature laboratory and astrophysical plasmas. The Skylab-observed line intensity ratio I(212.12)/I(423.98) for the solar flare of August 9, 1973 is found to be within 25 percent of the theoretical value of 47.5 at the temperature of the maximum Ar XV fractional abundance in ionization equilibrium. Observational data for the ratio I(221.12)/I(266.23) are found to be inconsistent with the value of N(e) = 10 to the 11th/cu cm derived from the Ca XVII line strengths in the same flare by Keenan et al. (1988). Title: Studies of the Gas and Dust Distribution in the Local Interstellar Medium Authors: Catney, M.; Bates, B.; Keenan, F. P. Bibcode: 1988IrAJ...18..255C Altcode: Previous results on the gas and dust distribution in the local interstellar medium are discussed, with special attention given to the search for possible dust concentrations in regions of the sky containing high velocity gas components. High-resolution maps of the 4 Lac region reveal an emission feature which contains much structure, extends from the galactic plane, and is inclined at an angle of about 45 deg to the plane. An IR emission known as galactic cirrus, noted at high galactic latitudes, is suggested by Low et al. (1984) to be due to the presence of dust. Title: AR III in planetary nebulae. Authors: Keenan, F. P.; Johnson, C. T.; Kingston, A. E. Bibcode: 1988A&A...202..253K Altcode: Recent R-matrix calculations of electron impact excitation rates in Ar III are used to derive the theoretical temperature sensitive ratio R = I(3P1,2-1D2)/I(1D2-1S0) = I(7135 Å+7751 Å)/I(5192 Å). Electron temperatures estimated from the observed values of R in planetary nebulae are in good agreement with those deduced from O III. In addition, Ar III abundances determined from the 3P2-1D2 and 3P2-3P1 transitions at 7135 Å and 9 μm respectively are consistent, in contrast to results found using the excitation rates of Krueger and Czyzak. Title: An abundance and kinematical analysis of four early-type high latitude stars. Authors: Conlon, E. S.; Brown, P. J. F.; Dufton, P. L.; Keenan, F. P. Bibcode: 1988A&A...200..168C Altcode: Stellar absorption line profiles and equivalent widths are measured from high resolution INT and AAT optical spectra of four high galactic latitude targets and used in conjunction with model atmosphere codes to determine their atmospheric parameters and chemical compositions. Normal Population I abundances are derived, with typical errors of ±0.2 dex, implying z-distances in the range 1 - 2 kpc. Various explanations for the existence of such stars so far from the galactic plane are discussed, the most likely mechanism being cluster ejection. Title: Iras maps for a region of sky containing nearby high-velocity gas, identified from IUE spectra Authors: Bates, B.; Catney, M. G.; Keenan, F. P. Bibcode: 1988Ap&SS.146..195B Altcode: Detailed IRAS contour maps in the 60 and 100 μm wavebands are presented for a small region of sky towards which ‘high-velocity gas components’ (HVC) have been clearly identified in spectra of background stars obtained with the IUE satellite. There is a coincidence in direction on the sky between the strongest regions of absorption produced by HVC gas and compact regions of brightest IR emission. However, there is no clear evidence at present for identifying the HVC directly with the IR emission due to insufficient spatial informatin along the lines-of-sight examined. A comparison of Hi column densities obtained from both the 100 μm emission and colour excess data indicates that dust emission, rather than atomic line emission, is the dominant contribution to the IRAS observations in the sightlines considered. The angular sizes of the brightest IR emitting regions are small and are of approximate dimensions ∼0.5×0.3 pc2 if located at a distance ∼220 pc estimated for the HVC gas. Title: Chromospheric mass motions during a flare on UV Ceti Authors: Phillips, K. J. H.; Bromage, G. E.; Dufton, P. L.; Keenan, F. P.; Kingston, A. E. Bibcode: 1988ESASP.281a.311P Altcode: 1988uvai....1..311P; 1988IUES....1..315P; 1988IUE88...1..311P Simultaneous optical and IUE observations of a flare on UV Ceti in 1980 are reported. The IUE spectra show only slight increase of C IV line emission. The optical spectrophotometric observations show, from Balmer line profiles, turbulent broadening in quiescent and flare spectra, and downward-directed flow (of 100 km/sec) during the flare. The latter is particularly reminiscent of solar flares, and probably arises from the formation of a chromospheric condensation, as modeled for solar flares. Title: S XV Emission-Line Ratios in the Sun Authors: McCann, S. M.; Keenan, F. P. Bibcode: 1988ApJ...328..344M Altcode: Recently calculated electron impact collision rates for S xv are used to derive the electron temperature sensitive emission-line ratio G = x + y + z/w, where z is the forbidden 1s21S-1s2s 3S, w is the resonance 1s2 1S-1s2p 1P and x and y, the intercombination 1s2 1S-1s2p 3P2 and 1s2 1S-1s2p 3P1 transitions, respectively. The value of R = z/x + y, the electron density sensitive ratio, was also calculated in its low-density limit (Ro), and both are plotted as functions of the electron temperature. These are found to be in much better agreement with the observed values of Ro and G obtained by the Flat Crystal Spectrometer on the Solar Maximum Mission satellite for the 1980 November 5 flare than are the previous results of Pradhan and Shull (1981). This improvement provides support for the methods and the atomic data adopted in our calculations. Title: CA XV Line Ratios in Solar Flares Authors: Keenan, F. P.; Aggarwal, K. M.; Berrington, K. A.; Widing, K. G. Bibcode: 1988ApJ...327..473K Altcode: Recent R-matrix calculations of electron impact excitation rates for Ca XV have been used to obtain theoretical density-sensitive emission line ratios which are applicable to solar flares. Results for electron densities derived from the I(208.71 A)/I(200.95 A), I(181.90 A)/I(200.95 A), and I(215.37 A)/I(200.95 A) values for solar flares obtained by the Skylab NRL S082A slitless spectrograph are in excellant agreement. Ca XV electron densities are found to compare favorably with those determined from the line ratios of ions formed at similar electron temperatures. The results provide support for the accuracy of the adopted atomic data and for the line ratio calculation method. Title: EUV emission line ratios for Si IV in the solar transition region. Authors: Keenan, F. P.; Doyle, J. G. Bibcode: 1988JPhys..49..227K Altcode: 1988IAUCo.102..227K Theoretical electron temperature sensitive emission line ratios in Si IV involving the 3d 2D - 3p 2P and 4s 2S - 3p 2P multiplets at ≡1125 Å and 816 Å respectively are derived using R-matrix electron excitation rate calculations. A comparison of these with observational data for a solar active region obtained with the Harvard S-055 spectrometer on board Skylab reveals that there is good agreement between theory and observation for the ratio that includes the 2D3/2,5/2 - 2P3/2 transition at 1128.3 Å. Title: The comparison of helium-like ion emission line ratios with solar X-ray spectral data. Authors: McCann, S. M.; Keenan, F. P. Bibcode: 1988JPhys..49..331M Altcode: 1988IAUCo.102..331M Electron impact excitation rates recently calculated by Keenan, McCann and Kingston for transitions in the He-like ions Al XII, Si XIII and S XV are used to derive the electron temperature sensitive emission line ratio G and the density sensitive ratio R in its low density limit (R0). These ratios are compared with those calculated by other authors and with the values obtained for solar flares using instruments on board the P78-1 and Solar Maximum Mission satellites. Title: High-Resolution Spectroscopy of Astronomical Objects Authors: Keenan, F. P. Bibcode: 1988IrAJ...18..161K Altcode: This paper reviews recent advancements in the main astrophysics research interest of the Physics Department at QUB, that of high-resolution spectroscopy of astronomical objects. The major areas of study are early-type stars, the interstellar medium and emission-line regions of Seyfert galaxies and planetary nebulae. These are discussed separately in detail. Title: Theoretical Emission Line Strengths for the Beryllium-Like Ion Sxiii Compared to Extreme Ultraviolet Observations of Solar Flares Authors: Keenan, F. P.; McCann, S. M.; Widding, K. G. Bibcode: 1988SoPh..117...69K Altcode: A comparison of Skylab S082A observations for several solar flares with calculations of the electron temperature sensitive emission line ratio R1 = I(2s2p1P − 2s21S)/I(2s2p3P1 - 2s21S) = = I(256.68 Å)/I(491.45 Å) in Be-like SXIII reveals good agreement between theory and experiment, which provides observational support for the accuracy of the adopted atomic data. However, observed values of the electron density sensitive ratio R2 = I(2s2p1P − 2s21S)/I(2p23P2 - 2s2p3P2) = = I(256.68 Å)/I(308.96 Å) all lie below the theoretical high density limit, which is probably due to blending in the 308.96 Å line. Title: Interstellar CA II absorption towards early-type stars at high galactic latitudes. Authors: Keenan, F. P.; Conlon, E. S.; Brown, P. J. F.; Dufton, P. L. Bibcode: 1988A&A...192..295K Altcode: New high resolution AAT and INT observations of the Ca II 3933 Å interstellar line towards nine early-type stars at high galactic latitudes are presented. These are combined with the authors' earlier AAT data to investigate the distribution of Ca II in the galactic halo. A comparison of these results with Ca II equivalent widths for extragalactic sightlines implies that there is a significant amount of this ion out to z ≅ 1 kpc, but not much beyond z ≅ 2 kpc. No coincident high velocity Ca II absorption is detected in the spectra of stars near known high velocity clouds (HVC). Although this may indicate that the HVCs are either at greater distances than the stars or have angular extents smaller than the separations of the stellar and HVC sightlines, it is also possible that they are nearby but contain too little Ca II to produce an observable absorption line. Title: Electron Density Diagnostics for Late-Type Stellar Atmospheres Authors: Keenan, F. P.; Dufton, P. L.; Aggarwal, K. M.; Kingston, A. E. Bibcode: 1988ApJ...324.1068K Altcode: R-matrix calculations of electron excitation rates in C III, O III, and Si IV have been used to obtain several theoretical emission-line ratios for a range of electron temperatures and densities applicable to late-type stellar atmospheres. Data are derived for the ratios I(C III 1908 A)/I(O III 1666 A), I(O III 1666 A)/I(Si IV 1402 A), and I(C III 1908 A)/I(Si IV 1402 A). It is suggested that differences found between the results and those of Doschek et al. (1978) are due to the present adoption of improved atomic data. Title: Electron impact excitation rates for transitions in beryllium-like P XII, S XIII, Cl XIV, Ar XV and K XVI Authors: Keenan, F. P. Bibcode: 1988PhyS...37...57K Altcode: The R-matrix electron excitation rates determined by Berrington et al. (1985) for C III, O V, Ne VII, and Si XI and by Dufton et al. (1983) for Ca XVII are used to interpolate the rates for Be-like P XII, S XIII, Cl XIV, Ar XV, and K XVI. The results are presented in a series of tables and briefly characterized. The accuracy of the present findings is estimated as + or - 10 percent within 0.8 dex of log Tmax, where Tmax is the temperature of maximum fractional abundance for ionization equilibrium. The applicability of the results to the diagnostics of astrophysical and laboratory plasmas is indicated. Title: High Resolution Observations of Early-Type Halo Stars PHL 1580 Authors: Keenan, F. Bibcode: 1988iue..prop.3215K Altcode: No abstract at ADS Title: Emission-Line Ratios for O III in Gaseous Nebulae and a Comparison between Theory and Observation Authors: Keenan, F. P.; Aggarwal, K. M. Bibcode: 1987ApJ...319..403K Altcode: Recent R-matrix calculations of electron excitation rates in O III are used to derive electron temperature and density-sensitive emission-line ratios R1 = I(2322 A)/I(1661 A + 1667 A), R2 = I(1661 A + 1667 A)/I(4960 A + 5009 A), and R3 = I(4363 A)/I(4960 A + 5009 A) for a range of Te (7500-40,000 K) and Ne 10 to the 2nd to 10 to the 7th/cu cm applicable to gaseous nebulae. Electron temperatures and densities deduced from these and observed values of R1, R2, and R3 for several planetary nebulae and a Seyfert galaxy in general show good internal agreement and also compare favorably with results deduced from the line ratios of other species, thereby providing support for the atomic data adopted in the calculations. Title: NE IX Emission-Line Ratios in Solar Active Regions Authors: Keenan, F. P.; McKenzie, D. L.; McCann, S. M.; Kingston, A. E. Bibcode: 1987ApJ...318..926K Altcode: Emission-line ratios for Ne IX are derived and compared with observational data for solar active regions obtained with the SOLEX B spectrometer on the P78-1 satellite. Excellent agreement is obtained, providing support for the atomic data adopted in the calculations and resolving discrepancies between existing theoretical calculations and solar data. The calculated R-ratio for the low-density limit agrees well with the SOLEX observations. Title: Relative emission line strengths for Fe VII in astrophysical plasmas. Authors: Keenan, F. P.; Norrington, P. H. Bibcode: 1987A&A...181..370K Altcode: Recent R-matrix calculations of electron impact excitation rates in Fe VII are used to derive relative emission line strengths for a range of electron temperatures (Te of between 8000 and 120,000 K, inclusively) and densities (Ne of between 10 to the 4th/cu cm and 10 to the 10th/cu cm, inclusively) applicable to gaseous nebulae. The results are found to be significantly different from those of Nussbaumer and Storey (1982), especially at low temperatures. Title: A search for far-infrared (IRAS) emission from early-type stars at high galactic latitudes. Authors: Keenan, F. P.; Conlon, E. S.; Brown, P. J. F. Bibcode: 1987A&A...178..317K Altcode: Recently Lamers et al. (1986) have found that HR 4049 (B supergiant at z = 1300 pc) is surrounded by a dust cloud which produces a large IR excess, from which it is inferred that the star may be a much less luminous low mass object close to the Galactic plane. Here, the results of a search for strong FIR (IRAS) emission from a sample of early-type high-Galactic-latitude stars, estimated to be at z-distances of up to 9000 pc from optical spectral analyses, are reported. No IR emission was detected for any of the stars investigated, which would not be expected if they were nearby objects with dust clouds. It is therefore concluded that they are normal stars at the large distances previously estimated. Title: Non-LTE abundance analysis of the early-type high galactic latitude star HD 100340. Authors: Keenan, F. P.; Brown, P. J. F.; Conlon, E. S.; Dufton, P. L.; Lennon, D. J. Bibcode: 1987A&A...178..194K Altcode: Stellar equivalent widths and line profiles, measured from high resolution AAT and IUE spectra, are used in conjunction with non-LTE and LTE model atmosphere calculations to estimate the atmospheric parameters and chemical composition of the early-type high galactic latitude star HD 100340. The effective temperature (Teff= 25000K), surface gravity (log g = 3.8) and abundances of He, C, O, Al, Si, and Fe are similar to those of Population I OB stars, from which it is concluded that HD 100340 is a normal star at a distance from the galactic plane of z = 4.6±0.8 kpc. Several possible explanations for the existence of this star at such a large z-distance are discussed, including ejection from the galactic plane and formation in the halo. Title: The SI III 1892 A/C III 1908 A emission-line ratio in late-type stars Authors: Keenan, F. P.; Kingston, A. E.; Dufton, P. L. Bibcode: 1987MNRAS.225..859K Altcode: Theoretical values of the density-sensitive emission-line ratio R = I(Si III 3s21S-3s3p3P1)/I(C III 2s21S-2s2p3P1 = I(1892 Å)/I(1908 Å) are presented for a range of electron densities (108 ≤ Ne ≤ 1013cm-3) applicable to late-type stellar atmospheres. These results differ from the earlier calculations of Doschek et al. and Cook & Nicolas, mainly due to the improved electron excitation rates for Si III adopted in the present analysis. Title: Theoretical emission line ratios for Si XIII compared to solar observations Authors: McCann, S. M.; Keenan, F. P. Bibcode: 1987SoPh..112...83M Altcode: The electron collision excitation rates recently calculated for transitions in Si XIII by Keenan et al. (1987) are used to derive the electron temperature sensitive ratio G(=(f + i)/r and the density sensitive ratio R(=f/i), where i, f, and r are the intercombination (1s21S − 1s2p3P1, 2) forbidden (1s21S − 1s2s3S), and resonance (1s21S − 1s2p1P), transitions respectively. Also estimated are the values of R in the low-density limit (R0) as a function of electron temperature. The theoretical G ratio at the temperature of maximum emissivity for Si XIII, G(Tm) = 0.70, is in much better agreement with the observed G for the 1985, May 5 flare determined by McKenzie et al. (G = 0.60 ± 0.07) than is the earlier calculation of Pradhan, who derived G(Tm) = 0.85. The error in the observed R0 ratio is so large that both our result and Pradhan's fall within the acceptable limits of uncertainty and hence one cannot estimate which of the two is the more accurate. Title: Al XII line ratios in the Sun Authors: Keenan, F. P.; McCann, S. M. Bibcode: 1987SoPh..109...31K Altcode: Recent calculations of electron impact excitation rates in He-like AlXII are used to derive the theoretical electron temperature and density sensitive emission line ratios G ( = (f + i)/r and R ( = f/i, where f, i, and r are the forbidden 1s21S − 1s2s3S, intercombination 1s21S − 1s2p3P and resonance 1s21S − 1s2p1P transitions, respectively. These ratios are found to be significantly different from earlier calculations, and are in much better agreement with X-ray spectral data for two solar flares obtained with the SMM and P78-1 satellites. Title: Relative emission line strengths for the sodium-like ions AL III and SI IV in the sun Authors: Keenan, F. P.; Dufton, P. L.; Kingston, A. E. Bibcode: 1986A&A...169..319K Altcode: Recent R-matrix calculations of electron excitation rates for the Na-sequence ions Al III and Si IV are used to determine theoretical emission line ratios applicable to the solar transition region. A comparison of the Al III results with high resolution (≅0.06 Å) solar data obtained with the NRL S082-B spectrograph on board Skylab shows reasonable agreement between theory and observations. However a similar analysis for Si IV using low resolution (≅2 Å) EUV satellite spectra for the quiet sun and an active region reveals that the calculations and observational data are incompatible. It is shown that this is probably due to the Si IV 3d2D3/2 - 3p2P1/2 and 3d2D3/2,5/2 - 3p2P3/2 transitions at 1122.5 Å and 1128.3 Å respectively being blended with lines arising from ions with relatively low ionization potentials. Title: The variation of interstellar element abundances with hydrogen density Authors: Keenan, F. P.; Dufton, P. L.; Hibbert, A.; Murray, M. J. Bibcode: 1986MNRAS.222..143K Altcode: The variation of the interstellar nitrogen, oxygen and magnesium abundances with mean line-of-sight density >nH< is analysed in terms of a two-component model first employed by Jenkins, Savage and Spitzer (1986), which consists of warm, low-density neutral gas and cold clouds. In all cases the gas-phase abundances have been deduced using reliable oscillator strengths specifically calculated for this purpose. Depletions in the warm and cold gas, denoted Dw and Dc respectively, are derived from non-linear least-squares fits to the data. Values of Dw for the species considered are found to be small (≅0.1 dex), consistent with the low reddening and hence grain content in such sight-lines. Title: Evidence for Recent Star Formation in the Galactic halo Authors: Keenan, F. P. Bibcode: 1986IrAJ...17..483K Altcode: Observational data for PHL 346 obtained with the 2.5 m Issac Newton telescope on August 1985 are studied. Measured stellar Stromgren colors, hydrogen-line profiles, and helium and metal-line equivalent widths are compared with those predicted by local thermodynamic equilibrium model-atmosphere calculations. Effective temperature, surface gravity, microturbulent velocity, and helium and metal abundances for the star are derived. A mass of 13 + or - 2 solar masses, a lifetime of 11 x 10 to the 6th yr, a distance from the galactic plane of 8.7 + or - 1.5 kpc, and a velocity in the z direction of +56 + or - 10 km/s are calculated for the star. The data reveal that the star was not ejected from the galactic plane, but that it formed out of galactic fountain gas at about 6 kpc from the disc. Title: IUE and optical studies of nearby interstellar gas Authors: Keenan, F. P.; Bates, B.; Catney, M. G. Bibcode: 1986ESASP.263..565K Altcode: 1986NIA86......565K; 1986niia.conf..565K Red-shifted high velocity interstellar gas components with velocities up to ≅100 km s-1 have been detected in the IUE spectra of several stars in the Galactic direction l ≅ 100°, b ≅ -7°. These are compared with complementary high resolution optical observations of the NaD interstellar lines, which allow the distribution of the gas to be mapped more extensively than in earlier surveys. New calculations of the temperature sensitive N(Mg I)/N(Na I) ratio are presented, and used in conjunction with the UV results to partially derive physical conditions within several of the high velocity clouds. Title: The abundance of phosphorus in the interstellar medium. Authors: Dufton, P. L.; Keenan, F. P.; Hibbert, A. Bibcode: 1986A&A...164..179D Altcode: New oscillator strengths for P II resonance transitions are used in conjunction with published Copernicus observations to derive P II column densities toward 51 stars. It is found that phosphorus is: (a) undepleted along sightlines containing predominantly low density neutral gas and (b) depleted by approximately 0.5 dex in cold clouds. These results differ from the recent analysis of Jenkins et al., principally due to changes in the atomic data but also due to a consequential decrease in estimated b-values. The reliability of other atomic data currently adopted in analyses of interstellar observations is also briefly discussed. Title: A Model Atmosphere Analysis of the Faint Early-Type Halo Star PHL 346 Authors: Keenan, F. P.; Lennon, D. J.; Brown, P. J. F.; Dufton, P. L. Bibcode: 1986ApJ...307..694K Altcode: Stellar equivalent widths and hydrogen line profiles, measured from high-resolution optical spectra obtained with the 2.5 m Issac Newton Telescope, are used in conjunction with model atmosphere calculations to determine the atmospheric parameters and chemical composition of the faint, high galactic latitude early-type star PHL 346. The effective temperature (Teff = 22,600 + or - 1000 K) and surface gravity (log g = 3.6 + or - 0.2), as well as the chemical composition, are found to be similar to those of normal OB stars. Therefore, it is concluded that PHL 346 is an ordinary Population I object, at a z distance of 8.7 + or - 1.5 kpc. The relatively small stellar velocity in the z-direction (Vz = +56 + or - 10 km/s) then implies that PHL 346 must have been formed in the halo, possibly from galactic fountain material at a z distance of about 6 kpc. Title: The chemical composition of six southern clusters and associations. Authors: Brown, P. J. F.; Dufton, P. L.; Lennon, D. J.; Keenan, F. P. Bibcode: 1986MNRAS.220.1003B Altcode: Seventy-one early-type main-sequence stars have been observed spectroscopically in five southern galactic clusters and a loose association. Hydrogen-line profiles and helium-diffuse-line equivalent widths have been measured for all stars, together with line strengths for metal and helium nondiffuse lines in 27 stars with small projected rotational velocities. Stromgren photometry has been obtained for stars where previous results do not exist, and effective temperatures have been determined from the index. Surface gravities have been estimated primarily from theoretical profiles fitted to the H-delta absorption line, and also from H-beta photometry. Abundances, deduced from comparison with LTE and non-LTE model-atmosphere calculations, are generally found to be consistent with a normal early-type stellar composition. Title: An approximate calculation of the effect of opacity on SI III emission line ratios near the solar limb Authors: Keenan, F. P.; Kingston, A. E. Bibcode: 1986MNRAS.220..493K Altcode: The present analysis of the Si III spectrum obtained by the Skylab spectrograph as the slit was stepped across the solar disk, and out above the limb, interprets the ratio between a pair of these lines to be due to the effect of opacity; its variation is consistent with a simple model for the atmosphere, allowing the calculation of optical depths for several of the Si III transitions at the limb and solar center. The results obtained are noted to compare well with those estimated on the basis of the solar model D or Gabriel (1976). An effective thickness for the Si III-emitting region of the solar atmosphere is calculated to be 26 km, in excellent agreement with the 22-km value deduced from Gabriel's solar transition region model D. Title: Fine-structure population ratios for the 2P ground state of C II Authors: Keenan, F. P.; Lennon, D. J.; Johnson, C. T.; Kingston, A. E. Bibcode: 1986MNRAS.220..571K Altcode: Results of R-matrix calculations of electron excitation rates for the 2s22p2P1/2-2s22p2P3/2 fine-structure transition in C II are used to derive density sensitive population ratios n(2s22p2P3/2)/n(2s22p2P1/2) for the ranges of electron and neutral hydrogen densities (ne= 10-3 - 103cm-3; nH= 0 - 1000 cm-3) applicable to H I and H II regions. These are found to differ significantly from the earlier calculations of Smeding & Pottasch, and lead to electron density estimates between 40 and 60 per cent smaller. Title: Theoretical Ne v emission line ratios compared to solar observations Authors: Keenan, F. P.; Aggarwal, K. M.; Widing, K. G. Bibcode: 1986SoPh..105...47K Altcode: The recent level population calculations for Ne v by Aggarwal are used to determine the theoretical emission line ratios R1 = I(2s2p31Do - 2s22p21De)/I(2s2p33D20- 2s22p23P1e) and R2 = I(2s2p31Do-2s22p21De)/I(2s2p33D30-2s22p23P2e). A comparison of these with observational data for a solar flare and erupting prominence obtained with the NRL XUV spectrograph on board Skylab reveals that R1 and R2 are in their predicted high density limits. Although the ratios cannot be used as density diagnostics for values of ne typical of the solar transition region, it is shown that they are temperature sensitive and hence may be employed to determine the electron temperatures of Ne v line emitting regions. Title: The Derivation of Solar Coronal Electron Temperature from the 1 1S--n 1P/1 1S--2 1P Emission-Line Ratios in MG XI Authors: Keenan, F. P.; Kingston, A. E.; McKenzie, D. L. Bibcode: 1986ApJ...303..486K Altcode: Recent R-matrix calculations of electron excitation rates for transitions in Mg XI are used to determine the theoretical emission-line ratios as a function of electron temperature. These are found to be more temperature sensitive than the normal diagnostic for He-like ions, by factors of approximately 2.6 and 5.9 respectively, between Te = 1 × 106 K and 1 × 1O7 K. Electron temperatures deduced from R1, and R2 ratios observed by the P78-1 satellite for solar flares and active regions are in excellent agreement with those previously determined by other methods. Title: Plasma densities from the He-like ion NE IX Authors: Doyle, J. G.; Keenan, F. P. Bibcode: 1986A&A...157..116D Altcode: The authors present line emissivity data for the three principal lines of the He-like ion Ne IX. This data is compared with high resolution solar flare observations from the Solar Maximum Mission. During the rise phase of flares it is shown that the forbidden line is blended with a high temperature line, as opposed to the intercombination line suggested by McKenzie (1985). It is suggested that the electron density during the rise phase of flares be determined from the intercombination to resonance line ratio which the authors have integrated over a multi-thermal plasma and is shown to be only slightly dependent on the assumed differential emission measure distribution. Scattering of resonance line photons from the line-of-sight is shown to be unimportant. Title: Mg vii and Si ix line ratios in the sun Authors: Keenan, F. P.; Kingston, A. E.; Aggarwal, K. M.; Widing, K. G. Bibcode: 1986SoPh..103..225K Altcode: Recent R-matrix calculations of electron excitation rates for Mg VII and Si IX are used to determine the theoretical density sensitive emission line ratios R1= I(2s2p31D0 - 2s22p21De)/I(2s2p33S0 - 2s22p23P2e) and R2= I(2s2p31P0 - 2s22p21De)/I(2s2p33S0 - 2s22p23P2e). These are found to be quite similar to the earlier results of Mason and Bhatia. Electron densities derived using observed R1 and R2 ratios from Skylab NRL XUV spectra of solar flares and active regions are in good agreement, and compare favourably with those deduced from ions formed at similar electron temperatures to Mg VII and Si IX. Title: Observations of early-type stars at high galactic latitudes. Authors: Keenan, F. P.; Brown, P. J. F.; Lennon, D. J. Bibcode: 1986A&A...155..333K Altcode: Using equivalent widths and line profiles measured from high resolution AAT spectra in conjunction with model atmosphere calculations, it is shown that a sample of eleven high galactic latitude early-type stars are normal, distant objects. Stellar velocities in the z-direction determined from the spectra, coupled with the galactic gravitational field g(z), allow the times the stars would have taken to reach their present positions if they were ejected from the disc to be derived. A comparison of these times with the evolutionary ages indicate that at least four of the stars have been formed in situ, possibly from galactic fountain material. Title: S V Line Ratios in the Sun Authors: Dufton, P. L.; Hibbert, A.; Keenan, F. P.; Kingston, A. E.; Doschek, G. A. Bibcode: 1986ApJ...300..448D Altcode: In the present prediction of level populations and emission line intensity ratios for electron densities and temperatures appropriate to the sun, on the basis of new atomic data for S V, the electron impact collision rates for spin-forbidden transitions, and the intercombination transition spontaneous radiative rate, are noted to be substantially larger than previously ascertained. The S V intensity ratio is shown to be a useful electron density diagnostic for log N(e) greater than 11.5 ratios deduced from observations obtained with a slit spectrograph aboard Skylab generally agree with the theoretical values presented. Title: Possible effects of organelle charge and density on cell metabolism Authors: Bates, B.; Catney, M. G.; Keenan, F. P. Bibcode: 1986AdSpR...6b..47B Altcode: 1986AdSpR...6...47B To respond to gravity a biological system must: First, perceive the stimulus; and, second transduce the stimulus into an appropriate response. This laboratory has studied a system of perception and transduction involving the gravity-induced asymmetric distribution of a plant growth hormone. From these studies we have developed a working theory which states as its postulates that: a) The perception of the gravitational stimulus involved a perturbation of the plant's bio-electric field; and b) that the transduction of the stimulus involved voltage-gating of hormone movement from the plant's vascular tissue into the hormone responsive growing tissue. These studies may provide the simplest system for studing the mechanism whereby the gravity signal is translated into a biological response.

Present Address: Plant Breeding Institute, 62-095 Morowana Goslina, Przebedowo - 7, woj. Poznan, POLAND Title: The chemical composition of the young open cluster NGC 6611. Authors: Brown, P. J. F.; Dufton, P. L.; Lennon, D. J.; Keenan, F. P.; Kilkenny, D. Bibcode: 1986A&A...155..113B Altcode: Four color photometric and spectroscopic observations for eight early-type main sequence stars in the cluster NGC 6611 were obtained at the South African and Anglo-Australian observatories. Equivalent widths and line profiles were measured for lines of hydrogen, helium and seven other elements present in the spectra of five stars. Effective temperatures were derived from ionization equilibria while surface gravities were estimated from profiles fitted to H-delta and H-epsilon absorption lines. Abundances, deduced from comparison with LTE and non-LTE model atmosphere calculations are found to be consistent with normal early-type stellar abundances. NGC 6611 lies at a distance of approximately 1 kpc from NGC 6231, whose early-type main sequence stars possibly exhibit an underabundance in nitrogen. Hence the present study implies the possibility of abundance variations over relatively small distance scales. Title: Improved theoretical line ratios for C iii in the Sun Authors: Keenan, F. P.; Berrington, K. A. Bibcode: 1985SoPh...99...25K Altcode: The recent twelve-state R-matrix calculations of electron excitation rates in CIII by Berrington are used to derive level populations applicable to the solar transition region. Line ratios R = I(2p2 3Pe - 2s2p3P°)/I(2s2p1P° - 2s2 1Se) and R2=I(2p2 1Se - 2s2p1P°)/I(2p2 3Pe - 2s2p3P°) deduced from these data in conjunction with the relevent transition probabilities are found to be in much better agreement with the observed quiet Sun values than those determined from the level population calculations of Keenan et al. Title: Population ratios for the fine structure ground state of SI II applicable to the interstellar medium Authors: Keenan, F. P.; Johnson, C. T.; Kingston, A. E.; Dufton, P. L. Bibcode: 1985MNRAS.214P..37K Altcode: Using recent R-matrix calculations of electron excitation rates for the 3s23p2P1/2-3s23p2P3/2 fine structure transition in Si II, the electron density sensitive population ratio n(2P3/2)/n(2P1/2) has been derived for the ranges of temperature (100 - 20000K) and hydrogen density (0 - 1000 cm-3) applicable to H I and H II regions. The results differ appreciably from those of Smeding & Pottasch, and lead to electron density estimates approximately 30 to 40 per cent larger. Title: The abundance of oxygen in the interstellar medium. Authors: Keenan, F. P.; Hibbert, A.; Dufton, P. L. Bibcode: 1985A&A...147...89K Altcode: O I equivalent widths observed by the Copernicus satellite and Doppler widths determined from curves-of-growth for weak N I lines are used to rederive column densities towards 26 early-type stars. Oxygen is found to have a mean abundance of approximately 50 percent of its solar value towards both reddened and unreddened stars. In addition, there appears to be no correlation between depletion and total hydrogen column density, in contrast to the results of York et al. (1983), who found a greater depletion for sightlines with a log of the total hydrogen column density of less than 20.5. Title: Oscillator strengths for transitions in N I and the interstellar abundance of nitrogen. Authors: Hibbert, A.; Dufton, P. L.; Keenan, F. P. Bibcode: 1985MNRAS.213..721H Altcode: Oscillator strengths based on configuration interaction wavefunctions are presented for both optically allowed and forbidden transitions in N I. Particular attention is given to the multiplets at 951 Å (2p3 4S-2p23d2D), 952 Å (2p3 4S-2p23d4D) and 1160 Å (2p3 4S-2p23s2P) which have been extensively observed by the COPERNICUS satellite. For these transitions, the radiative rates are estimated to have an accuracy of 20 per cent or better. A re-analysis of the COPERNICUS observational data indicates there is no depletion of nitrogen towards reddened stars. Possible causes of a small depletion (≅0.2 dex) towards several nearby unreddened stars are discussed. Title: The l(1)S-n(1)P/1(1)S-2(1)P emission-line ratios in O VII as temperature diagnostics for solar flares and active regions Authors: Keenan, F. P.; Kingston, A. E.; McKenzie, D. L. Bibcode: 1985ApJ...291..855K Altcode: Recent R-matrix calculations of O VII electron excitation rates by Tayal and Kingston are used to determine the theoretical emission-line ratios R1 = I(1s2 1S-ls3p1P)/I(1s2 1S-ls2p1P) and R2 = I(1s2 1S-ls4p1P)/ I(1s2 1S-ls2p1P). These ratios are found to vary by factors of 3.3 and 4.9, respectively, between Te = 6 x 1O5 and 2 x 106 K. However, G = [I(1s2 1S-1s2s3S) + I(1s2 1S-ls2p3P)]/I(1s2 1S-ls2p1P), a commonly used temperature diagnostic for He-like ions, only varies by a factor of 1.8. Electron temperatures derived using observed values of R1 and R2 from P78-1 satellite spectra of solar flares and active regions are in good agreement and compare favorably with those deduced from G. Title: The Interstellar Abundance of Nitrogen Authors: Keenan, F. P.; Hibbert, A.; Dufton, P. L. Bibcode: 1985IrAJ...17...20K Altcode: Interstellar nitrogen abundances toward 25 stars are determined on the basis of the N I equivalent widths of Bohlin et al. (1983) and the oscillator strengths calculated by Hibbert et al. (1985) using configuration-interaction wavefunctions. The results are presented in tables and compared to those obtained by York et al. (1983) using oscillator strengths deduced for the observed curves of growth of other N I lines. N I is found to be undepleted toward reddened and moderately reddened stars, in agreement with theoretical models of nitrogen formation and adhesion into grains or grain surfaces in the interstellar medium and in disagreement with the finding of depletion by Ferlet (1981) and York et al. (1983). Toward unreddened stars, a depletion of 0,2 dex is attributed to contamination of Lyman-alpha lines by stellar absorption, to systematic errors in the data observations or the oscillator strengths, or to the presence of N-depleted matter toward these objects. Title: The masses of early-type stars in the galactic halo determined from ultraviolet resonance line profiles. Authors: Keenan, F. P.; Dufton, P. L. Bibcode: 1984A&A...139..227K Altcode: Terminal velocities for stellar winds in intermediate and high galactic latitude OB stars have been determined from high resolution IUE ultraviolet spectra. These velocities, together with previous estimates, have been used to deduce stellar masses which are found to be similar to those derived from conservative and non-conservative evolutionary tracks for Population I stars. It is therefore concluded that the stars are not subluminous, nearby objects but are normal and at the large z-distances calculated by previous authors. Title: Mg ix and Si xi line ratios in the sun Authors: Keenan, F. P.; Kingston, A. E.; Dufton, P. L.; Doyle, J. G.; Widing, K. G. Bibcode: 1984SoPh...94...91K Altcode: New theoretical emission line ratios for the Be-sequence ions MgIX and SiXI are presented. A comparison with observational data for two solar flares and an active region loop obtained with the Harvard EUV spectrometer and NRL XUV spectroheliograph aboard Skylab reveals that these plasmas are in ionization equilibrium at coronal temperatures. Unfortunately most of the density diagnostics are not particularly useful under solar plasma conditions, as they vary only slightly over the electron density range 108-1013cm−3. However the SiXI ratioI(3Pe2 -3Po2)/I(3Po1 -1Se0) is density sensitive in the range 108 to 1010cm−3, which is representative of electron densities found in solar active regions or small flares. Title: Theoretical Ne ix line ratios compared to solar observations Authors: Keenan, F. P.; Tayal, S. S.; Kingston, A. E. Bibcode: 1984SoPh...94...85K Altcode: R-matrix calculations of the 11S - 23S and 11S - 23P electron excitation rates in He - like CV, OVII, and MgXI by Kingston and Tayal are used to interpolate results for NeIX. Adoption of these in emission line strength calculations leads to values for the density-sensitiveR ratio very similar to those of Pradhanet al. and Wolfsonet al., although the temperature-sensitiveG ratios are approximately 10 to 20 % lower than those deduced by these authors. However the present theoretical value ofG at the temperature of maximum NeIX emission,G(Tm) = 0.82, is in excellent agreement with those observed by the SMM and P78-1 satellites for the 1980, November5 flare (G = 0.83 ± 0.01) and nonflaring active regions (G = 0.80 ± 0.05), respectively. Title: SI III emission line strengths in low density plasmas. Authors: Dufton, P. L.; Keenan, F. P.; Kingston, A. E. Bibcode: 1984MNRAS.209P...1D Altcode: Theoretical emissivity ratios appropriate to homogeneous optically thin plasmas are presented for the Si III lines at 1883 and 1892 Å. These lines are a useful density diagnostic for Ne ≥ 104cm-3, their use being illustrated for the planetary nebulae NGC 7662 and V1016 Cygni. Title: Further studies of nearby high velocity interstellar gas. Authors: Bates, B.; Brown-Kerr, W.; Giaretta, D. L.; Keenan, F. P. Bibcode: 1984ESASP.218..145B Altcode: 1984iue..conf..145B Red shifted high velocity gas components (HVC) were detected in spectra of nine out of a survey of 47 stars. The properties of gas density and thickness of the material responsible for the HVC appear quite similar to those derived from direct observations of supernova remnants (SNR). The majority of the survey stars whose spectra show HVC lie close to the Galactic plane near l = 88 to 110 deg. A distance estimate places the HVC material within 190 pc. The improved mapping of the sky and the distance estimate to the HVC material are discussed in terms of an association with nearby radio loops. The possibility that the material may be produced by two interacting SNR (Loops 2 and 3) is considered. Title: Observational evidence for non-Maxwellian electron energy distributions in the solar transition region Authors: Dufton, P. L.; Kingston, A. E.; Keenan, F. P. Bibcode: 1984ApJ...280L..35D Altcode: Calculations of Si III emission-line strengths, which incorporate the non-Maxwellian electron energy distributions given by Shoub, are compared with Skylab observations for the quiet Sun and a solar flare. The good agreement provides plausible evidence for the existence of such electron energy distributions in the lower solar transition region. Title: Theoretical emission line ratios for O VII in low-density plasmas. Authors: Keenan, F. P.; Tayal, S. S.; Kingston, A. E. Bibcode: 1984SoPh...92...75K Altcode: New electron excitation rates for O VII calculated by Tayal and Kingston using the R-matrix method are used to determine theoretical emission line strengths. Values of the electron density sensitive ratio R (forbidden line to intercombination line) are found to be very similar to those deduced by other authors. However the temperature sensitive ratios G (intercombination plus forbidden lines to resonance line) are approximately 20% lower than the best previous estimates. The observed value of G for solar active regions (G = 1.0 ± 0.1) predicts an electron temperature in the range 1.1 × 106 K < Te < 1.8 × 106 K, which overlaps that of maximum O VII emissivity, TM = 1.8 × 106 K. In addition, the theoretical G versus Te curve is in excellent agreement with that observed for a Tokamak plasma. Title: The nitrogen-deficient cluster NGC 6231. Authors: Keenan, F. P.; Brown, P. J. F.; Dufton, P. L.; Lennon, D. J. Bibcode: 1984ApJ...279L..11K Altcode: Spectra of five main-sequence B type stars have been obtained for the wavelength range from 3900 to 4020 A at a spectral resolution of 0.2 A with the Anglo-Australian Telescope. Analysis of the absorption-line strengths yields a nitrogen underabundance of 0.5 + or - 0.1 dex with other element abundances being normal. This composition is believed to reflect that of the interstellar medium from which the cluster recently formed, implying that significant galactic abundance variations are present on distance scales of the order of 1 kpc. Title: MG XI line ratios in the sun Authors: Keenan, F. P.; Kingston, A. E.; Tayal, S. S. Bibcode: 1984MNRAS.207P..51K Altcode: The recent R-matrix calculations of the 1(1)S-2(3)S and 1(1)S-2(3)P electron excitation collision rates in Mg XI by Tayal and Kingston (1984) are used to determine the ratio R of the forbidden to the intercombination line and the ratio G of the forbidden plus intercombination lines to the resonance line. These ratios are respectively electron density and temperature sensitive. Values for R very similar to those deduced by Wolfson et al. (1983), Pradhan and Shull (1981), and Pradhan (1982) are found. The results for G, however, are 25-30 percent smaller than those calculated by these authors. The theoretical value of G at the temperature of maximum emission is now in excellent agreement with that observed for the November 5, 1980 flare by the SMM satellite. Title: Level populations for Be-sequence ions in astrophysical plasmas Authors: Keenan, F. P.; Berrington, K. A.; Burke, P. G.; Kingston, A. E.; Dufton, P. L. Bibcode: 1984MNRAS.207..459K Altcode: Level populations for the 10 n = 2 states of ions in the Be-sequence from C III to Si XI are presented. The results are for two ranges of electron density (Ne = 108 - 1013cm-3 and Ne = 102 - 107cm-3), the former applicable to the solar corona and transition region and the latter to other astrophysical objects such as quasars and Seyfert galaxies. Title: The Effect of a Non-Maxwellian Electron Velocity Distribution on Be-Like Ion Diagnostics in the Sun Authors: Keenan, F. P. Bibcode: 1984SoPh...91...27K Altcode: Non-Maxwellian collision rates of the Be-sequence ions CIII and OV in the solar transition region are derived for quiet Sun and flare conditions using the electron velocity distribution functions of Shoub. The rates are found to be enhanced relative to the Maxwellian values but only at low temperatures where the fractional abundances of these species is very small. This implies that the electron density and temperature diagnostics used by previous authors for the transition region will be unchanged by non-Maxwellian effects. It is noted that such effects will only be important for species that are formed at low temperatures and have large transition energies such as HeI. Title: Photoionization rates in the interstellar medium Authors: Keenan, F. P. Bibcode: 1984MNRAS.206..449K Altcode: The Gondhalekar et al. (1980) determination of the radiation field from 2740 A down to the Lyman limit at 912 A is the basis of the present calculation of photoionization rates for several species that are of importance in the interstellar medium. The results obtained are compared with previous estimates by De Boer et al. (1973). It is noted that large radiation field variations will occur in regions of space near OB associations or within dense dust clouds, with corresponding effects on the photoionization rates. Title: An LTE analysis of the blue halo star HD 214080. Authors: Keenan, F. P.; Lennon, D. J. Bibcode: 1984A&A...130..179K Altcode: Stellar equivalent widths and hydrogen line profiles measured from a high quality coudé spectrum, are used to determine accurate atmospheric parameters for the early-type halo star HD 214080. Abundances of helium plus eleven other species are also derived, and are found to be similar to those of normal OB stars, from which it is concluded that HD 214080 is an ordinary Population I object. The stellar velocity coupled with its z-distance imply that HD 214080 cannot have been ejected from the disc as has been proposed for other halo stars. It is concluded that the star was probably formed in the halo, possibly as a result of cloud-cloud collisions at high galactic latitudes. Title: Line ratios for solar ultra-violet lines of O v Authors: Doyle, J. G.; Dufton, P. L.; Keenan, F. P.; Kingston, A. E. Bibcode: 1983SoPh...89..243D Altcode: New O V rate coefficients are used to calculate the ratio of the intensity of the 760 Å multiplet to that of the 630 Å line. Results are given for a range of electron densities and temperatures. The theoretical ratios are compared with observed line ratios for different solar regions. Title: On the nature of early-type stars in the galactic halo. Authors: Keenan, F. P.; Dufton, P. L. Bibcode: 1983MNRAS.205..435K Altcode: Effective temperatures and surface gravities of 46 intermediate and high galactic latitude OB stars have been estimated from Stromgren /C1/ and H-beta photometry. In addition, helium, calcium and magnesium abundances relative to hydrogen have been derived for eleven stars. The typical OB-type stellar parameters indicate that they are normal Population I stars, several of which require ejection velocities of more than 100 km/s from the plane in order to reach their present z-distances during their lifetimes. The observed correlation between peculiar velocity and mass for stars with /z/ not less than 400 pc is compatible with the Blaauw runaway hypothesis as the acceleration mechanism. A plot of log N(Na I) versus E(B-V) implies that the gas-to-dust ratio in the halo is probably similar to that found for material in the galactic disc. This implies that the sputtering of calcium from grain surfaces is probably responsible for the observed velocity dependence of the N(Na I)/N(Ca II) ratio. Title: Early-type Stars at Large Distances from the Galactic Plane Authors: Keenan, F. P. Bibcode: 1983IrAJ...16..131K Altcode: Tobin and Kaufmann (1984) have shown that three early-type halo stars are normal, distant objects, and there appears to be increasing evidence to support the large distances derived for these stars. The present investigatiton is concerned with research which provides some insight into the nature and possible origin of these objects. The nature of the early-type stars in the Galactic halo is discussed, taking into account atmospheric parameters and chemical compositions, and distances and ejection velocities. In connection with a consideration of the origin of the early-type halo stars, it is pointed out that some mechanism has to be invoked to accelerate stars to large velocities in order to explain their presence in the halo. Attention is given to the 'runaway' hypothesis considered by Zwicky (1957). Title: IUE observations of high velocity interstellar gas tentatively associated with Radio Loop II. Authors: Bates, B.; Brown-Kerr, W.; Giaretta, D. L.; Keenan, F. P. Bibcode: 1983A&A...122...64B Altcode: Red-shifted high velocity gas components (HVC) have been positively detected in IUE spectra of six out of a sample of eleven selected stars across a region of sky of some 40°. Properties of the HVC determined from the spectra of three stars indicate that the material is cool gas with a density nH ≈ 100 cm-3 and thickness ≈0.1 pc. The HVC velocities are consistent with a large expanding spherical shell of gas having the parameters of Radio Loop II, in which case the expansion velocity deduced for the shell is ≈100 km s-1. Whilst the authors tentatively associate the HVC with Loop II the IUE observations suggest also that they may be smaller scale features which are connected with the larger loop. Title: Interstellar CA II and NA I line profiles towards halo OB stars. Authors: Keenan, F. P.; Dufton, P. L.; McKeith, C. D.; Blades, J. C. Bibcode: 1983MNRAS.203..963K Altcode: High resolution Ca II and Na I interstellar line profiles towards several halo OB stars are presented. The profiles have been corrected where necessary for the presence of stellar features, and analyzed using multicomponent models to derive information on the radial velocities, internal velocity dispersions, and column densities of individual interstellar clouds. A method is described for estimating peculiar velocities for the clouds, and a significant trend of decreasing R = N(Na I)/N(Ca II) with increasing peculiar velocity is found. The ratio, R, is also shown to be generally smaller in the halo than in the plane, implying that many of the halo clouds may have peculiar velocities. The data indicate that there are both few clouds and a small Ca II density beyond the absolute z value of 2 kpc. Title: The Galactic Halo Authors: Keenan, F. P. Bibcode: 1982IrAJ...15..309K Altcode: A survey of observations and analyses of phenomena associated with the theoretical galactic halo (GH) or corona is presented, with a focus on research performed at Queen's University in Belfast. The origin and main features of the GH theory are outlined, and the previous observations supporting it are reviewed, including visible clouds at high Galactic latitudes (z), UV absorption lines in the GH, absorption in the haloes of other galaxies, and early-type stars in the GH. The Queen's University work is based on spectroscopic observations of 18 high-z OB stars obtained at high resolution (lambda/delta lambda = 20,000) in the 389-402 and 576-604-nm bands with the Anglo-Australian Telescope in September 1979 and 1980. The stars are found to be normal, with no evidence of subluminosity, and to lie at z distances of about 0.3-3.5 kpc; hence they are considered good tracers of GH gas. A velocity dependence of the N(Na I)/N(Ca II) ratio is observed and attributed to Ca sputtering from grain surfaces rather than to the collisional ionization of Na I. Title: Atmospheric parameters and chemical composition of eighteen halo OB stars. Authors: Keenan, F. P.; Dufton, P. L.; McKeith, C. D. Bibcode: 1982MNRAS.200..673K Altcode: Stellar equivalent widths and He line profiles, measured from 5 and 10 A/mm IPCS spectra obtained at the AAT, are presented for 18 halo OB stars. Effective temperatures and gravities have been estimated using Stromgren and H-beta photometry in conjunction with these data. Also derived are the abundances relative to hydrogen of helium, carbon, nitrogen, oxygen and calcium. From the normal chemical compositions and atmospheric parameters obtained, it is concluded that the stars are not subluminous and show no evidence of any other peculiarities. Using conservative and nonconservative evolutionary tracks, masses, ages and distances are deduced for the stars, implying that several of them have been ejected from the galactic plane with velocities in excess of 100 km/s. Title: A fine analysis of stellar and interstellar lines towards four halo Bstars. Authors: Keenan, F. P.; McKeith, C. D.; Dufton, P. L.; Blades, J. C. Bibcode: 1981MNRAS.197..799K Altcode: High resolution observations of Ca II and Na I interstellar line profiles toward four halo B stars are analyzed in terms of multicloud models. Stellar CNO lines present in the spectra have been used in conjunction with an LTE model atmosphere program to derive values of effective temperature and microturbulence. Using these atmospheric parameters, stellar contributions to the interstellar Ca II and Na I profiles have been calculated and removed. The subsequent renormalized interstellar line profiles were analyzed to derive information on the radial velocities, internal velocity dispersions and column densities within individual interstellar clouds. The Na I/Ca II ratio decreases from a value of 2 to 0.02 with increasing radial velocity; this range is smaller than that found by previous workers using the doublet ratio method. Additionally, the stellar CNO lines in the halo stars imply a composition similar to that found for unevolved B stars in the galactic plane.