Author name code: culhane
ADS astronomy entries on 2022-09-14
=author:"Culhane, J.L." OR =author:"Culhane, Len"
------------------------------------------------------------------------
Title: Photospheric and Coronal Abundances in an X8.3 Class Limb Flare
Authors: Doschek, G. A.; Warren, H. P.; Harra, L. K.; Culhane, J. L.;
Watanabe, T.; Hara, H.
Bibcode: 2018ApJ...853..178D
Altcode:
We analyze solar elemental abundances in coronal post-flare
loops of an X8.3 flare (SOL2017-09-10T16:06) observed on the west
limb on 2017 September 10 near 18 UT using spectra recorded by
the Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinode
spacecraft. The abundances in the corona can differ from photospheric
abundances due to the first ionization potential (FIP) effect. In
some loops of this flare, we find that the abundances appear to be
coronal at the loop apices or cusps, but steadily transform from
coronal to photospheric as the loop footpoint is approached. This
result is found from the intensity ratio of a low-FIP ion spectral
line (Ca XIV) to a high-FIP ion spectral line (Ar XIV) formed at
about the same temperature (4-5 MK). Both lines are observed close in
wavelength. Temperature, which could alter the interpretation, does
not appear to be a factor based on intensity ratios of Ca XV lines
to a Ca XIV line. We discuss the abundance result in terms of the
Laming model of the FIP effect, which is explained by the action of
the ponderomotive force in magnetohydrodynamic (MHD) waves in coronal
loops and in the underlying chromosphere.
Title: Non-thermal distributions and energy transport in the solar
flares
Authors: Matthews, Sarah; del Zanna, Guilio; Calcines, Ariadna;
Mason, Helen; Mathioudakis, Mihalis; Culhane, Len; Harra, Louise;
van Driel-Gesztelyi, Lidia; Green, Lucie; Long, David; Baker, Deb;
Valori, Gherardo
Bibcode: 2017arXiv171200773M
Altcode:
Determining the energy transport mechanisms in flares remains a central
goal in solar flares physics that is still not adequately answered
by the 'standard flare model'. In particular, the relative roles of
particles and/or waves as transport mechanisms, the contributions of low
energy protons and ions to the overall flare budget, and the limits of
low energy non-thermal electron distribution are questions that still
cannot be adequately reconciled with current instrumentation. In this
'White Paper' submitted in response to the call for inputs to the Next
Generation Solar Physics Mission review process initiated by JAXA,
NASA and ESA in 2016, we outline the open questions in this area and
possible instrumentation that could provide the required observations
to help answer these and other flare-related questions.
Title: Helioseismology and Dynamics of the Solar Interior
Authors: Thompson, M. J.; Brun, A. S.; Culhane, J. L.; Gizon, L.;
Roth, M.; Sekii, T.
Bibcode: 2017hdsi.book.....T
Altcode:
No abstract at ADS
Title: Erratum to: The Magnetic Helicity Budget of a CME-Prolific
Active Region
Authors: Green, L. M.; López Fuentes, M.; Mandrini, C. H.; Démoulin,
P.; van Driel-Gesztelyi, L.; Culhane, J. L.
Bibcode: 2016SoPh..291..335G
Altcode: 2015SoPh..tmp..179G
No abstract at ADS
Title: A Comparison of Global Magnetic Field Skeletons and
Active-Region Upflows
Authors: Edwards, S. J.; Parnell, C. E.; Harra, L. K.; Culhane, J. L.;
Brooks, D. H.
Bibcode: 2016SoPh..291..117E
Altcode: 2015SoPh..tmp..161E
Plasma upflows have been detected in active regions using Doppler
velocity maps. The origin and nature of these upflows is not well known
with many of their characteristics determined from the examination
of single events. In particular, some studies suggest these upflows
occur along open field lines and, hence, are linked to sources of
the solar wind. To investigate the relationship these upflows may
have with the solar wind, and to probe what may be driving them, this
paper considers seven active regions observed on the solar disc using
the Extreme ultraviolet Imaging Spectrometer aboard Hinode between
August 2011 and September 2012. Plasma upflows are observed in all
these active regions. The locations of these upflows are compared
to the global potential magnetic field extrapolated from the Solar
Dynamics Observatory, Helioseismic and Magnetic Imager daily synoptic
magnetogram taken on the day the upflows were observed. The structure
of the magnetic field is determined by constructing its magnetic
skeleton in order to help identify open-field regions and also sites
where magnetic reconnection at global features is likely to occur. As
a further comparison, measurements of the temperature, density and
composition of the plasma are taken from regions with active-region
upflows. In most cases the locations of the upflows in the active
regions do not correspond to areas of open field, as predicted by
a global coronal potential-field model, and therefore these upflows
are not always sources of the slow solar wind. The locations of the
upflows are, in general, intersected by separatrix surfaces associated
with null points located high in the corona; these could be important
sites of reconnection with global consequences.
Title: How Can Active Region Plasma Escape into the Solar Wind from
Below a Closed Helmet Streamer?
Authors: Mandrini, C. H.; Nuevo, F. A.; Vásquez, A. M.; Démoulin,
P.; van Driel-Gesztelyi, L.; Baker, D.; Culhane, J. L.; Cristiani,
G. D.; Pick, M.
Bibcode: 2014SoPh..289.4151M
Altcode: 2014arXiv1409.7369M; 2014SoPh..tmp..115M
Recent studies show that active-region (AR) upflowing plasma,
observed by the EUV-Imaging Spectrometer (EIS) onboard Hinode, can
gain access to open-field lines and be released into the solar wind
(SW) via magnetic-interchange reconnection at magnetic null-points in
pseudo-streamer configurations. When only one bipolar AR is present
on the Sun and is fully covered by the separatrix of a streamer, such
as AR 10978 in December 2007, it seems unlikely that the upflowing AR
plasma can find its way into the slow SW. However, signatures of plasma
with AR composition have been found at 1 AU by Culhane et al. (Solar
Phys.289, 3799, 2014) that apparently originated west of AR 10978. We
present a detailed topology analysis of AR 10978 and the surrounding
large-scale corona based on a potential-field source-surface (PFSS)
model. Our study shows that it is possible for the AR plasma to move
around the streamer separatrix and be released into the SW via magnetic
reconnection, which occurs in at least two main steps. We analyse data
from the Nançay Radioheliograph (NRH) in a search for evidence of the
chain of magnetic reconnections that we propose. We find a noise storm
above the AR and several varying sources at 150.9 MHz. Their locations
suggest that they might be associated with particles accelerated during
the first-step reconnection process at a null point well outside of
the AR. We find no evidence of the second reconnection step in the
radio data, however. Our results demonstrate that even when it appears
highly improbable for the AR plasma to reach the SW, indirect channels
involving a sequence of reconnections can make it possible.
Title: Tracking Solar Active Region Outflow Plasma from Its Source
to the Near-Earth Environment
Authors: Culhane, J. L.; Brooks, D. H.; van Driel-Gesztelyi, L.;
Démoulin, P.; Baker, D.; DeRosa, M. L.; Mandrini, C. H.; Zhao, L.;
Zurbuchen, T. H.
Bibcode: 2014SoPh..289.3799C
Altcode: 2014SoPh..tmp...90C; 2014arXiv1405.2949C
Seeking to establish whether active-region upflow material contributes
to the slow solar wind, we examine in detail the plasma upflows from
Active Region (AR) 10978, which crossed the Sun's disc in the interval 8
to 16 December 2007 during Carrington rotation (CR) 2064. In previous
work, using data from the Hinode/EUV Imaging Spectrometer, upflow
velocity evolution was extensively studied as the region crossed the
disc, while a linear force-free-field magnetic extrapolation was used
to confirm aspects of the velocity evolution and to establish the
presence of quasi-separatrix layers at the upflow source areas. The
plasma properties, temperature, density, and first ionisation potential
bias [FIP-bias] were measured with the spectrometer during the disc
passage of the active region. Global potential-field source-surface
(PFSS) models showed that AR 10978 was completely covered by the
closed field of a helmet streamer that is part of the streamer
belt. Therefore it is not clear how any of the upflowing AR-associated
plasma could reach the source surface at 2.5 R⊙ and
contribute to the slow solar wind. However, a detailed examination of
solar-wind in-situ data obtained by the Advanced Composition Explorer
(ACE) spacecraft at the L1 point shows that increases in
O7+/O6+, C6+/C5+, and Fe/O -
a FIP-bias proxy - are present before the heliospheric current-sheet
crossing. These increases, along with an accompanying reduction in
proton velocity and an increase in density are characteristic of
both AR and slow-solar-wind plasma. Finally, we describe a two-step
reconnection process by which some of the upflowing plasma from the
AR might reach the heliosphere.
Title: The Location of Non-thermal Velocity in the Early Phases of
Large Flares—Revealing Pre-eruption Flux Ropes
Authors: Harra, Louise K.; Matthews, Sarah; Culhane, J. L.; Cheung,
Mark C. M.; Kontar, Eduard P.; Hara, Hirohisa
Bibcode: 2013ApJ...774..122H
Altcode:
Non-thermal velocity measurements of the solar atmosphere, particularly
from UV and X-ray emission lines have demonstrated over the decades
that this parameter is important in understanding the triggering of
solar flares. Enhancements have often been observed before intensity
enhancements are seen. However, until the launch of Hinode, it has
been difficult to determine the spatial location of the enhancements to
better understand the source region. The Hinode EUV Imaging Spectrometer
has the spectral and spatial resolution to allow us to probe the early
stages of flares in detail. We analyze four events, all of which
are GOES M- or X-classification flares, and all are located toward
the limb for ease of flare geometry interpretation. Three of the
flares were eruptive and one was confined. In all events, pre-flare
enhancement in non-thermal velocity at the base of the active region
and its surroundings has been found. These enhancements seem to be
consistent with the footpoints of the dimming regions, and hence may
be highlighting the activation of a coronal flux rope for the three
eruptive events. In addition, pre-flare enhancements in non-thermal
velocity were found above the looptops for the three eruptive events.
Title: Observing Photons in Space: A Guide to Experimental Astronomy
Authors: Huber, M. C. E.; Pauluhn, A.; Culhane, J. L.; Timothy, J. G.;
Wilhelm, K.; Zehnder, A.
Bibcode: 2013opsg.book.....H
Altcode:
No abstract at ADS
Title: Plasma outflows at the border of active regions and the
solar wind
Authors: Nuevo, F. A.; Mandrini, C. H.; Vásquez, A. M.; Deumoulin,
P.; Van Driel-Gesztely, L.; Baker, D.; Cristiani, G. D.; Pick, M.;
Culhane, J. L.
Bibcode: 2013BAAA...56..387N
Altcode:
We present a detailed topological analysis of active region (AR)
10978; based on a Potential Field Source Surface (PFSS) model. AR
10978 is a standard bipolar region which appears fully covered by
the magnetic field lines of a coronal streamer. Despite this simple
magnetic configuration; our analysis shows that it is possible for
the AR plasma; contained in the outflows observed at the AR borders;
to be released into the solar wind via magnetic reconnection.
Title: Observing Photons in Space: A Guide to Experimental Spae
Astronomy
Authors: Huber, M. C. E.; Pauluhn, A.; Culhane, J. L.; Timothy, J. G.;
Wilhelm, K.; Zehnder, A.
Bibcode: 2013ops..book.....H
Altcode:
No abstract at ADS
Title: Tracking Solar Active Region Outflow Plasma from its Source
to the near-Earth Environment
Authors: Culhane, J. L.; Brooks, D.; Zurbuchen, T.; van
Driel-Gesztelyi, L.; Fazakerley, A. N.; DeRosa, M. L.
Bibcode: 2012AGUFMSH53A2255C
Altcode:
In a recent study of persistent active region outflow from AR 10978 in
the period 10 - 15, December, 2007, Brooks and Warren (2011), using the
Hinode EUV Imaging Spectrometer (EIS) instrument showed the presence
of a strong low-FIP element enhancement in the outflowing plasma that
was replicated three days later in the in-situ solar wind measurements
made by the ACE/SWICS instrument. In the present work, we examine the
outflowing plasma properties (Te, Ne, v, abundances) as a function
of time in greater detail as AR 10978 passes the Earth-Sun line. The
structure of the magnetic field above the two outflow regions - E and
W of the AR, is also examined. Following an assessment of the relevant
magnetic structures between Sun and Earth, the properties of the solar
wind plasma arriving at ACE approximately three days later are measured
and compared with those of the outflowing AR plasma. The relationship
of these measurements to the in-situ magnetic field observed by the
ACE magnetometer is also studied. Finally the role of persistent AR
outflows in contributing to the slow solar wind is assessed.
Title: Magnetic Topology of Active Regions and Coronal Holes:
Implications for Coronal Outflows and the Solar Wind
Authors: van Driel-Gesztelyi, L.; Culhane, J. L.; Baker, D.; Démoulin,
P.; Mandrini, C. H.; DeRosa, M. L.; Rouillard, A. P.; Opitz, A.;
Stenborg, G.; Vourlidas, A.; Brooks, D. H.
Bibcode: 2012SoPh..281..237V
Altcode: 2012SoPh..tmp..228V
During 2 - 18 January 2008 a pair of low-latitude opposite-polarity
coronal holes (CHs) were observed on the Sun with two active regions
(ARs) and the heliospheric plasma sheet located between them. We use
the Hinode/EUV Imaging Spectrometer (EIS) to locate AR-related outflows
and measure their velocities. Solar-Terrestrial Relations Observatory
(STEREO) imaging is also employed, as are the Advanced Composition
Explorer (ACE) in-situ observations, to assess the resulting impacts on
the solar wind (SW) properties. Magnetic-field extrapolations of the two
ARs confirm that AR plasma outflows observed with EIS are co-spatial
with quasi-separatrix layer locations, including the separatrix of a
null point. Global potential-field source-surface modeling indicates
that field lines in the vicinity of the null point extend up to the
source surface, enabling a part of the EIS plasma upflows access
to the SW. We find that similar upflow properties are also observed
within closed-field regions that do not reach the source surface. We
conclude that some of plasma upflows observed with EIS remain confined
along closed coronal loops, but that a fraction of the plasma may be
released into the slow SW. This suggests that ARs bordering coronal
holes can contribute to the slow SW. Analyzing the in-situ data, we
propose that the type of slow SW present depends on whether the AR is
fully or partially enclosed by an overlying streamer.
Title: Characteristics of the Nonthermal Velocity Signature Observed
in the Impulsive Phase of the 2007 May 19 Flare
Authors: Hara, H.; Watanabe, T.; Bone, L. A.; Culhane, J. L.; van
Driel-Gesztelyi, L.; Young, P. R.
Bibcode: 2009ASPC..415..459H
Altcode:
The Hinode EUV Imaging Spectrometer (EIS) observed a long duration
flare with a weak impulsive phase that appears to conform to the
standard two-ribbon flare reconnection model. EIS scanned the flare
site during the impulsive phase and observed Fe XXIII and Fe XXIV line
emission that closely followed the flare hard X-ray emission while the
line profiles showed significant non-thermal broadening. We suggest
that a shock originating at the reconnection site which sweeps up and
heats the coronal plasma can account for our observations.
Title: Formation, Interaction and Merger of an Active Region and a
Quiescent Filament Prior to Their Eruption on 19 May 2007
Authors: Bone, L. A.; van Driel-Gesztelyi, L.; Culhane, J. L.;
Aulanier, G.; Liewer, P.
Bibcode: 2009SoPh..259...31B
Altcode:
We report observations of the formation of two filaments - one
active and one quiescent, and their subsequent interactions prior to
eruption. The active region filament appeared on 17 May 2007, followed
by the quiescent filament about 24 hours later. In the 26 hour interval
preceding the eruption, which occurred at around 12:50 UT on 19 May
2007, we see the two filaments attempting to merge and filament material
is repeatedly heated suggesting magnetic reconnection. The filament
structure is observed to become increasingly dynamic preceding the
eruption with two small hard X-ray sources seen close to the active
part of the filament at around 01:38 UT on 19 May 2007 during one of
the activity episodes. The final eruption on 19 May at about 12:51 UT
involves a complex CME structure, a flare and a coronal wave. A magnetic
cloud is observed near Earth by the STEREO-B and WIND spacecraft about
2.7 days later. Here we describe the behaviour of the two filaments
in the period prior to the eruption and assess the nature of their
dynamic interactions.
Title: Stereoscopic Analysis of the 19 May 2007 Erupting Filament
Authors: Liewer, P. C.; De Jong, E. M.; Hall, J. R.; Howard, R. A.;
Thompson, W. T.; Culhane, J. L.; Bone, L.; van Driel-Gesztelyi, L.
Bibcode: 2009SoPh..256...57L
Altcode: 2009arXiv0904.1055L
A filament eruption, accompanied by a B9.5 flare, coronal dimming,
and an EUV wave, was observed by the Solar TERrestrial Relations
Observatory (STEREO) on 19 May 2007, beginning at about 13:00 UT. Here,
we use observations from the SECCHI/EUVI telescopes and other solar
observations to analyze the behavior and geometry of the filament before
and during the eruption. At this time, STEREO A and B were separated by
about 8.5°, sufficient to determine the three-dimensional structure
of the filament using stereoscopy. The filament could be followed in
SECCHI/EUVI 304 Å stereoscopic data from about 12 hours before to about
2 hours after the eruption, allowing us to determine the 3D trajectory
of the erupting filament. From the 3D reconstructions of the filament
and the chromospheric ribbons in the early stage of the eruption,
simultaneous heating of both the rising filamentary material and the
chromosphere directly below is observed, consistent with an eruption
resulting from magnetic reconnection below the filament. Comparisons
of the filament during eruption in 304 Å and Hα show that when it
becomes emissive in He II, it tends to disappear in Hα , indicating
that the disappearance probably results from heating or motion, not
loss, of filamentary material.
Title: Magnetic Flux Emergence, Activity, Eruptions and Magnetic
Clouds: Following Magnetic Field from the Sun to the Heliosphere
Authors: van Driel-Gesztelyi, L.; Culhane, J. L.
Bibcode: 2009SSRv..144..351V
Altcode: 2008SSRv..tmp..185V
We present an overview of how the principal physical properties of
magnetic flux which emerges from the toroidal fields in the tachocline
through the turbulent convection zone to the solar surface are linked
to solar activity events, emphasizing the effects of magnetic field
evolution and interaction with other magnetic structures on the
latter. We compare the results of different approaches using various
magnetic observables to evaluate the probability of flare and coronal
mass ejection (CME) activity and forecast eruptive activity on the
short term (i.e. days). Then, after a brief overview of the observed
properties of CMEs and their theoretical models, we discuss the
ejecta properties and describe some typical magnetic and composition
characteristics of magnetic clouds (MCs) and interplanetary CMEs
(ICMEs). We review some individual examples to clarify the link between
eruptions from the Sun and the properties of the resulting ejecta. The
importance of a synthetic approach to solar and interplanetary magnetic
fields and activity is emphasized.
Title: The Origin and Dynamics of Solar Magnetism
Authors: Thompson, M. J.; Balogh, A.; Culhane, J. L.; Nordlund, Å.;
Solanki, S. K.; Zahn, J. -P.
Bibcode: 2009odsm.book.....T
Altcode:
No abstract at ADS
Title: Magnetic Flux Emergence, Activity, Eruptions and Magnetic
Clouds: Following Magnetic Field from the Sun to the Heliosphere
Authors: van Driel-Gesztelyi, L.; Culhane, J. L.
Bibcode: 2009odsm.book..351V
Altcode:
We present an overview of how the principal physical properties of
magnetic flux which emerges from the toroidal fields in the tachocline
through the turbulent convection zone to the solar surface are linked
to solar activity events, emphasizing the effects of magnetic field
evolution and interaction with other magnetic structures on the
latter. We compare the results of different approaches using various
magnetic observables to evaluate the probability of flare and coronal
mass ejection (CME) activity and forecast eruptive activity on the
short term (i.e. days). Then, after a brief overview of the observed
properties of CMEs and their theoretical models, we discuss the
ejecta properties and describe some typical magnetic and composition
characteristics of magnetic clouds (MCs) and interplanetary CMEs
(ICMEs). We review some individual examples to clarify the link between
eruptions from the Sun and the properties of the resulting ejecta. The
importance of a synthetic approach to solar and interplanetary magnetic
fields and activity is emphasized.
Title: Flows and Nonthermal Velocities in Solar Active Regions
Observed with the EUV Imaging Spectrometer on Hinode: A Tracer of
Active Region Sources of Heliospheric Magnetic Fields?
Authors: Doschek, G. A.; Warren, H. P.; Mariska, J. T.; Muglach, K.;
Culhane, J. L.; Hara, H.; Watanabe, T.
Bibcode: 2008ApJ...686.1362D
Altcode: 2008arXiv0807.2860D
From Doppler velocity maps of active regions constructed from spectra
obtained by the EUV Imaging Spectrometer (EIS) on the Hinode spacecraft
we observe large areas of outflow (20-50 km s-1) that can
persist for at least a day. These outflows occur in areas of active
regions that are faint in coronal spectral lines formed at typical
quiet-Sun and active region temperatures. The outflows are positively
correlated with nonthermal velocities in coronal plasmas. The bulk
mass motions and nonthermal velocities are derived from spectral line
centroids and line widths, mostly from a strong line of Fe XII at
195.12 Å. The electron temperature of the outflow regions estimated
from an Fe XIII to Fe XII line intensity ratio is about (1.2-1.4) ×
106 K. The electron density of the outflow regions derived
from a density-sensitive intensity ratio of Fe XII lines is rather low
for an active region. Most regions average around 7 × 108
cm-3, but there are variations on pixel spatial scales
of about a factor of 4. We discuss results in detail for two active
regions observed by EIS. Images of active regions in line intensity,
line width, and line centroid are obtained by rastering the regions. We
also discuss data from the active regions obtained from other orbiting
spacecraft that support the conclusions obtained from analysis of the
EIS spectra. The locations of the flows in the active regions with
respect to the longitudinal photospheric magnetic fields suggest that
these regions might be tracers of long loops and/or open magnetic
fields that extend into the heliosphere, and thus the flows could
possibly contribute significantly to the solar wind.
Title: Multi-scale reconnections in a complex CME
Authors: van Driel-Gesztelyi, L.; Goff, C. P.; Démoulin, P.; Culhane,
J. L.; Matthews, S. A.; Harra, L. K.; Mandrini, C. H.; Klein, K. -L.;
Kurokawa, H.
Bibcode: 2008AdSpR..42..858V
Altcode:
A series of three flares of GOES class M, M and C, and a CME were
observed on 20 January 2004 occurring in close succession in NOAA
10540. Types II, III, and N radio bursts were associated. We use
the combined observations from TRACE, EIT, Hα images from Kwasan
Observatory, MDI magnetograms, GOES, and radio observations from
Culgoora and Wind/ WAVES to understand the complex development of this
event. We reach three main conclusions. First, we link the first two
impulsive flares to tether-cutting reconnections and the launch of
the CME. This complex observation shows that impulsive quadrupolar
flares can be eruptive. Second, we relate the last of the flares, an
LDE, to the relaxation phase following forced reconnections between
the erupting flux rope and neighbouring magnetic field lines, when
reconnection reverses and restores some of the pre-eruption magnetic
connectivities. Finally, we show that reconnection with the magnetic
structure of a previous CME launched about 8 h earlier injects electrons
into open field lines having a local dip and apex (located at about six
solar radii height). This is observed as an N-burst at decametre radio
wavelengths. The dipped shape of these field lines is due to large-scale
magnetic reconnection between expanding magnetic loops and open field
lines of a neighbouring streamer. This particular situation explains
why this is the first N-burst ever observed at long radio wavelengths.
Title: Strongly Blueshifted Phenomena Observed with Hinode EIS in
the 2006 December 13 Solar Flare
Authors: Asai, Ayumi; Hara, Hirohisa; Watanabe, Tetsuya; Imada,
Shinsuke; Sakao, Taro; Narukage, Noriyuki; Culhane, J. L.; Doschek,
G. A.
Bibcode: 2008ApJ...685..622A
Altcode: 2008arXiv0805.4468A
We present a detailed examination of strongly blueshifted emission
lines observed with the EUV Imaging Spectrometer on board the Hinode
satellite. We found two kinds of blueshifted phenomenon associated
with the X3.4 flare that occurred on 2006 December 13. One was related
to a plasmoid ejection seen in soft X-rays. It was very bright in all
the lines used for the observations. The other was associated with the
faint arc-shaped ejection seen in soft X-rays. The soft X-ray ejection
is thought to be a magnetohydrodynamic (MHD) fast-mode shock wave. This
is therefore the first spectroscopic observation of an MHD fast-mode
shock wave associated with a flare.
Title: Long Duration Flare Observed with Hinode EIS
Authors: Culhane, J. L.; Hara, H.; Watanabe, T.; Matsuzaki, K.; Harra,
L. K.; Cargill, P.; Mariska, J. T.; Doschek, G. A.
Bibcode: 2008ASPC..397..121C
Altcode:
The first Long Duration Event (LDE) observed with Hinode EIS using
a high spectral resolution raster scan is described. The hot plasma
features include a cusp-shaped arcade associated with a thermal RHESSI
source, cooling post-flare loops, complex plasma flows and an EIT
observation that shows expanding loops and inflows characteristic of
the standard magnetic reconnection model for solar flares. A Coronal
Mass Ejection (CME) is also seen by LASCO. The cusp is well observed
in the Ca XVII line and we find enhanced line broadening above this
region. Doppler velocity observations for the post-flare loops show both
up-flows and down-flows that are interpreted as due to siphon flows.
Title: Long Duration Thermal Hard X-ray Sources Observed in Two
Eruptive Flares
Authors: Bone, L. A.; Culhane, J. L.; van Driel-Gesztelyi, L.; Hara, H.
Bibcode: 2008ASPC..397..160B
Altcode:
We present observations of two eruptive flares on 17 of December
2006 (C1.9) and 19 of May 2007 (B9.7) which had good coverage with
both Hinode and RHESSI. In these flares we see a long lived, gradual
thermal hard X-ray source of low emission measure and, relative to
the loops observed with GOES and XRT, high temperature. The lack of a
non-thermal hard X-ray component and impulsive behaviour is inconsistent
with electron beam driven chromospheric evaporation.
Title: Hinode EIS and XRT Observations of Hot Jets in Coronal Holes -
Does the Plasma Escape?
Authors: Baker, D.; van Driel-Gesztelyi, L.; Kamio, S.; Culhane,
J. L.; Harra, L. K.; Sun, J.; Young, P. R.; Matthews, S. A.
Bibcode: 2008ASPC..397...23B
Altcode:
X-ray jets have been detected in the extreme ultraviolet (EUV) and
soft X-ray observations of Hinode's EIS and XRT instruments. Both
instruments were used to observe the jets in polar and on-disk coronal
holes (CHs). Here, we present a multi-wavelength study of an X-ray
jet and its associated bright point found in an equatorial CH on 19
June 2007. Light curves (LCs) in 22 different emission lines were
compared to that of Hinode/XRT. As we found in a previous study of
two polar X-ray jets, this jet shows a post-jet increase in its EUV
LCs. The post-jet enhancement appears cooler than the jet. We suggest
this feature arises because the hot plasma of the jet, having failed to
reach escape speeds, cools and falls back along the near vertical paths
expected to be created by reconnection with open field lines of CHs. In
addition to the increase in post-jet EUV intensity, we found tentative
evidence of impact heating possibly caused by the fall-back of plasma.
Title: Study of Two Long Duration Eruptive Flares with the Hinode
and RHESSI Spacecraft
Authors: Culhane, J. L.; Bone, L.; Williams, D. R.; Brooks, D. H.;
Vandriel-Gesztelyi, L.; Hara, H.; Veronig, A.
Bibcode: 2007AGUFMSH52C..05C
Altcode:
Two eruptive flares that occurred on 17 December 2006 and 19 May
2007 were observed by the instruments on the Hinode and RHESSI
spacecraft. Both share some of the characteristics of the well known
event observed with Yohkoh in February, 1992 (Tsuneta et al., 1992)
in that they seem largely thermal in character and exhibit many of
the features of the standard Carmichael, Hirayama, Sturrock, Kopp,
Pneuman (CHSKP) flare model. However for these events, much additional
(e.g. SOHO) data is available including the observation of an associated
erupting filament on 19th May that was seen at the Kanzelhoehe Solar
Observatory. In this talk the role of the outflow termination shock
in heating the flare plasma will be re-examined. In particular the
presence of plasma over a wide temperature range in the flare cusps
and the possibility of non-thermal effects following the shock heating,
will be assessed. The behaviour of the erupting filament material will
also be discussed.
Title: Solar Transition Region Features Observed with Hinode/EIS
Authors: Young, Peter R.; Del Zanna, Giulio; Mason, Helen E.; Doschek,
George A.; Culhane, Len; Hara, Hirohisa
Bibcode: 2007PASJ...59S.727Y
Altcode: 2007arXiv0706.1856Y
Two types of solar active region feature prominent at transition region
temperatures are identified in Hinode/EIS data of AR 10938 taken on
2007 January 20. The footpoints of 1 MK TRACE loops are shown to emit
strongly in emission lines formed at log T = 5.4-5.8, allowing the
temperature increase along the footpoints to be clearly seen. A density
diagnostic of Mg VII yields the density in the footpoints, with one
loop showing a decrease from 3 × 109 cm-3 at the
base to 1.5 × 109 cm-3 at a projected height
of 20 Mm. The second feature is a compact active region transition
region brightening which is particularly intense in O V emission
(log T = 5.4) but also has a signature at temperatures up to log T =
6.3. The Mg VII diagnostic gives a density of 4 × 1010
cm-3, and emission lines of Mg VI and Mg VII show line
profiles broadened by 50kms-1 and wings extending beyond
± 200kms-1. Continuum emission in the short wavelength
band is also found to be enhanced, and is suggested to be free-bound
emission from recombination onto He+.
Title: Hinode EUV Study of Jets in the Sun's South Polar Corona
Authors: Culhane, Len; Harra, Louise K.; Baker, Deborah; van
Driel-Gesztelyi, Lidia; Sun, Jian; Doschek, George A.; Brooks, David
H.; Lundquist, Loraine L.; Kamio, Suguru; Young, Peter R.; Hansteen,
Viggo H.
Bibcode: 2007PASJ...59S.751C
Altcode:
A number of coronal bright points and associated plasma jet features
were seen in an observation of the South polar coronal hole during
2007 January. The 40" wide slot was used at the focus of the Hinode
EUV Imaging Spectrometer to provide spectral images for two of these
events. Light curves are plotted for a number of emission lines that
include He II 256Å (0.079MK) and cover the temperature interval from
0.4MK to 5.0MK. Jet speed measurements indicate values less than the
escape velocity. The light curves show a post-jet enhancement in a
number of the cooler coronal lines indicating that after a few minutes
cooling, the plasma fell back to its original acceleration site. This
behavior has not been previously observed by e.g., the Yohkoh Soft
X-ray Telescope due to the comparatively high temperature cut-off
in its response. The observations are consistent with the existing
models that involve magnetic reconnection between emerging flux and the
ambient open field lines in the polar coronal hole. However we do not
have sufficient coverage of lines from lower temperature ion species
to register the Hα-emitting surge material that is associated with
some of these models.
Title: Hot and Cool Loops Composing the Corona of the Quiet Sun
Authors: Matsuzaki, Keiichi; Hara, Hirohisa; Watanabe, Tetsuya; Dere,
Kenneth P.; Brown, Charles M.; Culhane, Len
Bibcode: 2007PASJ...59S.683M
Altcode:
We performed a raster scan observation of the quiet Sun with the EUV
Imaging Spectrometer (EIS) aboard Hinode and simultaneously analyzed
observed emission lines of Fe VIII to XV. From a combined analysis,
radiance maps from the observed emission lines were deconvolved into
plasma components at five representative temperatures between 0.40MK and
2.63MK. While the lowest temperature component shows network structures
on spatial scales of between 10" and 20", the higher temperature
components show thread-like patterns on larger scales. A comparison of
emission measures at the different temperatures suggests that the lowest
temperature component is mainly composed of bodies of small loops,
rather than a collection of foot points of the higher temperature
loops. The difference in morphologies is interpreted as being due to
different magnetic field configurations, loops within super-granule
cells and fields extending beyond the boundaries of super-granule cells,
with distinct peak temperatures following a loop scaling law.
Title: Temperature and Density Structures of Solar Corona, A Test
of Iron Line Diagnostic Capability of EIS Instrument on Board Hinode
Authors: Watanabe, Tetsuya; Hara, Hirohisa; Culhane, Len; Harra,
Louise K.; Doschek, George A.; Mariska, John T.; Young, Peter R.
Bibcode: 2007PASJ...59S.669W
Altcode:
Increased diagnostic capability of the EUV Imaging Spectrometer
(EIS) aboard Hinode (former Solar-B) has been demonstrated with
a set of iron emission lines emerging in the two EIS observing
wavelength bands (170-210Å and 250-290Å) and their line-intensity
ratios. ``Abundance-uncertainty'' free relative emission measure
distributions as a function of temperature were deduced using only iron
emission lines of various ionization stages. First-light spectra of a
small active region show iron lines ranging from FeVIII (185.2Å and
186.6Å) through FeXVII (204.7Å, 254.9Å, and 269.4Å). Spectra of a
C-class flare confirms the presence of one of these higher temperature
lines (FeXVII at 254.9Å) more clearly, as well showing FeXXIV (192.0Å
and 255.1Å) and FeXXIII (263.8Å), which are normally only seen at
flare temperatures.
Title: The Temperature and Density Structure of an Active Region
Observed with the Extreme-Ultraviolet Imaging Spectrometer on Hinode
Authors: Doschek, George A.; Mariska, John T.; Warren, Harry P.;
Culhane, Len; Watanabe, Tetsuya; Young, Peter R.; Mason, Helen E.;
Dere, Kenneth P.
Bibcode: 2007PASJ...59S.707D
Altcode:
The Extreme-Ultraviolet Imaging Spectrometer (EIS) on Hinode
produces high resolution spectra that can be combined via rasters
into monochromatic images of solar structures, such as active
regions. Electron temperature and density maps of the structures can
be obtained by imaging the structures in different spectral lines with
ratios sensitive to either temperature or density. Doppler maps and
ion temperature maps can be made from spectral line wavelengths and
profiles, respectively. In this paper we discuss coronal temperature
and density distributions within an active region, illustrating the
power of EIS for solar plasma diagnostics.
Title: EUV Emission Lines and Diagnostics Observed with Hinode/EIS
Authors: Young, Peter R.; Del Zanna, Giulio; Mason, Helen E.; Dere,
Ken P.; Landi, Enrico; Landini, Massimo; Doschek, George A.; Brown,
Charles M.; Culhane, Len; Harra, Louise K.; Watanabe, Tetsuya; Hara,
Hirohisa
Bibcode: 2007PASJ...59S.857Y
Altcode: 2007arXiv0706.1857Y
Quiet Sun and active region spectra from the Hinode/EIS instrument are
presented, and the strongest lines from different temperature regions
discussed. A list of emission lines recommended to be included in EIS
observation studies is presented based on analysis of blending and
diagnostic potential using the CHIANTI atomic database. In addition
we identify the most useful density diagnostics from the ions covered
by EIS.
Title: Velocity Structure of Jets in a Coronal Hole
Authors: Kamio, Suguru; Hara, Hirohisa; Watanabe, Tetsuya; Matsuzaki,
Keiichi; Shibata, Kazunari; Culhane, Len; Warren, Harry P.
Bibcode: 2007PASJ...59S.757K
Altcode: 2007arXiv0711.2848K
The velocity structures of jets in a coronal hole have been derived
for the first time. Hinode observations revealed the existence
of many bright points in coronal holes. They are loop-shaped and
sometimes associated with coronal jets. Spectra obtained with the
Extreme-ultraviolet Imaging Spectrometer aboard Hinode were analyzed
to infer the Doppler velocity of bright loops and jets in a coronal
hole of the north polar region. Elongated jets above bright loops are
found to be blue-shifted by 30kms-1 at maximum, while foot
points of bright loops are red-shifted. Blue-shifts detected in coronal
jets are interpreted as being upflows produced by magnetic reconnection
between emerging flux and the ambient field in the coronal hole.
Title: Wavelength Determination for Solar Features Observed by the
EUV Imaging Spectrometer on Hinode
Authors: Brown, Charles M.; Hara, Hirohisa; Kamio, Suguru; Feldman,
Uri; Seely, John F.; Doschek, George A.; Mariska, John T.; Korendyke,
Clarence M.; Lang, James; Dere, Kenneth P.; Culhane, Len; Thomas,
Roger J.; Davila, Joseph M.
Bibcode: 2007PASJ...59S.865B
Altcode:
A wavelength calibration of solar lines observed by the high
resolution EUV Imaging Spectrometer (EIS) on the Hinode satellite
is reported. Spectral features of the quiet sun and of two mildly
active areas were measured and calibrated. A listing of the stronger
observed lines with identification of the leading contributor ions
is presented. 41 lines are reported, with 90% identified. Wavelength
precisions (2σ) of ±0.0031Å for the EIS short band and ±0.0029Å
for the EIS long band are obtained. These lines, typical of 1-2
×106 K plasmas, are recommended as standards for the
establishment of EIS wavelength scales. The temperature of EIS varies
by about 1D.5 C around the orbit and also with spacecraft pointing. The
correlation of these temperature changes with wavelength versus pixel
number scale changes is reported.
Title: The Solar-B EUV Imaging Spectrometer: an Overview of the
EIS Instrument
Authors: Culhane, J. L.
Bibcode: 2007ASPC..369....3C
Altcode:
The Solar-B mission includes an Extreme-UV Imaging Spectrometer
(EIS). This instrument detects photons in the wavelength ranges 170
- 210 Å and 250 - 290 Å which include emission lines from several
highly ionised species that exist over the temperature range of 4.7
to 7.3 in Log T. In this summary paper, we will describe the design
and operation of the instrument, present its performance parameters
e.g. spectral and spatial resolution and sensitivity, and summarize
its calibration. Its role in the Solar-B mission will be illustrated
with reference to some key science topics. The anticipated observing
strategy for the first three months of the mission will be outlined.
Title: Nonthermal Velocities in Solar Active Regions Observed with
the Extreme-Ultraviolet Imaging Spectrometer on Hinode
Authors: Doschek, G. A.; Mariska, J. T.; Warren, H. P.; Brown, C. M.;
Culhane, J. L.; Hara, H.; Watanabe, T.; Young, P. R.; Mason, H. E.
Bibcode: 2007ApJ...667L.109D
Altcode:
We discuss nonthermal velocities in an active region as revealed
by the Extreme-Ultraviolet Imaging Spectrometer (EIS) on the Hinode
spacecraft. The velocities are derived from spectral line profiles in
the extreme-ultraviolet (EUV) from a strong line of Fe XII at 195.12 Å
by fitting each line profile to a Gaussian function. We compare maps
of the full width at half-maximum values, the Fe XII spectral line
intensity, the Fe XII Doppler shift, the electron temperature, and
electron density. We find that the largest widths in the active region
do not occur in the most intense regions, but seem to concentrate in
less intense regions, some of which are directly adjacent to coronal
loops, and some of which concentrate in regions which also exhibit
relative Doppler outflows. The increased widths can also occur over
extended parts of the active region.
Title: CME Propagation Characteristics from Radio Observations
Authors: Pohjolainen, S.; van Driel-Gesztelyi, L.; Culhane, J. L.;
Manoharan, P. K.; Elliott, H. A.
Bibcode: 2007SoPh..244..167P
Altcode: 2007arXiv0711.3168P
We explore the relationship among three coronal mass ejections (CMEs),
observed on 28 October 2003, 7 November 2004, and 20 January 2005,
the type II burst-associated shock waves in the corona and solar wind,
as well as the arrival of their related shock waves and magnetic clouds
at 1 AU. Using six different coronal/interplanetary density models,
we calculate the speeds of shocks from the frequency drifts observed
in metric and decametric radio wave data. We compare these speeds
with the velocity of the CMEs as observed in the plane-of-the-sky
white-light observations and calculated with a cone model for the 7
November 2004 event. We then follow the propagation of the ejecta using
Interplanetary Scintillation measurements, which were available for the
7 November 2004 and 20 January 2005 events. Finally, we calculate the
travel time of the interplanetary shocks between the Sun and Earth and
discuss the velocities obtained from the different data. This study
highlights the difficulties in making velocity estimates that cover
the full CME propagation time.
Title: The Sun - Earth Workshop: A Summary of the Outcome
Authors: Culhane, J. L.; Siscoe, G. L.
Bibcode: 2007SoPh..244....3C
Altcode:
This special issue includes a set of papers that deal with extended
solar activity, the launching of CMEs at the Sun, their propagation
through interplanetary space, and the detection and study of the
ejecta near Earth and of their interaction with the Earth's magnetic
environment. In particular solar events that occurred on 28 October
2003, 6 and 7 November 2004, and 20 January 2005, for which the related
shocks arrived at Earth about two days later, are considered. The
summary paper extracts the principal outcomes that were arrived at in
the areas treated during the workshop and seeks to draw conclusions
both on the progress made and on possible directions for future work
in these areas.
Title: The EUV Imaging Spectrometer for Hinode
Authors: Culhane, J. L.; Harra, L. K.; James, A. M.; Al-Janabi, K.;
Bradley, L. J.; Chaudry, R. A.; Rees, K.; Tandy, J. A.; Thomas, P.;
Whillock, M. C. R.; Winter, B.; Doschek, G. A.; Korendyke, C. M.;
Brown, C. M.; Myers, S.; Mariska, J.; Seely, J.; Lang, J.; Kent,
B. J.; Shaughnessy, B. M.; Young, P. R.; Simnett, G. M.; Castelli,
C. M.; Mahmoud, S.; Mapson-Menard, H.; Probyn, B. J.; Thomas, R. J.;
Davila, J.; Dere, K.; Windt, D.; Shea, J.; Hagood, R.; Moye, R.; Hara,
H.; Watanabe, T.; Matsuzaki, K.; Kosugi, T.; Hansteen, V.; Wikstol, Ø.
Bibcode: 2007SoPh..243...19C
Altcode:
The EUV Imaging Spectrometer (EIS) on Hinode will observe solar corona
and upper transition region emission lines in the wavelength ranges
170 - 210 Å and 250 - 290 Å. The line centroid positions and profile
widths will allow plasma velocities and turbulent or non-thermal line
broadenings to be measured. We will derive local plasma temperatures and
densities from the line intensities. The spectra will allow accurate
determination of differential emission measure and element abundances
within a variety of corona and transition region structures. These
powerful spectroscopic diagnostics will allow identification
and characterization of magnetic reconnection and wave propagation
processes in the upper solar atmosphere. We will also directly study
the detailed evolution and heating of coronal loops. The EIS instrument
incorporates a unique two element, normal incidence design. The optics
are coated with optimized multilayer coatings. We have selected highly
efficient, backside-illuminated, thinned CCDs. These design features
result in an instrument that has significantly greater effective area
than previous orbiting EUV spectrographs with typical active region
2 - 5 s exposure times in the brightest lines. EIS can scan a field
of 6×8.5 arc min with spatial and velocity scales of 1 arc sec and
25 km s−1 per pixel. The instrument design, its absolute
calibration, and performance are described in detail in this paper. EIS
will be used along with the Solar Optical Telescope (SOT) and the X-ray
Telescope (XRT) for a wide range of studies of the solar atmosphere.
Title: The Hinode (Solar-B) Mission: An Overview
Authors: Kosugi, T.; Matsuzaki, K.; Sakao, T.; Shimizu, T.; Sone,
Y.; Tachikawa, S.; Hashimoto, T.; Minesugi, K.; Ohnishi, A.; Yamada,
T.; Tsuneta, S.; Hara, H.; Ichimoto, K.; Suematsu, Y.; Shimojo, M.;
Watanabe, T.; Shimada, S.; Davis, J. M.; Hill, L. D.; Owens, J. K.;
Title, A. M.; Culhane, J. L.; Harra, L. K.; Doschek, G. A.; Golub, L.
Bibcode: 2007SoPh..243....3K
Altcode:
The Hinode satellite (formerly Solar-B) of the Japan Aerospace
Exploration Agency's Institute of Space and Astronautical Science
(ISAS/JAXA) was successfully launched in September 2006. As the
successor to the Yohkoh mission, it aims to understand how magnetic
energy gets transferred from the photosphere to the upper atmosphere
and results in explosive energy releases. Hinode is an observatory
style mission, with all the instruments being designed and built to
work together to address the science aims. There are three instruments
onboard: the Solar Optical Telescope (SOT), the EUV Imaging Spectrometer
(EIS), and the X-Ray Telescope (XRT). This paper provides an overview
of the mission, detailing the satellite, the scientific payload, and
operations. It will conclude with discussions on how the international
science community can participate in the analysis of the mission data.
Title: Hinode Euv Study Of Jets In The Sun’s South Polar Corona
Authors: Culhane, J. L.; Brooks, D. H.; Doschek, G. A.; Harra, L. K.;
van Driel-Gesztelyi, L.; Baker, D.; Lundquist, L. L.; Hansteen, V. H.;
Kamio, S.
Bibcode: 2007AAS...210.7201C
Altcode: 2007BAAS...39..178C
Using the Hinode EUV Imaging Spectrometer coronal jets were observed
on 20-JAN-2007 over a range of emission lines and corresponding plasma
temperatures using the 40 arc sec wide slot images. In this preliminary
analysis, jet plasma temperature and emissivity have been estimated
while, based on assumptions about the jet morphology, electron density
estimates are given and jet velocity measured. The evolution of the
jets will be followed in a number of different EUV emission lines and
jet energy input as a function of time will be assessed with reference
to the magnetic field topologies involved.
Title: Hinode EIS Observations of Solar Active Regions
Authors: Mariska, John T.; Doschek, G. A.; Warren, H. P.; Brooks,
D. H.; Young, P. R.; Watanabe, T.; Culhane, J. L.
Bibcode: 2007AAS...210.7202M
Altcode: 2007BAAS...39R.178M
The EUV Imaging Spectrometer (EIS) on the Hinode satellite provides
high spatial and spectral resolution data along a 512 arcsec slit in
two wavelength ranges, 170--210 Angstroms and 250--290 Angstroms. These
wavelengths mostly contain emission lines from upper transition region
and coronal plasmas. Emission from these wavelengths is routinely
imaged using instruments such as the EIT on SOHO and TRACE, but there
are few high-resolution spectra to aid in more deeply understanding
the physical conditions and dynamics associated with the intensity
variations seen in the images. In this presentation, we show some
initial results from EIS active region studies aimed at mapping the
density, temperature, nonthermal broadening, and Doppler shifts in
active regions. This presentation focusses on spectroheliograms of
active regions in diagnostically interesting spectral lines. These
show the overall active region morphology and the behavior of Doppler
shifts, nonthermal velocities, and densities as a function of position,
but at the expense of high time resolution. Other presentations will
focus on how the observed physical parameters vary with time.
Title: Iron Line Ratio Analysis in an Active Region
Authors: Watanabe, Tetsuya; Hara, H.; Culhane, J. L.; Harra, L. K.;
Doschek, G. A.; Mariska, J. T.; Young, P. R.; Hinode EIS Team
Bibcode: 2007AAS...210.7204W
Altcode: 2007BAAS...39..179W
Increased diagnostic capability of the EIS instrument on board Hinode
(Solar-B) is demonstrated with a set of iron emission lines appearing
in the two EIS observing wavelengths (170 - 210 A & 250 - 290
A) and their line intensity ratios. First-light spectra of a small
active region show iron lines at the ionization stages of FeVIII
(185.2 A & 186.6 A) through FeXVII (204.7 A, 254.9 A, & 269.4
A). Decay phase spectra of a C-class flare confirms the presence of
this higher temperature line; FeXVII at 254.9 A more clearly, as well
as those lines of flare temperatures; FeXXIV (192.0 A & 255.1 A)
and FeXXIII (263.8 A).
Title: A Multiple Flare Scenario where the Classic Long-Duration
Flare Was Not the Source of a CME
Authors: Goff, C. P.; van Driel-Gesztelyi, L.; Démoulin, P.; Culhane,
J. L.; Matthews, S. A.; Harra, L. K.; Mandrini, C. H.; Klein, K. L.;
Kurokawa, H.
Bibcode: 2007SoPh..240..283G
Altcode:
A series of flares (GOES class M, M and C) and a CME were observed in
close succession on 20 January 2004 in NOAA 10540. Radio observations,
which took the form of types II, III and N bursts, were associated with
these events. We use the combined observations from TRACE, EIT, Hα
images from Kwasan, MDI magnetograms and GOES to understand the complex
development of this event. Contrary to a standard interpretation,
we conclude that the first two impulsive flares are part of the CME
launch process while the following long-duration event flare represents
simply the recovery phase. Observations show that the flare ribbons
not only separate but also shift along the magnetic inversion line
so that magnetic reconnection progresses stepwise to neighboring flux
tubes. We conclude that "tether cutting" reconnection in the sheared
arcade progressively transforms it to a twisted flux tube, which
becomes unstable, leading to a CME. We interpret the third flare,
a long-duration event, as a combination of the classical two-ribbon
flare with the relaxation process following forced reconnection between
the expanding CME structure and neighboring magnetic fields.
Title: Decametric N Burst: A Consequence of the Interaction of Two
Coronal Mass Ejections
Authors: Démoulin, P.; Klein, K. -L.; Goff, C. P.; van
Driel-Gesztelyi, L.; Culhane, J. L.; Mandrini, C. H.; Matthews, S. A.;
Harra, L. K.
Bibcode: 2007SoPh..240..301D
Altcode:
Radio emissions of electron beams in the solar corona and interplanetary
space are tracers of the underlying magnetic configuration and of
its evolution. We analyse radio observations from the Culgoora and
WIND/WAVES spectrographs, in combination with SOHO/LASCO and SOHO/MDI
data, to understand the origin of a type N burst originating from NOAA
AR 10540 on January 20, 2004, and its relationship with type II and
type III emissions. All bursts are related to the flares and the CME
analysed in a previous paper (Goff et al., 2007). A very unusual feature
of this event was a decametric type N burst, where a type III-like
burst, drifting towards low frequencies (negative drift), changes drift
first to positive, then again to negative. At metre wavelengths, i.e.,
heliocentric distances ≲1.5R⊙, these bursts are ascribed
to electron beams bouncing in a closed loop. Neither U nor N bursts are
expected at decametric wavelengths because closed quasi-static loops
are not thought to extend to distances ≫1.5R⊙. We take
the opportunity of the good multi-instrument coverage of this event to
analyse the origin of type N bursts in the high corona. Reconnection
of the expanding ejecta with the magnetic structure of a previous CME,
launched about 8 hours earlier, injects electrons in the same manner as
with type III bursts but into open field lines having a local dip and
apex. The latter shape was created by magnetic reconnection between
the expanding CME and neighbouring (open) streamer field lines. This
particular flux tube shape in the high corona, between 5R⊙
and 10R⊙, explains the observed type N burst. Since the
required magnetic configuration is only a transient phenomenon formed
by reconnection, severe timing and topological constraints are present
to form the observed decametric N burst. They are therefore expected
to be rare features.
Title: Study of CME transit speeds for the event of 07-NOV-2004
Authors: Culhane, J. L.; Pohjolainen, S.; van Driel-Gesztelyi, L.;
Manoharan, P. K.; Elliott, H. A.
Bibcode: 2007AdSpR..40.1807C
Altcode:
Several methods for CME speed estimation are discussed. These include
velocity derivation based on the frequency drifts observed in metric
and decametric radio wave data using a range of coronal density
models. Coronagraph height-time plots allow measurement of plane-of-sky
and expansion speeds. These in turn can enable propagation speeds to
be derived from a range of empirical relations. Simple geometric e.g.,
cone, models can provide propagation velocity estimates for suitable
halo or partial halo events. Interplanetary scintillation observations
allow speed estimates at large distances from the Sun detecting in
particular the deceleration of the faster CMEs. Related interplanetary
shocks and the arrival times and speeds of the associated magnetic
clouds at Earth can also be considered. We discuss the application of
some of these methods to the transit to Earth of a complex CME that
originated earlier than 16:54 U.T. on 07-NOV-2004. The difficulties
in making velocity estimates from radio observations, particularly
under disturbed coronal conditions, are highlighted.
Title: Magnetic coupling of the Sun Earth system The view from
STEREO
Authors: Matthews, S. A.; Culhane, J. L.
Bibcode: 2007AdSpR..39.1791M
Altcode:
The STEREO mission, launched on October 25 2006, will provide the first
stereoscopic view of the Sun and its magnetic environment. A suite of
identical instruments on two continuously separating spacecraft will
monitor the onset of solar eruptive phenomena, and track them as the
shocks and ejected material propagate through the interplanetary medium
(IPM). The combination of remote sensing and in situ instrumentation
will provide new insights into the onset of eruptions, the extent of
their effects on the global structure of the low corona, and their
subsequent evolution through the IPM. These observations will provide
new constraints on the processes involved and allow us to distinguish
between competing models of eruptive solar phenomena.
Title: Build-up of a CME and its Interaction with Large-Scale
Magnetic Structures
Authors: van Driel-Gesztelyi, L.; Goff, C. P.; Demoulin, P.; Culhane,
J. L.; Klein, K. L.; Mandrini, C. H.; Matthews, S. A.; Harra, K. L.;
Kurokawa, H.
Bibcode: 2006IAUJD...3E..86V
Altcode:
Introduction: A series of flares (GOES class M, M and C) and a
CME were observed on 20-JAN-2004 occurring in close succession in
NOAA 10540. Types II, III and a N radio bursts were associated. We
investigate the link between the flares (two impulsive flares followed
by an LDE) and the CME as well as the origin of the rare decametric
N-burst. Methods: We use the combined observations from TRACE, SOHO/EIT,
H-alpha images from Kwasan Observatory, SOHO/MDI magnetograms, GOES
and radio observations from Culgoora and Wind/WAVES as well as magnetic
modelling to understand the complex development of this event. Results:
We link the first two impulsive flares to tether-cutting reconnections
and the launch of the CME, while the last of the flares, an LDE,
to the relaxation phase following forced reconnections between the
erupting flux rope and neighbouring magnetic field lines. We show
that reconnection with the magnetic structure of a previous CME,
launched about 8 hours earlier, injects electrons into open field
lines having a local dip and apex of about 6 solar radii height. The
dipped shape of these field lines was due to large-scale magnetic
reconnection between expanding magnetic loops and open field lines of a
neighbouring streamer. This particular situation explains the observed
decametric N burst. Discussion: This complex observation shows that
impulsive quadrupolar flares can be eruptive, while an LDE may remain
a confined event. We find that reconnection forced by the expanding CME
structure is followed by a relaxation phase, when reconnection reverses
and restores some of the pre-eruption magnetic connectivities. The
observed decametric N-burst was caused by the interaction of two CMEs
and reconnection of their expanding magnetic field with neighbouring
streamer field lines - a very particular interplay, which explains
why N-bursts are so rare.
Title: The extreme UV imaging spectrometer for the JAXA Solar-B
mission
Authors: Culhane, J. L.; Doschek, G. A.; Watanabe, T.; Smith, A.;
Brown, C.; Hara, H.; Harra, L. K.; James, A. M.; al Janabi, K.;
Kent, B.; Korendyke, C.; Lang, J.; Mariska, J.; Myers, S.; Seely,
J.; Simnett, G.; Tandy, J.; Thomas, R.; Windt, D. L.
Bibcode: 2006SPIE.6266E..0TC
Altcode: 2006SPIE.6266E..22C
The ISAS/JAXA Solar-B mission includes an Extreme-UV Imaging
Spectrometer (EIS). It detects photons in the wavelength ranges 17 -
21 nm and 25 - 29 nm which include emission lines from several highly
ionised species that exist at temperatures log T = 4.7, 5.6, 5.8,
5.9 and 6.0 - 7.3 K. Instrument throughput is increased substantially
by the use of multilayer coatings optimized for maximum reflectance
in the two selected wavelength bands. The use of back-illuminated
CCDs provides significantly enhanced quantum efficiency over that
previously available from microchannel plate systems. In this paper we
will describe the design and operation of the instrument and present
its performance parameters e.g. spectral and spatial resolution and
sensitivity. Preliminary results of recent calibration measurements
will be described. The role of EIS in the Solar-B mission will be
illustrated with reference to the anticipated observing strategy for
the first three months of the mission which will be outlined.
Title: The Extreme Ultraviolet Imaging Spectrometer (EIS) on Solar-B
Authors: Doschek, George A.; Brown, C. M.; Korendyke, C. M.; Mariska,
J. T.; Myers, S. H.; Seely, J. F.; Dere, K. P.; Lang, J.; Culhane,
J. L.; Watanabe, T.
Bibcode: 2006SPD....37.3604D
Altcode: 2006BAAS...38S.260D
The Extreme Ultraviolet Imaging Spectrometer (EIS) for Solar-B is a
high throughput state-of-the-art instrument designed to obtain solar
spectra and images in two wavelength bands centered near 195 and 270
Angstroms. Traditional spectra can be obtained using narrow slits or
images of solar structures can be obtained in individual spectral
lines using wide slots. Essentially, the instrument obtains images
in wavebands similar to TRACE but in each spectral line within the
waveband. This removes electron temperature ambiguities inherent in
broadband imagers and allows dynamic effects to be detected via Doppler
shifts and densities and other plasma parameters to be measured via
spectroscopic plasma diagnostics. After a brief description of how
the instrument works and a comparison with previous instrumentation
(sensitivity, etc.), the presentation will focus on the science that
can be accomplished with EIS, presented in the form of sample observing
sequences. The focus will be on active regions and solar flares with a
consideration of topics such as temperature and density distributions
in active region loops and their evolution, dynamical motions in active
region loops, the reconnection site in solar flares, and temperature
evolution of multimillion degree flare loops.
Title: Non-thermal broadening of coronal emission lines in the onset
phase of solar flares and CMEs
Authors: Kay, H. R. M.; Matthews, S. A.; Harra, L. K.; Culhane, J. L.
Bibcode: 2006A&A...447..719K
Altcode:
The non-thermal broadening of soft X-ray emission lines is commonly seen
during the early stages of solar flares and is thought to be associated
with either the initial flare energy release or the evaporation of
chromospheric plasma. Here we investigate the magnitude of non-thermal
broadening for a sample of 12 flares associated with both eruptive and
non-eruptive events, i.e. those with and without associated coronal mass
ejections (CMEs), using the Bragg Crystal Spectrometer (BCS) on the
Yohkoh spacecraft. The maximum non-thermal broadening of the eruptive
flares was found to be on average lower than for the flares which were
not associated with CMEs. There was no evidence of any relationship
between the maximum non-thermal broadening and the initial CME speed.
Title: Lines in the range 3.2 6.1 Å observed in RESIK spectra
Authors: Sylwester, B.; Sylwester, J.; Siarkowski, M.; Phillips,
K. J. H.; Culhane, J. L.; Lang, J.; Brown, C.; Kuznetsov, V. D.
Bibcode: 2006AdSpR..38.1534S
Altcode:
RESIK is a Bragg bent crystal X-ray spectrometer on board the CORONAS-F
satellite. Between 24 August 2002 and 22 May 2003 RESIK collected
a large number of solar X-ray spectra in four energy bands covering
the range 3.2 6.1 Å. A recent absolute calibration has allowed us to
make detailed identification of observed spectral features, and from
observed line and continuum fluxes to get temperature, emission measure,
etc. The lines were identified using spectra averaged over periods of
various solar activity levels. These averaged spectra contain a number
of strong lines with transitions in H- and He-like ions of K, Ar, S
and Si. Some of them are resonance parent lines and their satellites
which were observed with other spectrometers and have been described
elsewhere. Here, we report detection of several lines not previously
observed in solar spectra, including lines of H-like and He-like S
and Si ions with transitions 1s np and 1s2 1snp, n up to
10. In addition we provide identification of the He-like Cl (Cl XVI)
triplet in the range 4.43 4.45 Å. The feature at 4.182 Å, which is
the wavelength of the H-like Cl (Cl XVII) Lyα line, is probably a
blend of S XIV satellites from cooler plasma.
Title: Temperature-sensitive line ratio diagnostics based on Si
satellite-to-resonance line ratios for 1s2 1snp transitions
Authors: Phillips, K. J. H.; Dubau, J.; Sylwester, J.; Sylwester,
B.; Culhane, J. L.; Doschek, G. A.; Lang, J.
Bibcode: 2006AdSpR..38.1543P
Altcode:
Dielectronic satellite lines due to 1s2n‧l‧ 1snpn‧l‧
(n = 3, 4) transitions in Li-like Si (Si XII) occur at 5.818 and
5.565 Å, on the long wavelength side of the He-like Si (Si XIII)
1s2 1s3p and 1s2 1s4p lines at 5.681 and 5.384 Å,
respectively. They have been extensively observed with the RESIK crystal
spectrometer on the Russian spacecraft CORONAS-F. As with corresponding
satellites 1s2nl 1s2pnl on the long-wavelength side of
the Si XIII 1s2 1s2p resonance line, there is an inverse
temperature dependence of the intensity ratio of the satellites to the
He-like ion lines (Isat/IHe). New atomic data
are used to calculate the Si XII satellite line intensities and thus
the Isat/IHe ratio. RESIK observations of the
ratio in solar flares, together with temperatures from the ratio of
the two GOES X-ray channels, are compared with theoretical variation
of the ratio with temperature. The good agreement indicates this to
be a valuable temperature diagnostic for solar flares and laboratory
plasmas such as tokamaks. There are implications for similar satellites
in Fe line spectra which are observed with broad-band resolution by
the RHESSI solar flare mission.
Title: Multi-scale reconnections in a complex CME
Authors: van Driel-Gesztelyi, L.; Goff, C.; Demoulin, P.; Culhane,
J. L.; Matthews, S. A.; Harra, L. K.; Mandrini, C. H.; Klein, K. L.;
Kurokawa, H.
Bibcode: 2006cosp...36.2371V
Altcode: 2006cosp.meet.2371V
A series of flares GOES class M M and C and a CME were observed on
20-JAN-2004 occurring in close succession in NOAA 10540 Types II III
and an N radio bursts were associated We use the combined observations
from TRACE EIT H-alpha images from Kwasan Observatory MDI magnetograms
GOES and radio observations from Culgoora and Wind WAVES to understand
the complex development of this event We link the first two impulsive
flares to tether-cutting reconnections and the launch of the CME while
the last of the flares an LDE to the relaxation phase following forced
reconnections between the erupting flux rope and neighbouring magnetic
field lines We show that reconnection with the magnetic structure of
a previous CME launched about 8 hours earlier injects electrons into
open field lines having a local dip and apex of about 6 solar radii
height The dipped shape of these field lines was due to large-scale
magnetic reconnection between expanding magnetic loops and open field
lines of a neighbouring streamer This particular situation explains
the observed decametric N burst and why N-bursts are so rare
Title: Analysis of potassium abundance in a large number of flares
Authors: Sylwester, J.; Sylwester, B.; Phillips, K. J. H.; Culhane,
J. L.; Brown, C.; Lang, J.; Stepanov, A. I.
Bibcode: 2006AdSpR..38.1490S
Altcode:
An initial study of spectra observed in the shortest wavelength
channel (3.40-3.80 Å) of the RESIK X-ray spectrometer on CORONAS-F
indicates the presence of substantial flare-to-flare variations in
the line-to-continuum ratio of several lines, in particular He-like
potassium (K XVIII) lines, occurring in the range 3.53-3.57 Å. The
observed variations are larger than those expected from temperature
variations. This has motivated a study of possible variations in
the potassium abundance in the observed spectra. With a new RESIK
calibration available, we have obtained absolute fluxes of the K
XVIII resonance line as well as the continuum and lines observed in
other RESIK channels (3.40-6.05 Å) for some 1163 intervals observed
early in 2003. Analysis of these observations allowed us to determine
the average absolute potassium abundance for the period studied and
investigate the variability of abundance. The results obtained are
presented and discussed.
Title: a Series of Compact Flares with AN Associated CME
Authors: Goff, C. P.; van Driel-Geszrelyi, L.; Culhane, J. L.;
Matthews, S. A.; Harra, L. K.; Démoulin, P.; Mandrini, C. H.;
Kurokawa, H.
Bibcode: 2005ESASP.600E.157G
Altcode: 2005ESPM...11..157G; 2005dysu.confE.157G
No abstract at ADS
Title: Relating Near-Earth Observations of AN Interplanetary Coronal
Mass Ejection to the Conditions at its Site of Origin in the Solar
Corona
Authors: Fazakerley, A. N.; Harra, L. K.; Culhane, J. L.; van
Driel-Gesztelyi, L.; Lucek, E.; Matthews, S. A.; Owen, C. J.; Mazelle,
C.; Balogh, A.; Réme, H.
Bibcode: 2005ESASP.600E..47F
Altcode: 2005dysu.confE..47F; 2005ESPM...11...47F
No abstract at ADS
Title: Flows in the solar atmosphere due to the eruptions on the
15th July, 2002
Authors: Harra, L. K.; Démoulin, P.; Mandrini, C. H.; Matthews,
S. A.; van Driel-Gesztelyi, L.; Culhane, J. L.; Fletcher, L.
Bibcode: 2005A&A...438.1099H
Altcode:
Which kind of flows are present during flares? Are they compatible
with the present understanding of energy release and which model
best describes the observations? We analyze successive flare events
in order to answer these questions. The flares were observed in the
magnetically complex NOAA active region (AR) 10030 on 15 July 2002. One
of them is of GOES X-class. The description of these flares and how
they relate to the break-out model is presented in Gary & Moore
(2004). The Coronal Diagnostic Spectrometer on board SOHO observed
this active region for around 14 h. The observed emission lines
provided data from the transition region to the corona with a field
of view covering more than half of the active region. In this paper
we analyse the spatially resolved flows seen in the atmosphere from
the preflare to the flare stages. We find evidence for evaporation
occurring before the impulsive phase. During the main phase, the
ongoing magnetic reconnection is demonstrated by upflows located at
the edges of the flare loops (while downflows are found in the flare
loops themselves). We also report the impact of a filament eruption
on the atmosphere, with flows up to 300 km s-1 observed at
transition-region temperatures in regions well away from the location
of the pre-eruptive filament. Our results are consistent with the
predictions of the break out model before the impulsive phase of the
flare; while, as the flare progresses, the directions of the flows are
consistent with flare models invoking evaporation followed by cooling
and downward plasma motions in the flare loops.
Title: Relating near-Earth observations of an interplanetary coronal
mass ejection to the conditions at its site of origin in the solar
corona
Authors: Fazakerley, A. N.; Harra, L. K.; Culhane, J. L.; van
Driel-Gesztelyi, L.; Lucek, E.; Matthews, S. A.; Owen, C. J.; Mazelle,
C.; Balogh, A.; Rème, H.
Bibcode: 2005GeoRL..3213105F
Altcode:
A halo coronal mass ejection (CME) was detected on January 20, 2004. We
use solar remote sensing data (SOHO, Culgoora) and near-Earth in situ
data (Cluster) to identify the CME source event and show that it was a
long duration flare in which a magnetic flux rope was ejected, carrying
overlying coronal arcade material along with it. We demonstrate that
signatures of both the arcade material and the flux rope material are
clearly identifiable in the Cluster and ACE data, indicating that the
magnetic field orientations changed little as the material traveled
to the Earth, and that the methods we used to infer coronal magnetic
field configurations are effective.
Title: The Extreme Ultraviolet Imaging Spectrometer on Solar-B
Authors: Mariska, J. T.; Brown, C. M.; Doschek, G. A.; Korendyke,
C. M.; Myers, S. H.; Seely, J. F.; Dere, K. P.; Lang, J.; Culhane,
J. L.; Watanabe, T.
Bibcode: 2005AGUSMSP43A..02M
Altcode:
The Extreme Ultraviolet Imaging Spectrometer (EIS) is currently under
development for flight on the Japanese Solar-B satellite. EIS uses a
multilayer-coated off-axis telescope mirror and a multilayer-coated
toroidal grating spectrometer to produce stigmatic spectra of solar
regions isolated by a 1024 arcsec high slit. The instrument produces
monochromatic images either by rastering the solar image across a
narrow entrance slit or by using a very wide slit. Half of each optic
is coated to optimize reflectance at 19.5 nm, and the other half to
optimize reflectance at 27.0 nm, with each wavelength range imaged
onto a separate CCD detector. EIS can provide key dynamical and density
diagnostic information. Combining EIS data with observations from the
other instruments on Solar-B should provide a detailed picture of solar
atmospheric processes from the visible surface into the corona. In
this presentation, we provide details of the instrument's expected
performance based on calibration of the individual flight optics and
end-to-end testing at the Rutherford Appleton Laboratory in the UK.
Title: Book Review: Book review
Authors: Culhane, Len
Bibcode: 2005SpPol..21..233C
Altcode:
For more than a decade, the UN and the European Space Agency have
organized a series of international workshops on Basic Space Science
to facilitate a dialogue between scientists from developing and
industrialized nations. In an introduction consisting of five papers,
the present book explains the background to this initiative and then
presents, by geographical region, a selection from the topics that have
been discussed at the workshops. Four sections, organized by region
of the Earth (Asia/Pacific, Latin America/Caribbean, Sub-Saharan
Africa, Western Asia/Northern Africa), contain some 25 separate
contributions. Section 5 includes six papers on the development of
small ground-based astronomical telescope facilities, while Section
6 has five papers that discuss potential future projects for space
science and astronomy in developing countries. A concluding section
presents some eight astrophysical topics and associated problems and
is aimed at providing material on astronomy that could conveniently
be included in a university physics course.
Title: Resik: A Bent Crystal X-ray Spectrometer for Studies of Solar
Coronal Plasma Composition
Authors: Sylwester, J.; Gaicki, I.; Kordylewski, Z.; Kowaliński,
M.; Nowak, S.; Płocieniak, S.; Siarkowski, M.; Sylwester, B.;
Trzebiński, W.; Bakała, J.; Culhane, J. L.; Whyndham, M.; Bentley,
R. D.; Guttridge, P. R.; Phillips, K. J. H.; Lang, J.; Brown, C. M.;
Doschek, G. A.; Kuznetsov, V. D.; Oraevsky, V. N.; Stepanov, A. I.;
Lisin, D. V.
Bibcode: 2005SoPh..226...45S
Altcode:
We describe the RESIK (REntgenovsky Spektrometr s Izognutymi Kristalami)
instrument, consisting of two double-channel X-ray spectrometers,
designed to observe solar active region and flare plasmas. RESIK is
one of the instruments making up the scientific payload of the Russian
CORONAS-F solar mission. The uncollimated spectrometer uses two silicon
and two quartz bent crystals observing flare, active region and coronal
spectra in four wavelength bands with a resolving power (λ/Δ λ)
of ∼1000. The wavelength coverage, 3.3-6.1 Å, includes emission
lines of Si, S, Cl, Ar, and K and in the third diffraction order,
the wavelength range includes He-like Fe lines (1.85 Å) and Ni lines
(1.55 Å) with dielectronic satellites, emitted during intense, hot
flares. The instrument is believed to be the best calibrated space-borne
crystal spectrometer flown to date. The spectrometer dynamically adjusts
the data gathering intervals from 1 s to 5 minutes, depending on the
level of solar X-ray emission at the time of observation. The principal
aims of RESIK are the measurements of relative and absolute element
abundances in the emitting plasma and the temperature distribution of
plasma (differential emission measure) over the temperature interval 3
and 50 MK. This paper summarizes the scientific objectives of RESIK
and describes the design, characteristics, and performance of the
instrument.
Title: Preface
Authors: Culhane, Len; Harrison, Richard
Bibcode: 2005AdSpR..36.1477C
Altcode:
No abstract at ADS
Title: The Solar-B EUV imaging spectrometer and its science goals
Authors: Culhane, J. L.; Harra, L. K.; Doschek, G. A.; Mariska, J. T.;
Watanabe, T.; Hara, H.
Bibcode: 2005AdSpR..36.1494C
Altcode:
The Solar-B mission includes an Extreme-UV Imaging Spectrometer
(EIS). It detects photons in the ranges 170-210 and 250-290 Å which
include emission lines from several highly ionised species that exist
at temperatures log T = 4.7, 5.6, 5.8, 5.9 and 6.0-7.3 K. In this
paper, we will describe the design and operation of the instrument
and present its performance parameters, e.g., spectral and spatial
resolution and sensitivity. Preliminary results of recent calibration
measurements will be described. Its role in the Solar-B mission will
be illustrated with reference to several key science topics that the
EIS is expected to address. The anticipated observing strategy for
the first three months of the mission will be outlined.
Title: X-Ray and EUV Observations of Large-Scale Coronal Structures
Authors: Culhane, J. L.; Foley, C. R.
Bibcode: 2004ASPC..325..205C
Altcode:
Large-scale coronal streamers, first recognized in solar eclipse images
and in white-light coronagraph data, are now more frequently observed
with space-borne coronagraphs e.g. LASCO on SOHO, out to a distance
of ∼ 30 R⊙. The SOHO spectrometers, CDS and SUMER, have
been used for emission line intensity studies of these structures. The
SOHO UVCS has undertaken UV spectroscopy and visible polarimetry
studies of the corona to a height of ∼ 12 R⊙. Yohkoh
SXT observations of large coronal structures, made in the period
before December 1992, will be discussed. Subsequent observations by
the SOHO instruments will also be reviewed. The origin of the slow
solar wind will be discussed. The properties of transequatorial loop
systems will be reviewed and their relationship to coronal heating,
CME occurrence and flaring examined. Recent work on the relationship
between solar coronal and stellar X-ray radiance and unsigned magnetic
flux will be briefly described.
Title: Instrumentation for Photon Detection in Space
Authors: Culhane, J. L.
Bibcode: 2004spsc.book..365C
Altcode:
No abstract at ADS
Title: Identification of Lines in the Range 3.35 A - 6.1 A Observed
in RESIK Spectra
Authors: Sylwester, B.; Sylwester, J.; Siarkowski, M.; Phillips,
K. J. H.; Culhane, J. L.; Lang, J.; Brown, C.; Kuznetsov, V. D.
Bibcode: 2004cosp...35.2663S
Altcode: 2004cosp.meet.2663S
RESIK is the Bragg bent crystal X-ray spectrometer on board CORONAS-F
satellite. Between August 24, 2002 and May 22, 2003, the instrument
collected a large database of solar X-ray spectra in four energy bands
covering the range 3.35 Å - 6.1 Å. We have recently calibrated the
spectra in order to determine an absolute wavelength scale and absolute
photon fluxes. This has allowed us to make detailed indentifications
of observed spectral features, and to interpret the observed line
and continuum fluxes in terms of basic plasma characteristics
like temperature and emission measure. Our line identifications
have been made using spectra averaged over periods of various solar
activity levels, e.g. flare rise and decay phases, non-flaring active
regions and quiet Sun. The spectra contain a number of strong lines
corresponding to the transitions in H- and He-like ions of K, Ar, S
and Si. Some of these lines are resonance lines and their satellites
which have already been noted by previous authors using data from
other spectrometers, but several lines have never been observed in
solar spectra before. These include lines of H-like and He-like S and
Si corresponding to transitions 1s - np and 1s^2 -1s np with n up to
∼10. In addition we provide indentification of the H-like Cl (Cl
XVII) Ly-alpha lines at 4.182 Å, and He-like Cl (Cl XVI) triplet in
the range 4.43 Å,- 4.45 Å, never before observed simultaneously. We
will present detailed identifications of these lines in this paper.
Title: Analysis of Potassium Abundance Variability in Selected
Solar Flares
Authors: Sylwester, J.; Sylwester, B.; Phillips, K. J. H.; Culhane,
J. L.; Brown, C.; Lang, J.; Stepanov, A. I.
Bibcode: 2004cosp...35.2639S
Altcode: 2004cosp.meet.2639S
A quick-look inspection of spectra observed in the shortwavelength
channel (3.35 Å,- 3.8 Å) of the RESIK X-ray spectrometer on Coronas-F
indicates the presence of substantial flare-to-flare variations in
the line-to-continuum ratio of several lines, in particular He-like
potassium (K XVIII) lines, occurring at 3.53 Å,- 3.57 Å. The
observed variations are larger those expected from temperature
variations. This has motivated a detailed study of possible variations
in the flare-to-flare potassium abundance. With newly calibrated RESIK
spectra, we have obtained absolute fluxes of the K XVIII resonance,
intercombination and forbidden lines as well as the continuum and
lines observed in other RESIK channels (3.35 Å,- 6.1 Å). These
data have allowed us to determine the absolute potassium abundance
for a selection of flares, mostly short-lived with a range of X-ray
importance. The results obtained are presented and discussed.
Title: Temperature-sensitive Line Ratios Diagnostics of the
non-flaring Corona based on Satellite-to-Resonance Line Ratios for
1s^2-1s(np) Transitions
Authors: Phillips, K. J. H.; Dubau, J.; Sylwester, J.; Sylwester,
B.; Kordylewski, Z.; Culhane, J. L.; Doschek, G. A.; Lang, J.
Bibcode: 2004cosp...35.2579P
Altcode: 2004cosp.meet.2579P
One of the most convenient electron temperature diagnostics of
hot astrophysical plasmas is the intensity ratio of dielectronic
satellite lines to resonance lines in the X-ray region. Until now,
this diagnostic has been applied to satellites near the 1s-2p lines of
H-like ions or the 1s^2 - 1s2p lines of He-like ions, these lines being
extensively observed with crystal spectrometers during flares. However,
satellites near the 1s^2 - 1snp (n>2) lines of He-like ions,
unlike those near the 1s^2 - 1s2p lines, have the important advantage
of being well separated from their parent lines and unblended with
other lines. Spectra from the RESIK spectrometer on Coronas-F,
covering the wavelength range 3.4 Å,- 6.1 Å, are highly suited
for observation of these satellites, due to transitions from the n =
3, 4 and 5 levels to the n = 1 level, near corresponding resonance
lines of H-like and He-like Si (Si XIII, Si XIV) and S (S XV, S XVI)
ions. New calculations of satellite intensity factors presented in
this paper enable temperatures to be calculated from observed ratios
of Li-like Si (Si XII) 1s^2 2p ^2P1/2,3/2 - 1s 2p (^3P) 3p
^2D3/2,5/2 satellite complex (5.816 Å) near He-like Si (Si
XIII) 1s^2 ^1S_0 - 1s 3p ^1P_1} resonance (5.681 Å) line. These lines
are well observed in recent quiet and non-flaring active region RESIK
X-ray spectra, and therefore provide the most sensitive temperature
diagnostic tool for physical conditions in weakly active corona.
Title: Solar-B EIS and its Science Goals
Authors: Culhane, J. L.; Doschek, D. A.; Watanabe, T.
Bibcode: 2004cosp...35.4214C
Altcode: 2004cosp.meet.4214C
The EUV Imaging Spectrometer (EIS) instrument is designed to study
the emission line spectrum of coronal and transition region plasma in
the wavelength range 15nm to 30nm. It will obtain information on the
dynamics, velocity, temperature and density of the emitting plasma with
a spatial resolution of ∼ 2 arc sec. EIS represents the next stage in
the development of scanning imaging EUV spectrometers. It has about a
factor ten larger effective aperture than the SOHO Coronal Diagnostic
Spectrometer, due to the use of multilayer-coated optical elements,
along with an even greater enhancement in wavelength resolution. In
this paper, the EIS instrument features will be described and estimates
given for its expected performance. In particular, the emission line
spectra are registered with sufficient time and spatial resolution to
allow determination of plasma dynamics and temperature as a function of
position within solar flare and solar active region loops. Spectra will
be accurately related in position to the images obtained by the Solar-B
white light and X-ray telescopes. Thus the EIS science aims will be
discussed in the context of its anticipated role in the Solar-B mission.
Title: The CCD and readout electronics for the OMC instrument
on Integral
Authors: Walton, D. M.; Thomas, P. D.; Culhane, J. L.; Jordan, B.;
Smith, A.; Dibbens, A. P.; Bradley, L. J.
Bibcode: 2003A&A...411L.275W
Altcode:
The Optical Monitoring Camera (OMC) on ESA's Integral gamma-ray
astronomy satellite is devoted to optical wavelength observations
simultaneously covering the same field-of-view as the gamma-ray and
X-ray instruments. The OMC consists of a refracting telescope with a
CCD as the imaging device in the focal plane. Here we describe the
CCD and its associated readout electronics, in particular pointing
out features of interest to users of the OMC instrument and its data.
Title: OMC: An Optical Monitoring Camera for INTEGRAL. Instrument
description and performance
Authors: Mas-Hesse, J. M.; Giménez, A.; Culhane, J. L.; Jamar, C.;
McBreen, B.; Torra, J.; Hudec, R.; Fabregat, J.; Meurs, E.; Swings,
J. P.; Alcacera, M. A.; Balado, A.; Beiztegui, R.; Belenguer, T.;
Bradley, L.; Caballero, M. D.; Cabo, P.; Defise, J. M.; Díaz, E.;
Domingo, A.; Figueras, F.; Figueroa, I.; Hanlon, L.; Hroch, F.;
Hudcova, V.; García, T.; Jordan, B.; Jordi, C.; Kretschmar, P.;
Laviada, C.; March, M.; Martín, E.; Mazy, E.; Menéndez, M.; Mi,
J. M.; de Miguel, E.; Muñoz, T.; Nolan, K.; Olmedo, R.; Plesseria,
J. Y.; Polcar, J.; Reina, M.; Renotte, E.; Rochus, P.; Sánchez, A.;
San Martín, J. C.; Smith, A.; Soldan, J.; Thomas, P.; Timón, V.;
Walton, D.
Bibcode: 2003A&A...411L.261M
Altcode:
The Optical Monitoring Camera (OMC) will observe the optical emission
from the prime targets of the gamma-ray instruments onboard the ESA
mission INTEGRAL, with the support of the JEM-X monitor in the X-ray
domain. This capability will provide invaluable diagnostic information
on the nature and the physics of the sources over a broad wavelength
range. Its main scientific objectives are: (1) to monitor the optical
emission from the sources observed by the gamma- and X-ray instruments,
measuring the time and intensity structure of the optical emission
for comparison with variability at high energies, and (2) to provide
the brightness and position of the optical counterpart of any gamma-
or X-ray transient taking place within its field of view. The OMC is
based on a refractive optics with an aperture of 50 mm focused onto
a large format CCD (1024 x 2048 pixels) working in frame transfer
mode (1024 x 1024 pixels imaging area). With a field of view of
5ox5o it will be able to monitor sources down
to magnitude V = 18. Typical observations will perform a sequence of
different integration times, allowing for photometric uncertainties
below 0.1 mag for objects with Vle16 .
Title: SADE: The starspot and dynamo explorer
Authors: Martens, P. C. H.; Acton, L. W. A.; Klumpar, D.; Kankelborg,
C.; Stern, R. A.; Peres, G.; Culhane, J. L.
Bibcode: 2003AdSpR..32.1123M
Altcode:
We propose a mission called SADE, the Starspot And Dynamo Explorer, to
study dynamo activity in nearby late-type stars. The onboard instruments
will be a Ca-K telescope for magnetically dominated chromospheric
emission, and an X-ray grazing incidence telescope to study coronal
emission. We design the mission for a life-time of 15 years or longer
to capture a full activity cycle for most solar-type stars. We aim to
firmly establish the spectrum of the relation between chromospheric
and corona' emission in late-type stars, and capture one or more stars
going into or coming out of a Maunder type minimum. Operation costs will
be kept to a minimum by automating mission operations to a maximum,
and have the science operations be carried out by students at Montana
State University.
Title: Patterns of X-ray line emission variability as observed by
the RESIK Bragg spectrometer
Authors: Sylwester, J.; Sylwester, B.; Culhane, J. L.; Doschek, G. A.;
Oraevsky, V. N.; Phillips, K. J. H.
Bibcode: 2003ESASP.535..733S
Altcode: 2003iscs.symp..733S
RESIK is a unique Bragg bent crystal spectrometer operating continuously
since August 2001. By now, it has collected ~10 GB of solar flare and
active region spectra in a very much unexplored spectral region between
3.2 Å and 6.1 Å. In this paper we present a number of representative
observations covering periods of various solar activity: from the most
active level (M+ flares) to exceptionally quiet corona. We present also
a tentative list of the spectral features observed. In the wavelength
range observed by RESIK there are a number of strong emission lines
corresponding to H- and He-like resonance transitions of Si, S, Ar and K
ions. These lines are formed by thermal plasma of temperature between
5 and 50 MK, and therefore their analysis reveal the distribution
of hot plasma over this interval. RESIK sees lines from a number of
different elements, so it is possible to do abundance analyses. The
elements concerned have a wide range of first ionisation potentials
(FIPs) so it has been possible to examine the dependence of coronal or
flare abundances on FIP. We have observed substantial variations of
the K/Ar line ratio, and respective line/continuum ratios, which can
be best explained by allowing for changes in the chemical composition
of the coronal plasma
Title: Flare characteristics: Properties of eruptive and non-eruptive
events and their associations
Authors: Kay, H. R. M.; Culhane, J. L.; Harra, L. K.; Matthews, S. A.
Bibcode: 2003AdSpR..32.1051K
Altcode:
The complex: relationship between solar flares and coronal mass
ejections is investigated using a comparison of flare parameters for
a total of 69 ejective and non-ejective flares. In the case of solar
flares which do not show mass ejection there seems to be a clear
relationship between the peak intensity and duration, with higher
intensity events being of longer duration. Systematic differences in
the relationship between peak temperature and intensity for the two
types of events are also evident, with flares accompanied by CMEs
tending to have lower peak temperatures than non-ejective events of
the same intensity. Whilst there appears to be a clear relationship
between the length of rise and decay phase in a flare, there are
no systematic differences in the parameters between ejective and
non-ejective flares. A total of eleven EIT waves were found, all of
which were associated with CMEs. There is no apparent correlation
between the occurrence of an EIT wave and the peak intensity or rise
time of the associated flare.
Title: Expected Performance of the Extreme Ultraviolet Imaging
Spectrometer on Solar-B
Authors: Mariska, J. T.; Brown, C. M.; Dere, K. P.; Doschek, G. A.;
Korendyke, C. M.; Myers, S. H.; Seely, J. F.; Culhane, J. L.;
Watanabe, T.
Bibcode: 2003SPD....34.2006M
Altcode: 2003BAAS...35..845M
The Extreme Ultraviolet Imaging Spectrometer (EIS) is currently under
development for flight on the Japanese Solar-B satellite. EIS uses a
multilayer-coated off-axis telescope mirror and a multilayer-coated
toroidal grating spectrometer to produce stigmatic spectra of solar
regions isolated by a 1024 arcsec high slit. The instrument produces
monochromatic images either by rastering the solar image across a
narrow entrance slit or by using a very wide slit. Half of each optic
is coated to optimize reflectance at 19.5 nm, and the other half to
optimize reflectance at 27.0 nm, with each wavelength range imaged
onto a separate CCD detector. In this presentation we provide an
update on the EIS hardware development and show details of the expected
performance of the instrument in solar quiet regions, active regions,
and flares.
Title: The soft X-ray characteristics of solar flares, both with
and without associated CMEs
Authors: Kay, H. R. M.; Harra, L. K.; Matthews, S. A.; Culhane, J. L.;
Green, L. M.
Bibcode: 2003A&A...400..779K
Altcode:
The complex relationship between solar flares and coronal mass ejections
is investigated using a comparison of flare parameters for a total
of 69 ejective and non-ejective flares. In the case of solar flares
which do not show mass ejection there seems to be a clear relationship
between the peak intensity and duration, with higher intensity events
being of longer duration. Systematic differences in the relationship
between peak temperature and intensity for the two types of event are
also evident, with flares associated with CMEs tending to have lower
peak temperatures than non-ejective events of the same intensity. Whilst
there appears to be a clear relationship between the length of rise and
decay phase in a flare, there are no systematic differences in these
parameters for ejective and non-ejective flares. A total of eleven
``EIT waves'' were found, all of which were associated with CMEs. There
is no apparent correlation between the occurrence of an EIT wave and
the peak temperature, intensity or rise time of the associated flare.
Title: Evidence for a Flux Rope driven EUV wave and CME: Comparison
with the Piston Shock Model
Authors: Foley, C. R.; Harra, L. K.; Matthews, S. A.; Culhane, J. L.;
Kitai, R.
Bibcode: 2003A&A...399..749F
Altcode:
This paper examines the relationship between a coronal wave, filament
eruption, flare and Coronal Mass Ejection (CME) which occurred on
2001, April 10th. We study the pre-flare activity which includes the
eruption of a filament and a coronal wave. A large X-ray flare and
a CME follow. We discuss how these phenomena are related and compare
our results to recent models. These are found to be largely consistent
with the numerical simulations of a flux rope driven CME as presented
recently in Chen et al. (2002).
Title: Introduction
Authors: Culhane, J. L.; Hunt, J. C. R.; Coates, A. J.
Bibcode: 2003RSPTA.361....5C
Altcode:
The space environment is currently of intense interest as the subject
of multidisciplinary studies in science, applications and engineering,
including the remote observation of the Earth and planets, probing
the Sun-Earth connection, studying the Earth's environment from space,
hazard warning and forecasting and exploring the underlying space and
spacecraft technologies. There are natural connections between these
areas in terms of the scientific techniques and the space technology
required. Some of the connections are only now being discovered and
exploited, and this conference, held at The Royal Society on 16-18
October 2001, provided a timely focus for pursuing these further and
identifying others.
Title: Multi-wavelength observations of the pre-cursor phase of
solar flares
Authors: Matthews, S. A.; Harra, L. K.; Culhane, J. L.
Bibcode: 2003AdSpR..32.2553M
Altcode:
Observational studies of the pre-cursor phase of solar flares have
shown that there are many and varied signatures that may or may not
indicate the probable onset of a flare. Combining data from Yohkoh,
SOHO and TRACE and more recent observations from RHESSI, SOHO and TRACE
we, investigate the relationships between the different manifestations
of pre-flare behaviour in two solar flares with a view to determining
how they are related to the subsequent flare energy release. We find
that in one case the preflare activity seems strongly related to the
subsequent flare and probably represents a build-up of energy in the
active region prior to flare onset. The second case we find to be less
clear cut suggesting that significant further work remains to be done
in order to determine which pre-flare signatures are most useful in
indicating the build-up to flare onset.
Title: The Coronal Emission of Photospheric Magnetic Fragments
Authors: McDonald, L.; Culhane, J. L.; Matthews, S. A.; Harra, L. K.
Bibcode: 2002SoPh..211..125M
Altcode:
This paper examines the relationship between magnetic dipoles in the
photosphere and X-ray bright points (XBPs) in the corona, using an XBP
special campaign dataset obtained by the Yohkoh SXT and the NSO/Kitt
Peak magnetograph. We find that for the cases where a simple dipole
exists in the photosphere, the condition that they are separated by a
distance less than the interaction distance defined by Longcope1998 is
favorable for an XBP to be observed. For the cases where the magnetic
topology is more complicated due to the addition of an extra fragment,
we find that the geometry of the magnetic fragments is a major factor
that determines if an XBP is observed. XBPs are more likely to be formed
above magnetic fragments arranged in such a way that photospheric
motions giving rise to reconnection between any two fragments will
also give rise to reconnection with the remaining fragment.
Title: RESIK observations of highly ionized argon and potassium
X-ray emission lines in solar flares
Authors: Sylwester, J.; Culhane, J. L.; Doschek, G. A.; Oraevsky,
V. N.; Phillips, K. J. H.; Sylwester, B.
Bibcode: 2002ESASP.506..765S
Altcode: 2002svco.conf..765S; 2002ESPM...10..765S
The first detailed solar X-ray spectra obtained by the RESIK bent
crystal spectrometer aboard the CORONAS-F obervatory are presented
and instrument performance discussed. RESIK is a bent crystal
spectrometer covering four soft X-ray spectral ranges (3.369-3.879 Å,
3.821-4.326 Å, 4.307-4.890 Å 4.960-6.086 Å), some of which have
not been well covered by previous instruments. RESIK forms spectra
in each of these ranges in 250 bins simultaneously in intervals
of 10 s or so. Many flares, including several of GOES X-class,
and bright active regions have now been observed in detail. (See
http://www.cbk.pan.wroc.pl/2002.htm for examples.) In this paper,
observations of spectral lines due to K XVIII, Ar XVIII, Ar XVII, S XV,
Si XIV and Si XIII ions will be shown and the time evolution of their
intensities will be discussed. These observations will eventually
allow for precise determination of differential emission measure
(DEM) and chemical composition of the hot flare plasma, and should,
alongside data from the RHESSI, TRACE, and SOHO spacecraft, enable
new and detailed insight into solar flare mechanisms.
Title: The Magnetic Helicity Budget of a cme-Prolific Active Region
Authors: Green, L. M.; López fuentes, M. C.; Mandrini, C. H.;
Démoulin, P.; Van Driel-Gesztelyi, L.; Culhane, J. L.
Bibcode: 2002SoPh..208...43G
Altcode:
Coronal mass ejections (CMEs) are thought to be the way by which the
solar corona expels accumulated magnetic helicity which is injected
into the corona via several methods. DeVore (2000) suggests that a
significant quantity is injected by the action of differential rotation,
however Démoulin et al. (2002b), based on the study of a simple bipolar
active region, show that this may not be the case. This paper studies
the magnetic helicity evolution in an active region (NOAA 8100) in
which the main photospheric polarities rotate around each other during
five Carrington rotations. As a result of this changing orientation of
the bipole, the helicity injection by differential rotation is not a
monotonic function of time. Instead, it experiences a maximum and even
a change of sign. In this particular active region, both differential
rotation and localized shearing motions are actually depleting the
coronal helicity instead of building it. During this period of five
solar rotations, a high number of CMEs (35 observed, 65 estimated)
erupted from the active region and the helicity carried away has
been calculated, assuming that each can be modeled by a twisted flux
rope. It is found that the helicity injected by differential rotation
(≈−7×1042 Mx2) into the active region cannot
provide the amount of helicity ejected via CMEs, which is a factor 5
to 46 larger and of the opposite sign. Instead, it is proposed that
the ejected helicity is provided by the twist in the sub-photospheric
part of the magnetic flux tube forming the active region.
Title: Solar cycle variation of the temperature structure within
the cores of coronal streamers
Authors: Culhane, J. L.; Foley, C. R.; Patsourakos, S.; Mackay, D.
Bibcode: 2002ESASP.508..371C
Altcode: 2002soho...11..371C
We use the Coronal Diagnostic Spectrometer onboard the Solar and
Heliospheric Observatory (SOHO) to analyze conditions in coronal
streamer structures observed close to solar minimum (1996, July 8) and
near maximum (1999, August 5). From emission line intensities (Fe IX-XV
ions), the line ratio method gives the radial temperature behaviour. The
solar minimum peak values were about 1.4 MK at 1.3 R0, while
near solar maximum values were consistent with Yohkoh observations at
the last maximum, displaying an asymptotic temperature of around 2.2
MK above 1.2 R0. We discuss the observations in relation to
possible mechanisms for energy deposition in large coronal structures.
Title: Multi-wavelength observations of an X-class flare without a
coronal mass ejection.
Authors: Green, L. M.; Matthews, S. A.; van Driel-Gesztelyi, L.;
Harra, L. K.; Culhane, J. L.
Bibcode: 2002SoPh..205..325G
Altcode:
Developments in our knowledge of coronal mass ejections (CMEs) have
shown that many of these transients occur in association with solar
flares. On the occasions when there is a common occurrence of the
eruption and the flare, it is most likely that the flare is of high
intensity and/or long-duration (Burkepile, Hundhausen, and Webb,
1994; Munro et al., 1979; Webb and Hundhausen, 1987). A model for
the relationship between the long-duration event and eruption has
been developed (Carmichael, 1964; Sturrock, 1966; Hirayama, 1974;
Kopp and Pneuman, 1976), but not so for the high-intensity flares and
eruptions. This work investigates the magnetic topology changes that
occur for a X1.2 GOES classification flare which has no associated
CME. It is found that the flare is likely to result from the interaction
between two pre-existing loops low in the corona, producing a confined
flare. Slightly higher in the corona, a loop is observed which
exhibits an outward motion as a result of the reconfiguration during
reconnection. The objective of this work is to gain insight on the
magnetic topology of the event which is critical in order to determine
whether a high-intensity flare is likely to be related to a CME or not.
Title: Trajectories of microwave prominence eruptions
Authors: Hori, K.; Culhane, J. L.
Bibcode: 2002A&A...382..666H
Altcode:
On the basis of 17 GHz microwave images from the Nobeyama
Radioheliograph near solar maximum (1999-2000), we examined trajectories
of 50 prominence eruptions in order to address how prominence motions
affect or reflect the surrounding coronal structures. We marked the
heliocentric latitude of the top of the moving prominences on the
white-light synoptic maps, which were constructed at 2.5-4.5 solar
radii from the LASCO C2 coronagraph on the SOHO spacecraft. We found
that i) 92% of the prominence eruptions were associated with coronal
mass ejections (CMEs) and that the remaining 8% show weak mass motions
confined to nearby streamers, and ii) coronal mass motions involving
prominence eruptions and CMEs are not random but are organized
by bundles of streamers. Our findings support the idea of multiple
plasma sheets emanating from active regions, arcades, trans-equatorial
interconnecting loops, and polar crown filaments, through which coronal
mass is transported toward interplanetary space. This study suggests
that microwave observations can provide useful information on the
activity at the base of such ``coronal mass corridors''.
Title: What are the Origins of Quiescent Coronal Soft X-Rays?
Authors: Foley, C. R.; Culhane, J. L.; Patsourakos, S.; Yurow, R.;
Moroney, C.; Mackay, D.
Bibcode: 2002mwoc.conf..341F
Altcode:
We have examined the evolution and modulation of the Sun's atmosphere
from the photosphere up to the outer corona through the decline and
rise of solar cycles 22, and 23 respectfully. For this we have used
Yohkoh soft X-ray telescope (SXT) images, Kitt peak magnetograms and EUV
spectra provided by the Coronal Diagnostic Spectrometer (CDS). We find
as Hara (1996, 1997) found, that there is a modulation of the coronal
brightness which varies annually in the high latitude activity zones,
and that this is linked to the presence and disappearance of active
regions on the sun's disk. We interpret our results with regards to the
emergence and diffusion of magnetic flux. We find that the appearance
of high latitude activity zones may be explained simply by the decay
of diffused active region flux, We also find evidence for a positive
temperature gradient within the corona from the emission profiles in
the different lines.
Title: Observations of the White Dwarf G191-B2B with a High Resolution
EUV Spectrometer
Authors: Cruddace, R. G.; Kowalski, M. P.; Yentis, D. J.; Fritz, G. G.;
Gursky, H.; Barstow, M. A.; Bannister, N. P.; Fraser, G. W.; Spragg,
J. E.; Lapington, J. S.; Tandy, J. A.; Sanderson, B.; Culhane, J. L.;
Barbee, T. W.; Kordas, J. F.; Goldstein, W.
Bibcode: 2002ASPC..264...38C
Altcode: 2002ccea.conf...38C
No abstract at ADS
Title: High-Resolution Spectroscopy of G191-B2B in the
Extreme-Ultraviolet
Authors: Cruddace, R. G.; Kowalski, M. P.; Yentis, D.; Brown, C. M.;
Gursky, H.; Barstow, M. A.; Bannister, N. P.; Fraser, G. W.; Spragg,
J. E.; Lapington, J. S.; Tandy, J. A.; Sanderson, B.; Culhane, J. L.;
Barbee, T. W.; Kordas, J. F.; Goldstein, W.; Fritz, G. G.
Bibcode: 2002ApJ...565L..47C
Altcode: 2001astro.ph.12254C
We report a high-resolution (R=3000-4000) spectroscopic observation of
the DA white dwarf G191-B2B in the extreme-ultraviolet band 220-245
Å. A low-density, ionized He component is clearly present along
the line of sight, which if completely interstellar implies a He
ionization fraction considerably higher than is typical of the local
interstellar medium. However, some of this material may be associated
with circumstellar gas, which has been detected by analysis of the C
IV absorption-line doublet in a Hubble Space Telescope/Space Telescope
Imaging Spectrograph spectrum. A stellar atmosphere model assuming a
uniform element distribution yields a best fit to the data that includes
a significant abundance of photospheric He. The 99% confidence contour
for the fit parameters excludes solutions in which photospheric He
is absent, but this result needs to be tested using models allowing
abundance gradients.
Title: Trajectories of Microwave Prominence Eruptions
Authors: Hori, K.; Culhane, J. L.
Bibcode: 2002mwoc.conf..305H
Altcode:
We examine the trajectories of 50 prominence eruptions observed in
microwave continuum emission near solar maximum (1999-2000). On the
basis of Nobeyama Radioheliograph 17 GHz images, we address two major
questions; i) what triggers the prominence activity, and ii) how
does the prominence motion affect or reflect the surrounding coronal
structures. We found that most prominence activity is related to some
weak energy release (or heating) taking place in the lower corona as
suggested by the increase of the brightness temperature. By combining
the 17 GHz prominence images with white-light synoptic maps from the
LASCO C2 coronagraph on the SOHO spacecraft, we verify that 94% of
the prominence eruptions were associated with coronal mass ejections
(CMEs) and that the remaining 6% show weak mass motions confined to
streamers. We confirm that coronal mass motions involving prominence
eruptions and CMEs are not random but are organized by bundles of
streamers. The large scale evolution of coronal features within 4.5
solar radii suggests that streamers are a signature of multiple plasma
sheets emanating from active region belts, arcades, trans-equatorial
interconnecting loops, and polar crown filaments, through which
coronal mass is transported toward interplanetary space. This implies
that magnetic forces exerted by streamers (or plasma sheets) play an
important role in driving transient mass motions away from the Sun,
against solar gravity.
Title: Solar cycle variation of the temperature structure within
the cores of coronal streamers
Authors: Foley, C. R.; Patsourakos, S.; Culhane, J. L.; MacKay, D.
Bibcode: 2002A&A...381.1049F
Altcode:
We use the Coronal Diagnostic Spectrometer onboard the Solar and
Heliospheric Observatory (SOHO) to analyze conditions in coronal
streamer structures observed close to solar minimum (1996 July 8)
and near maximum (1999 August 5). We measured the intensities of
emission lines from Fe IX-XV ions and found the most intense emission
to be from Fe XI at solar minimum and from Fe XV at solar maximum. We
then used the line ratio method with transitions in selected ions to
extract the radial temperature behavior in the structures. The solar
minimum peak values were about 1.4 MK at 1.3 Rsun, while
values derived close to solar maximum were consistent with the Yohkoh
observations at the last maximum, displaying an apparently asymptotic
temperature of around 2.2 MK above 1.2 Rsun. We discuss the
observations in relation to possible mechanisms for energy deposition
in large coronal structures at different phases of the solar cycle.
Title: The EUV Imaging Spectrometer and its Role in the Solar-B
Mission
Authors: Culhane, J. L.; Doschek, G. A.; Watanabe, T.; Lang, J.
Bibcode: 2002ISSIR...2..327C
Altcode: 2002rcs..conf..327C; 2002ESASR...2..327C
Given the importance of the SOHO EUV instrument calibration techniques
for the Japan/US/UK Solar-B mission, the nature of Solar-B is briefly
described and the three scientific instruments on board the spacecraft
are discussed. The EUV Imaging Spectrometer (EIS) instrument is
described in some detail since it is anticipated that the SOHO
calibration techniques will have direct application to the absolute
calibration of EIS. The key scientific aims of Solar-B are presented.
Title: Anatomy of a Flare and Coronal Mass Ejection
Authors: Foley, C. R.; Harra, L. K.; Culhane, J. L.; Mason, K. O.;
Hori, K.; Matthews, S. A.; Iles, R. H. A.
Bibcode: 2002mwoc.conf..253F
Altcode:
In this paper we present the observations of a flare, CME and their
interaction obtained with the SOHO, Trace, and Yohkoh spacecraft. More
specifically we show evidence for wave-like motions in the Trace 171
observations, of comparable speed to those usually inferred from EIT
observations and thus termed `EIT waves'. We find that these waves
commence at the same time at which a prominence is observed to rise
within the active region and signifies the start of a gradual coronal
mass ejection. The prominence is observed with the Coronal Diagnostic
Spectrometer, on SOHO, with red and blueshifts which can only be
reconciled if the structure is rotating close to the plane of the
image with an angle of ~ 72o, to line of sight. During,
the impulsive phase of the flare the prominence and CME is observed
to accelerate from 190km/s to 900km/s.
Title: The timing of non-thermal soft X-ray emission line broadenings
in solar flares
Authors: Ranns, N. D. R.; Harra, L. K.; Matthews, S. A.; Culhane, J. L.
Bibcode: 2001A&A...379..616R
Altcode:
We study 59 solar limb flares using the Bragg Crystal Spectrometer
(BCS) on Yohkoh and the Burst and Transient Source Experiment (BATSE)
to investigate the relative timings between the Hard X-Ray (HXR)
emission and the observed non-thermal broadenings of X-ray emission
lines (Vnt). We show that the duration of the HXR flux
rise to maximum emission affects the relative timing of the main
Vnt peak with respect to the main HXR peak. In ~20% of the
flares studied, secondary peaks in Vnt are observed. These
are always associated with a strong HXR pulse and usually occur after
the associated HXR pulse. There are also flares that show a relationship
between the decay times of Vnt and HXR flux. These results
are conducive to a causal relationship between the HXR flux and
Vnt. We divided the sample of flares into two classes,
gradual rise and impulsive rise, depending on the shape of the HXR
lightcurve up to maximum emission. We show that the Vnt
behaviour differs in the two classes. The implications are discussed
with a view to understanding the mechanism of Vnt generation.
Title: Long term evolution of a non-active region sigmoid and its
CME activity
Authors: Glover, A.; Harra, L. K.; Matthews, S. A.; Hori, K.; Culhane,
J. L.
Bibcode: 2001A&A...378..239G
Altcode:
Recent studies have considered sigmoidal features in the Solar corona to
possess a high probability of eruption. Unlike these studies which have
focussed only on active region sigmoids, the present work centres on
a large area which developed S-like morphology unconfined by a single
active region. The S-like feature formed near the central meridian
on 8th May 2000 and was observed to erupt, with an associated CME,
twice over a period of 3 days. We observe considerable CME and flaring
activity in two previous rotations, consistent with the observation
of active regions and emerging flux. We illustrate sigmoid formation
through the appearance of highly sheared soft X-ray loops overlying
an extended filament channel. This arises from the gradual diffusion
of flux associated with a large, dispersing active region over the
period of three solar rotations. This scenario is indicative of shear
build-up within the region over several rotations. The observed CMEs act
to remove helicity from the highly sheared sigmoidal feature, finally
producing an approximately potential filament channel on 10th May 2000.
Title: Magnetic field configurations and the likelihood of coronal
mass ejections
Authors: Culhane, J. L.; Glover, A.; Green, L. M.; Harra, L. K.;
Matthews, S. A.; Hori, K.
Bibcode: 2001ESASP.493..193C
Altcode: 2001sefs.work..193C
No abstract at ADS
Title: Coronal heating in the Sun and late-type stars
Authors: Harra, L. K.; Culhane, J. L.
Bibcode: 2001Obs...121..217H
Altcode:
No abstract at ADS
Title: Coronal mass ejections and their association to active
region flaring.
Authors: Green, L. M.; Harra, L. K.; Matthews, S. A.; Culhane, J. L.
Bibcode: 2001SoPh..200..189G
Altcode:
Since the discovery of coronal mass ejections (CMEs), flaring has been
thought to be associated in some way with the ejection in either cause
or effect. When CMEs were first discovered in the 1970s it was suggested
that they were powered by solar flares (e.g., Dryer, 1982). Research
since then (Harrison, 1986) has indicated that there is an associated
flare that occurs shortly after the CME. To investigate this further,
and making no assumption that a particular flare is causally connected
to the CME, flaring activity in nine active regions that show one or
more CME signatures has been studied for several hours before and after
CME launch. Although the initiation of the CME may occur on size scales
larger than the active region itself, definite changes are seen in
the flaring activity which may be related to the ejection. This work
indicates that the energy released from the active region magnetic
field via flaring is greater prior to the CME launch than after.
Title: The Extreme Ultraviolet Imaging Spectrometer on Solar-B
Authors: Mariska, J. T.; Brown, C. M.; Dere, K. P.; Doschek, G. A.;
Korendyke, C. M.; Culhane, J. L.; Watanabe, T.
Bibcode: 2001AGUSM..SH41A12M
Altcode:
Emission lines in the extreme ultraviolet spectral region provide a
sensitive probe of the high-temperature plasma in the solar transition
region and corona. Simultaneously achieving high spatial, spectral, and
temporal resolution in this wavelength region has been challenging. We
describe the design and capabilities of the Extreme Ultraviolet
Imaging Spectrometer (EIS) planned for flight on the Japanese Solar-B
satellite. EIS consists of a multilayer-coated off-axis telescope
mirror and a multilayer-coated toroidal grating spectrometer. The
telescope mirror forms a solar image on the spectrometer entrance slit
assembly and the spectrometer forms stigmatic spectra of the solar
region isolated by the 1024 arcsec high slit. The instrument includes
thin-film aluminum filters to reject longer wavelength radiation and
CCD detectors at the focal plane. Articulation of the primary mirror
provides roughly 1600 arcsec of east-west coarse pointing freedom
and 360 arcsec of fine east-west motion for rastering. Monochromatic
images are formed either by rastering the solar image across a narrow
entrance slit or by using a very wide slit. Half of each optic is
coated to optimize reflectance at 19.5 nm, and the other half to
optimize reflectance at 27.0 nm. Each wavelength range is imaged onto
a separate CCD detector. The EIS spectral range contains emission lines
formed over a temperature range from roughly 0.1 to 20 MK. Bright lines
in the selected wavelength bands will yield precision measurements of
line-of-sight velocities and nonthermal plasma motions. This spectral
range also includes several pairs of density-sensitive lines.
Title: Nonthermal Velocity Evolution in the Precursor Phase of a
Solar Flare
Authors: Harra, L. K.; Matthews, S. A.; Culhane, J. L.
Bibcode: 2001ApJ...549L.245H
Altcode:
We present observations of two solar flares occurring in Active Region
7590 on 1993 October 3 using data from the Yohkoh spacecraft. The
hard X-ray bursts from the two flares occurred within an 18 minute
interval, with the soft X-ray emission having a shorter separation of
~5 minutes. Both flares occurred within one Yohkoh orbit, and hence
we have continuous coverage of the soft X-ray line broadening at the
peak of the first flare, reducing to the active region level of 33.5
km s-1 in S XV (66.1 km s-1 in Ca XIX) and then
increasing to the peak in the second flare. The rise above the active
region background level begins 11 minutes before the start of the second
flare as defined by the start of the hard X-ray emission. During this
extended rise time of Vnt, there is no increase in the light
curves or the electron temperature. We suggest that this increase is
an indicator of turbulent changes in the active region prior to the
flare that are related to the flare trigger mechanism.
Title: Improving the effectiveness of international collaboration
in space science
Authors: Culhane, J. L.; Worms, J. C.
Bibcode: 2001SpPol..17..179C
Altcode:
From the start of the 20th century, a strong tradition of collaboration
has developed in the physical sciences. World War II and the following
period changed this situation with a quickening of the pace of
application. Thus, while basic research continues to benefit from
collaboration among scientists worldwide, the increasingly complex
background in which science evolves, through higher implementation
costs and more difficult approval processes, renders collaboration
among nations ever more pressing. Space science, with its comparatively
high access cost but large fundamental importance, substantial public
appeal and outstanding ability to motivate young people, shares this
need. This article focuses on a recent ESSC-ESF study undertaken to
improve the effectiveness of such cooperative efforts. Related findings
and recommendations are presented along with a proposed operational
structure for their implementation.
Title: The Temperature of The Extended Solar Corona
Authors: Foley, C. R.; Culhane, J. L.; Mackay, D.
Bibcode: 2001IAUS..203..505F
Altcode:
We use the Coronal Diagnostic Spectrometer instrument on board the
Solar and Heliospheric Observatory to analyse coronal helmet streamer
structures observed close to the solar minimum / maximum on the 1996
July 8 / 1999 July 4-5th. The radial variation of peak electron
temperature is extracted out to 2 solar radii. These are found to
agree well with Yohkoh observations close to the solar maximum, but
are found to be reduced by around half a million close to the solar
minimum. Extrapolations of the photospheric field observations of MDI
are used to aid interpreted with regard to the energy depostion in
the low corona and solar wind.
Title: Soft X-ray/EUV Wavelengths
Authors: Cruddace, R. G.; Kowalski, M. P.; Yentis, D. J.; Fritz,
G. G.; Gursky, H.; Barstow, M. A.; Bannister, N. P.; Fraser, G. W.;
Culhane, J. L.; Lapington, J. S.; Barbee, T. W., Jr.; Kordas, J. F.;
Heidemann, K.
Bibcode: 2001AGM....18.P119C
Altcode: 2001AGAb...18R.194C
Astrophysical spectrometers of high resolving power (R~ 10000) and high
effective area (>100 cm2), working in the 50-300 Å band,
are feasible using normal-incidence, multilayer-coated, ion-etched
diffraction optics. They show promise for studying the structure,
density, temperature, composition and dynamic characteristics
of, for example, stellar coronae, white dwarf atmospheres and the
interstellar medium. We describe a prototype instrument, employing a
microchannelplate detector in the focal-plane, which in February 2001
was flown successfully on a NASA sounding rocket. This instrument had
a resolving power of 3000, an effective area of 3 cm2, and
operated in the band 220-245 Å band. In this mission the spectrometer
obtained a high-resolution spectrum of the white dwarf G191-B2B,
during an observation lasting 300 seconds, The primary scientific
goal was to detect ionised helium in the spectrum, to distinguish
between the interstellar and photospheric components, and with these
results to elucidate the evolutionary path of this star. We describe
the results of the data analysis performed to date.
Title: Preface
Authors: Culhane, J. L.; Bentley, R. D.; Doyle, G.
Bibcode: 2001AdSpR..26.1711C
Altcode:
No abstract at ADS
Title: Location of the source of soft X-ray non-thermal line
broadenings in a solar flare
Authors: Ranns, N. D. R.; Matthews, S. A.; Harra, L. K.; Culhane, J. L.
Bibcode: 2000A&A...364..859R
Altcode:
We determine the location of the source of the non-thermal Soft
X-ray line broadenings in an M1.7 two-ribbon solar flare using
multi-wavelength observations. Using a combination of the Yohkoh Soft
X-ray Telescope (SXT), Hard X-ray Telescope (HXT), Bragg Crystal
Spectrometer (BCS) and the Transition Region and Coronal Explorer
(TRACE), we find the source of the non-thermal broadenings, at their
peak value, to be located in and above the SXR flare loops, not at the
flare loop footpoints. After eliminating the footpoints as a potential
source we discuss the likelihood that the source of non-thermally
broadened emission lines is either evaporating chromospheric plasma
or plasma above the Soft X-ray flare loop that is associated with the
flare energy release.
Title: Extreme-ultraviolet imaging spectrometer designed for the
Japanese Solar-B satellite
Authors: Culhane, J. L.; Korendyke, Clarence M.; Watanabe, Tetsuya;
Doschek, George A.
Bibcode: 2000SPIE.4139..294C
Altcode:
The Extreme-ultraviolet Imaging Spectrometer combines, for the first
time, high spectral, spatial and temporal resolution in a satellite
based, solar extreme ultraviolet instrument. The instrument optical
design consists of a multilayer-coated off- axis paraboloid mirror
telescope followed by a toroidal grating spectrometer. The instrument
includes thin film aluminum filters to reject longer wavelength solar
radiation and employs CCD detectors at the focal plane. The telescope
mirror is articulated to allow sampling of a large fraction of the
solar surface from a single spacecraft pointing position. Monochromatic
images are obtained either by rastering the solar image across the
narrow entrance slit or by using a wide slit or slot in place of
the slit. Monochromatic images of the region centered on the slot are
obtained in a single exposure. Half of each optic is coated to maximize
reflectance at 195 angstrom; the other half is coated to maximize
reflectance at 270 angstrom. The two EUV wavelength bands were selected
to optimize spectroscopic plasma diagnostic capabilities. Particular
care was taken to choose wavelength ranges with relatively bright
emission lines to obtain precision line of sight and turbulent bulk
plasma velocity measurements from observed line profiles. The EIS
spectral range contains emission lines formed over a temperature
range from approximately 105 - 107 K. The
wavelength coverage also includes several density sensitive emission
line pairs. These line pairs provide spatial resolution independent
density diagnostics at nominal coronal temperatures and densities. Each
wavelength band is imaged onto a separate CCD detector. The main EIS
instrument characteristics are: wavelength bands -- 180 - 204 angstrom
and 250 - 290 angstrom; spectral resolution -- 0.0223 angstrom/pixel
(23 - 34 km/second-pixel); slit dimensions -- 4 slits: 1 X 1024 arc-
seconds and 50 X 1024 arc-seconds with two positions unspecified as
of this writing; fine raster range -- >6 arc-minutes on the sun;
coarse raster range -- > 1600 arc- seconds on the sun; largest
spatial field of view in a single exposure -- 50 X 1024 arc-seconds;
nominal time resolution for active region velocity studies -- 3.4s. The
Solar-B satellite is scheduled for launch in August 2005 into a nominal
600 km sun-synchronous orbit.
Title: The Energy Supply to X-ray Bright Points
Authors: McDonald, L.; Culhane, J. L.; Harra, L. K.; Matthews, S. A.
Bibcode: 2000SoPh..196..137M
Altcode:
X-ray bright points (XBPs) are usually assumed to be isolated
structures in the solar atmosphere that are powered exclusively by
magnetic reconnection. We analyse a large XBP that does not satisfy
this assumption. The XBP is observed to be connected to an active region
approximately 280 000 km away by a magnetic loop. We find that the soft
X-ray intensity and thermal energy of the XBP are very sensitive to the
existence of the magnetic loop. Both the intensity and energy decrease
significantly at the times when the loop disappears, indicating that
the loop is a medium for energy transfer from the active region to
the XBP. We deduce that the mechanism for the energy transfer is most
likely to be Alfvén or fast-mode magnetoacoustic waves created by
photospheric motions in the active region. These waves can dissipate
energy at the density gradient between the XBP and the loop via phase
mixing or resonant absorption.
Title: A Method to Determine the Heating Mechanisms of the Solar
Corona
Authors: Priest, E. R.; Foley, C. R.; Heyvaerts, J.; Arber, T. D.;
Mackay, D.; Culhane, J. L.; Acton, L. W.
Bibcode: 2000ApJ...539.1002P
Altcode:
One of the paradigms about coronal heating has been the belief that the
mean or summit temperature of a coronal loop is completely insensitive
to the nature of the heating mechanisms. However, we point out that
the temperature profile along a coronal loop is highly sensitive to
the form of the heating. For example, when a steady state heating
is balanced by thermal conduction, a uniform heating function makes
the heat flux a linear function of distance along the loop, while
T7/2 increases quadratically from the coronal footpoints;
when the heating is concentrated near the coronal base, the heat flux
is small and the T7/2 profile is flat above the base;
when the heat is focused near the summit of a loop, the heat flux
is constant and T7/2 is a linear function of distance
below the summit. It is therefore important to determine how the
heat deposition from particular heating mechanisms varies spatially
within coronal structures such as loops or arcades and to compare it
to high-quality measurements of the temperature profiles. We propose
a new two-part approach to try and solve the coronal heating problem,
namely, first of all to use observed temperature profiles to deduce the
form of the heating, and second to use that heating form to deduce the
likely heating mechanism. In particular, we apply this philosophy to
a preliminary analysis of Yohkoh observations of the large-scale solar
corona. This gives strong evidence against heating concentrated near the
loop base for such loops and suggests that heating uniformly distributed
along the loop is slightly more likely than heating concentrated at
the summit. The implication is that large-scale loops are heated in
situ throughout their length, rather than being a steady response
to low-lying heating near their feet or at their summits. Unless
waves can be shown to produce a heating close enough to uniform, the
evidence is therefore at present for these large loops more in favor
of turbulent reconnection at many small randomly distributed current
sheets, which is likely to be able to do so. In addition, we suggest
that the decline in coronal intensity by a factor of 100 from solar
maximum to solar minimum is a natural consequence of the observed
ratio of magnetic field strength in active regions and the quiet Sun;
the altitude of the maximum temperature in coronal holes may represent
the dissipation height of Alfvén waves by turbulent phase mixing;
and the difference in maximum temperature in closed and open regimes
may be understood in terms of the roles of the conductive flux there.
Title: Emerging flux as a driver for homologous flares
Authors: Ranns, N. D. R.; Harra, L. K.; Matthews, S. A.; Culhane, J. L.
Bibcode: 2000A&A...360.1163R
Altcode:
We present multi-wavelength observations of 2 M-class solar flares
observed by SoHO and Yohkoh, which appear to be homologous. By
examination of the flare loop morphology and footpoints we propose
a schematic reconnection scenario of a two loop interaction in
a quadrupolar magnetic configuration, for both flares (Machado
?; Mandrini ?). After the first flare, the combination of chance
emergence of new flux at an opportune location and a subsequent flare,
of the type described by Heyvaerts et al. (?), form a new quadrupolar
configuration in which the second flare occurred. Therefore though the
two M-class flares are homologous by definition, they appear to conform
to a scenario in which the preflare conditions are reformed after the
first flare by emerging flux, rather than models which involve the
continual shearing of a single magnetic structure.
Title: Observations of Solar Flares
Authors: Culhane, J. L.
Bibcode: 1999ESASP.448.1337C
Altcode: 1999mfsp.conf.1337C; 1999ESPM....9.1337C
No abstract at ADS
Title: Nonthermal Electron Energy Deposition in the Chromosphere
and the Accompanying Soft x-ray Flare Emission
Authors: McDonald, L.; Harra-Murnion, L. K.; Culhane, J. L.
Bibcode: 1999SoPh..185..323M
Altcode:
We analyse four solar flares which have energetic hard X-ray emissions,
but unusually low soft X-ray flux and GOES class (C1.0-C5.5). These are
compared with two other flares that have soft and hard X-ray emission
consistent with a generally observed correlation that shows increasing
hard X-ray accompanied by increasing soft X-ray flux. We find that
in the four small flares only a small percentage of the nonthermal
electron beam energy is deposited in a location where the heating rate
of the electron beam exceeds the radiative cooling rate of the ambient
plasma. Most of the beam energy is subsequently radiated away into
the cool chromosphere and so cannot power chromospheric evaporation
thus reducing the soft X-ray emission. We also demonstrate that in the
four small flares the nonthermal electron beam energy is insufficient
to power the soft X-ray emitting plasma. We deduce that an additional
energy source is required, and this could be provided by a DC-electric
field (where quasi-static electric field channels in the coronal loops
accelerate electrons, and those electrons with velocity below a critical
velocity will heat the ambient plasma via Joule heating) in preference
to a loop-top thermal source (where heat flux deposited in the corona
is conducted along magnetic field lines to the chromosphere, heating the
coronal plasma and giving rise to further chromospheric evaporation).
Title: Flare dynamics.
Authors: Antonucci, E.; Alexander, D.; Culhane, J. L.; de Jager, C.;
MacNeice, P.; Somov, B. V.; Zarro, D. M.
Bibcode: 1999mfs..conf..331A
Altcode:
The following topics were dealt with: results from soft X-ray spectra,
chromospheric evaporation, nature of nonthermal line broadening,
flare modelling.
Title: Omc: AN Optical Monitoring Camera for Integral
Authors: Giménez, A.; Mas-Hesse, J. M.; Jamar, C.; McBreen, B.;
Culhane, J. L.; Fabregat, J.; Swings, J. P.; Meurs, E.; Torra, J.;
Hudec, R.
Bibcode: 1999ApL&C..39..347G
Altcode:
No abstract at ADS
Title: Nature of the heating mechanism for the diffuse solar corona
Authors: Priest, E. R.; Foley, C. R.; Heyvaerts, J.; Arber, T. D.;
Culhane, J. L.; Acton, L. W.
Bibcode: 1998Natur.393..545P
Altcode:
The temperature of the Sun's outer atmosphere (the corona) exceeds that
of the solar surface by about two orders of magnitude, but the nature
of the coronal heating mechanisms has long been a mystery. The corona
is a magnetically dominated environment, consisting of a variety of
plasma structures including X-ray bright points, coronal holes and
coronal loops. The latter are closed magnetic structures that occur
over a range of scales and are anchored at each end in the solar
surface. Large-scale regions of diffuse emission are made up of many
long coronal loops. Here we present X-ray observations of the diffuse
corona from which we deduce its likely heating mechanism. We find that
the observed variation in temperature along a loop is highly sensitive
to the spatial distribution of the heating. From a comparison of
the observations and models we conclude that uniform heating gives
the best fit to the loop temperature distribution, enabling us to
eliminate previously suggested mechanisms of low-lying heating near
the footpoints of a loop. Our findings favour turbulent breaking and
reconnection of magnetic field lines as the heating mechanism of the
diffuse solar corona.
Title: OMC: An optical monitoring camera for INTEGRAL
Authors: Mas-Hesse, J. M.; Giménez, A.; Jamar, C.; McBreen, B.;
Culhane, J. L.; Fabregat, J.; Swings, J. P.; Meurs, E.; Torra, J.;
Hudec, R.; OMC Technical Team
Bibcode: 1998PhST...77...44M
Altcode:
No abstract at ADS
Title: RESIK: High Sensitivity Soft X-ray Spectrometer for the Study
of Solar Flare Plasma
Authors: Sylwester, J.; Gaicki, I.; Kordylewski, Z.; Nowak, M.;
Kowalinski, S.; Sjarkowski, M.; Bentley, W.; Trzebinski, R. D.;
Whyndham, M. W.; Guttridge, P. R.; Culhane, J. L.; Lang, J.; Phillips,
K. J. H.; Brown, C. M.; Doschek, G. A.; Oraevsky, V. N.; Boldyrev,
S. I.; Kopaev, I. M.; Stepanov, A. I.; Klepikov, V. Yu.
Bibcode: 1998ESASP.417..313S
Altcode: 1998cesh.conf..313S
No abstract at ADS
Title: Iron and calcium abundances in solar flares from the
multitemperature analysis of X-ray spectra (abstract)
Authors: Fludra, A.; Bentley, R. D.; Culhane, J. L.; Lemen, J. R.;
Sylwester, J.
Bibcode: 1998PAICz..88...91F
Altcode:
No abstract at ADS
Title: Scientific Achievements of the YOHKOH Mission
Authors: Culhane, J. L.
Bibcode: 1998ESASP.417...55C
Altcode: 1998cesh.conf...55C
No abstract at ADS
Title: The Solar Flare Dynamics Imager: A Low-Cost Mission for This
Solar Maximum
Authors: Wulser, J. -P.; Bruner, M. E.; Strong, K. T.; Canfield,
R. C.; Culhane, J. L.; Mariska, J. T.; Polidan, R.
Bibcode: 1997SPD....28.0232W
Altcode: 1997BAAS...29R.898W
The Solar Flare Dynamics Imager (SolFDI) is a very low-cost flare
mission proposed for this upcoming solar maximum. It is based on a small
solar EUV telescope/spectrograph for Spartan Lite, NASA's new ejectable
hitchhiker spacecraft. The experiment's main scientific objective is
to investigate the spatial, temporal, and velocity structure of the
upflowing hot plasma frequently observed in soft X-ray lines during
solar flares. Past observations were spatially unresolved, and the
nature of these plasma flows, and their relationship with the impulsive
phase flare energy release are not well understood. The second objective
is to image the spatial and velocity structure of eruptive flares. Such
observations can ultimately reveal the true three-dimensional geometry
of the eruptive component of the flare. The Solar Flare Dynamics
Imager will observe flares in a few selected extreme ultraviolet lines,
including a high temperature Fe XXIV line. The instrument uses normal
incidence multilayer coated optics to provide simultaneous imaging and
spectroscopy in these lines with good spatial, spectral, and temporal
resolution. The instrument is designed to fit within the envelope
of the Spartan Lite ejectable hitchhiker spacecraft. Spartan Lite is
smaller, and costs a fraction of a SMEX spacecraft. But if launched
into the upcoming solar maximum, its 6-12 month mission duration would
be sufficient to achieve SolFDI's scientific objectives.
Title: Isolating the Footpoint Characteristics of a Solar Flare Loop
Authors: Harra-Murnion, L. K.; Culhane, J. L.; Hudson, H. S.; Fujiwara,
T.; Kato, T.; Sterling*, A. C.
Bibcode: 1997SoPh..171..103H
Altcode:
We analyse the physical characteristics of a C5.7 class flare which
was observed on 27 September, 1993 using data from the soft X-ray
telescope (SXT), the Bragg crystal spectrometer (BCS), and the hard
X-ray telescope (HXT) on Yohkoh. The flare takes the form of a simple
loop which is much brighter at one of its footpoints than anywhere
else for a period of 2 min. During this time there is an increase in
the soft X-ray fluxes, and a corresponding peak in hard X-rays. The
parameters derived from the hard X-ray and soft X-ray spectra and images
are assumed to be from the footpoint. This flare showed two peaks in
the non-thermal velocity, the first one simultaneous with the footpoint
brightening. The non-thermal velocity corresponding to these first few
minutes is unusually large - by a factor of 80%, 68%, and 26% relative
to the second peak in the Fexxv, Caxix, and Sxv channels respectively.
Title: OMC: An Optical Monitoring Camera for INTEGRAL
Authors: Giménez, A.; Mas-Hesse, J. M.; Jamar, C.; McBreen, B.;
Culhane, J. L.; Fabregat, J.; Swings, J. P.; Meurs, E.; Torra, J.;
Hudec, R.; OMC technical Team
Bibcode: 1997ESASP.382..613G
Altcode: 1997trun.conf..613G
No abstract at ADS
Title: An investigation of small goes flares with intense hard
x-ray bursts
Authors: McDonald, L.; Harra-Murnion, L. K.; Culhane, J. L.;
Schwartz, A.
Bibcode: 1997AdSpR..20.2327M
Altcode:
Most solar flare observations show that intense hard X-ray bursts come
from large flares that have a large GOES classification (large peak 1
- 8 A˚ flux). This correlation, known as the ``Big Flare Syndrome'',
suggests that more intense flares tend to have harder spectra. We have
observed 7 flares that are exceptions to this. These flares have small
GOES classifications ranging from B1.4 to C5.5 and peak hard X-ray
count rates similar to those often observed from M class flares. This
paper examines the cause of this anomoly using the Yohkoh Soft X-Ray
Telescope, Hard X-Ray Telescope, and Bragg Crystal Spectrometer. Two
hypotheses are proposed for the exceptions: (1) flares with multiple
magnetic loops and common footpoints, producing multiple hard X-ray
emission regions and low density thermal plasma distributed over a
large volume, and (2) high densities in the magnetic loops restricting
the propagation of the non-thermal electrons in the loop after magnetic
reconnection has occurred and suppressing chromospheric evaporation. Two
of the flares support the first hypothesis. The other flares either
have data missing or are too small to be properly analysed by the
Yohkoh instruments.
Title: High-Resolution Observations of the Extreme Ultraviolet Sun
Authors: Harrison, R. A.; Fludra, A.; Pike, C. D.; Payne, J.;
Thompson, W. T.; Poland, A. I.; Breeveld, E. R.; Breeveld, A. A.;
Culhane, J. L.; Kjeldseth-Moe, O.; Huber, M. C. E.; Aschenbach, B.
Bibcode: 1997SoPh..170..123H
Altcode:
This paper presents first results of the Coronal Diagnostic Spectrometer
(CDS) recently launched aboard the Solar and Heliospheric Observatory
(SOHO). CDS is a twin spectrometer, operating in the extreme ultraviolet
range 151-785 Å. Thus, it can detect emission lines from trace
elements in the corona and transition region which will be used to
provide diagnostic information on the solar atmosphere. In this paper,
we present early spectra and images, to illustrate the performance of
the instrument and to pave the way for future studies.
Title: YOHKOH observations of the solar corona
Authors: Culhane, J. L.
Bibcode: 1997AdSpR..19.1839C
Altcode:
The Yohkoh soft X-ray telescope obtains several images every 90
minutes. Data from the declining phase of the solar cycle have been
used to compare the X-ray signal with other indicators of activity
and to study coronal heating. X-ray emission from a north polar
coronal hole is found broadly consistent with results of previous
EUV observations. In diffuse emission regions, temperature rises to
around 2.2 MK and levels off in the height range 1.5 - 1.9 R_o. Such
emission underlies streamers and may be the source of the low-speed
solar wind. X-ray signatures for Coronal Mass Ejection (CME) events
which involve the detection of reduced X-ray intensities in the corona,
have been developed with Yohkoh data. CME observations are described.
Title: Extreme ultraviolet observations of the solar corona: first
results from the coronal diagnostic spectrometer on SOHO
Authors: Harrison, R. A.; Fludra, A.; Sawyer, E. C.; Culhane, J. L.;
Norman, K.; Poland, A. I.; Thompson, W. T.; Kjeldseth-Moe, O.;
Aschenbach, B.; Huber, M. C. E.; Gabriel, A. H.; Mason, H. E.
Bibcode: 1997AdSpR..20.2239H
Altcode:
We present first results from the Coronal Diagnostic Spectrometer (CDS)
aboard the ESA/NASA Solar and Heliospheric Observatory (SOHO). CDS is
a double spectrometer operating in the 151-785 A˚ range. This region
of the solar spectrum is rich in emission lines from trace elements
in the solar atmosphere, which can be used to derive diagnostic
information on coronal and transition region plasma. Early spectra are
presented and well identified lines are listed. In addition, examples
of images in selected wavelength ranges are shown, for a prominence,
a loop system and a bright point, demonstrating well the power of such
extreme ultraviolet observations.
Title: The ISO Long-Wavelength Spectrometer.
Authors: Clegg, P. E.; Ade, P. A. R.; Armand, C.; Baluteau, J. -P.;
Barlow, M. J.; Buckley, M. A.; Berges, J. -C.; Burgdorf, M.; Caux,
E.; Ceccarelli, C.; Cerulli, R.; Church, S. E.; Cotin, F.; Cox, P.;
Cruvellier, P.; Culhane, J. L.; Davis, G. R.; di Giorgio, A.; Diplock,
B. R.; Drummond, D. L.; Emery, R. J.; Ewart, J. D.; Fischer, J.;
Furniss, I.; Glencross, W. M.; Greenhouse, M. A.; Griffin, M. J.; Gry,
C.; Harwood, A. S.; Hazell, A. S.; Joubert, M.; King, K. J.; Lim, T.;
Liseau, R.; Long, J. A.; Lorenzetti, D.; Molinari, S.; Murray, A. G.;
Naylor, D. A.; Nisini, B.; Norman, K.; Omont, A.; Orfei, R.; Patrick,
T. J.; Pequignot, D.; Pouliquen, D.; Price, M. C.; Nguyen-Q-Rieu;
Rogers, A. J.; Robinson, F. D.; Saisse, M.; Saraceno, P.; Serra, G.;
Sidher, S. D.; Smith, A. F.; Smith, H. A.; Spinoglio, L.; Swinyard,
B. M.; Texier, D.; Towlson, W. A.; Trams, N. R.; Unger, S. J.; White,
G. J.
Bibcode: 1996A&A...315L..38C
Altcode:
The Long-Wavelength Spectrometer (LWS) is one of two complementary
spectrometers aboard the European Space Agency's Infrared Space
Observatory (ISO) (Kessler et al., 1996A&A...315L..49D). It operates
over the wavelength range 43-196.9μm at either medium (about 150
to 200) or high (6800 to 9700) spectral resolving power. This Letter
describes the instrument and its modes of operation; a companion paper
(Swinyard et al, 1996) describes its performance and calibration.
Title: Department of Space and Climate Physics, (Mullard Space Science
Laboratory), University College London. Report for the period 1993
April 1 to 1995 March 31.
Authors: Culhane, J. L.
Bibcode: 1996QJRAS..37..373C
Altcode:
No abstract at ADS
Title: YOHKOH Observations of Fe XXVI X-Ray Line Emission from
Solar Flares
Authors: Pike, C. D.; Phillips, K. J. H.; Lang, J.; Sterling, A.;
Watanabe, T.; Hiei, E.; Culhane, J. L.; Cornille, M.; Dubau, J.
Bibcode: 1996ApJ...464..487P
Altcode:
We report on observations from the Bragg Crystal Spectrometer (B CS)
on board the Japanese solar flare spacecraft Yohkoh showing Fe XXVI
Lyα X-ray line emission at 1.78 Å. Some 75 events over a 2 yr period
between 1991 December 6 and 1993 December 31 have been analyzed. The
greater sensitivity of the BCS compared with previous instruments has
enabled such emission to be detected from a wider group of flares than
has previously been possible. The likelihood of detecting Fe XXVI lines
in a flare is found to increase sharply with the electron temperature
obtained from the Fe XXV line spectrum, also observed by the BCS,
and with GOES X-ray class. The width of the Lyα1, line,
measured after the impulsive stage, is greater than that determined by
thermal Doppler broadening, but this is explained by the nonzero spatial
extent of flares. Electron temperatures from the intensity ratio of a
nearby feature due to Fe XXV dielectronic satellites and the Fe XXVI
Lyα1 line are obtained from new atomic parameters from
the superstructure code, details of which are described. This revises
earlier calculations that have been extensively used. Comparison
of these temperatures with those from the Fe XXV spectra provides
evidence for a single loose grouping of flares, with the difference
between the two temperatures ranging from nearly zero to about 20 MK. A
"superhot" component would seem to be more or less developed according
to whether the temperature difference is large or nearly zero. Flares
at both extremes are examined in detail. The gradually varying part
of the 14-33 keV X-ray emission for these events, as observed by the
Hard X-ray Telescope on Yohkoh, has a hardness ratio corresponding
to temperatures and emission measures similar to those from Fe XXVI
line ratios, pointing to a common origin for their emission. Many of
the flares studied occurred in particular active regions with great
magnetic complexity, although Fe XXVI flares do not seem to be a
distinct class within large X-ray flares.
Title: Fe XXVI line emission observed by YOHKOH
Authors: Pike, C. D.; Pillips, K. J. H.; Lang, J.; Sterling, A.;
Watanabe, T.; Hiei, E.; Culhane, J. L.
Bibcode: 1996AdSpR..17d..51P
Altcode: 1996AdSpR..17...51P
Observations from the Bragg Crystal Spectrometer (BCS) on board
the Japanese solar flare space-craftYohkoh showing Fe xxvi Ly-alpha
X-ray line emission at about 1.78 Angstroms are reported. Some 75
events over a two-year-long period between December 1991 and December
1993 have been analyzed. The greater sensitivity of the BCS compared
with previous instruments has enabled such emission to be detected
from a wider group of flares than has previously been possible. The
likelihood of detecting Fe xxvi lines in a flare is found to increase
sharply with the electron temperature obtained from the Fe xxv line
spectrum, also observed by the BCS, and with GOES X-ray class. The
width of the Lyalpha_1 line, measured after the impulsive stage, is
rather greater than that determined by thermal Doppler broadening,
and if the excess broadening is attributed to turbulence, velocities
of up to 70 km s^-1 are indicated. Comparison of electron temperatures
obtained from the Fe xxvi spectrum with Fe xxv temperatures provides
evidence for a single loose grouping of flares, with the difference
between the two temperatures ranging from nearly zero to about 20 x
10^6K. A ``superhot'' component would seem to be more or less developed
according as the temperature difference is large or nearly zero.
Title: YOHKOH observations of high temperature plasma in solar flares
Authors: Culhane, J. L.
Bibcode: 1996AdSpR..17d..29C
Altcode: 1996AdSpR..17...29C
After a summary of results from previous missions and of Hα
observations, results from Yohkoh are presented. These deal with
plasma motions, impulsive soft X-ray footpoint brightenings and the
distribution of X-ray emitting plasma in flaring coronal loops. The
observations suggest that soft X-ray emission originates from locally
heated gas and from plasma that flows up from the chromosphere following
energy transport from the flare site by both thermal conduction and
non-thermal electrons. A DC electric field model is reviewed which
can explain the observations.
Title: Solar flare, coronal and heliospheric
dynamics. Proceedings. E2.2 Symposium of COSPAR Scientific Commission
E which was held during the Thirtieth COSPAR Scientific Assembly,
Hamburg (Germany), 11 - 21 Jul 1994.
Authors: Culhane, J. L.; Hiei, E.
Bibcode: 1996AdSpR..17d....C
Altcode: 1996AdSpR..17.....C
The following topics were dealt with: solar flare studies, Yohkoh
observations of magnetic reconnection, high temperature plasma in solar
flares, hard X-ray fluxes in solar flares, particle acceleration during
flares, ground-based observations of flares, UV observations, radio
bursts, chromospheric condensations, energetic particle transport in
solar flares, solar active regions, coronal structure, solar magnetic
cycle, coronal holes, coronal dynamic phenomena, coronal magnetic
fields, heliosphere dynamics, Ulysses data, interplanetary magnetic
field, heliospheric density structure, signatures of fast coronal mass
ejections in the interplanetary space, interplanetary shock waves,
future missions and instrumentation.
Title: Meeting Overview
Authors: Culhane, J. L.
Bibcode: 1996ASPC..111....3C
Altcode:
No abstract at ADS
Title: Solar spectroscopy with the BCS on YOHKOH
Authors: Culhane, J. L.
Bibcode: 1996ASPC..109..181C
Altcode: 1996csss....9..181C
No abstract at ADS
Title: Isolating the Footpoint Characteristics of a Solar Flare Loop
Authors: Harra-Murnion, L. K.; Culhane, J. L.; Fujiwara, T.; Hudson,
H. S.; Kato, T.; Sterling, A. C.
Bibcode: 1996mpsa.conf..527H
Altcode: 1996IAUCo.153..527H
No abstract at ADS
Title: Temperature Structure of the Diffuse Corona
Authors: Foley, C. R.; Culhane, J. L.; Acton, L. W.; Lemen, J. R.
Bibcode: 1996mpsa.conf..419F
Altcode: 1996IAUCo.153..419F
No abstract at ADS
Title: Evolution of two small solar flares.
Authors: Fludra, A.; Doyle, J. G.; Metcalf, T.; Lemen, J. R.; Phillips,
K. J. H.; Culhane, J. L.; Kosugi, T.
Bibcode: 1995A&A...303..914F
Altcode:
Data from the YOHKOH satellite have been analysed for two small flares
(GOES class C) of total duration of 10 and 60 minutes. Upflows in S
XV, Ca XIX and Fe XXV lines were compared and the presence of a range
of upflow velocities was found. Emission from flare loop footpoints
corresponding to plasma moving with a typical velocity of 200-400km/s
is seen in soft X-ray images. In one of these events (23 June 1992),
which occurred in sheared loops being part of a sparse magnetic arcade,
with initial energy release taking place near one of the footpoints, a
large proportion of upflowing plasma was seen at least 1 minute before
the first peak in hard X-rays. In the second event (13 July 1992), the
increase of soft X-ray emission began more than 3 minutes before, and
weak mass upflows one minute before the rapid increase of temperature
and the onset of the detectable hard X-ray emission. This event was
probably triggered by emerging magnetic flux and accompanied by heating
and restructuring of two nearby magnetic loops. In both events the
emission measure of upflowing plasma is present simultaneously to,
and is very well correlated in time with the hard X-ray flux in the
14-23keV band. Differential emission measure in the temperature range
5-60x10^6^K was derived from S XV, Ca XIX and Fe XXV line and continuum
fluxes, and from images in two broad band soft X-ray filters, and
used to analyse the thermal contribution to the hard X-ray emission. A
non-thermal component of the hard X-ray emission is found at the peak
of the 23 June 1992 flare. The hard X-ray emission in the 13 July 1992
flare is primarily thermal, however, a possibility of an enhanced tail
of the electron energy distribution above 14keV is also indicated. The
chromospheric evaporation in these flares was driven both by electron
beams and thermal conduction, with conduction predominating during most
of the rise phase of the 13 July 1992 flare. In both events, the soft
X-ray emission measure at flare maximum was a few times 10^48^cm^-3^
with an electron temperature 19 and 24x10^6^K; the estimated lower
limit of the electron density is ~10^11^cm^-3^. The broadening of
Ca XIX spectral lines in the decay phase of these flares indicates
persisting random motions with a velocity of 60km/s, which is very
similar to the non-thermal broadening observed previously by SMM in
M and X class flares.
Title: Spacelab 2 measurement of the solar coronal helium abundance
Authors: Gabriel, A. H.; Culhane, J. L.; Patchett, B. E.; Breeveld,
E. R.; Lang, J.; Parkinson, J. H.; Payne, J.; Norman, K.
Bibcode: 1995AdSpR..15g..63G
Altcode: 1995AdSpR..15...63G
The abundance of helium relative to hydrogen has been measured with
the ``Coronal Helium Abundance Spacelab Experiment'' (CHASE) from the
space shuttle Challenger in 1985. Previous solar measurements have
proved difficult due to the temperature-sensitivity of the electron
excitation rates for the observed lines. In this approach scattered
Lyman Alpha (Lyalpha) radiation of helium and hydrogen formed in
the corona were measured with a grazing-incidence spectrometer and
compared with the intensity of the illuminating flux from the solar
chromosphere. The abundance ratio by number of atoms was found to be
0.070 with an uncertainty of 0.011. Scattered light in the telescope
is the main source of error.
Title: YOHKOH Results in the Context of the High-Latitude Heliosphere
Authors: Culhane, J. L.
Bibcode: 1995SSRv...72...17C
Altcode:
Designed primarily to study solar activity, Yohkoh includes an X-ray
telescope that obtains full-sun coronal images which show a range of
features. Coronal X-ray emission-exclusive of flares, is notable for
its variability even in the largest structures. A mass ejection event
is related to magnetic field reconnection. Such events exhibit both
accelerated and decelerated behaviour. Coronal hole temperatures are
estimated from the filter ratio method. A plasma component at around
2.106 K is identified. X-ray emission is detected from
the South polar coronal hole. A preliminary comparison of Spartan
coronagraph images with Yohkoh data suggests that polar plumes or rays
are not connected to bright points.
Title: Observations of Coronal Temperature Structure by Yohkoh
Authors: Acton, L. W.; Culhane, J. L.; Lemen, J. R.; Sturrock, P. A.
Bibcode: 1995SPD....26..615A
Altcode: 1995BAAS...27..964A
No abstract at ADS
Title: Temperature Structure of the Diffuse Corona
Authors: Foley, C. A.; Acton, L. W.; Culhane, J. L.; Lemen, J. R.
Bibcode: 1995SPD....26..716F
Altcode: 1995BAAS...27R.969F
No abstract at ADS
Title: YOHKOH Results in the Context of the High-Latitude Heliosphere
Authors: Culhane, J. L.
Bibcode: 1995hlh..conf...17C
Altcode:
No abstract at ADS
Title: Yohkoh observations of the creation of high-temperature plasma
in the flare of 16 December 1991
Authors: Culhane, J. L.; Phillips, A. T.; Inda-Koide, M.; Kosugi,
T.; Fludra, A.; Kurokawa, H.; Makishima, K.; Pike, C. D.; Sakao, T.;
Sakurai, T.; Doschek, G. A.; Bentley, R. D.
Bibcode: 1994SoPh..153..307C
Altcode:
Yohkoh observations of an impulsive solar flare which occurred on 16
December, 1991 are presented. This flare was a GOES M2.7 class event
with a simple morphology indicative of a single flaring loop. X-ray
images were taken with the Hard X-ray Telescope (HXT) and soft X-ray
spectra were obtained with the Bragg Crystal Spectrometer (BCS)
on board the satellite. The spectrometer observations were made at
high sensivity from the earliest stages of the flare, are continued
throughout the rise and decay phases, and indicate extremely strong
blueshifts, which account for the majority of emission in CaXIX during
the initial phase of the flare. The data are compared with observations
from other space and ground-based instruments. A balance calculation
is performed which indicates that the energy contained in non-thermal
electrons is sufficient to explain the high temperature plasma which
fills the loop. The cooling of this plasma by thermal conduction
is independently verified in a manner which indicates that the loop
filling factor is close to 100%. The production of `superhot' plasma
in impulsive events is shown to differ in detail from the morphology
and mechanisms appropriate for more gradual events.
Title: The 1991 November 9 Flare at 03.2 UT: Observations from YOHKOH
Authors: Doschek, G. A.; Mariska, J. T.; Strong, K. T.; Bentley, R. D.;
Brown, C. M.; Culhane, J. L.; Lang, J.; Sterling, A. C.; Watanabe, T.
Bibcode: 1994ApJ...431..888D
Altcode:
We discuss X-ray spectra and soft X-ray images of an M1.9 flare that
occurred on 1991 November 9 near 03.2 UT. These data were obtained with
instrumentation on the Japanese Yohkoh spacecraft. They cover the entire
rise phase and peak flare emission, and the beginning of the decay
phase. We determine the dynamics, temperature, and emission measure
of the flare as inferred from the X-ray line profiles of resonance
lines of Fe XXV, Ca XIX, and S XV. We discuss the morphology of the
flare as inferred from the soft X-ray images. The November 9 flare is
atypical in that a stronger than usual blueshifted emission component
(relative to the stationary component) is observed for the resonance
lines at flare onset. We discuss several methods for deconvolving the
blueshifted component from the stationary component. The X-ray line
profiles are consistent with predictions of numerical simulations
of chromospheric evaporation. The X-ray images reveal a flare with a
complicated loop geometry that is not fully understood. Many of the
features in the images are moving upwards at speeds ranging from a
few km/s to about 800 km/s. The blueshifted emission begins near the
onset of hard X-ray emission, implying that particle acceleration and
upflowing plasma have a common energy source.
Title: Energy Transport Mechanisms and the Event of 16th December 1991
Authors: Culhane, J. L.; Phillips, A. T.; Kosugi, T.; Inda-Koide,
M.; Pike, C. D.
Bibcode: 1994kofu.symp..117C
Altcode:
The flare of 16th December 1991 had relatively simple structure,
which has made it useful for studing the energetics of chromospheric
evaporation. Energy balance calculations for this flare support
an electron beam energy deposition hypothesis for this event. The
creation of `super-hot' plasma is also investigated, using YOHKOH Hard
X-ray Telescope images. Contrary to previously reported events, the
`super-hot' plasma in the 16th December flare is generated, and remains
close to the chromospheric footpoints, with a decay time consistent
with saturated thermal conduction to the chromosphere.
Title: Long Duration Events in Magnetic Arcades and Large Loops
Authors: Fludra, A.; Jakimiec, J.; Tomczak, M.; Culhane, J. L.; Acton,
L. W.
Bibcode: 1994kofu.symp..393F
Altcode:
A number of long duration flares, with decay time between 1 and
17 hours, have been analysed using the Yohkoh Soft X-ray Telescope
images and spectra from the Bragg Crystal Spectrometer. X-ray images
suggest that these events typically occur in the following magnetic
field configurations: magnetic arcade, expanding arch, or large loops
triggered and heated up by a low-lying, compact, impulsive flare
located below these high loops. A continued energy release is observed
during decay of these events. Single loop flare models should not be
indiscriminately applied to analysis of thermodynamics of these flares
due to their more complex structure and restructuring of the magnetic
field, and often increasing height.
Title: Mullard Space Science Laboratory, University College
London. Report for the period 1991 April 1 to 1993 March 31.
Authors: Culhane, J. L.
Bibcode: 1994QJRAS..35..107C
Altcode: 1994QJRAS..35..107.
No abstract at ADS
Title: The Correlation of Solar Flare Hard X-Ray Bursts with Doppler
Blueshifted Soft X-Ray Flare Emission
Authors: Bentley, R. D.; Doschek, G. A.; Simnett, G. M.; Rilee, M. L.;
Mariska, J. T.; Culhane, J. L.; Kosugi, T.; Watanabe, T.
Bibcode: 1994ApJ...421L..55B
Altcode:
We have investigated the temporal correlation between hard X-ray
bursts and the intensity of Doppler blueshifted soft X-ray spectral
line emission. We find a strong correlation for many events that have
intense blueshifted spectral signatures and some correlation in events
with modest blueshifts. The onset of hard X-rays frequently coincides to
within a few seconds with the onset of blueshifted emission. The peak
intensity of blueshifted emission is frequently close in time to the
peak of the hard X-ray emission. Decay rates of the blueshifted and hard
X-ray emission are similar, with the decay of the blueshifted emission
tending to lag behind the hard X-ray emission in some cases. There
are, however, exceptions to these conclusions, and, therefore, the
results should not be generalized to all flares. Most of the data for
this work were obtained from instruments flown on the Japanese Yohkoh
solar spacecraft.
Title: Dynamics of a Low Energetic Solar Flare
Authors: Doyle, J. G.; Fludra, A.; Bentley, R. D.; Culhane, J. L.;
Metcalf, T.; Lemen, J. R.; Kosugi, T.
Bibcode: 1994ASPC...64..402D
Altcode: 1994csss....8..402D
No abstract at ADS
Title: The Flare of 16 December 1991
Authors: Culhane, J. L.; Phillips, A.; Pike, D.; Inda, M.; Kosugi,
T.; Sakao, T.
Bibcode: 1994xspy.conf...95C
Altcode:
No abstract at ADS
Title: Hα and X-Ray Signatures of Chromospheric Evaporation Observed
during the Early Phase of the 15 November 1991 Flare
Authors: Wülser, J. -P.; Canfield, R. C.; Acton, L. W.; Culhane,
J. L.; Phillips, A.; Fludra, A.; Sakao, T.; Masuda, S.; Kosugi, T.
Bibcode: 1994xspy.conf...75W
Altcode:
No abstract at ADS
Title: The 1992 January 5 Flare at 13.3 UT: Observations from YOHKOH
Authors: Doschek, G. A.; Strong, K. T.; Bentley, R. D.; Brown, C. M.;
Culhane, J. L.; Fludra, A.; Hiei, E.; Lang, J.; Mariska, J. T.;
Phillips, K. J. H.; Pike, C. D.; Sterling, A. C.; Watanabe, T.; Acton,
L. W.; Bruner, M. E.; Hirayama, T.; Tsuneta, S.; Rolli, E.; Kosugi,
T.; Yoshimori, M.; Hudson, H. S.; Metcalf, T. R.; Wuelser, J. -P.;
Uchida, Y.; Ogawara, Y.
Bibcode: 1993ApJ...416..845D
Altcode:
We discuss X-ray spectra and soft X-ray images of an M1.9 flare that
occurred on 1992 January 5 near 13.3 UT. These data were obtained
with instrumentation on the Japanese Yohkoh spacecraft. They cover
the entire rise phase of the flare. To supplement these data we have
ground-based magnetograms and Hα spectroheliograms. We calculate
the electron temperature and emission measure of the flare as a
function of time during the early rise phase using X-ray spectral
line intensities and line ratios. Using spectral line widths, line
profile asymmetries, and wavelength shifts due to the Doppler effect,
we calculate the dynamical properties of the flare. The time development
of the morphology of the flare, as revealed by the soft X-ray images
and the Hα spectroheliograms, and the physical quantities inferred
from the X-ray spectra, are compared with chromospheric evaporation
models. There is an enhancement of blueshifted emission that is closely
correlated with the hard X-ray bursts. Heating of one loop in the flare
is consistent with a conduction-evaporation model, but heating is found
in several structures that do not appear to be physically associated
with each other. No standard evaporation model can adequately explain
all of the observations.
Title: Yohkoh observations of plasma upflows during solar flares
Authors: Culhane, J. L.; Phillips, A. T.; Pike, C. D.; Fludra, A.;
Bentley, R. D.; Bromage, B.; Doschek, G. A.; Hiei, E.; Inda, M.;
Mariska, J. T.; Phillips, K. J. H.; Sterling, A. C.; Watanabe, T.
Bibcode: 1993AdSpR..13i.303C
Altcode: 1993AdSpR..13..303C
Observations of two flares, an M 2.2 event on 16 December, 1991 and the
precursor to an X1 flare on 15 November, 1991 are presented. Spectra
obtained with the Bragg Crystal Spectrometer (BCS) are compared with
data from the Hard and Soft X-ray Telescopes (HXT, SXT) and the Wide
Band Spectrometer (WBS) on the satellite. For both events the creation
of upflowing plasma is detected. While the first event seems to conform
well to the chromospheric evaporation model for high temperature plasma
production, the behaviour for the second event is more complex.
Title: Determination of coronal abundances of sulphur, calcium and
iron using the yohkoh bragg crystal spectrometer
Authors: Fludra, A.; Culhane, J. L.; Bentley, R. D.; Doschek, G. A.;
Hiei, E.; Phillips, K. J. H.; Sterling, A.; Watanabe, T.
Bibcode: 1993AdSpR..13i.395F
Altcode: 1993AdSpR..13..395F
Using spectra from the Bragg Crystal Spectrometer on Yohkoh we have
derived coronal abundances of sulphur, calcium and iron during several
flares from the ratio of the flux in the resonance line to the nearby
continuum. Multi-thermal effects have been taken into account using
differential emission measure analysis. We have also determined the
abundance of S in cool active regions during a period of very low solar
activity. We compare the coronal abundances of S, Ca and Fe with their
photospheric values.
Title: A Comparison of Solar Flare Hard X-Ray Bursts with Doppler
Blue-Shifted Soft X-Ray Emission
Authors: Rilee, M. L.; Bentley, R. D.; Culhane, J. L.; Doschek, G. A.;
Mariska, J. T.; Simnett, G. M.; Watanabe, T.
Bibcode: 1993BAAS...25.1189R
Altcode:
No abstract at ADS
Title: Requirements for future solar-physics missions with X-ray
instrumentation.
Authors: Culhane, J. L.
Bibcode: 1993ESASP1157..147C
Altcode: 1993srfs.book..147C
Several overall requirements for solar X-ray missions are stated and
a brief outline of the underlying coronal physics is presented. The
available techniques for X-ray imaging of the Sun are discussed and
compared with reference to previous and on-going missions. Solar
X-ray spectroscopy is assessed in the same manner. Possible choices
for future instruments in these two areas are discussed.
Title: Yohkoh basks in sunlight
Authors: Culhane, Len
Bibcode: 1993Natur.362..496C
Altcode:
The Japanese Yohkoh solar-astronomy satellite uses a battery of
X-ray instruments, including soft X-ray and hard X-ray telescopes,
to study such complex magnetic field patterns as the reconnection
of field lines, which is important for the release of energy in the
solar atmosphere. By these means, X-ray jets have been observed in
the corona; the magnetic bipolar nature of the coronal bright points
has been firmly established as well.
Title: The ROSAT Wide Field Camera all-sky survey of
extreme-ultraviolet sources. I. The bright source catalogue.
Authors: Pounds, K. A.; Allan, D. J.; Barber, C.; Barstow, M. A.;
Bertram, D.; Branduardi-Raymont, G.; Brebner, G. E. C.; Buckley, D.;
Bromage, G. E.; Cole, R. E.; Courtier, M.; Cruise, A. M.; Culhane,
J. L.; Denby, M.; Donoghue, D. O.; Dunford, E.; Georgantopoulos, I.;
Goodall, C. V.; Gondhalekar, P. M.; Gourlay, J. A.; Harris, A. W.;
Hassall, B. J. M.; Hellier, C.; Hodgkin, S.; Jeffries, R. D.; Kellett,
B. J.; Kent, B. J.; Lieu, R.; Lloyd, C.; McGale, P.; Mason, K. O.;
Matthews, L.; Mittaz, J. P. D.; Page, C. G.; Pankiewicz, G. S.; Pike,
C. D.; Ponman, T. J.; Puchnarewicz, E. M.; Pye, J. P.; Quenby, J. J.;
Ricketts, M. J.; Rosen, S. R.; Sansom, A. E.; Sembay, S.; Sidher, S.;
Sims, M. R.; Stewart, B. C.; Sumner, T. J.; Vallance, R. J.; Watson,
M. G.; Warwick, R. S.; Wells, A. A.; Willingale, R.; Willmore, A. P.;
Willoughby, G. A.; Wonnacott, D.
Bibcode: 1993MNRAS.260...77P
Altcode:
The first all-sky survey for cosmic sources of extreme-ultraviolet
radiation has been carried out with the UK Wide Field Camera on
ROSAT. A first reduction of the survey data has yielded a catalogue
of 383 relatively bright EW sources, forming the WFC Bright Source
Catalogue. This represents a 30-fold increase in the number of
astrophysical objects detected in the ~60-200 eV energy band and
covers a flux range, in each of the two survey bands, of more than
2000. A search of the (typically ~1 -arcmin) error circles of the WFC
sources, using a variety of catalogues and the SIMBAD data base, has
identified probable optical counterparts of 73 per cent, including many
active stars, white dwarf stars and a variety of other galactic and
extragalactic objects. A follow-up programme of optical spectroscopy
has since added further identifications, but some 13 percent of the
EUV sources remain unidentified. Details of the EUV source positions
and count rates are given, together with optical identifications where
known. Considerations of survey completeness allow source counts (log
N-log S) to be derived for each survey band. It is found that the log
N-log S distributions are unusually flat for the white dwarf stars,
but almost Euclidean for the nearby main-sequence late-type stars. This
is probably an effect of local (<~ 100 pc) interstellar absorption,
since the more (EUV) luminous white dwarfs are potentially detected at
correspondingly greater distances than the late-type stars. In addition,
the sky distribution of identified white dwarfs is highly non uniform
also suggesting gross variations in the opacity of the interstellar
medium within ~100 pc.
Title: Determination of element abundances using the Yohkoh Bragg
Crystal Spectrometer.
Authors: Fludra, A.; Culhane, J. L.; Bentley, R. D.; Doschek, G. A.;
Hiei, E.; Phillips, K. J. H.; Sterling, A.; Watanabe, T.
Bibcode: 1993uxrs.conf..542F
Altcode: 1993uxsa.conf..542F
No abstract at ADS
Title: Yohkoh BCS Observations of Doppler Shifts Early in Solar Flares
Authors: Mariska, J. T.; Doschek, G. A.; Sterling, A. C.; Culhane,
J. L.; Hiei, E.; Watanabe, T.; Lang, J.
Bibcode: 1992AAS...180.2308M
Altcode: 1992BAAS...24..761M
No abstract at ADS
Title: Time Variation of Solar Flare Temperatures Determined from
YOHKOH BCS Spectra
Authors: Sterling, A. C.; Doschek, G. A.; Mariska, J. T.; Pike, C. D.;
Culhane, J. L.; Hiei, E.; Watanabe, T.; YOHKOH BCS Team
Bibcode: 1992AAS...180.3001S
Altcode: 1992BAAS...24..775S
Bragg Crystal Spectrometer (BCS) X-ray spectra analysis from past
satellite missions indicate that it is possible to estimate temperatures
in highly ionized flare plasmas to within about 12\ resonance lines
in different He-like ions. This procedure is particularly valuable
in cases where other temperature measuring methods are insufficient,
such as during the rise phase of flares with strong X-ray spectra
blue shifts. Here we examine this ratio variation in several flares
using data from the Fe XXV, Ca XIX, and S XV channels of the BCS
experiment onboard the Yohkoh satellite. We select flares for
which we have good rise phase data, and calibrate the ratios using
dielectronic-to-resonance line ratios in selected Fe XXV spectra
assuming constant elemental abundances in each event. The Yohkoh BCS is
about an order of magnitude more sensitive than previous X-ray flare
spectrometers, and is therefore able to examine the early stages of
flare development in greater detail than previously possible. For this
study we select events for which we have good rise phase data, but data
well into the decay phase is available for a number of the selected
events. This allows us, for the first time, to follow the evolution
of flare spectra from relatively cool temperatures (~ 12 MK in Fe XXV)
to previously quoted ``typical" flare temperatures (~ 17 MK in Fe XXV).
Title: Mullard Space Science Laboratory, University College
London. Report for the period 1989 August 1 to 1991 March 31.
Authors: Culhane, J. L.
Bibcode: 1991QJRAS..32..459C
Altcode: 1991QJRAS..32..459.
No abstract at ADS
Title: Position sensitive detectors in X-ray astronomy
Authors: Culhane, J. L.
Bibcode: 1991NIMPA.310....1C
Altcode:
Detectors for X-ray astronomy include gas filled proportional
and scintillation counters, microchannel plates, CCDs and single
photon microcalorimeters. The spatial and nondispersive spectral
resolutions of all of these systems are compared in the light of
present requirements. The current state of development in each of the
four areas is then discussed and the salient features of each system
evaluated. While the subject has seen gas filled detectors employed
from the beginning, the need for improved spectral resolution combined
with high quantum efficiency is leading to an increased emphasis on
solid state detectors in spite of the difficulties involved in cooling
these systems in orbit. Microchannel plates remain important photon
energies less than 1 keV because of their excellent spatial resolution.
Title: The Bragg Crystal Spectrometer for SOLAR-A
Authors: Culhane, J. L.; Hiei, E.; Doschek, G. A.; Cruise, A. M.;
Ogawara, Y.; Uchida, Y.; Bentley, R. D.; Brown, C. M.; Lang, J.;
Watanabe, T.; Bowles, J. A.; Deslattes, R. D.; Feldman, U.; Fludra,
A.; Guttridge, P.; Henins, A.; Lapington, J.; Magraw, J.; Mariska,
J. T.; Payne, J.; Phillips, K. J. H.; Sheather, P.; Slater, K.;
Tanaka, K.; Towndrow, E.; Trow, M. W.; Yamaguchi, A.
Bibcode: 1991SoPh..136...89C
Altcode:
The Bragg Crystal Spectrometer (BCS) is one of the instruments which
makes up the scientific payload of the SOLAR-A mission. The spectrometer
employs four bent germanium crystals, views the whole Sun and observes
the resonance line complexes of H-like FeXXVI and He-like FeXXV,
CaXIX, and SXV in four narrow wavelength ranges with a resolving power
(λ/Δλ) of between 3000 and 6000. The spectrometer has approaching
ten times better sensitivity than that of previous instruments thus
permitting a time resolution of better than 1 s to be achieved. The
principal aim is the measurement of the properties of the 10 to 50
million K plasma created in solar flares with special emphasis on the
heating and dynamics of the plasma during the impulsive phase. This
paper summarizes the scientific objectives of the BCS and describes
the design, characteristics, and performance of the spectrometers.
Title: A study of the flaring and quiscent X-ray and UV emission
from II Pegasi.
Authors: Tagliaferri, G.; White, N. E.; Doyle, J. G.; Culhane, J. L.;
Hassall, B. J. M.; Swank, J. H.
Bibcode: 1991A&A...251..161T
Altcode:
An investigation has been conducted of the rotational modulation of the
transition-region UV and coronal X-ray emission for the RS CVn system II
Pegasi. The X-ray light curve is dominated by a strong flare detected at
orbital phase, where the minimum of the photometric wave occurred. The
flare parameters derived show that the flare originates with a height
greater than half the stellar radius. The characteristics of the flare
are similar to those of a solar two-ribbon flare; a comparison of the
midtransition region density with that in the coronal region shows a
very steep pressure gradient.
Title: Iron and calcium abundances in solar flares from the
multi-temperature analysis of X-ray spectra
Authors: Fludra, A.; Bentley, R. D.; Culhane, J. L.; Lemen, J. R.;
Sylwester, J.
Bibcode: 1991AdSpR..11a.155F
Altcode: 1991AdSpR..11Q.155F
A generalized method of calculating the distribution of the emission
measure with temperature (DEM) for optically thin plasma has been
developed. The method simultaneously uses line flux ratios in addition
to line fluxes. When a ratio of lines from the same element is used,
the resulting DEM is independent of this element's abundance. The method
has been applied to derive the absolute abundances of iron in solar
flares from X-ray spectra recorded by the Bent Crystal Spectrometer on
SMM. The iron abundances have been found to vary between flares. The
calcium abundances have also been calculated using the same method and
are found to be in close agreement with the values derived from the
line-to-continuum technique (Lemen et al., 1990 and Sylwester et al.,
1990). The variation of iron and calcium abundances is compared. A
correction to the ionization balance for iron is proposed.
Title: The SOLAR-A Bragg Crystal Spectrometer (Extended Abstract)
Authors: Culhane, J. L.; Hiei, E.; Bentley, R. D.; Brown, C. M.;
Doschek, G. A.; Feldman, U.; Lang, J.; Watanabe, T.
Bibcode: 1991LNP...387...22C
Altcode: 1991fpsa.conf...22C
No abstract at ADS
Title: The physics of solar flares. Proceedings.
Authors: Culhane, J. L.; Jordan, C.
Bibcode: 1991psf..conf.....C
Altcode:
First published in Philos. Trans. R. Soc. London, Ser A, Vol. 336,
No. 1643, p. 321 - 495 (1991). The purpose of this volume is to review
the contribution of the three spacecraft (P78-1, SMM, and Hinotori)
to the study of solar flares. It also includes discussions of the
current theoretical basis of some aspects of solar flares (including
magnetic energy conversion).
Title: Plasma diagnostics with the Solar-A Bragg Crystal Spectrometer
Authors: Culhane, J. L.; Hiei, E.; Bentley, R. D.; Brown, C. M.;
Doschek, G. A.; Feldman, U.; Lang, J.; Watanabe, T.
Bibcode: 1991AdSpR..11e..77C
Altcode: 1991AdSpR..11...77C
A Bragg Crystal spectrometer is one of the instruments on the Solar-A
mission. Using bent crystals, the spectrometer will observe the
resonance line complexes of the H-like Fe XXVI, and He-like Fe XXV
and Ca XIX ions with a sensitivity 5 to 10 times that of the SMM Bent
Crystal Spectrometer. It will also study the lower temperature lines
of He-like S XV. The improved sensitivity will allow observations
much earlier in the impulsive phase of flares than has previously been
possible. The new observations should help to answer questions about
plasma heating and dynamics. As well as providing information on line
profiles and shifts, the selected spectral lines will also provide
electron temperature and emission measure estimates over a range from
5 to 50 MK. The onboard microprocessor will permit spectral resolution
to be traded against time resolution during an observation.
Title: Mullard Space Science Laboratory, University College
London. Report for the period 1988 August 1 to 1989 July 31.
Authors: Culhane, J. L.
Bibcode: 1990QJRAS..31..191C
Altcode: 1990QJRAS..31..191.
No abstract at ADS
Title: The X-ray orbital lightcurve of TY Pyx : a 3.2-day eclipsing
RS CVn system.
Authors: Culhane, J. L.; White, N. E.; Shafer, R. A.; Parmar, A. N.
Bibcode: 1990MNRAS.243..424C
Altcode:
An Exosat observation of one orbital cycle of the eclipsing 3.2-d
RS CVn system TY Pyx is reported. This system contains two almost
identical GV stars, which is unusual because most RS CVns contain F or
G main-sequence star and a K subgiant. The X-ray light curves of the
primary and secondary eclipses are different above and below 1 keV. At
lower energies a sharp eclipse is seen, but at higher energies it is
absent. This confirms earlier observations that the 1.5-4.0 x 10 to
the 7th K emission from the RS CVn systems is not eclipsed and comes
from an extended region, whereas the 7 x 10 to the 6th K emission
comes from more compact solarlike active regions. Modeling the X-ray
eclipse detected at low energies requires two emission regions, one
on each star, covering less than 20 percent of the stellar surface. To
avoid a strong orbital modulation caused by both regions being either
simultaneously visible, or not visible, they must be located 180 deg
apart in longitude. The derived longitudes are 0 and 180 deg; i.e.,
they point at each other on the inward faces of the two stars.
Title: X-Ray Eclipse Mapping of AR Lacertae
Authors: White, N. E.; Shafer, R. A.; Horne, K.; Parmar, A. N.;
Culhane, J. L.
Bibcode: 1990ApJ...350..776W
Altcode:
Exosat data of the binary cycle of the eclipsing RS CVn system AR Lac
are studied. The data reveal that at energies of less than 1 ke V a
factor of 2 intensity modulation is detected and at energies greater
than 1 ke V no orbital modulation is observed. The chi-squared and
maximum entropy methods are used to model low-energy modulation. The
relation between the low-temperature component and height is
examined. It is observed that 50 pct of the X-ray flux comes from a
surface area covering up to 16 pct of the K star and 25 pct of the G
star and that peak coronal pressure is about 100 dyne/sq cm.
Title: The Decay Phase of Three Large Solar Flares
Authors: Fludra, A.; Bentley, R. D.; Culhane, J. L.; Jakimiec, J.;
Lemen, J. R.; Sylwester, J.; Moorthy, S. T.
Bibcode: 1990PDHO....7..266F
Altcode: 1990ESPM....6..266F; 1990dysu.conf..266F
No abstract at ADS
Title: Comments on the future observatories and their X-ray
spectroscopy capability
Authors: Culhane, J. L.
Bibcode: 1990hrxr.conf..281C
Altcode: 1990IAUCo.115..281C
The use of planned space X-ray observatories with resolving
power E/Delta E greater than 25 at photon energies above 5 keV for
spectroscopic observations is discussed. Particular attention is given
to the types of instruments capable of the resolution required (CCDs,
Bragg spectrometers, microcalorimeters, and transmission gratings);
moderate-scale satellites planned to follow the Rosat mission (the
Soviet Spectrum-X, the ESA X-ray telescopes, the Japanese Astro-D,
and the German Spectrosat); and the large X-ray observatories (NASA
AXAF and ESA XMM). Tables of numerical specifications and sample
spectra obtained with the Einstein Observatory Focal-Plane Crystal
Spectrometer and the SMM X-ray Polychromator are provided.
Title: An EXOSAT observation of spectral variability from the RS
CVn binary AR Lac
Authors: White, N. E.; Parmar, A. N.; Shafer, R. A.; Horne, K.;
Culhane, J. L.
Bibcode: 1990hrxr.conf..176W
Altcode: 1990IAUCo.115..176W
The eclipsing RS CVn system AR Lac (G2IV + K0IV) has been
observed continuously for one 2-day binary cycle with the Exosat
observatory. Below 1 keV, a factor of two intensity modulation is
seen with a flat bottomed minimum around the time of primary eclipse
and a shallow dip preceeding primary eclipse. Above 1 keV, where only
emission with temperatures greater than 10 exp 7 K would be detected,
no orbital modulation or eclipse is seen. This suggests that the
greater than 20 million degree emission comes from a large region,
comparable in size to the binary separation. The modulation in the
less than 1 keV lightcurve has been modeled by chi-squared fitting to
X-ray bright spots and by using maximum entropy deconvolution. The
lower temperature emission is found to originate in compact regions
with a pressure and temperature similar to that of the flaring sun.
Title: Book Review: X-ray detectors in astronomy. / CUP, 1989
Authors: Culhane, J. L.
Bibcode: 1989Obs...109..244C
Altcode: 1989Obs...109..244F
No abstract at ADS
Title: X-ray Eclipse Mapping of Stellar Activity in RSCVn
Systems with EXOSAT
Authors: Culhane, J. L.; White, N. E.; Parmar, A. N.; Shafer, R. A.;
Harre, K.
Bibcode: 1989BAAS...21.1083C
Altcode:
No abstract at ADS
Title: Mullard Space Science Laboratory. University College
London. Report for the period 1987 August 1 to 1988 July 31.
Authors: Culhane, J. L.
Bibcode: 1989QJRAS..30..253C
Altcode: 1989QJRAS..30..253.
No abstract at ADS
Title: Chromospheric explosions.
Authors: Doschek, G. A.; Antiochos, S. K.; Antonucci, E.; Cheng,
C. -C.; Culhane, J. L.; Fisher, G. H.; Jordan, C.; Leibacher, J. W.;
MacNiece, P.; McWhirter, R. W. P.; Moore, R. L.; Rabin, D. M.; Rust,
D. M.; Shine, R. A.
Bibcode: 1989epos.conf..303D
Altcode:
The work of this team addressed the question of the response and
relationship of the flare chromosphere and transition region to the
hot coronal loops that reach temperatures of about 107K
and higher. Flare related phenomena such as surges and sprays were
also discussed. The team members debate three main topics: 1) whether
the blue-shifted components of X-ray spectral lines are signatures of
"chromospheric evaporation"; 2) whether the excess line broadening of UV
and X-ray lines is accounted for by "convective velocity distribution"
in evaporation; and 3) whether most chromospheric heating is driven by
electron beams. These debates illustrated the strengths and weaknesses
of our current observations and theories.
Title: A combined radio and X-ray observation of Algol.
Authors: van den Oord, G. H. J.; Kuijpers, J.; White, N. E.; van der
Hulst, J. M.; Culhane, J. L.
Bibcode: 1989A&A...209..296V
Altcode:
The detection of Algol (Beta Per) at 1.4 GHz is reported. The eclipsing
phase of Algol has been observed in radio and at X-ray energies. The
radio emission is explained as synchrotron radiation from electrons
with energies of about 1 MeV. The magnetic field strength is of the
order of tens of Gauss. The radio and X-ray emission are cospatial but
the energy in the radio component is 1,000,000 times smaller than that
of the X-ray component. The simultaneous observation indicates that
an energetic particle component can be present in a quiescent X-ray
emitting corona.
Title: CDS: The Coronal Diagnostic Spectrometer
Authors: Patchett, B. E.; Harrison, R. A.; Sawyer, E. C.; Aschenbach,
B.; Culhane, J. L.; Doschek, G. A.; Gabriel, A. H.; Huber, M. C. E.;
Jordan, C.; Kjeldseth-Moe, O.
Bibcode: 1988sohi.rept...39P
Altcode:
The prime objective of the Coronal Diagnostic Spectrometer (CDS) is to
obtain intensity ratios of selected extreme-ultraviolet line pairs, with
spatial and temporal scales appropriate to the fine-scale features of
the solar atmosphere. This will be done simultaneously across a large
portion of the solar atmosphere. From this, density and temperature
information will be derived which coupled with a modest capability for
the detection of flows will be used to study the energy and mass balance
of the atmosphere. Understanding the heating of the solar corona and the
acceleration of the solar wind are the ultimate goals of this research.
Title: The Bragg Crystal Spectrometer Experiment on SOLAR-A
Authors: Hiei, E.; Culhane, J. L.; Doschek, G. A.
Bibcode: 1988BAAS...20..710H
Altcode:
No abstract at ADS
Title: X-ray spectroscopy of high temperature plasma in solar flares
Authors: Culhane, J. L.
Bibcode: 1988AdSpR...8k..67C
Altcode: 1988AdSpR...8...67C
X-ray spectroscopic observations with high wavelength resolution provide
information on plasma density, temperature and emission measure together
with bulk and turbulent velocity data for the hot plasma. Observations
carried out during the 1980 solar maximum with spectrometers on the
SMM, P78-1 and Hinotori spacecraft will be reviewed with emphasis on
the advances made possible by these missions. During the next solar
maximum, flare studies with particular emphasis on the impulsive phase
will be undertaken by the Japanese Solar-A mission. Those instruments
designed to study the hot plasma will be described and their proposed
role in clarifying the nature of the impulsive phase discussed.
Title: CHASE Observations of the Solar Corona
Authors: Breeveld, E. R.; Culhane, J. L.; Norman, K.; Parkinson,
J. H.; Gabriel, A. H.; Lang, J.; Patchett, B. E.; Payne, J.
Bibcode: 1988ApL&C..27..155B
Altcode:
The Coronal Helium Abundance Spacelab Experiment (CHASE) was undertaken
to make a precision measurement which could have significant
cosmological implications. The CHASE UV-spectrometer was flown
successfully on the Spacelab 2 mission. Observations of many spectral
lines were made including the Lyman-alpha lines of hydrogen at 121.6
nm and of ionized helium at 30.4 nm both on the solar disk where the
lines are excited, and in the corona, where the lines are formed by
resonance scattering of the disk radiation. When the instrument scatter
function has been measured, these observations will enable the solar
helium abundance to be measured.
Title: Development of X-ray calorimetric detectors and data processing
techniques at London University.
Authors: Hepburn, I. D.; Ade, P. A. R.; Griffin, M. J.; Holland,
W. S.; Culhane, J. L.; Kessel, R.; Walton, D. M.
Bibcode: 1988ltdd.conf..165H
Altcode: 1988ltdn.conf..165H
The authors describe research in progress in which they have designed
and constructed thermal detectors which are capable of measuring
the small pulses of energy produced by the absorption of X-rays in
the 1 - 10 keV energy range. At present these detectors are operated
at 3He temperature (0.34K), which results in an inherent
energy resolution of 673 eV. The authors also present a preliminary
discussion on the possible processing techniques that can be applied
to the raw data; such processing improves the achievable resolution
to around 350 eV.
Title: X-ray objective grating spectrograph.
Authors: Catura, R. C.; Stern, R. A.; Cash, W.; Windt, D. L.; Culhane,
J. L.; Lappington, J.; Barnsdale, K.
Bibcode: 1988SPIE..830..204C
Altcode:
A grazing incidence X-ray spectrograph for investigating the spectra
of cosmic X-ray sources is described. The overall instrument design
is reviewed, and the key components of the spectrograph, including the
gratings, telescope, and detector, are examined. Preliminary performance
measurements are reported and plans for the instrument are addressed.
Title: An EXOSAT observation of 1.5 orbital cycles of the 0.7 day
short-period RS CVn system ER Vul.
Authors: White, N. E.; Culhane, J. L.; Parmar, A. N.; Sweeney, M. A.
Bibcode: 1987MNRAS.227..545W
Altcode:
Two Exosat observations of the short-period 0.7-day eclipsing RS Cvn
binary system ER Vul are reported. The first observation in October
1984, lasted for 3 hr, while the second in May 1985, covered 1.5
orbital cycles. The overall counting rate decreased by a factor of
about 2 in the 6 months separating the two observations. No strong
orbital modulation of the X-ray flux was evident, nor were any deep
eclipses seen. The spectrum measured in the 0.05-6 keV band was well
fitted by a two-component thermal plasma model with temperaures of
6 and 40 million degrees. The failure to detect any strong orbital
modulation indicates for both temperature components either loop
heights larger than a stellar radius, or more compact loops that
are uniformly distributed as a function of longitude. The failure to
detect deep eclipses cannot convicingly be used to distinguish these two
possibilities because only latitudes greater than 10 deg are occulted,
although there was some evidence for a 10-20 percent occultation of
the low-energy light curve at secondary optical eclipse.
Title: EXOSAT observations of the SNR PKS 1209-52.
Authors: Kellett, B. J.; Branduardi-Raymont, G.; Culhane, J. L.;
Mason, I. M.; Mason, K. O.; Whitehouse, D. R.
Bibcode: 1987MNRAS.225..199K
Altcode:
Spatially resolved spectroscopy of the supernova remnant PKS 1209-52
and the point source within it is presented, based on observations
made with the EXOSAT PSD detector. The authors find evidence that
the shock front of the supernova remnant is interacting with an
interstellar cloud. The data further indicate that the whole remnant
is not in pressure equilibrium. The average PSD spectrum of the SNR is
fitted with a Raymond & Smith line-emission model: the best-fit
temperature is 1.7×106K and the absorbing column is
1.4×1021cm-2. The spectrum of the point source
is harder than that of the supernova remnant, but requires a similar
absorbing column. The authors suggest that this source is the neutron
star remnant of the supernova explosion.
Title: The X-Ray Orbital Lightcurve of AR Lac
Authors: White, N. E.; Shafer, R.; Parmar, A. N.; Culhane, J. L.
Bibcode: 1987LNP...291..521W
Altcode: 1987csss....5..521W; 1987LNP87.291..521W
Using the EXOSAT observatory we have obtained the X-ray light curve
of the 2 day eclipsing RS CVn binary system AR Lac continuously around
one complete binary cycle. A deep minimum centered on primary eclipse
is seen in the low energy telescope (0.05-2.0 keV), whereas the ME
(1.0-10.0 keV) flux remained constant. This shows that the 5-7 million
and the 15-30 million degree components found by Swank et al. (1981)
using the Einstein SSS originate in two distinct regions. The failure
to detect an eclipse in the ME indicates that the 15-30 million degree
plasma comes from a region larger than the radii of the underlying
stars. Modelling of the X-ray light curve shows that the lower
temperature emission originates from two localized regions on the G
star at longitudes of 3° and 150° with azimuthal angular extents
of ∼60°. The measured volume can be combined with the RTV scaling
relation to infer loop heights of 7,000 km. In addition there is a
large structure on the K star that extends from a longitude of 180°
to 270° with a height of order one stellar radius; this (probably)
contains much hotter plasma with a temperature of 15-20 million degrees.
Title: Chromospheric explosions
Authors: Doschek, G. A.; Antiochos, S. K.; Antonucci, E.; Cheng,
C. -C.; Culhane, J. L.; Fisher, G. H.; Jordan, C.; Leibacher, J. W.;
MacNeice, P.; McWhirter, R. W. P.
Bibcode: 1986epos.conf..4.1D
Altcode: 1986epos.confD...1D
Three issues relative to chromospheric explosions were debated. (1)
Resolved: The blue-shifted components of x-ray spectral lines are
signatures of chromospheric evaporation. It was concluded that
the plasma rising with the corona is indeed the primary source of
thermal plasma observed in the corona during flares. (2) Resolved:
The excess line broading of UV and X-ray lines is accounted for by a
convective velocity distribution in evaporation. It is concluded that
the hypothesis that convective evaporation produces the observed
X-ray line widths in flares is no more than a hypothesis. It is
not supported by any self-consistent physical theory. (3) Resolved:
Most chromospheric heating is driven by electron beams. Although it
is possible to cast doubt on many lines of evidence for electron
beams in the chromosphere, a balanced view that debaters on both
sides of the question might agree to is that electron beams probably
heat the low corona and upper chromosphere, but their direct impact
on evaporating the chromosphere is energetically unimportant when
compared to conduction. This represents a major departure from the
thick-target flare models that were popular before the Workshop.
Title: Early results from the CHASE experiment flown on Spacelab 2.
Authors: Gabriel, A. H.; Patchett, B. E.; Lang, J.; Culhane, J. L.;
Norman, K.; Parkinson, J. H.
Bibcode: 1986JBIS...39..207G
Altcode:
The Coronal Helium Abundance Spacelab Experiment (CHASE), flown on
the Space Shuttle as part of the Spacelab 2 payload on July 29, 1985,
was designed to measure the abundance of helium relative to hydrogen;
a measure of this quantity is an important verification of models
of the birth of the universe. In addition to this primary objective,
the instrument was used to study the properties of the corona. CHASE
instrumentation and operation are described, and preliminary data are
examined. The instrument consists of a grazing incidence spectrometer
covering the wavelength range of 150 A to 1350 A, illuminated by a
grazing incidence telescope of 28 cm focal length; the spectrometer
module incorporated the mechanism control electronics, detector
preamplifiers, high voltage supplies and a sensor to indicate the
offset from the sun center. Spectral lines are indicated schematically,
and it is noted that there is no problem separating the He II line from
the nearby Si XI line. Mapping of large areas of the sun revealed that
at low temperature, two bright points are apparent, whereas at high
temperature, these coalesce to form a single bright patch in the center.
Title: Results from the Coronal Helium Abundance Spectrometer
Authors: Culhane, J. L.
Bibcode: 1986BAAS...18..672C
Altcode:
No abstract at ADS
Title: EXOSAT Observations of AR Lac: X-Ray Light Curve Reconstruction
&the 3D Structure of Stellar Active Regions
Authors: Shafer, R. A.; White, N. E.; Parmar, A. N.; Culhane, J. L.
Bibcode: 1986BAAS...18..704S
Altcode:
No abstract at ADS
Title: X-ray observations and the structure of stellar coronae.
Authors: Culhane, J. L.
Bibcode: 1986Obs...106....5C
Altcode:
No abstract at ADS
Title: The soft X-ray spectrum of NGC 4151.
Authors: Pounds, K. A.; Warwick, R. S.; Culhane, J. L.; de Korte,
P. A. J.
Bibcode: 1986MNRAS.218..685P
Altcode:
EXOSAT observations of the Seyfert galaxy NGC 4151 over the period 1983
July - 1984 April have revealed a steeply decreasing flux in the 2 -
10 keV band. Other observations have shown that this coincided with
a fall in the whole infrared-to-ultraviolet continuum and a marked
weakening of the broad emission lines. The X-ray spectral shape,
however, remained unchanged, although - in accord with previous
measurements - a power-law spectrum attenuated with a simple column of
cold gas does not provide a satisfactory spectral fit below about 3 keV,
where a lower relative opacity is required. Inclusion of additional
low energy data from the EXOSAT telescopes allows the modelling of the
absorbing column to be improved and reveals a second, separate, soft
X-ray spectral component. It is suggested that this soft component
may be thermal emission from a hot intercloud medium in the narrow
emission line region.
Title: An EXOSAT Observation of Quiescent and Flare Coronal X-Ray
Emission from Algol
Authors: White, N. E.; Culhane, J. L.; Parmar, A. N.; Kellett, B. J.;
Kahn, S.; van den Oord, G. H. J.; Kuijpers, J.
Bibcode: 1986ApJ...301..262W
Altcode:
X-ray emission from the Algol system is believed to originate in a
corona associated with the K star. The authors have used the EXOSAT
Observatory to make a 35 hr continuous observation centered on the
occultation of the K star by the B star primary. The spectrum of
the quiescent emission in the 1 - 10 keV band gives a temperature of
2.5×107K. This spectrum, extrapolated to lower energies,
can account for more than 80% of the observed count rate. No obvious
X-ray eclipse was seen. An X-ray flare was detected with a rise time
of ≡1700 s and an exponential decay of ≡7000 s. The 0.1 - 10 keV
peak luminosity was 1.4×1031ergs s-1. The peak
temperature was 6×107K, with an iron K line confirming
the thermal character of the emission.
Title: Chromospheric explosions.
Authors: Doschek, G. A.; Antiochos, S. K.; Antonucci, E.; Cheng,
C. -C.; Culhane, J. L.; Fisher, G. H.; Jordan, C.; Leibacher, J. W.;
MacNiece, P.; McWhirter, R. W. P.; Moore, R. L.; Rabin, D. M.; Rust,
D. M.; Shine, R. A.
Bibcode: 1986NASCP2439....4D
Altcode:
The work of this team addressed the question of the response and
relationship of the flare chromosphere and transition region to the
hot coronal loops that reach temperatures of about 107K
and higher. Flare related phenomena such as surges and sprays are
also discussed. The team members debated three main topics: 1. whether
the blue-shifted components of X-ray spectral lines are signatures of
"chromospheric evaporation"; 2. whether the excess line broadening of UV
and X-ray lines is accounted for by "convective velocity distribution"
in evaporation; and 3. whether most chromospheric heating is driven
by electron beams.
Title: High resolution imaging with a solid scintillator-based
detector
Authors: Schwarz, H. E.; Lapington, J. S.; Culhane, J. L.
Bibcode: 1986SPIE..597..397S
Altcode:
A prototype optical image intensifier is coupled to a phosphor-coated
fibre optic to provide an imaging soft X-ray detector. The authors
show that high quantum efficiency is combined with high position
resolution and some energy resolution. They estimate the dark current
and particle background rejection factors of this detector and discuss
its suitability for space applications such as X-ray astronomy.
Title: Soft X-ray observations of high-velocity features in the 29
June 1980 flares
Authors: Bentley, R. D.; Lemen, J. R.; Culhane, J. L.; Phillips,
K. J. H.
Bibcode: 1986A&A...154..255B
Altcode:
During the impulsive phase of two flares on 29 June 1980, short
lived emission line features have been observed in soft X-rays,
near the resonance lines of Fe XXV and Ca XIX, by the Bent Crystal
Spectrometer on the Solar Maximum Mission. They are coincident with hard
X-ray bursts and with the onset of Hα sprays. They appear to result
from a different type of phenomenon from the unresolved blue-shifted
component from the resonance lines reported by Feldman et al. (1980)
and Antonucci et al. (1982). The authors believe that these discrete
line features are due to Doppler-shifted resonance line emission from
well collimated, moving plasma with large line-of-sight velocities.
Title: X-ray instrumentation in astronomy
Authors: Culhane, J. L.
Bibcode: 1986xria.conf.....C
Altcode:
No abstract at ADS
Title: X-ray instrumentation in astronomy. Proceedings of a conference
held at Cannes, France, 2 - 4 December 1985.
Authors: Culhane, J. L.
Bibcode: 1986SPIE..597.....C
Altcode:
Recent developments in X-ray and EUV astronomical instrumentation are
discussed in reviews and reports. Topics examined include optical
systems for the NASA Advanced X-ray Astrophysics Facility (AXAF),
specialized X-ray systems, advanced X-ray optics, gas-filled X-ray
detectors, instrumentation for spectrometry on AXAF, X-ray and EUV
spectrometers, microchannel plate detectors, and solid-state detectors.
Title: EXOSAT observations of a strong soft X-ray excess in MKN 841.
Authors: Arnaud, K. A.; Branduardi-Raymont, G.; Culhane, J. L.;
Fabian, A. C.; Hazard, C.; McGlynn, T. A.; Shafer, R. A.; Tennant,
A. F.; Ward, M. J.
Bibcode: 1985MNRAS.217..105A
Altcode:
EXOSAT observations of the spectrum of the Seyfert 1 galaxy MKN 841
show that it is well-fitted by a power law of photon index 1.6,
similar to that of other Seyferts, and a large additional soft
component. The X-ray luminosity over the observed band exceeds
4×1044erg s-1. A single-temperature blackbody
fit to the soft X-rays and the short-wavelength ultraviolet continuum
gives a luminosity of 2×1046erg s-1 while an
accretion disc spectrum fitted to the same points gives a luminosity
of 4.3×1045erg s-1. The flux measured by both
the EXOSAT low- and medium-energy instruments exhibits 12 per cent
amplitude variability on a time-scale of one day.
Title: X-ray applications of deep-depletion CCDs.
Authors: Walton, D. M.; Culhane, J. L.; Stern, R. A.; Catura, R. C.
Bibcode: 1985ESASP.239..291W
Altcode: 1985cxrs.work..291W
Results are presented demonstrating the successful use of deep-depletion
CCDs as single photon X-ray detectors. CCDs as focal plane X-ray
detectors for X-ray astronomy offer high spatial resolution combined
with good energy resolution. The importance of deep-depletion CCDs is a
significantly higher X-ray quantum efficiency than that of conventional
CCDs. The application of CCDs to an X-ray astronomy mission such as
XMM is described.
Title: An imaging optical/UV monitor for XMM.
Authors: Mason, K. O.; Allington-Smith, J.; Culhane, J. L.; Cordova,
F. A.; Priedhorsky, W. C.; Murdin, P. G.; Bingham, R.; Margon, B.;
Hutchings, J. B.
Bibcode: 1985ESASP.239..255M
Altcode:
The authors propose that a sensitive instrument affording photometry
and spectroscopy at optical and ultraviolet wavelengths could be added,
with minimal expenditure, to the complement of AXAF detectors. An AXAF
Imaging Optical/UV Monitor would enable simultaneous X-ray, optical,
and ultraviolet data to be obtained for every AXAF field.
Title: Capabilities of spectroscopy in the context of X-ray astronomy
in the1990's.
Authors: Culhane, J. L.
Bibcode: 1985ESASP.239....5C
Altcode: 1985cxrs.work....5C
The mission philosophies and parameters of the NASA AXAF and ESA XMM
X-ray astronomy observatories are reviewed. The scientific topics that
require an observatory of the XMM class are outlined and the relevance
of angular and spectral resolution to these aims is discussed. The
observing requirements of surveys and point source detection; galatic
clusters; active galatic nuclei; normal galaxies and halos; stars;
X-ray binaries; supernova remnants; and the interstellar medium are
considered.
Title: The soft X-ray spectrum of NGC 4151
Authors: Pounds, K. A.; Warwick, R. S.; Culhane, J. L.; de Korte, P.
Bibcode: 1985SSRv...40..585P
Altcode: 1985SSRev..40..585P
EXOSAT observations of the Seyfert galaxy NGC 4151 over the period
July 1983 to April 1984 have revealed a decreasing flux in the 2 10
keV band. In accord with previous measurements a power law spectrum
attenuated with a simple column of cold gas does not provide a
satisfactory spectral fit below ∼3 keV, where a lower relative
opacity is required. Inclusion of additional low energy data from the
EXOSAT telescopes allows the modelling of the absorbing column to be
improved and reveals a second, separate, soft X-ray spectral component.
Title: Position sensitive detectors for the proposed AXAF imaging
optical/UVmonitor (AXIOM).
Authors: Allington-Smith, J. R.; Mason, I. M.; Schwarz, H. E.; Culhane,
J. L.
Bibcode: 1985ITNS...32..119A
Altcode:
A description is given of the imaging detectors of the AXIOM instrument
proposed for NASA's Advanced X-ray Astrophysics Facility (AXAF). The
instrument is aligned with the X-ray telescope and consists of a
diffraction limited, 30-cm aperture, telescope with redundant position
sensitive detectors at the focus. This allows simultaneous imaging
at optical and near UV wavelengths of the X-ray target objects. The
proposed detectors cover a field of view of 8.5 x 8.5 sq arcmin with a
resolution of 1 arcsec (= 50 microns FWHM). The quantum efficiency peaks
at 30 percent and exceeds 10 percent over the wavelength range 125 to
540 nm. The detector design consists of a bi-alkali photocathode on a
UV-transmitting window, proximity focussed onto a microchannel plate
intensifier with a wedge and strip readout system, and is optimized for
high count rates both from point sources and from the sky background.
Title: An EXOSAT Observation of the Morphology of the Coronal X-Ray
Emission from Algol
Authors: White, N. E.; Culhane, J. L.; Parmar, A. N.; Kellett, B.;
Kahn, S.; van den Oord, G. H. J.; Kuijpers, J.
Bibcode: 1985SSRv...40...25W
Altcode:
The X-ray emission from Algol is thought to originate in a corona
associated with the K star in this system. We report the results of a 35
hr continuous EXOSAT observation through secondary optical eclipse that
was designed to measure the structure of the corona. No obvious X-ray
eclipse was seen. The spectrum measured by the ME gives a temperature of
2.5 × 107 K, consistent with the hard component previously
seen by the Einstein SSS. The soft component previously reported by
the SSS would only contribute at most 25% to the count rate seen in
the LE (used with Al/P). The lack of a hard X-ray eclipse indicates the
dimensions of the higher temperature emission region to be comparable
to or greater than the size of the K star. An X-ray flare was detected
with a peak luminosity of 1.4 × 1031 erg s-1
and a total duration of 8 hours. The peak temperature was 5.0 keV with
an emission measure of 9.4 × 1053 cm-3. The
thermal nature of the flare is confirmed by the detection of an iron
line with an EW of ∼2 keV. By equating the observed decay time of
the flare to a known cooling law gives a dimension for the flaring
loop of ∼0.3 stellar radii. This is much smaller than the dimensions
of the hard component inferred from the lack of an eclipse. It seems
probable that the flare occurred in one of the loops responsible for
the lower temperature component seen by the SSS.
Title: A simultaneous X-ray and radio observation of a flare from
Algol
Authors: Parmar, A. N.; Culhane, J. L.; White, N. E.; van den Oord,
G. H. J.
Bibcode: 1985AdSpR...5c..69P
Altcode: 1985AdSpR...5...69P
An X-ray flare was observed from Algol using the low and medium energy
detectors on the European Space Agency's EXOSAT observatory. Spectra
obtained during the flare are well fitted by thermal continua while
an Fe XXV emission feature was also detected. The strength of this
feature indicates a cosmic abundance for iron. The data indicate that
the flare occurred in a loop of height approximately 0.25 of the K
star radius & with a magnetic field >300 Gauss.
Title: EXOSAT observations of SN 1006.
Authors: Jones, L. R.; Pye, J. P.; Culhane, J. L.
Bibcode: 1985xra..conf..305J
Altcode: 1984xra..conf..305J
Comparison of EXOSAT images of the whole of the remnant, with greater
spatial resolution (≡30 arcsec) than obtained previously, with an
Einstein Observatory image and a radio map, do not support a synchrotron
origin for the soft X-ray emission.
Title: Soft X-ray observations of high-velocity features in the 29
June 1980flares.
Authors: Bentley, R. D.; Lemen, J. R.; Phillips, K. J. H.; Culhane,
J. L.
Bibcode: 1985RALR...85.....B
Altcode:
During the impulsive phase of two flares on 29 June 1980, short
lived emission line features have been observed in soft X-rays,
near the resonance lines of Fe XXV and Ca XIX, by the Bent Crystal
Spectrometer on the Solar Maximum Mission. They are coincident with hard
X-ray bursts and with the onset of Hα sprays. They appear to result
from a different type of phenomenon from the unresolved blue-shifted
component from the resonance lines reported by Feldman et al. (1980)
and Antonucci et al. (1982). The authors believe that these discrete
line features are due to Doppler-shifted resonance line emission from
well collimated, moving plasma with large line-of-sight velocities.
Title: A search for X-ray emitting coronal structures in algol
Authors: Culhane, J. L.; White, N. E.; Kahn, S.; Parmar, A. N.;
Blissett, R. J.; Kellen, B.
Bibcode: 1985AdSpR...5c..73C
Altcode: 1985AdSpR...5...73C
Algol was observed with the low energy imaging X-ray telescope and the
medium energy detectors on the ESA EKOSAT spacecraft during the time
of secondary optical eclipse when the B star passes in front of its K
type companion. An examination of the X-ray light curves allows us to
set preliminary lower limits to the size of an X-ray emitting corona
associated with the K star. The medium energy detector indicates a
continuum temperature of 24.3.106 K. The detection of Pe
XVII and Pe XVIII emission lines in an objective grating spectrum of
the source positively indicates the presence of hot coronal material.
Title: SMM observations of K-alpha radiation from fluorescence of
photospheric iron by solar flare X-rays
Authors: Parmar, A. N.; Culhane, J. L.; Rapley, C. G.; Wolfson, C. J.;
Acton, L. W.; Phillips, K. J. H.; Dennis, B. R.
Bibcode: 1984ApJ...279..866P
Altcode:
High-resolution Fe K-alpha spectra near 1.94 A observed during solar
flares with the Bent Crystal Spectrometer on the Solar Maximum Mission
are presented. The evidence for two possible excitation mechanisms,
electron impact and fluorescence, is examined. It is found that the
fluorescence mechanism satisfactorily describes the results, while the
observations do not support electron collisional excitation of the Fe
K-alpha transitions in low ionization stages (II-XII) of iron. Using
Bai's model of the fluorescent excitation process, the photospheric iron
abundance relative to that of hydrogen is estimated to be 5-6 x 10 to
the -5th. The mean height of the soft X-ray source producing the K-alpha
fluorescence is calculated on the basis of this model for about 40 large
flares. The solar K-alpha lines are found to be about 25 percent wider
than those measured in the laboratory. Weak line features observed at
wavelengths shorter than that of the K-alpha lines are discussed.
Title: Mullard Space Science Laboratory - University College - London
Authors: Culhane, J. L.
Bibcode: 1984QJRAS..25..189C
Altcode: 1984QJRAS..25..189.
No abstract at ADS
Title: EXOSAT Observations of Galactic and Extra-Galactic Sources
Authors: Mason, K. O.; Branduardi-Raymont, G.; Culhane, J. L.
Bibcode: 1984BAAS...16..469M
Altcode:
No abstract at ADS
Title: The EXOSAT imaging X-ray detectors.
Authors: Mason, I. M.; Branduardi-Raymont, G.; Culhane, J. L.; Corbet,
R. H. D.; Ives, J. C.; Sanford, P. W.
Bibcode: 1984ITNS...31..795M
Altcode:
No abstract at ADS
Title: The X-ray spectra of active galactic nuclei.
Authors: Culhane, J. L.
Bibcode: 1984PhST....7..134C
Altcode: 1984PhyS....7..134C
Recent observations of the X-ray spectra of active galactic nuclei are
reviewed. After an outline of the properties of these sources deduced
from observations at other wavelengths, the relevance of X-ray spectra
to our understanding of the X-ray emission mechanisms and of the
ultimate source of energy is discussed. The emission and absorption
features that are observed arise from the interaction of the X-rays
from the active nuclei with the surrounding gas. Observations of these
features are reviewed and the information they provide on the nature
of the surrounding gas is discussed.
Title: Results from the X-ray polychromator on SMM
Authors: Culhane, J. L.; Acton, L. W.; Gabriel, A. H.
Bibcode: 1984MmSAI..55..673C
Altcode:
Observations of the soft X-ray emitting plasma by means of the
X-Ray Polychromator (XRP) on the Solar Maximum Mission satellite are
described. The scientific advances achieved by use of the XRP are
in the areas of: (1) flare morphology, (2) spectroscopy and plasma
diagnostics, (3) chromospheric evaporation and the physics of flare
loops, (4) studies of the microwave emission mechanisms of active
regions, (5) the fluorescent excitation of Fe II K-alpha radiation,
(6) measurement of variations of calcium abundance for X-ray plasmas,
and (7) soft X-ray observations of spray transients. The findings in
each of these areas are discussed.
Title: New applications of X-ray optical techniques.
Authors: Culhane, J. L.; Cash, W.; Catura, R. C.
Bibcode: 1984NIMPA.221..251C
Altcode:
No abstract at ADS
Title: Deep-depletion CCDs for X-ray astronomy.
Authors: Walton, D.; Stern, R. A.; Catura, R. C.; Culhane, J. L.
Bibcode: 1984SPIE..501..306W
Altcode:
The successful use of deep-depletion silicon CCDs as single photon
X-ray detectors is described. At an X-ray energy of 5.9 keV, a quantum
efficiency of 76 percent for a 56 micron deep, 4000 ohm-cm RCA CCD
has been measured (three times that of a conventional CCD). The high
X-ray quantum efficiency, high spatial resolution, and ability to
reject charged particle background make the deep-depletion CCD one
of the strongest contenders for focal plane instrumentation on AXAF,
the Advance X-ray Astrophysics Facility.
Title: Observations of the iron emission lines in the X-ray spectrum
of the supernova remnant Cassiopeia A.
Authors: Manzo, G.; Peacock, A.; Taylor, B. G.; Andresen, R. D.;
Culhane, J. L.; Catura, R. C.
Bibcode: 1983A&A...122..124M
Altcode:
Observations of the X-ray spectrum of the supernova remnant Cassiopeia
A over the energy range 2-10 keV are presented. The results, obtained
by the use of two gas scintillation proportional counter spectrometers
flown on an Aries rocket confirm the presence of a strong blend
of emissions lines between 6.5-7.5 keV. The principal line in the
blend is tentatively considered to result from the 1s-2p transition
in Hydrogen-like iron, Fe XXVI. The equivalent width of the blend is
found to be 952 ± 143 eV consistent with the previous observations
made with conventional proportional counters. Evidence for a weaker
blend probably from the 1s-3p transition in Fe XXVI is also found. This
transition, which can be clearly resolved by the spectrometer from the
stronger blend has an equivalent width of 434 ± 102 eV. If the line
emission does result primarily from transitions in hydrogenic iron then
a significant component of the high temperature plasma associated with
the shocked circumstellar material must be at temperatures above 1.5
108 K.
Title: X-ray Astronomy
Authors: Culhane, J. L.; Sanford, P. W.; Helfand, David J.
Bibcode: 1983AmJPh..51..285C
Altcode:
No abstract at ADS
Title: The environmental background in gas-filled detectors for
X-ray astronomy.
Authors: Mason, I. M.; Culhane, J. L.
Bibcode: 1983ITNS...30..485M
Altcode:
No abstract at ADS
Title: Application of the wedge and strip anode to position sensing
with microchannel plates and proportional counters.
Authors: Siegmund, O. H. W.; Clothier, S.; Thornton, J.; Lemen, J.;
Harper, R.; Mason, I. M.; Culhane, J. L.
Bibcode: 1983ITNS...30..503S
Altcode:
No abstract at ADS
Title: High resolution large area modular array of reflectors (LAMAR)
WolterType I X-ray telescope for Spacelab.
Authors: Catura, R. C.; Acton, L. W.; Brown, W. A.; Gilbreth, C. W.;
Springer, L. A.; Vieira, J. R.; Culhane, J. L.; Mason, I. W.; Siegmund,
O.; Patrick, T. J.; Sheather, P. H.; Pounds, K. A.; Cooke, B. A.;
Evans, K.; Pye, J.; Smith, G.; Wells, A.; Spragg, J. E.; Whitford,
C. H.; Garmire, G.; Margon, B.; Fabian, A.
Bibcode: 1983OptEn..22..132C
Altcode:
A Wolter Type I x-ray telescope, intended both for astronomical
observations and to serve as a prototype module for the large area
modular array of reflectors (LAMAR) mission, is now in definition study
under NASA's Spacelab program. The five mirror telescope presently
being designed is to have a blur circle radius of 20 arc sec and an
effective area of about 400 cm2 at 1/4 keV, 200 cm2 in the 0.5 to
2 keV range, and 50 cm2 between 2 and 5 keV. Future expansion to a
full ten mirror telescope will approximately double these effective
areas. A rotary interchange mechanism will allow either of two imaging
proportional counters (IPCs) to be placed at the telescope focus; one
operating between 0.15 and 2 keV and the other optimized for the 0.6
to 6 keV energy range. During flight, the telescope will utilize an
instrument pointing system for a series of observations lasting from
six minutes to several hours. This investigation has dual objectives:
The primary objective is scientific and involves observational study
of galactic and extragalactic x-ray sources, extending the work of the
Einstein Observatory to much fainter sources and to higher energies. The
second objective is to provide an assessment of the cost and improved
performance of utilizing Wolter Type l x-ray optics for the LAMAR
mission and to extend the technology for producing these optics to
still higher angular resolution and toward lower cost.
Title: Solar Flares
Authors: Culhane, J. L.
Bibcode: 1982Obs...102..116C
Altcode:
No abstract at ADS
Title: Impulsive Phase of Flares in Soft X-Ray Emission
Authors: Antonucci, E.; Gabriel, A. H.; Acton, L. W.; Culhane, J. L.;
Doyle, J. G.; Leibacher, J. W.; Machado, M. E.; Orwig, L. E.; Rapley,
C. G.
Bibcode: 1982SoPh...78..107A
Altcode:
Observations using the Bent Crystal Spectrometer instrument on the
Solar Maximum Mission show that turbulence and blue-shifted motions
are characteristic of the soft X-ray plasma during the impulsive phase
of flares, and are coincident with the hard X-ray bursts observed
by the Hard X-ray Burst Spectrometer. A method for analysing the
Ca XIX and Fe XXV spectra characteristic of the impulsive phase
is presented. Non-thermal widths and blue-shifted components in the
spectral lines of Ca XIX and Fe XXV indicate the presence of turbulent
velocities exceeding 100 km s-1 and upward motions of
300-400 km s-1.
Title: Solar flare X-ray spectra from the Solar Maximum Mission Flat
Crystal Spectrometer
Authors: Phillips, K. J. H.; Fawcett, B. C.; Kent, B. J.; Gabriel,
A. H.; Leibacher, J. W.; Wolfson, C. J.; Acton, L. W.; Parkinson,
J. H.; Culhane, J. L.; Mason, H. E.
Bibcode: 1982ApJ...256..774P
Altcode:
High-resolution solar X-ray spectra obtained with the Flat Crystal
Spectrometer aboard the Solar Maximum Mission from two solar flares and
a nonflaring active region are analyzed. The 1-22 A region was observed
during the flare on 1980 August 25, while smaller spectral regions were
repeatedly covered during the 1980 November 5 flare. Voigt profiles
were fitted to spectral lines to derive accurate wavelengths and to
resolve blends. During the August 25 flare, 205 lines were found in
the range 5.68-18.97 A, identifications being provided for all but 40
(mostly weak) lines. Upper limits to flare densities are derived from
various line ratios, the hotter (about 10 to the 7th K) ions giving an
electron density of less than 10 to the 12th per cu cm for the August
25 flare. Other observed line ratios (e.g., in Fe XVII and Mg XII)
indicate a need for revisions in theoretical calculations.
Title: X-ray spectral classification of supernova remnants in the
Large Magellanic Cloud
Authors: Clark, D. H.; Tuohy, I. R.; Dopita, M. A.; Mathewson, D. S.;
Long, K. S.; Szymkowiak, A. E.; Culhane, J. L.
Bibcode: 1982ApJ...255..440C
Altcode:
The solid state spectrometer on the Einstein Observatory was used
to measure the 0.6-4.5 keV X-ray spectra of six prominent supernova
remnants in the Large Magellanic Cloud, namely, N132D, N63A, N49,
0525-66.0, N157B, and 0540-69.3. Thermal emission is detected from the
first four remnants and is similar in nature to that observed from young
galactic SNRs. In contrast, N157B and 0540-69.3 have featureless X-ray
spectra which are well described by power-law models. The present data
support a synchrotron origin for the X-rays from N157B and 0540-69.3,
although an alternative emission mechanism is considered for the
latter object.
Title: Individual electrons detected after the interaction of ionizing
radiation with gases
Authors: Siegmund, O. H. W.; Culhane, J. L.; Mason, I. M.; Sanford,
P. W.
Bibcode: 1982Natur.295..678S
Altcode:
The interaction of ionizing radiation (X rays or high-energy particles)
with gases results in the creation of electron-ion pairs. For low-energy
X rays a small cluster of primary ionization is produced close to
the point of the initial photoionization. High-energy particles,
however, lose a small fraction of their energy in each of a number of
ionizing collisions resulting in a long track composed of clusters
of ionization. We report here that the light signals emitted by a
parallel-plate proportional counter are fast enough to allow the
individual electrons in the ionization clusters to be resolved. By
counting the number of electrons for low energy X ray events we
demonstrate an improvement in energy resolution of more than a factor
of two over conventional proportional counters.
Title: The X-ray spectrometer experiment on the first spacelab flight
Authors: Andresen, R. D.; Peacock, A.; Sims, M. R.; Taylor, B. G.;
Culhane, J. L.; Ives, J. C.; Kellock, S.; Boella, G.; Villa, G.;
Manzo, G.; Re, S.
Bibcode: 1982AdSpR...2d.281A
Altcode: 1982AdSpR...2..281A
The First Spacelab Flight - scheduled for September 1983 -
will carry a multidisciplinary payload intended to demonstrate
that valuable scientific results can be achieved with such short
duration missions. The payload complement includes a spectrometer
to undertake observations of the brighter cosmic X-ray sources. The
primary scientific objectives of this experiment are the study of
detailed spectral features in cosmic X-ray sources and their associated
temporal variations over a wide energy range from about 2 keV up to 80
keV. The instrument based on the gas scintillation proportional counter,
will have an effective area of some 180 cm2 with an energy
resolution of ∼ 9% FWHM at 7 keV. The key performance parameters of
the instrument, which include calibration results and the sensitivity
of the planned observations, are discussed.
Title: A proportional counter/image intensifier system for the
detection of low energy X-rays
Authors: Siegmund, O. H. W.; Culhane, J. L.; Mason, I. M.
Bibcode: 1982AdSpR...2d.229S
Altcode: 1982AdSpR...2R.229S
Proportional counters (PC's) and gas scintillation proportional counters
(GSPC's) currently used for detection of low energy X-rays provide
information on event position and energy. Although at 1.5 keV PC's
have good position resolution (~ 200 μm FWHM) they have relatively
poor energy resolution (~ 40% FWHM). Conversely GSPC's have reasonable
energy resolution (~ 20% FWHM), but poor spatial resolution (~ 1mm
FWHM). We describe a scheme in which a parallel plate PC with
a transparent anode deposited on a fibre optic substrate has been
used. This allows the light emitted by electron avalanches caused by
X-ray events in the PC to be detected by an image intensifier with
electronic readout. Using this scheme spatial resolution better than
that of conventional PC's should be attainable. In addition avalanches
induced by single electrons can be resolved through observation of
the time structure of the light flash. Using the ability to count the
number of primary electrons created by each X-ray event, it is shown
that energy resolution can be achieved which is comparable to that of
the GSPC.
Title: X-ray Astronomy
Authors: Culhane, J. L.; Stanford, P. W.; Cohn, Haldan
Bibcode: 1982PhT....35f..56C
Altcode:
No abstract at ADS
Title: Book-Review - X-Ray Astronomy
Authors: Culhane, J. L.; Sanford, P. W.
Bibcode: 1982S&T....63..159C
Altcode:
No abstract at ADS
Title: Book-Review - X-Ray Astronomy
Authors: Culhane, J. L.; Sanford, P. W.; Ray, T. P.
Bibcode: 1982Obs...102..240C
Altcode:
No abstract at ADS
Title: Book-Review - X-Ray Astronomy
Authors: Culhane, J. L.; Sanford, P. W.
Bibcode: 1982Sci...215..316C
Altcode:
No abstract at ADS
Title: Solar Flare X-Ray Spectra Observed with the X-Ray Polychromator
on the Solar Maximum Mission.
Authors: Culhane, J. L.
Bibcode: 1982uxsa.coll....1C
Altcode: 1982IAUCo..73....1C
No abstract at ADS
Title: An Astronomers Guide to EXOSAT
Authors: Culhane, J. L.
Bibcode: 1982Obs...102R.108C
Altcode:
No abstract at ADS
Title: High resolution large area modular array of reflectors /LAMAR/
Wolter type I X-ray telescope for Spacelab
Authors: Catura, R. C.; Acton, L. W.; Brown, W. A.; Gilbreth, C. W.;
Springer, L. A.; Vieira, J. R.; Culhane, J. L.; Mason, I. W.; Siegmund,
O.; Patrick, T. J.
Bibcode: 1982SPIE..284..169C
Altcode:
The Spacelab Wolter type I X-ray telescope, which is intended for
both astronomical observations and the functional verification of
the future Large Area Modular Array of Reflectors (LAMAR) concept,
comprises five mirrors and is designed to have a blur circle radius
of 20 arcsec, with effective areas of (1) 400 sq cm at 0.25 keV,
(2) 200 sq cm in the 0.5-2.0 keV range, and (3) 50 sq cm between
2 and 5 keV. A rotary interchange mechanism allows either of two
imaging proportional counters to be placed at the telescope focus. The
telescope's primary objective is the observational study of galactic
and extragalactic X-ray sources, extending the work of the Einstein
Observatory to fainter sources and higher energies. Secondarily, the
costs and performance to be expected from the use of this telescope
type in the LAMAR mission will be assessed.
Title: Fluorescent excitation of photospheric Fe K-α emission during
solar flares
Authors: Parmar, A. N.; Culhane, J. L.; Rapley, C. G.; Phillips,
K. J. H.; Wolfson, C. J.; Acton, L. W.; Dennis, B. R.
Bibcode: 1982AdSpR...2k.151P
Altcode: 1982AdSpR...2..151P
The Bent Crystal Spectrometer on the NASA Solar Maximum Mission
satellite provides high spectral and temporal resolution observations of
the Fe Kα lines. We have analysed spectra from almost 50 solar flares
that occurred during 1980. These data strongly support fluorescent
excitation of photospheric iron by photons of E > 7.11 keV emitted
by the hot coronal plasma produced during the flare. After comparison
of the data with a model, we discuss the observed Kα line widths,
estimates of the size of the emitting region, the height of the coronal
source and the photospheric iron abundance.
Title: The Coronal Helium Abundance Experiment on SPACELAB-2
Authors: Patchett, B. E.; Norman, K.; Gabriel, A. H.; Culhane, J. L.
Bibcode: 1981SSRv...29..431P
Altcode:
The Coronal Helium Abundance Spacelab Experiment, (CHASE), basically
consists of a grazing incidence telescope and spectrometer sensitive
over the range 150 1335 Å. Whilst aimed primarily at deriving the solar
helium abundance from measurements of coronal resonance scattering,
its specification has been extended in order to provide a more general
purpose solar XUV facility. The instrument will be flown on the Spacelab
2 Mission, currently scheduled for launch in November 1984.
Title: Observations of transitions of hydrogen-like Fe XXVI in solar
flare spectra
Authors: Parmar, A. N.; Culhane, J. L.; Rapley, C. G.; Antonucci,
E.; Gabriel, A. H.; Loulergue, M.
Bibcode: 1981MNRAS.197P..29P
Altcode:
Observations of solar flare spectra over the wavelength range
1.769-1.796 A with the Bent Crystal Spectrometer on the NASA
Solar Maximum Mission satellite are presented. The 2P3/2, 2P1/2
and associated satellite transitions of Fe XXVI are identified,
their intensities and widths estimated and the results compared with
theoretical predictions. For two spectra, which include the isolated n
= 2 satellite features, the observations can be reproduced by plasma
temperatures of 24,000,000 and 28,400,000 K. Linewidth measurements
show evidence for nonthermal velocities of up to 150 km/s. Emission
measures derived from the Fe XXVI observations are compared with those
from lower temperature Ca XIX and Fe XXV measurements and an emission
measure decreasing with temperature is found.
Title: A European X-ray astrophysics mission
Authors: Culhane, J. L.
Bibcode: 1981xras.nasa..183C
Altcode:
Five instruments (Bragg Spectrometer, Large Area Proportional
and Scintillation Counter Detectors, Wide Field X-ray Cameras and
a Gamma-Ray Burst Monitor) are discussed and estimates of their
performance are given. Their scientific aims are summarized and sample
observing programmes are discussed.
Title: X-ray Spectroscopy of Solar Flares
Authors: Culhane, J. L.
Bibcode: 1981IrAJ...15...69C
Altcode:
After a brief review of the nature of the solar corona, the X-ray output
of solar flares is discussed in some detail with particular reference
to emission line excitation mechanisms and to the information that can
be obtained about the flare plasma from studies of the intensities,
profiles and wavelengths of these lines. The X-ray crystal spectrometers
on the NASA Solar Maximum Mission spacecraft are described and the
interpretation of the spectra obtained with these instruments is
discussed.
Title: Extragalactic γ -rays: Discussion
Authors: Culhane, J. L.
Bibcode: 1981RSPTA.301..602C
Altcode:
No abstract at ADS
Title: Measured Response of a Wolter I X-Ray Telescope Figured by
Diamond Turning
Authors: Catura, R. C.; Bardas, D.; Brown, W. A.; Roethig, D. T.;
Culhane, J. L.; Berthelsdorf, R.; Franks, A.
Bibcode: 1981BAAS...13..510C
Altcode:
No abstract at ADS
Title: X-ray line widths and coronal heating
Authors: Acton, L. W.; Wolfson, C. J.; Joki, E. G.; Culhane, J. L.;
Rapley, C. G.; Bentley, R. D.; Gabriel, A. H.; Phillips, K. J. H.;
Hayes, R. W.; Antonucci, E.
Bibcode: 1981ApJ...244L.137A
Altcode:
Preliminary results of spectroscopy and imaging of a solar active region
and flare plasma in soft X-ray emission lines are presented. Observed
X-ray line widths in a nonflaring active region are broader than the
Doppler width corresponding to the local electron temperature. An
analysis of 41 soft X-ray flares within a single active region reveals
a preference for flares to occur at locations that already show
enhanced X-ray emission and to favor magnetic complexity over high
gradient. However, flares do not appear to be directly responsible
for the heating and X-ray production of the active regions.
Title: Observations of the limb solar flare on 1980 April 30 with
the SMM X-ray polychromator
Authors: Gabriel, A. H.; Phillips, K. J. H.; Acton, L. W.; Wolfson,
C. J.; Culhane, J. L.; Rapley, C. G.; Bentley, R. D.; Kayat, M. A.;
Jordan, C.; Antonucci, E.
Bibcode: 1981ApJ...244L.147G
Altcode:
No abstract at ADS
Title: X-Ray Emission from Active Galaxies
Authors: Hayes, M. J. C.; Bell Burnell, S. J.; Culhane, J. L.; Barr,
P.; Sanford, P. W.; Ward, M. J.; Ives, J. C.
Bibcode: 1981SSRv...30...39H
Altcode:
All the Ariel V spectrometer observations of Seyfert and narrow
emission line galaxies (including some not previously published)
are reviewed. The X-ray spectral properties of this class of object
are examined and the data are used to investigate the nature of the
source. Low energy absorption and iron line emission features are
found to be variable. The low energy absorption can be explained in
terms of clouds in the broad line region moving across the line of
sight. There is no correlation between X-ray luminosity and low energy
absorption, which implies that the accreting material is different from
the obscuring material. Variable iron line emission may be explained
as recombination emission from highly photoionized gas, but the iron
line emission expected at low luminosities has not been detected.
Title: Ariel-Vi Observations of SCORPIO-X-1
Authors: Pollock, A. M. T.; Goodall, C. V.; Carpenter, G. F.; Bedford,
D. K.; Cruise, A. M.; Cole, R. E.; Osborne, J. P.; Culhane, J. L.
Bibcode: 1981SSRv...30..347P
Altcode:
It has so far proved empirically quite successful to describe the entire
continuum electromagnetic spectrum of Sco X-1 in terms of emission
from an isothermal plasma at a temperature of about 50 million K. The
need to consider multiple Compton scatterings in the calculation of
the emergent spectrum is emphasized, noting that this process produces
important modifications in the spectral shape at X-ray and ultraviolet
wavelengths. It is thought that the lack of variability in the data
discussed may be evidence of the effects of Comptonization
Title: The use of diamond turned & replicated wolter 1 telescopes
for high sensitivity X-ray astronomy
Authors: Culhane, J. L.; Catura, R. C.; Pounds, K. A.; de Korte, P.;
Franks, A.; Garmire, G. P.; Fabian, A.; Margon, B.
Bibcode: 1981SSRv...30..581C
Altcode:
Following the success of Einstein, it is clear that telescopes of very
large area (∼10 cm) with angular resolution (∼20″) are needed for
deep X-ray surveys and other observations. After a discussion of these
objectives, which form the basis of the NASA LAMAR mission, the design
& performance of a five mirror telescope is described. The system
was studied for possible flight on Spacelab to undertake observations
& to act as a prototype module for LAMAR. Both diamond turning
& replication methods of mirror production are discussed. The
performance of a single Wolter I telescope with diamond turned mirrors
will be described.
Title: Spherical crystal cosmic X-ray spectrometer.
Authors: Schnopper, H. W.; Koch, L.; Cantin, M.; Mougin, B.; Rocchia,
R.; Berthelsdorf, R. F.; Culhane, J. L.
Bibcode: 1981SSRv...30..607S
Altcode:
For spectral studies at energies ∼ 3keV, higher than those usually
neglected by grazing incidence telescopes with high efficiency,
freestanding, self-focussing, crystal arrays offer the most practical
way to achieve adequate sensitivity through concentration. Such
spectrometers can be designed for the entire range of energies that can
be diffracted by crystals, ∼ 5oo eV to 104 eV, and, for
energies below 3keV, can have sensitivities greater than or comparable
with that of instruments at the focal plane of a large telescope.
Title: X-ray spectra of solar flares obtained with a high-resolution
bent crystal spectrometer
Authors: Culhane, J. L.; Rapley, C. G.; Bentley, R. D.; Gabriel,
A. H.; Phillips, K. J.; Acton, L. W.; Wolfson, C. J.; Catura, R. C.;
Jordan, C.; Antonucci, E.
Bibcode: 1981ApJ...244L.141C
Altcode:
Preliminary results obtained for three solar flares with the bent
crystal spectrometer on the SMM are presented. Resonance and satellite
lines of Ca XIX and XVIII and Fe XXV and XXIV are observed together
with the Fe XXVI Lyman-alpha line. Plasma properties are deduced from
line ratios and evidence is presented for changes of line widths
coincident with the occurrence of a hard X-ray impulsive burst. Fe
K-alpha spectra from a disk center and a limb flare agree with the
predictions of a fluorescence excitation model. However, a transient
Fe K-alpha burst observed in a third flare may be explained by the
collisional ionization of cool iron by energetic electrons.
Title: Cosmic X-Ray Observations Performed with a Gas Scintillation
Spectrometer
Authors: Andresen, R. D.; Manzo, G.; Peacock, A.; Taylor, B. G.;
Catura, R. C.; Culhane, J. L.; Berthelsdorf, R.
Bibcode: 1981SSRv...30..243A
Altcode:
Observations of the spectrum of CAS-A in the X-ray energy range 3
to 10 keV have been made using two gas scintillation proportional
counters flown on an Aries rocket. Analysis of the data from the 180
second observation has resolved the emission features at ∼7 keV,
which results from transitions in highly ionised iron.
Title: X-Ray Astronomy in the Future
Authors: Culhane, J. L.
Bibcode: 1981SSRv...30..537C
Altcode:
It is shown how, from a beginning in 1962, X-ray observations have
reached a position of prime importance in astronomy. It is thought
that, in the 1980s, significant progress will come in two areas. One is
the physics of bright X-ray sources, the other is sky surveys and the
study of all detectable sources. For purposes of classification, bright
sources are taken as those giving rise to fluxes greater than 1 microJy.
Title: The X-Ray Imaging Telescopes on EXOSAT
Authors: de Korte, P. A. J.; Bleeker, J. A. M.; den Boggende, A. J. F.;
Branduardi-Raymont, G.; Brinkman, A. C.; Culhane, J. L.; Gronenschild,
E. H. B. M.; Mason, I.; McKechnie, S. P.
Bibcode: 1981SSRv...30..495D
Altcode:
The instrument configuration and performance characteristics of the
X-ray imaging telescopes on EXOSAT are described. The instrument
comprises two fully independent Wolter I imaging telescopes. Each
telescope can be used in either of two principal modes: (i) an
imaging mode with either a position sensitive proportional counter
or a channel multiplier array plate in the focal plane, (ii) a
spectrometer mode which features a 500 lines/mm and/or a 1000 lines/mm
transmission grating as dispersive element. Preliminary results from
the calibration of the fully integrated experiment indicate an ultimate
angular resolution of 8.5 arc sec full width at half maximum or 17.5
arc sec half-power beam width. The ultimate wavelength resolution in
the spectrometer mode ranges from 1Å for wavelengths below 50Å, to
5Å at wavelengths near 300Å. A method for estimating the telescope
performance is given which reasonably accounts for the influence of
the X-ray source spectrum and the degree of interstellar absorption
on the counting statistics. A comparison between EXOSAT and the
EINSTEIN telescope in terms of band width/resolution and minimum
source detectability shows an enhanced potential for EXOSAT relative
to EINSTEIN for sources with T ≦ 107K and low column
densities (< 4 × 1020cm-2) and a reduced
potential for sources with hard, or heavily cut-off, spectra.
Title: Solar maximum mission experiment: Early results from the soft
X-ray polychromator experiment
Authors: Gabriel, A. H.; Antonucci, E.; Phillips, K. J. H.; Culhane,
J. L.; Bentley, R. D.; Parmar, A. N.; Rapley, C. G.; Acton, L. W.;
Leibacher, J. W.; Wolfson, C. J.; Strong, K. T.; Jordan, C.
Bibcode: 1981AdSpR...1m.267G
Altcode: 1981AdSpR...1Q.267G
The X-Ray Polychromator experiment has been in operation on the
SMM satellite for over three months. It is observing flares and
active regions in the wavelength range 1Å to 23Å using a number
of different modes. These include polychromatic imaging, high
resolution line profiles, high dispersion spectra, and light curves
with high time-resolution. Data are described together with some of
the preliminary analysis and interpretation.
Title: Low energy observations of Cygnus X-2 by Ariel VI
Authors: Cruise, A. M.; Cole, R. E.; Culhane, J. L.; Osborne, J.;
Zarnecki, J.; Goodall, C. V.; Bedford, D. K.; Campbell, D. J.;
Carpenter, G. F.; Pollock, A. M. T.; Willmore, A. P.
Bibcode: 1981AdSpR...1m.211C
Altcode: 1981AdSpR...1..211C
Ariel VI observations of Cygnus X-2 have revealed a rather flat spectrum
between 0.1 and 1.5 keV with variable emission at low energy. Of the
two conflicting interpretations of this object in terms of i) a distant
high-luminosity (Lx ~ 1038 ergs s-1)
binary and ii) a nearby low-luminosity (Lx ~ 1035
ergs s-1) degenerate dwarf system, our measurements support
the latter.
Title: Solar Maximum Mission experiment: early results from the soft
X-ray polychromator experiment.
Authors: Gabriel, A. H.; Culhane, J. L.; Acton, L. W.; Antonucci,
E.; Bentley, R. D.; Jordan, C.; Leibacher, J. W.; Parmar, A. N.;
Phillips, K. J. H.; Rapley, C. G.; Wolfson, C. J.; Strong, K. T.
Bibcode: 1981hea..conf..267G
Altcode:
No abstract at ADS
Title: High resolution large area modular array of reflectors (LAMAR)
Wolter Type I x-ray telescope for Spacelab
Authors: Catura, R. C.; Acton, L. W.; Brown, W. A.; Gilbreth, C. W.;
Springer, L. A.; Vieira, J. R.; Culhane, J. L.; Mason, I. W.; Siegmund,
O.; Patrick, T. J.; Sheather, P. H.; Pounds, K. A.; Cooke, B. A.;
Evans, K.; Pye, J.; Smith, G.; Wells, A.; Spragg, J. E.; Whitford,
C. H.; Franks, A.; Gale, B.; Lindsey, K.; Stedman, M.; Garmire, G.;
Margon, B.; Fabian, A.
Bibcode: 1981SPIE..284..169C
Altcode:
No abstract at ADS
Title: Book-Review - X-Ray Astronomy
Authors: Culhane, J. L.; Sandford, P. W.
Bibcode: 1981JBAA...91..611C
Altcode:
No abstract at ADS
Title: Low energy observations of Cygnus X-2 by Ariel VI.
Authors: Cruise, A. M.; Goodall, C. V.; Bedford, D. K.; Campbell,
D. J.; Carpenter, G. F.; Cole, R. E.; Culhane, J. L.; Osborne, J.;
Pollock, A. M. T.; Willmore, A. P.; Zarnecki, J.
Bibcode: 1981hea..conf..211C
Altcode:
No abstract at ADS
Title: Extragalactic X-ray astronomy.
Authors: Culhane, J. L.
Bibcode: 1981ScPrD..67..223C
Altcode:
No abstract at ADS
Title: Ariel V observations of A 4.8-(HR). Periodicity in the "high
state" X-Ray spectrum of CYG X-3.
Authors: Blissett, R. J.; Mason, K. O.; Culhane, J. L.
Bibcode: 1981MNRAS.194...77B
Altcode:
Observations of Cygnus X-3 in 1975 May with the Ariel V proportional
counter spectrometer reveal the existence of 4.8-hr periodic variations
in the X-ray spectrum. Periodicity is observed in both the 2-6 keV
continuum shape, and in the apparent energy of the iron-line, and
occurs at a time of high mean source intensity. These results are
compared with a similar behaviour noted by Becker et al. for the
"low-state" spectrum. In contrast to the low-state observations,
the data presented here do not suggest phase dependent absorption by
material local to the source.
Title: Iron line emission and variability in the X-ray spectrum of
the Seyfert galaxy NGC 5548
Authors: Hayes, M. J. C.; Culhane, J. L.; Blissett, R. J.; Barr, P.;
Burnell, S. J. B.
Bibcode: 1980MNRAS.193P..15H
Altcode:
The MSSL spectrometer on the Ariel V satellite has detected a variable
iron emission feature in the X-ray spectrum of NGC 5548. Comparison with
other observations indicates that both the slope and intensity of the
continuum spectrum are variable. It is suggested that the iron emission
is due to fluorescent excitation of the gas in the broad emission-line
region surrounding the X-ray emitting nucleus of the galaxy.
Title: Light from electron avalanches and background rejection in
X-ray astronomy
Authors: Siegmund, O. H. W.; Sanford, P. W.; Mason, I. M.; Culhane,
J. L.; Cockshott, R.
Bibcode: 1980Natur.287..808S
Altcode:
We have developed the parallel plate imaging proportional counter
to register images of cosmic X-ray sources in the focal planes of
X-ray telescopes1,2. An important factor determining the
sensitivity of such an instrument, particularly for extended source
studies, is the background count rate induced in the detector by the
interaction of charged particles such as cosmic rays. This background in
wire anode proportional counters can be reduced by applying risetime
discrimination to the charge pulse3. We report here
that a modified version of the parallel plate imaging proportional
counter has been constructed as shown in Fig. 1a, to investigate the
application of risetime discrimination to the scintillation pulses
caused by the electron avalanche process4. We show that
efficient background event rejection (>90%) is achieved and discuss
an application of this system for X-ray astronomy.
Title: Ariel V X-ray observations of two type I Seyfert galaxies
Authors: Hayes, M. J. C.; Culhane, J. L.; Burnell, S. J. B.
Bibcode: 1980MNRAS.192P...1H
Altcode:
X-ray spectra of the type I Seyfert galaxies ESO 012-G21 and Markarian
464 obtained by the proportional counter spectrometer on board Ariel
5 are presented. ESO 012-G21 is found to have an X-ray luminosity
of 1.5 x 10 to the 44th erg/sec at a redshift of 0.03 and a Hubble
constant of 50 km/sec per Mpc, and is identified with the X-ray source
3U 0055-79. An X-ray luminosity varying within a year from 3 to 0.9 x
10 to the 44th erg/sec has been obtained for Mkn 464, and a column of
absorbing of around 2.5 x 10 to the 23 H atoms/sq cm has been detected
in front of the source. Evidence for a low energy cut-off in the X-ray
spectrum of Mkn 464 is also noted.
Title: A spectral study of Wray 977, the optical counterpart of the
binary X-ray pulsar 4U 1223-62.
Authors: Parkes, G. E.; Mason, K. O.; Murdin, P. G.; Culhane, J. L.
Bibcode: 1980MNRAS.191..547P
Altcode:
Optical spectra of Wray 977 at dispersions of 25 and 33 Å
mm-1 have been obtained, and a spectral type of B2 Ia
e derived, implying a stellar mass of 25 -3 SMsun. The
P-Cygni type emission line profiles in the spectrum indicate that Wray
977 has an extended, expanding atmosphere, and velocity progressions
in the Balmer and strong He I series indicate that the atmosphere is
also accelerating. The mass loss rate is probably greater than ∼3 ×
10-6 Msun yr-1. A distance of 1.8 ±
0.4 kpc is derived implying that the average X-ray luminosity of 4U
1223-62 is ∼1036 erg -1. The study has shown
that the profiles of spectral features are constant from day to day,
contrary to the report of Vidal. The models are discussed.
Title: X-ray astronomy with the Einstein observatory
Authors: Culhane, J. L.
Bibcode: 1980Natur.284..509C
Altcode:
No abstract at ADS
Title: Hot Gas in Clusters of Galaxies
Authors: Culhane, J. L.
Bibcode: 1980RSPTA.296..385C
Altcode: 1980RSLPT.296..385C
The title of the paper indicates that our understanding of cluster
X-ray sources has progressed considerably since their discovery in
1971. We now believe that the extended X-ray emission that is observed
is due to the presence of high temperature (T ≈ 108
K) gas in the clusters. The paper includes a review of the present
status of cluster X-ray observations and an account of the evidence
that points to brems-strahlung from hot plasma as the X-ray emission
mechanism. Current ideas about the origin of the intracluster plasma
and its heating mechanism are examined and the possible role of cluster
X-raystudies in furthering out understanding of the evolution of the
Universe is discussed.
Title: The soft X-ray polychromator for the Solar Maximum Mission.
Authors: Acton, L. W.; Culhane, J. L.; Gabriel, A. H.; Bentley,
R. D.; Bowles, J. A.; Firth, J. G.; Finch, M. L.; Gilbreth, C. W.;
Guttridge, P.; Hayes, R. W.; Joki, E. G.; Jones, B. B.; Kent, B. J.;
Leibacher, J. W.; Nobles, R. A.; Patrick, T. J.; Phillips, K. J. H.;
Rapley, C. G.; Sheather, P. H.; Sherman, J. C.; Stark, J. P.; Springer,
L. A.; Turner, R. F.; Wolfson, C. J.
Bibcode: 1980SoPh...65...53A
Altcode:
The 1.4-22.4 Å range of the soft X-ray spectrum includes a multitude
of emission lines which are important for the diagnosis of plasmas
in the 1.5-50 million degree temperature range. In particular, the
hydrogen and helium-like ions of all abundant solar elements with Z
> 7 have their primary transitions in this region and these are
especially useful for solar flare and active region studies. The soft
X-ray polychromator (XRP) is a high resolution experiment working
in this spectral region. The XRP consists of two instruments with
a common control, data handling and power system. The bent crystal
spectrometer is designed for high time resolution studies in lines of Fe
I-Fe XXVI and Ca XIX. The flat crystal scanning spectrometer provides
for 7 channel polychromatic mapping of flares and active regions in
the resonance lines of O VIII, Ne IX, Mg XI, Si XIII, S XV, Ca XIX,
and Fe XXV with 14″ spatial resolution. In its spectral scanning
mode it covers essentially the entire 1.4-22.5 Å region.
Title: Hot gas in clusters of galaxies.
Authors: Culhane, J. L.
Bibcode: 1980HiA.....5..387C
Altcode:
No abstract at ADS
Title: The X-ray spectra of clusters of galaxies and their
relationship to other cluster properties.
Authors: Mitchell, R. J.; Dickens, R. J.; Burnell, S. J. B.; Culhane,
J. L.
Bibcode: 1979MNRAS.189..329M
Altcode:
Observations with the MSSL proportional counter spectrometer on the
Ariel 5 satellite of the X-ray spectra of 20 candidate clusters of
galaxies are reported. The data are compared with the results from
the OSO 8 satellite, and the combined sample of some 30 cluster X-ray
spectra are analyzed. Generally larger values of X-ray luminosity than
obtained by Uhuru or the SSI are found, which, because of the larger
field of view, may indicate significant amounts of hot gas away from
the cluster centers. The validity of all X-ray cluster identifications
has been examined, and sources have been classified according to
certainty of identification. The incidence of X-ray line emission from
the clusters has been investigated, and temperatures derived on the
basis of an isothermal model. Relationships between X-ray, optical, and
radio properties of the clusters have been studied. The more massive,
centrally condensed clusters generally contain higher-temperature gas
and have a greater luminosity than the less massive, more irregular
clusters.
Title: Soft X-ray Observations of Cygnus X2 from Ariel VI.
Authors: Cruise, A. M.; Culhane, J. L.; Osborne, J.; Cole, R.;
Zarnecki, J.; Goodall, C. V.; Campbell, D.; Willmore, A. P.
Bibcode: 1979BAAS...11R.794C
Altcode:
No abstract at ADS
Title: The X-ray spectra of clusters of galaxies
Authors: Culhane, J. L.
Bibcode: 1979NW.....66..433C
Altcode:
The identification of extended sources of X-ray emission
associated with clusters of galaxies has been one of the major
achievements of X-ray astronomy. In this paper the present situation
regarding the identification of X-ray clusters is reviewed and
the relationship between X-ray and optical cluster properties is
briefly discussed. Measurements of X-ray extent have been made for
a small number of clusters and the status of these observations is
described. The nature of the X-ray emission process and the observations
which have led to our present understanding of cluster X-ray production
are examined in some detail. Observations at other wavelengths
that are relevant to this problem are also discussed. The available
evidence suggests that the X-ray emission is due to bremsstrahlung
from high-temperature ( T>2·107 K) gas that is present
in the space between cluster galaxies. Current models of the origin
of this gas and of its likely heating mechanism are presented.
Title: Association of coronal-line and filamentary emission in
Puppis-A.
Authors: Clark, D. H.; Murdin, P.; Zarnecki, J. C.; Culhane, J. L.
Bibcode: 1979MNRAS.188P..11C
Altcode:
Fe XIV coronal forbidden line emission from the supernova remnant
Puppis-A was spectroscopically detected. Two-dimensional spectral
data imply that the approximately 10 to the 6th K plasma coronal-line
component forms a halo surrounding the cooler approximately 10 to the
4th K optical filamentary component, suggesting that it originates
from evaporated plasma from dense cloudlets rather than swept-up
interstellar material. This result influences the interpretation of
X-ray emission from supernova remnants.
Title: NGC 4593 - a bright Seyfert galaxy with variable X-ray
emission.
Authors: Burnell, S. J. B.; Culhane, J. L.
Bibcode: 1979MNRAS.188P...1B
Altcode:
Ariel 5 observations of the X-ray source 4U 1240 - 05 support
suggestions that it should be identified with the galaxy NGC 4593
recently found to be type 1 Seyfert. Data on the source position and
spectrum are presented. The X-ray intensity appears to have varied by
a factor of more than two since the Uhuru observation.
Title: An investigation of the 1.9 Å feature in solar-flare X-ray
spectra.
Authors: Parkinson, J. H.; Veck, N. J.; Ashfield, M. E. C.; Culhane,
J. L.; Ku, W. H. -M.; Lemen, J. R.; Novic, R.; Acton, L. W.; Wolfson,
C. J.
Bibcode: 1979ApJ...231..551P
Altcode:
The 1.9 A feature, observed in the X-ray spectra of three solar flares
with the Columbia University and Lockheed Palo Alto Research Laboratory
spectrometers on the OSO 8 satellite, is shown to be due to a blend of
1s-2p transitions in a range of Fe ions. In the temperature range 9-16
x -10 to the 6th K, the feature has a mean wavelength of 1.900 + or -
0.009 A and is 0.04 A wider than a single line, indicating that the
main contributors are Fe XIX-Fe XXII. Most of the emission originates
from the dielectronic recombination process, and when inner-shell
excitation is included together with normal collisional excitation, the
observed intensity of the feature can be accounted for adequately. For
these events, if the electron density is below approximately 10 to the
12th/cu cm, deviations from ionization equilibrium will be significant
for ions more highly ionized than Fe XXI.
Title: The interstellar oxygen edge in the X-ray spectrum of the
Crab Nebula.
Authors: Charles, P. A.; Kahn, S. M.; Bowyer, S.; Blissett, R. J.;
Culhane, J. L.; Cruise, A. M.; Garmire, G.
Bibcode: 1979ApJ...230L..83C
Altcode:
Measurement of the X-ray spectrum of the Crab Nebula by the HEAO 1 A-2
low-energy (0.15-3 keV) detectors is reported. The spectral restoration
techniques described by Blissett and Cruise (1979) and Kahn and Blissett
(1979) are used to demonstrate explicitly the existence of a 'negative'
feature near 0.5 keV that is consistent with the edge expected due to
absorption by interstellar oxygen. For a simple power-law model with
photon index -2.08, the data require a column density of 3.0 + or -
0.1 x 10 to the 21st per sq cm and an oxygen abundance of 1.0 + or -
0.1 times the Brown and Gould (1970) value. Satisfactory fits can
also be achieved with the more sophisticated Fireman (1974) models,
but no model can be adjusted to fit the data without the inclusion of
interstellar oxygen.
Title: The Structure and Spectra of the X-Ray Sources in Clusters
of Galaxies
Authors: Culhane, J. L.
Bibcode: 1979RSPSA.366..403C
Altcode: 1979RSLPS.366..403C
The current state of our knowledge of the Perseus cluster at radio,
optical and X-ray wavelengths is reviewed to summarize the nature of
cluster sources. Recent results on the X-ray structure of clusters are
presented. Objects discussed include the Centaurus and Virgo clusters,
Abell 1367 and Abell 478. Preliminary results of a study of 30 cluster
X-ray spectra are reported. The derivation of the intra-cluster gas
parameters is described and the relations between these parameters and
other cluster properties are examined. The detection of highly ionized
iron emission lines in the spectra of several clusters is discussed
and estimates of iron abundance are presented.
Title: Cluster iron lines and the X-ray spectrum of SC 0627-544.
Authors: Berthelsdorf, R. F.; Culhane, J. L.
Bibcode: 1979MNRAS.187P..17B
Altcode:
Further observations with the MSSL proportional counter spectrometer on
the Ariel V satellite have led to the detection (at a confidence level
of at least 99 per cent) of a highly ionized iron emission feature in
the spectrum of the southern cluster SC 0627-544. The data obtained
are compared with previous observations of this source made by the
Goddard Space Flight Center's instrument on OSO-8. Iron emission
feature detections with greater than 99 per cent confidence levels
have now been made for five clusters of galaxies. A value of cluster
iron abundance is deduced from these data.
Title: Ariel V. Observations of Spectral Variability in Cygnus X-3
during a High Intensity State
Authors: Blissett, R. J.; Culhane, J. L.; Mason, K. O.
Bibcode: 1979BAAS...11..463B
Altcode:
No abstract at ADS
Title: [Fe X] and [Fe XIV] emission from Puppis A and other supernova
remnants.
Authors: Lucke, R. L.; Zarnecki, J. C.; Woodgate, B. E.; Culhane,
J. L.; Socker, D. G.
Bibcode: 1979ApJ...228..763L
Altcode:
Measurements of Fe XIV 5303-A and Fe X 6374-A forbidden emission from
several supernova remnants are reported, and their relation to X-ray
observations is discussed. The brightest Fe XIV forbidden-emission
region in Puppis A is interpreted as being the result of the supernova
shock wave's interacting with a dense cloud in the interstellar medium.
Title: Performance of a flight model gas scintillation counter
spectrometer for X-ray astronomy.
Authors: Peacock, A.; Andresen, R. D.; van Dordrecht, A.; Leimann,
E. -A.; Manzo, G.; Taylor, B. G.; Berthelsdorf, R.; Culhane, J. L.;
Ives, J. C.; Sanford, P. W.
Bibcode: 1979ITNS...26..486P
Altcode:
Results are presented on the performance of a large area gas
scintillation proportional counter (GSPC) experiment for application
as a spectrometer in X-ray astronomy. Two such counters will be
launched on an Aries sounding rocket in 1979. This experiment has a
total collecting area of 630 sq cm, and an energy resolution of 11%
for 6 keV X-rays. The intrinsic background rejection capability with
the aid of burst length discrimination was approximately 80% for an
X-ray acceptance of 80% at 6 keV.
Title: Cosmic X-ray telescope for ARIES rocket observations
Authors: Catura, R. C.; Acton, L. W.; Berthelsdorf, R.; Culhane,
J. L.; Sanford, P. W.; Franks, A.
Bibcode: 1979SPIE..184...23C
Altcode:
A rocket-borne Wolter Type I X-ray telescope having a focal length
of 2.3m, an entrance aperture of 66cm and a geometrical area of
380cm2 is nearing completion. The telescope mirrors are formed by
diamond turning their figures into forged aluminum substrates of
5083 alloy. These diamond-turned substrates are subsequently plated
with a thin coating of electroless nickel and polished to obtain the
final X-ray reflecting surfaces. Details of the rocket payload, the
X-ray telescope, its calculated response and the experience gained
in selecting the mirror substrate alloy are discussed and the current
status of the telescope is reviewed.
Title: Some recent coronal line observations of supernova remnants.
Authors: Zarnecki, J. C.; Lucke, R. L.; Woodgate, B. E.; Culhane,
J. L.; Socker, D.
Bibcode: 1979xras.proc..341Z
Altcode:
Observations of optical coronal lines from the supernova remnants Puppis
A and N 49 in the Large Magellanic Cloud carried out at Cerro Tololo and
the Anglo-Australian Observatory are reported. The eastern section of
Puppis A was searched for forbidden Fe X and Fe XIV emissions in order
to confirm the previous detection of a lower temperature component
of the X-ray source. Strong forbidden Fe XIV emission was detected
in one region consistent with the position of the previously observed
soft X-ray component, implying a cool localized component, possibly a
relatively dense interstellar cloud interacting with the expanding shock
front, superimposed on a more extended hotter region. The spectrum of
N 49 showed a broad feature at 5303 A, identified with the forbidden
Fe XIV line. Predictions of X-ray fluxes assuming a temperature of
2 x 10 to the 6th K and a density behind the shock front of 4/cu cm
for hydrogen densities of zero and 10 to the 21st/sq cm lead to the
suggestion that X-ray observations of N 49 may prove worthwhile.
Title: The nature of the X-ray source associated with the Vela pulsar.
Authors: Mason, K. O.; Culhane, J. L.
Bibcode: 1978MNRAS.185..673M
Altcode:
Summary. Investigation of the X-ray source associated with PSR0833 45,
using data from the Copernicus and Ariel V satellites, indicates a
significant enhancement in surface brightness within 6 arcmin of the
pulsar, while confirming that the emission is extended.
Title: The X-ray structure of supernova remnants II. Puppis-A.
Authors: Charles, P. A.; Culhane, J. L.; Zarnecki, J. C.
Bibcode: 1978MNRAS.185P..15C
Altcode:
Summary. We report here the final results of processing the Copernicus
0.6-1.5 keV observations of the supemova renmant (SNR) Puppis A using
the ART algorithm. The main X-ray emitting region is resolved into four
areas of X-ray emission, one of which is consistent with the position
of the softer component from which 0 VIII X-ray and Fe xiv coronal
line emission has recently been observed. The X-ray spatial structure
in Puppis A is briefly discussed in terms of current SNR models.
Title: Coronal lines in SNR spectra.
Authors: Murdin, P.; Clark, D. H.; Culhane, J. L.
Bibcode: 1978MmSAI..49..583M
Altcode:
Of the three components of the extended remnant of a supernova, the
thin filament and the peripheral shell of synchrotron emission have
been extensively studied. The third component, the shock-heated plasma,
however, is still poorly understood. Soft X-ray emission from the plasma
has been detected for at least eleven galactic supernova remnants
(SNRs). If the X-rays from SNRs do indeed originate in a rarefied
plasma with temperatures of the order of a few million degrees, the
plasma would also be expected to emit optical coronal lines, such as
the lambda 5303 Fe XIV line. Detection of such lines would provide for
a sensitive estimate of plasma temperature. Evidence is presented to
show that the reported coronal line identification in the Vela SNR is
unproven. However, it is believed that lambda 5303 has been detected
in N49 in the Large Magellanic Cloud, and in the Puppis A supernova.
Title: A search for X-ray line emission in the spectrum of the
Cygnus Loop.
Authors: Stark, J. P. W.; Culhane, J. L.
Bibcode: 1978MNRAS.184..509S
Altcode:
In connection with the reported investigation, a large area crystal
spectrometer was constructed for a flight on a Skylark sounding rocket
(SL 1212). The attitude control unit used was a stage V star pointing
system. Xi Cygnus was employed as the guide star. SL 1212 was launched
from the Woomera range, South Australia on June 11, 1977. The data
obtained in the investigation reveal that the flux in the selected O
VII emission lines is less than 6% of the total X-ray emission from
the source. The result implies that the temperatures characteristic of
the considered models are higher than has previously been determined
from X-ray continuum studies of the source. It is possible that the
oxygen abundance is depleted from the generally assumed cosmic value.
Title: Coronal lines in supernova remnant spectra.
Authors: Murdin, P.; Clark, D. H.; Culhane, J. L.
Bibcode: 1978MNRAS.183P..79M
Altcode:
The detection of coronal line emission offers the possibility of
studying the shock-heated plasma in supernova remnants (SNRs). A search
was performed for the 5303-A forbidden Fe XIV coronal line in the
SNRs N49 and Vela. The line was detected in the former at an intensity
suggesting a plasma temperature in the region of 2 million K. However,
a previously proposed detection for the Vela SNR was not confirmed.
Title: X-ray and optical observations of 3U 0900-40 (Vela X-1).
Authors: Charles, P. A.; Mason, K. O.; White, N. E.; Culhane, J. L.;
Sanford, P. W.; Moffat, A. F. J.
Bibcode: 1978MNRAS.183..813C
Altcode:
Copernicus and Ariel V observations of 3U0900-40 are presented. During
1975 February a region of low intensity was observed between binary
phase 0.5 and eclipse which was caused by an increase in photoelectric
absorption. This low state can be interpreted as the signature of
an accretion wake travelling across the line of sight. The source
also showed energy-independent flaring behaviour on timescales
of approximately 1 hr. The 283-s period measured by Copernicus in
1975 February was 0.017 s longer than that observed by SAS-3 in 1975
July. This is consistent with the secular decrease in period expected
for an accreting neutron star. An upper limit of 0.004 mag is placed
on the amplitude of broadband 283-s optical pulsations.
Title: Extragalactic X-ray Astronomy
Authors: Culhane, J. L.
Bibcode: 1978QJRAS..19....1C
Altcode:
The identification and classification of extragalactic X-ray sources
is discussed, with particular attention given to extended sources
associated with clusters of galaxies and to compact sources found
in the nuclei of active galaxies. Results obtained from the Uhuru
spacecraft and the Ariel-V satellite provide most of the data for the
identifications. Analysis of cluster X-ray spectra to yield information
on the heating of gases and the nature of the intergalactic medium is
discussed; investigation of the continuous X-ray spectra associated
with active galaxies may clarify the problem of the energy source
of active galaxies and quasars. Seyfert galaxies identified as X-ray
sources and X-ray emitting components of the Perseus, Virgo, Centaurus
and Coma clusters figure in the review.
Title: X-ray spectra and variability of some Seyfert galaxies and
other high latitude sources.
Authors: Stark, J. P.; Burnell, J. B.; Culhane, J. L.
Bibcode: 1978MNRAS.182P..23S
Altcode:
Observations from the Ariel V and Uhuru satellites have revealed five
extra-galactic X-ray sources through spectrographic analysis. Such
sources usually fall into two broad categories: galactic clusters
and active galaxies. A best-fit model was applied to graphs of the
sources' X-ray spectra, and the latter category was found to be more
consistent with the obtained data. Confidence limits for the data are
also presented.
Title: An imaging soft X-ray telescope for Spacelab.
Authors: Catura, R. C.; Culhane, J. L.; de Jager, C.; Garmire, G. P.;
Novick, R.
Bibcode: 1978nisa.symp..247C
Altcode: 1978nisa.conf..247C
No abstract at ADS
Title: Solar X-ray spectroscopy with bent crystal spectrometer (BCS).
Authors: Rapley, C. G.; Culhane, J. L.; Acton, L. W.; Catura, R. C.;
Joki, E. C.; Bakke, J. C.
Bibcode: 1978nisa.symp..121R
Altcode: 1978nisa.conf..121R
No abstract at ADS
Title: X-Ray Observations of Clusters of Galaxies
Authors: Culhane, J. L.
Bibcode: 1978IAUS...79..165C
Altcode: 1978lssu.conf..165C
The situation regarding identifications of clusters of galaxies with
X-ray sources is reviewed, and the luminosity function and possibly
relationships between a number of cluster X-ray and optical properties
are discussed for clusters listed in the second Ariel catalog. Recent
X-ray observations of superclusters are also recounted along with
cluster structural measurements by means of rocket observations with
imaging X-ray telescopes. The present status of iron-line observations
at 6.7 keV is described, and estimates of the iron abundance that
result from the iron-line data are examined. The contributions of
clusters and of X-ray emitting Seyfert galaxies to the diffuse X-ray
background are set at 14% and 6%, respectively, for the energy range
from 2 to 10 keV. The X-ray structures of the Perseus, Virgo, Centaurus,
and Abell 478 clusters are briefly described. It is noted that 30 to
40 clusters are known to be X-ray sources and that essentially all
clusters of galaxies will probably be X-ray sources.
Title: The X-Ray Spectrum and Structure of the Puppis a Supernova
Remnant
Authors: Zarnecki, J. C.; Culhane, J. L.; Toor, A.; Seward, F. D.;
Charles, P. A.
Bibcode: 1978ApJ...219L..17Z
Altcode:
No abstract at ADS
Title: A focussing iron line crystal spectrometer for Spacelab.
Authors: Catura, R. C.; Culhane, J. L.; Gabriel, A. H.; Rapley, C. G.;
Walker, A. B. C., Jr.; Woodgate, B. E.
Bibcode: 1978nisa.symp..271C
Altcode: 1978nisa.conf..271C
No abstract at ADS
Title: The X-ray temperatures of eight clusters of galaxies and
their relationship to other cluster properties.
Authors: Mitchell, R. J.; Ives, J. C.; Culhane, J. L.
Bibcode: 1977MNRAS.181P..25M
Altcode:
By combining X-ray spectral data obtained from the MSSL
proportional-counter spectrometer on the Ariel 5 satellite with optical
velocity-dispersion measurements for eight clusters of galaxies, it
is demonstrated that the observed X-ray emission probably arises from
the thermal bremsstrahlung mechanism and that the individual active
galaxies do not play an important role in supplying energy to the
intracluster medium. In addition, correlations between X-ray temperature
and luminosity, between X-ray temperature and cluster radius, and
between X-ray temperature and the mass of emitting gas are discussed.
Title: Bent crystal spectrometer for solar x-ray spectroscopy
Authors: Rapley, C. G.; Culhane, J. L.; Acton, L. W.; Catura, R. C.;
Joki, E. G.; Bakke, J. C.
Bibcode: 1977RScI...48.1123R
Altcode:
A bent crystal Bragg spectrometer is described which provides continuous
and simultaneous coverage for all x-ray wavelengths within its spectral
range. This instrument provides high spectral resolution but involves no
precision crystal rocking or position encoding mechanisms and therefore
may be highly ruggedized. Principles of operation are discussed and
its application to solar x-ray spectroscopy is described.
Title: A focussing iron line crystal spectrometer for Spacelab
Authors: Catura, R. C.; Culhane, J. L.; Rapley, C. G.; Gabriel, A. H.;
Walker, A. B. C., Jr.; Woodgate, B. E.
Bibcode: 1977cosp.meetS....C
Altcode:
A crystal spectrometer system is described which employs conical
focusing of 12 curved LiF crystal panels to minimize the detector
size and reduce the background counting rate. The wavelength range
from 1.70 to 1.98 A is covered, including the resonance lines of
Fe XXV and Fe XXVI as well as the Fe I K-alpha line and absorption
edge. Operation of the spectrometer is discussed, noting that diffracted
X-rays are registered in one-dimensional position-sensitive detectors
and that the arrival position of a photon in a detector is related
to its wavelength due to the fixed curvature of the crystal panels
in the dispersion plane. Some characteristics of the multianode
position-sensitive detectors are reviewed along with the crystal
arrangement and mounting. The instrument sensitivity is evaluated in
relation to the strengths of 6.7-keV emission features detected by
the Ariel 5 and OSO 8 proportional-counter spectrometers.
Title: An imaging soft X-ray telescope for Spacelab
Authors: Catura, R. C.; Culhane, J. L.; De Jager, C.; Garmire, G. P.;
Novick, R.
Bibcode: 1977cosp.meetR....C
Altcode:
A grazing-incidence soft X-ray telescope (SXT) of Wolter Type I
design is described which has been proposed for use in Spacelab
missions. The SXT consists of a four-mirror nested array of confocal
paraboloid-hyperboloid elements and is intended to have optimal
response in the wavelength range from 6 to 100 A (it also covers
the range between 100 and 1000 A). Basic elements of the SXT are
reviewed together with a design study of two different hyperboloid
lengths. An objective grating for studying point-source spectra is
examined, and several focal-plane detectors are discussed, including
an image-sensitive proportional counter, a channel electron multiplier
array, and a gas scintillation proportional counter. SXT sensitivity
is estimated for eight wavelength ranges between 8 and 1100 A.
Title: Solar X-ray spectroscopy with a Bent Crystal Spectrometer /BCS/
Authors: Rapley, C. G.; Culhane, J. L.; Acton, L. W.; Catura, R. C.;
Joki, E. C.; Bakke, J. C.
Bibcode: 1977cosp.meetR....R
Altcode:
A high-resolution Bent Crystal Spectrometer (BCS) which provides
simultaneous and continuous time coverage of a range of wavelengths is
described; its application to spectral studies of solar X-ray emission
is discussed. Design of the BCS and its accompanying position-sensitive
detector is considered. Calibrations of the crystal curvature, the
angle between a crystal reference plane and the collimator axis, and
the position response of the position-sensitive proportional counter
in determining absolute wavelengths are also mentioned. An active
solar region spectrum obtained during an airborne BCS test is compared
to wavelength data derived from theory or previous experiments, and
excellent agreement is found. Specifications for a BCS system to be
used in the Solar Maximum Mission satellite of 1979 are given.
Title: The X-ray spectrum and structure of the supernova remnant
IC 443.
Authors: Parkes, G. E.; Charles, P. A.; Culhane, J. L.; Ives, J. C.
Bibcode: 1977MNRAS.179...55P
Altcode:
Ariel V observations of IC 443 in the energy range from 1.1 to 7.5
keV are presented. The data permit the spectral parameters of this
source to be more tightly constrained than in previous observations
and provide information on the location of the emitting regions. No
evidence for iron line emission at 6.7 keV is found. A source model
is presented in which the initial explosion expands into a density
gradient in the northeastern direction. This model consistently
explains the observational properties of the remnant and predicts an
age of 12,700 yr.
Title: Detection of O VIII line emission in the X-ray spectrum of
Puppis A.
Authors: Zarnecki, J. C.; Culhane, J. L.
Bibcode: 1977MNRAS.178P..57Z
Altcode:
Summary. The detection of the 0 VIII resonance line at 18.97 A in the
X-ray spectrum of Puppis A is reported. The observation was carried
out by means of a Bragg crystal spectrometer flown on a sounding
rocket. Further evidence is obtained for the existence of material at
two temperatures in the source. An upper liinit is placed on the gas
column density to the source.
Title: Detection of iron line emission in the Ariel V X-ray spectrum
of the Centaurus cluster of galaxies.
Authors: Mitchell, R. J.; Culhane, J. L.
Bibcode: 1977MNRAS.178P..75M
Altcode:
Summary. Observations of the Centaurus cluster with the MSSL
proportionalcounter spectrometer on the Ariel V satellite reveal the
presence of a 7-keV feature which is identified with emission from Fe
xxv and Fe xxvi ions.
Title: The X-ray structure of supernova remnants - I. Cassiopeia A.
Authors: Charles, P. A.; Culhane, J. L.; Fabian, A. C.
Bibcode: 1977MNRAS.178..307C
Altcode:
Copernicus observations of the supernova remnant Cas A have been
reanalyzed using an algebraic reconstruction technique (ART) to
investigate further the X-ray structure of the source on a scale of
3 arcmin. This structure contains certain features similar to those
observed at radio wavelengths with a comparable beam size. Additional
X-ray observations through a 1.7-arcmin aperture confirm the main
features of the ART X-ray map. The reliability and accuracy of
the reconstruction technique are examined in detail. The spatial
inhomogeneity and high X-ray luminosity of Cas A may be due to the
blast wave interacting with matter ejected prior to the supernova
explosion. Alternatively, a 'reverse' shock may be heating material
ejected in the supernova itself.
Title: Extended soft X-ray emission from the Crab nebula.
Authors: Charles, P. A.; Culhane, J. L.
Bibcode: 1977ApJ...211L..23C
Altcode:
The grazing-incidence X-ray telescopes on the Copernicus satellite were
used to scan the Crab Nebula with an angular resolution of approximately
2 arcmin. Using a more precise technique for removing the non-X-ray
background, the 0.5-1.5-keV data from this scan are processed with
the ART algorithm. A significant extension to the northeast of the
nebula is found which is also evident in the raw data. A more diffuse
emission region is also apparent to the south of the nebula. These
features may be associated with the residual soft X-ray flux observed
during a lunar occultation of the Crab Nebula. The present data are
consistent with the extensions having a spectrum which is softer than
that of the main X-ray source in the Crab Nebula.
Title: X-rays from clusters of galaxies.
Authors: Culhane, J. L.
Bibcode: 1977cgci.conf..293C
Altcode:
No abstract at ADS
Title: X-Rays from Supernova Remnants
Authors: Culhane, J. L.
Bibcode: 1977ASSL...66...29C
Altcode: 1977supe.conf...29C
No abstract at ADS
Title: Cosmic X-Ray Spectroscopy.
Authors: Culhane, J. L.
Bibcode: 1977uxsa.collE...3C
Altcode: 1977IAUCo..43.....C
No abstract at ADS
Title: A study of four X-ray sources with properties similar to
Sco X-1.
Authors: Mason, K. O.; Charles, P. A.; White, N. E.; Culhane, J. L.;
Sanford, P. W.; Strong, K. T.
Bibcode: 1976MNRAS.177..513M
Altcode:
Copernicus and Ariel V observations are reported for four X-ray
sources which exhibit a correlation of intensity and spectral slope
on timescales similar to that seen in Sco X-1. These sources include
3U 0614+09, 3U 1702-36 (Sco X-2), 3U 1728-16 (GX 9+9), and 3U 1758-25
(GX 5-1). The mean spectral parameters of each source are given, the
short- and long-term behavior of different sources are described, and
it is suggested that the similar X-ray characteristics of these four
sources and Sco X-1 might indicate some degree of physical similarity
as well as a similar optical and radio appearance. The observations are
shown to strengthen the case for identifying 3U 0614+09 and 3U 1728-16
with relatively faint blue stars in or near their X-ray error boxes.
Title: Detection of an extreme-ultraviolet source in the southern sky.
Authors: Henry, P.; Bowyer, S.; Rapley, C. G.; Culhane, J. L.
Bibcode: 1976ApJ...209L..29H
Altcode:
The 3700 square degrees around the South Equatorial Pole have
been surveyed using a broad-band photometer with peak response at
90 A. One source was detected at about the same intensity as HZ
43. An extrapolation of the results implies that there are about 10
extreme-ultraviolet objects over the whole sky which are as bright
as HZ 43. Implications of these results for theories of white dwarf
evolution are briefly discussed.
Title: The Relation Between Temperature and X-ray Luminosity for
Clusters of Galaxies.
Authors: Mitchell, R. J.; Ives, J. C.; Culhane, J. L.
Bibcode: 1976BAAS....8..553M
Altcode:
No abstract at ADS
Title: The X-ray Temperature of Puppis A.
Authors: Charles, P. A.; Culhane, J. L.; Zarnecki, J. C.; Seward,
F. D.; Toor, A.
Bibcode: 1976BAAS....8..529C
Altcode:
No abstract at ADS
Title: A European X-Ray Spectroscopy and Polarimetry Payload for
Spacelab
Authors: Andresen, R. D.; Brinkman, A. C.; Beuermann, K.; Culhane,
J. L.; Griffiths, R.; Manno, V.; Rocchia, R.; Whitcomb, G.
Bibcode: 1976SSI.....2..325A
Altcode:
A group of instruments for X-ray spectroscopy and polarimetry studies
of a number of cosmic X-ray sources is being designed for possible
use on Spacelab. Large area Bragg spectrometers and polarimeters for
photon energies above 2 keV are described. For the energy range below 2
keV, both dispersive and non-dispersive spectrometers are employed at
the common focus of a nested array of paraboloids. Following a brief
outline of the scientific background to the mission, the properties
of the individual instruments are discussed.
Title: Proceedings of the symposium on the techniques of solar and
cosmic X-ray spectroscopy. Held at Holmbury, England, 22 and 23
May 1975.
Authors: Acton, L. W.; Culhane, J. L.
Bibcode: 1976SSI.....2....1A
Altcode: 1976STIA...7647776A
Papers are presented on the spectroscopic analysis of solar and cosmic
X-ray spectra, the absolute calibration of the reflection integral
of Bragg X-ray analyzer crystals, the design and construction of
modulation collimators, and Si(Li) X-ray astronomy aboard the HEAO-B
satellite. Attention is also given to the OSO 8 instrument for stellar
and solar X-ray spectroscopy and polarimetry, a soft X-ray spectrometer
for diffuse sources, instrumentation for solar spectrophotometry at
extreme ultraviolet and soft X-ray wavelengths, the calibration of
the Ariel 5 Bragg spectrometer and a European X-ray spectroscopy and
polarimetry payload for Spacelab. Individual items are announced in
this issue.
Title: A New Type of Crystal Spectrometer for Cosmic X-Ray Studies
Authors: Berthelsdorf, R. F.; Mitchell, R. J.; Culhane, J. L.
Bibcode: 1976SSI.....2..349B
Altcode:
A crystal spectrometer using a crystal panel curved in two dimensions
and a position sensitive proportional counter is described. The
instrument uses conical focussing to minimize detector size, and the
crystal panel is bent to simultaneously present a range of Bragg angles
to incoming X-rays, resulting in a one-to-one correspondence between
the energy of a reflected X-ray and its point of incidence on the
proportional counter. The advantages of such an instrument are high
sensitivity, mechanical simplicity, and the capability of measuring
spectra of rapidly varying sources.
Title: The X-ray structure of the Perseus cluster of galaxies.
Authors: Wolff, R. S.; Mitchell, R. J.; Charles, P. A.; Culhane, J. L.
Bibcode: 1976ApJ...208....1W
Altcode:
The X-ray source in the Perseus cluster has been studied both by
the Copernicus satellite and by sounding-rocket instruments flown
by Columbia University. The spatial and spectral data from these
observations are examined. A surface brightness distribution is obtained
which shows that the source consists of a compact core associated
with NGC 1275 and a more extended emission volume. The structure
of the central core region has been examined by means of an image
reconstruction technique, revealing a steeply declining luminosity
function and north-south elongation. The spectrum of the emission of
the core region is distinguished from that of the surrounding area
and found to be consistent with a hydrogen column density of 2.5 x 10
to the 21th/sq cm. A comparison between the isothermal and adiabatic
gas sphere models is presented which shows the need for at least two
components to provide the X-ray emission.
Title: Some implications of the X-ray data from old supernova
remnants.
Authors: Clark, D. H.; Culhane, J. L.
Bibcode: 1976MNRAS.175..573C
Altcode:
Several old supernova remnants emit soft X-rays. With certain
assumptions, and using a standard adiabatic shock-wave model, values
for the initial blast energy of a supernova and the age of its remnants
may be estimated. These parameters are evaluated using the most recently
available X-ray and radio results for four old supernova remnants. The
data imply high ratios of initial blast energy to interstellar density
and comparatively young ages for the remnants. These conclusions,
while at variance with some earlier estimates based on optical and
radio data, support the results of a statistical analysis of the most
recent catalog of radio remnants. Predicted X-ray fluxes for other
supernova remnants lying within 6 kpc of the sun are presented as a
guide to future observational programs.
Title: Detection of an Extreme Ultraviolet Source in the Southern
Hemisphere
Authors: Henry, P.; Bowyer, S.; Rapley, C. G.; Culhane, J. L.
Bibcode: 1976BAAS....8S.447H
Altcode:
No abstract at ADS
Title: The Spectra and Structure of Extra Galactic X-ray Sources
Authors: Culhane, J. L.
Bibcode: 1976BAAS....8R.445C
Altcode:
No abstract at ADS
Title: Observations of the Low Energy Diffuse X-ray Background
Authors: Rapley, C. G.; Bell-Burnell, S. J.; Culhane, J. L.
Bibcode: 1976BAAS....8..446R
Altcode:
No abstract at ADS
Title: `Copernicus' observations of extragalactic X-ray sources
Authors: Fabian, A. C.; Mitchell, R. J.; Davison, P. J. N.; Charles,
P. A.; Culhane, J. L.
Bibcode: 1976Ap&SS..42..249F
Altcode:
The MSSL X-ray detectors onCopernicus have been used to study a
number of extragalactic objects. At least three classes of unresolved
sources are found and we suggest that accretion may be the dominant
mechanism. The mass of the accreting object then determines the X-ray
emission properties.
Title: X-Ray Spectra of Cas A and Tycho's Supernova observed with
Ariel-5
Authors: Davison, P. J. N.; Culhane, J. L.; Mitchell, R. J.
Bibcode: 1976BAAS....8..448D
Altcode:
No abstract at ADS
Title: Periodic Modulation of the X-ray Flux from Four Galactic
X-ray sources
Authors: White, N. E.; Huckle, H. E.; Mason, K. O.; Charles, P. A.;
Pollard, G.; Culhane, J. L.; Sanford, P. W.
Bibcode: 1976BAAS....8Q.441W
Altcode:
No abstract at ADS
Title: Four Sources which show X-ray Behaviour similar to Sco X-1
Authors: Mason, K. O.; Charles, P. A.; White, N. E.; Culhane, J. L.;
Sanford, P. W.; Strong, K. T.
Bibcode: 1976BAAS....8..443M
Altcode:
No abstract at ADS
Title: X-ray spectra of Cassiopeia A and Tycho's supernova observed
with Ariel-5.
Authors: Davison, P. J. N.; Culhane, J. L.; Mitchell, R. J.
Bibcode: 1976ApJ...206L..37D
Altcode:
The proportional counter on Ariel-5 has observed the X-ray spectra
of Cas A and Tycho's supernova from 1.5 to 18 keV and 13 keV,
respectively. Both spectra are well fitted by two-component thermal
models. The higher-temperature component can in each case account
for an emission feature due to Fe XXV, which is observed at about 6.7
keV. Estimates of the iron abundance for each source are presented on
the basis of these models.
Title: Ariel 5 observations of the X-ray spectrum of the Perseus
cluster.
Authors: Mitchell, R. J.; Culhane, J. L.; Davison, P. J. N.; Ives,
J. C.
Bibcode: 1976MNRAS.175P..29M
Altcode:
An X-ray spectrum of the Perseus Cluster in the energy range 1.3-16
keV has been obtained with the MSSL collimated proportional counter
on Ariel 5. An emission feature has been detected at about 7 keV of
strength about 0.0035 photon per sq cm per sec. The existence of this
feature, which is due to Fe XXV and Fe XXVI transitions, provides strong
evidence for the presence of hot plasma in the cluster. In addition the
overall spectrum is well described by the bremsstrahlung emitted from
an adiabatic hydrostatic atmosphere of hot gas in the gravitational
potential well of the cluster.
Title: X-ray observations of NGC 5128.
Authors: Stark, J. P.; Davison, P. J. N.; Culhane, J. L.
Bibcode: 1976MNRAS.174P..35S
Altcode:
Observations of the active galaxy NGC 5128 (Centaurus A) have been made
by the satellite Ariel V for a two-day period in 1975 January, and by
the satellite Copernicus for one day in 1975 July. The observations from
Ariel V permit an accurate description of the X-ray spectrum to be made
over the band 1.3-28.7 keV. The best-fit spectrum is a power law with
photon index of -1.79 + or - 0.02 for a line-of-sight hydrogen column
density of 1.35 + or - 0.02 times 10 to the 23rd atom per sq cm. The
absence of an iron absorption feature in the spectrum allows us to set
an upper limit of twice the normal cosmic value to the abundance of
iron. The flux detected in January was higher than had been previously
observed, but by July this flux level had fallen by 40 per cent.
Title: The X-ray variability of Vela X-1 (3U 0900-40).
Authors: Charles, P. A.; Mason, K. O.; Culhane, J. L.; Sanford, P. W.;
White, N. E.
Bibcode: 1976NASSP.389..629C
Altcode: 1976NASSP.589..629C; 1976xrbi.nasa..629C
From observations of Vela X-1 with the MSSL 2.5-7.5 keV detector
onboard Copernicus, the behavior of the source can be characterized
by three phases: (1) high intensity, (2) low intensity, and (3)
eclipse. Combining data from the 1972 Uhuru observations with eclipse
observation yields a binary period of 8.963 + or - 0.001 days with
zero phase on 1975 Feb. 6.97 + or - 0.04 UT. The low intensity phase
is interpreted as being due to increased absorption in an accretion
wake traveling across the line of sight (the spectral slope remains
relatively constant throughout the cycle). Another period of enhanced
absorption immediately after exit from eclipse may be due to a
bow shock. Comparison of the two observations suggests that these
structures vary from cycle to cycle and, since the orbital period is
long, probably during each cycle.
Title: Copernicus observations of a number of galactic X-ray sources.
Authors: Culhane, J. L.; Mason, K. O.; Sanford, P. W.; White, N. E.
Bibcode: 1976NASSP.389....1C
Altcode: 1976NASSP.589....1C; 1976xrbi.nasa....1C
The Copernicus satellite was launched on 21 August 1972. The main
experiment on board is the University of Princeton UV telescope. In
addition a cosmic X-ray package of somewhat modest aperture was provided
by the Mullard Space Science Laboratory (MSSL) of University College
London. Following a brief description of the instrument, a list of
galactic sources observed during the year is presented. Although the
X-ray detection aperture is small, the ability to point the satellite
for long periods of time with high accuracy makes Copernicus an ideal
vehicle for the study of variable sources.
Title: Techniques of Solar and Cosmic X-ray Spectroscopy
Authors: Acton, L. W.; Culhane, J. L.
Bibcode: 1976SSI.....2.....A
Altcode:
No abstract at ADS
Title: Observations of the soft X-ray diffuse background.
Authors: Rapley, C. G.; Burnell, S. J. B.; Culhane, J. L.
Bibcode: 1976spre.conf..839R
Altcode: 1976spre.proc..839R
Observations of the soft X-ray diffuse background using a large
area, low-energy proportional counter aboard a Skylark rocket are
reported. Data have been obtained from a strip of sky extending from
the galactic plane to the North Galactic Pole. At least two regions of
enhanced emission and one absorption feature have been detected. We
discuss the association of these features with the radio loops and
two neutral hydrogen ridges. We show that there is strong evidence
for the existence of soft X-ray emission from beyond the bulk of the
galactic absorbing gas. It is likely that this emission is associated
with relatively local structures extending out of the galactic disc
rather than a galactic halo.
Title: X rays from supernova remnants.
Authors: Charles, P. A.; Culhane, J. L.
Bibcode: 1975SciAm.233f..38C
Altcode: 1975SciAm.233...38C
Analysis of X-ray emission from supernova remnants is aided by
grazing-incidence X-ray cameras borne by satellites and by utilizing
lunar occultation. The analysis provides new data on supernova ejecta
and the structure of the surrounding interstellar medium as the shocked
material ejected by the exploded supernova interacts with dust-gas
clouds. The presence in the Crab Nebula of a pulsar responsible for
enormous energy emission at visible, radio, and X-ray wavelengths is
confirmed, but the X-ray emission mechanism at work in Cassiopeia A and
in Tycho's nova appears to be complex interaction between high-velocity
magnetohydrodynamic shock waves and interstellar material swept up by
the shocks.
Title: Soft X-ray search of centre of Cygnus Loop
Authors: Snyder, W. A.; Henry, R. C.; Charles, P. A.; Culhane, J. L.;
Sanford, P. W.; Bleach, R.; Drake, J.
Bibcode: 1975Natur.258..214S
Altcode:
Equipment on the Copernicus satellite has been used to search for
evidence of a compact object in the center of the Cygnus Loop supernova
remnant. Rocket measurements reported by Rappaport et al. (1973)
indicate that a central object exists. However, the study conducted
with the aid of the satellite was negative. This negative result could
indicate that the X-ray source was simply not in its high-intensity
mode at the time of observation, or could arise because the source is
at some other location in the Loop.
Title: X-Ray Sources
Authors: White, N. E.; Huckle, H. E.; Mason, K. O.; Charles, P. A.;
Pollard, G.; Culhane, J. L.; Sanford, P. W.
Bibcode: 1975IAUC.2870....1W
Altcode:
N. E. White, H. E. Huckle, K. O. Mason, P. A. Charles, G. Pollard,
J. L. Culhane and P. W. Sanford, Mullard Space Science Laboratory,
write: "The Copernicus and Ariel 5 (experiment C) satellites have
made observations of seven galactic x-ray sources in the energy range
3-8 keV. The results of a search for modulation of the x-ray flux in
the period range 2.5-50 min are as follows: Source Satellite Date C
Period (min) A 3U 1223-62 Ariel 1975 Jan. 5 39 11.64 +/- 0.02 50 3U
1728-24 Copernicus 1972 Sept.11 47 4.315 +/- 0.004 12 3U 1728-24 "
1973 Mar. 25 31 4.39 +/- 0.07 20 3U 1813-14 " 1975 Aug. 1 254 31.9 +/-
0.1 4 C gives the mean count per min. The amplitude A (percent) quoted
is the peak to mean amplitude as a percentage of the mean flux. Four
sources, 3U 1702-36, 1728-16, 1757-25 and 1811-17, showed no detectable
modulation with upper limits to the amplitude, of 15, 5, 4 and 4
percent, respectively, when observed with Copernicus. The 4.3-min
period of 3U 1728-24 is close to twice the 2.3-min period suggested
by Lewin et al. (1971, Astrophys. J. 169, L17) from higher energy data."
Title: Copernicus: X-ray observations of several radio supernova
remnants.
Authors: Zarnecki, J. C.; Stark, J. P.; Charles, P. A.; Culhane, J. L.
Bibcode: 1975MNRAS.173..103Z
Altcode:
The MSSL X-ray detectors on Copernicus have observed five radio sources,
3C 392, DR4, MSHI5-52A and Downes Nos 83 and 84 in the energy range -
keV. The first three objects are thought to be supernova remnants. We
present here upper limits from our observations and in the case of 3C
392 a possible positive detection of X-ray emission. We also comment
on the variability of the X-ray source 3U 1901 + 03.
Title: Extended Soft X-Ray Emission from the Crab Nebula
Authors: Charles, P. A.; Culhane, J. L.
Bibcode: 1975BAAS....7R.505C
Altcode:
No abstract at ADS
Title: X-ray emission from the Centaurus cluster.
Authors: Mitchell, R. J.; Charles, P. A.; Culhane, J. L.; Davison,
P. J. N.; Fabian, A. C.
Bibcode: 1975ApJ...200L...5M
Altcode:
X-ray emission from the Centaurus cluster of galaxies has been studied
in the energy range 0.6-7.5 keV using the MSSL X-ray telescopes on
the Copernicus satellite. Exponential and power-law spectra fit the
data equally well. A value of the interstellar column density is
found which is in good agreement with radio observations. The X-ray
emission detected in the 12-minute field of view of the Copernicus
telescope is much greater than would be expected on the basis of the
Uhuru isothermal gas sphere model. This may indicate either that the
size of the extended X-ray source is less than reported by Kellogg
and Murray or that the galaxy NGC 4696 is a relatively compact source
embedded in the general emission from the cluster.
Title: Galactic X-ray sources
Authors: Culhane, J. L.
Bibcode: 1975xrat.rept....3C
Altcode:
Categories of galactic X-ray sources taken from the Uhuru catalog
are discussed. The Uhuru sources are classified by galactic latitude
into galactic and extra galactic populations. The galactic sources
include a group of highly luminous objects near the galactic center,
the compact X-ray sources in binary systems, and the X-ray emitting
supernova remnants. Galactic center sources are briefly dicussed and
compact object binary sources are examined in detail. The supernova
remnants are considered, and brief remarks are made about sources in
globular clusters and transient X-ray sources.
Title: Copernicus: the X-ray spectrum of Cassiopeia A.
Authors: Charles, P. A.; Culhane, J. L.; Zarnecki, J. C.; Fabian, A. C.
Bibcode: 1975ApJ...197L..61C
Altcode:
The MSSL X-ray telescopes on Copernicus have obtained the spectrum
of the supernova remnant Cas A in the energy range 0.5-7.5 keV. The
observations may be explained by a two-component thermal spectrum
with temperatures of 8 and 30 million degrees K. This result can be
broadly interpreted in terms of McKee's (1974) reverse-shock-wave
model of young remnants where the lower temperature is attributed
to the reverse shock and the higher one to the initial blast wave. A
3-sigma upper limit of 0.02 photons per sq cm per sec was also derived
for the emission from a line feature at 2 keV.
Title: Recent Copernicus Results on the X-ray Emission from Supernova
Remnants.
Authors: Charles, P. A.; Culhane, J. L.; Rapley, C. G.; Zarnecki,
J. C.; Fabian, A. C.
Bibcode: 1975BAAS....7Q.246C
Altcode:
No abstract at ADS
Title: Copernicus: The Spatial Distribution of the X-ray Emission
from IC443
Authors: Charles, P. A.; Culhane, J. L.; Rapley, C. G.
Bibcode: 1975ApL....16..129C
Altcode:
The MSSL X-ray instrumentation on the Copernicus satellite has observed
the spatial structure of the supernova remnant IC 443. The soft (0.5-1.4
keV) X-ray emission is found to be strongly correlated with the bright
optical filaments in the northeast. The total intensity is consistent
with previous observations of the remnant. An upper limit of 4 by 10
to the -11th power erg/sq cm/sec can also be assigned to the flux in
the 0.5-1.4-keV band from the nearby pulsar PSR 0611 + 22.
Title: An increase in the X-ray flux from Centaurus A.
Authors: Davison, P. J. N.; Culhane, J. L.; Mitchell, R. J.; Fabian,
A. C.
Bibcode: 1975ApJ...196L..23D
Altcode:
Observations of the 0.5-7.5 keV X-ray spectrum of Centaurus A (Cen A)
were made by the Copernicus satellite in June, 1973. The luminosity
of the source in the 2.5-7.5 keV range is found to have increased by
a factor of 4 in the two years since the last reported observation by
the Uhuru satellite. The value of the absorbing gas column density and
the power law index are consistent with those determined by Uhuru. The
luminosity increase indicates that the emitting region responsible
for it is only a few light years in extent, confirming that the X-ray
source is the nucleus of Cen A.
Title: Measured offset between the Crab pulsar and Tau X-1
Authors: Davison, P. J. N.; Culhane, J. L.
Bibcode: 1975Natur.253..610D
Altcode:
WE have used the MSSL X-ray detector on board the Copernicus spacecraft
to measure the effective diameter of the Crab Nebula and to measure the
location of the centroid of the emission with respect to the accurately
known pulsar position1.
Title: Copernicus: soft X-ray emission from certain features of the
Cygnus Loop.
Authors: Charles, P. A.; Culhane, J. L.; Zarnecki, J. C.
Bibcode: 1975ApJ...196L..19C
Altcode:
Observations made with the MSSL 0.5-1.5 keV X-ray telescope on board
Copernicus of several features of previous X-ray maps of the Cygnus
Loop, including the prominent filaments (NGC 6992-5) in the northeastern
part and a region in the northern part containing some scattered
filaments and a small peak in the radio emission, are discussed. A
thermal continuous spectrum is used to fit the satellite data to the
X-ray maps, and emission fluxes and spectra are calculated for the
filamentary regions. The results tend to confirm the existence of the
previously mapped bright X-ray emitting regions, and support Stevens'
interpretation that an encounter between the initial blast wave from
the supernova and an inhomogeneous interstellar medium has caused the
discrepancy between the observed optical filament velocities and the
implied shock velocities necessary for the observed X-ray emission.
Title: Spatially Resolved X-Ray Spectra of Coronal Active Regions
Authors: Catura, R. C.; Acton, L. W.; Joki, E. G.; Rapley, C. G.;
Culhane, J. L.
Bibcode: 1975IAUS...68...67C
Altcode:
No abstract at ADS
Title: X-ray astronomy with Copernicus.
Authors: Parkinson, J. H.; Culhane, J. L.; Hawkins, F. J.; Sanford,
P. W.
Bibcode: 1975spre.conf..663P
Altcode:
No abstract at ADS
Title: Upper Limits for X-Ray Emission from Jupiter as Measured from
the Copernicus Satellite
Authors: Vesecky, J. F.; Culhane, J. L.; Hawkins, F. J.
Bibcode: 1975ASSL...52..245V
Altcode: 1975msej.symp..245V
X-ray telescopic observations are made by the Copernicus satellite
for detecting X-ray emission from Jupiter analogous to X-rays from
terrestrial aurorae. Values of X-ray fluxes recorded by three Copernicus
detectors covering the 0.6 to 7.5 keV energy range are reported. The
detectors employed are described and the times at which the observations
were made are given. Resulting upper-limit spectra are compared with
previous X-ray observations of Jupiter. The upper-limit X-ray fluxes
are discussed in terms of magnetospheric activity on Jupiter.
Title: X-ray astronomy
Authors: Culhane, J. L.
Bibcode: 1975VA.....19....1C
Altcode:
The paper reviews the theory and practice of X-ray astronomy. Thermal
and nonthermal mechanisms which produce X-rays in the energy range from
0.1 to 20 keV are discussed, and X-ray absorption in the interstellar
medium is examined along with X-ray scattering by interstellar
grains. Instruments for X-ray astronomy are described, including gas
proportional counters, scintillation counters, solid-state detectors,
detectors with spatial resolution, various types of collimators,
X-ray telescopes, spectrometers, and polarimeters. The development
of solar X-ray studies is outlined, emphasizing X-ray emission from
coronal structures, from coronal active regions, and from solar
flares. Observations of extrasolar X-ray sources are discussed,
concentrating on their distribution and on descriptions of many X-ray
binaries, supernova remnants, and extragalactic sources. The diffuse
X-ray background is examined, and possible sources are considered for
the soft component of the diffuse flux.
Title: Copernicus: The X-ray structure of the Crab Nebula
Authors: Hawkins, F. J.; Mason, K. O.; Sanford, P. W.; Culhane, J. L.
Bibcode: 1974MNRAS.169P..41H
Altcode:
The extent of the X-ray emitting region in the Crab Nebula is derived
in two energy bands from observations by the Copernicus satellite. The
measurements are compared with previous results and discussed in terms
of a model for the nebular radiation.
Title: Studies of the X-Ray Emission from Supernova Remnants
Authors: Culhane, J. L.
Bibcode: 1974RSPSA.340..423C
Altcode:
Supernova remnants are now recognized as a class of soft X-ray
emitting-objects. The evolution of a remnant's X-ray emission is
discussed and a number of possible X-ray emission mechanisms are
described. The spectrum of the Crab Nebula has been studied with
Copernicus. The data have been used to derive a value of the gas
column density of the interstellar medium. The X-ray structure and
spectrum of the remnant Cassiopeia A have been investigated and the
results are presented. A high resolution X-ray map of the Puppis
A supernova remnant has been obtained and the interpretation of the
X-ray structure is discussed. X-ray emission has been detected from the
pulsar PSR 08 33-45. This observation is compared with data obtained
from the Uhuru satellite in order to derive the gas column density to
the source. Weak soft X-ray emission has been detected from the Cygnus
Loop in the regions expected but at a lower intensity - a search for
regions of higher intensity is continuing. A programme to identify
known radio remnants as X-ray emitters is in progress and the results
obtained so far are reported.
Title: A new type of crystal spectrometer for solar X-ray studies
Authors: Catura, R. C.; Joki, E. G.; Bakke, J. C.; Rapley, C. G.;
Culhane, J. L.
Bibcode: 1974MNRAS.168..217C
Altcode:
A new type of crystal spectrometer for the study of the solar X-ray
spectrum is described. Previous solar X-ray crystal spectrometers have
required a scanning mechanism to move both the crystal and the detector
so that the required range of wavelengths may be covered. By employing
a crystal bent in the plane of dispersion, a range of wavelengths may
be studied simultaneously by registering the dispersed spectrum with
a position sensitive X-ray detector. Details of the instrument are
presented together with some solar X-ray data obtained in an early
flight of the device.
Title: Some recent results in X-ray Astronomy
Authors: Culhane, J. L.
Bibcode: 1974MmSAI..45..831C
Altcode:
No abstract at ADS
Title: Detection of Soft X-Ray Emission from PSR 0833-45
Authors: Culhane, J. L.; Cruise, A. M.; Rapley, C. G.; Hawkins, F. J.
Bibcode: 1974ApJ...190L...9C
Altcode:
An observation of the Vela pulsar in the energy range 0.7-1.5
keV is presented. A comparison of the flux in this band with the
spectrum of the source 3U 0833-45 for the 2-10 keV band suggests
a low-energy turnover in the spectrum. The measurement is compared
with other observations, and possible explanations of the turnover
are discussed. Subject headings: pulsars - X-ray sources
Title: Copernicus: spectral studies of Cas-A and Pup-A
Authors: Charles, P. A.; Culhane, J. L.; Zarnecki, J. C.; Fabian, A. C.
Bibcode: 1974MmSAI..45..699C
Altcode:
No abstract at ADS
Title: Copernicus X-Ray Observations of NGC 1275 and the Core of
the Perseus Cluster
Authors: Fabian, A. C.; Zarneck, J. C.; Culhane, J. L.; Hawkins,
F. J.; Peacock, A.; Pounds, K. A.; Parkinson, J. H.
Bibcode: 1974ApJ...189L..59F
Altcode:
The Perseus cluster of galaxies has been studied with 0.5-1.5 keV and
1. .1 keV grazing-incidence X-ray telescope systems on the Orbiting
Astronomical Observatory, Copernicus. Observations with a range of
apertures (12', 6', and 2') defining the field of view reveal the
presence of a compact X-ray source centered 35ff + 30" north of NGC
1275. This has less than 3' extent, and we identify the X-ray source
with NGC 1275. The core of the extended cluster emission observed
with Uhurn is also detected. If it is assumed that the cluster core
X-ray emission distribution is independent of energy, then the X-ray
intensity of NGC 1275 is percent of the total cluster emission, and
may have a similar spectrum. We therefore deduce a 0.5-1.5 keV X-ray
luminosity of either 1 X 10 or 2.5 X 10 ergs 1 (H0 = 50 km s ' ) for
NGC 1275. We discuss the isothermal gas sphere model for the cluster
core, provide upper limits in the 0.5-1.5 keV range for NGC 1265 and
IC 310 which are within the cluster, and consider the compatibility
of our results with other published data. Subject headings: galaxies,
clusters of - X-ray sources
Title: Upper limit to the flux of soft X rays from λ-Sco
Authors: Strong, K. T.; Colley, M. W.; Culhane, J. L.
Bibcode: 1974Natur.248...34S
Altcode:
DURING a rocket flight on May 26, 1971 which carried a number of
large area thin window proportional counters, a soft X-ray source
was observed by Bleeker et al.1 in Scorpio. Photons in the
energy range 0.37 keV to 1.9 keV were detected from a position error
box of approximately 40 square degrees. This admittedly large error box
contains the bright star λ-Sco and it was suggested that this object
may be the source of the soft X-ray emission that was detected. It
is a B1 V star and exhibits a varying radial velocity with a period
of about 5.6 d. It has a visual magnitude of 1.62 and its distance is
estimated as 100 pc (ref. 2).
Title: Low Energy X-ray Observations of PSR 0833-45
Authors: Cruise, A. M.; Culhane, J. L.; Rapley, C. G.; Hawkins, F.
Bibcode: 1974BAAS....6..271C
Altcode:
No abstract at ADS
Title: Soft X-ray observations of supernova remnants.
Authors: Zarnecki, J. C.; Culhane, J. L.; Fabian, A. C.; Rapley,
C. G.; Boyd, R. L. F.; Parkinson, J. H.; Silk, R.
Bibcode: 1974olns.conf..565Z
Altcode:
No abstract at ADS
Title: Soft X-ray observations of supernova remnants
Authors: Zarnecki, J. C.; Culhane, J. L.; Fabian, A. C.; Rapley,
C. G.; Boyd, R. L. F.; Parkinson, J. H.; Silk, R.
Bibcode: 1974HiA.....3..565Z
Altcode:
Observations of a number of supernova remnants have been carried out
with the low energy X-ray telescope on the Copernicus satellite. Data
are presented on the X-ray structure of the remnants Cassiopeia A and
Puppis-A. Marginal detections or new upper limits are reported for
the remnants IC443, DR4, MSH15-52A, Downes 83, Downes 84, and 3C392.
Title: The solar X-ray spectrum.
Authors: Culhane, J. L.; Acton, L. W.
Bibcode: 1974ARA&A..12..359C
Altcode:
The characteristics of X-ray emission from the normal corona are
considered, giving attention to questions of spatial and spectral
distribution. Aspects of X-ray emission from solar flares are
also investigated. Details of X-ray spectroscopy for coronal plasma
diagnosis are discussed, taking into account techniques, the diagnosis
of equilibrium plasmas, and the diagnosis of nonthermal events. The
study of continuum emission and line emission is reported along with
investigations of departures from equilibrium.
Title: Low Energy X-ray Map of Puppis A Supernova Remnant
Authors: Zarnecki, J. C.; Culhane, J. L.; Fabian, A. C.; Rapley,
C. G.; Silk, R.; Parkinson, J. H.; Pounds, K. A.
Bibcode: 1973NPhS..243....4Z
Altcode: 1973Natur.243....4Z
THE low energy X-ray emission from the Puppis A supernova remnant
has recently been observed with the Mullard Space Science Laboratory
grazing incidence telescopes on Copernicus. The instrumentation has
been described before1. The observations reported here are
from the 0.5-1.5 keV detector system. The whole of the radio remnant
has been mapped using the 10 arc min field of view. Some additional
data from the 6 arc min field of view are also presented.
Title: The Soft X-Ray Structure of Cassiopeia A
Authors: Fabian, A. C.; Zarnecki, J. C.; Culhane, J. L.
Bibcode: 1973NPhS..242...18F
Altcode: 1973Natur.242...18F
The supernova remnant Cas A is identified as an extended source of
soft X-rays. No evidence is found for the presence of a compact X-ray
source. There are indications of non-uniformity in the X-ray surface
brightness.
Title: Further Results on Cooling Mechanisms for Soft X-ray Flares
Authors: Craig, I. J. D.; Culhane, J. L.; Phillips, K. J. H.; Vesecky,
J. F.
Bibcode: 1973NASSP.342..276C
Altcode: 1973heps.conf..276C
No abstract at ADS
Title: X-ray study of solar plage regions and a small flare.
Authors: Acton, L. W.; Catura, R. C.; Culhane, J. L.
Bibcode: 1973spre.conf..781A
Altcode: 1973spre....2..781A
No abstract at ADS
Title: Interstellar absorption of the lowenergy X-rays from the
Crab Nebula
Authors: Charles, P. A.; Culhane, J. L.; Tuohy, I. R.
Bibcode: 1973MNRAS.165..355C
Altcode:
Observations of the soft X-ray emission from the Crab Nebula, made
with the MSSL X-ray telescopes on board the satellite Copernicus,
require a review of the currently accepted interstellar abundances
of light elements. The soft X-ray data imply a gas column density of
( i o ) x 1021 atoms cm-2 using Brown & Gould X-ray absorption
cross-sections. Results obtained from 21 cm radio measurements indicate
a lower value of the column density. Better agreement between the
X-ray and radio values can be obtained by increasing the abundances
of helium and neon over those assumed by Brown & Gould.
Title: The sixteenth Herstmonceux conference, 1972 April 5 - 6. Cosmic
X-ray sources.
Authors: Pounds, K. A.; Miley, G. K.; Murdin, P.; Webster, B. L.;
Pacini, F.; Pringle, J. E.; Jackson, J. C.; Morrison, L. V.; Culhane,
J. L.; Sciama, D. W.; Fabian, A. C.; Brown, J. C.; Gabriel, A. H.;
Bingham, R. G.; Lategan, A. H.; Pagel, B. E. J.
Bibcode: 1972Obs....92..193P
Altcode:
No abstract at ADS
Title: Coronal survey in X-rays of O vii and Ne ix
Authors: Acton, L. W.; Catura, R. C.; Meyerott, A. J.; Wolfson, C. J.;
Culhane, J. L.
Bibcode: 1972SoPh...26..183A
Altcode:
We report some results of a rocket experiment flown on 29 April,
1971. A survey of the solar corona was carried out with a pair of
collimated Bragg spectrometers to study the resonance, intersystem and
forbidden line emission from the helium-like ions O VII (22 Å) and
Ne IX (13 Å). In the direction of dispersion the collimator provided
a field of view of 1.7'. Also, the continuum radiation near 3 Å was
monitored by a collimated proportional counter within a view angle
of 4.2'. The observed X-ray emission came from the general corona,
seven plage regions, and one dynamic feature- the late stage of a small
flare. From the intensity of the O VII and Ne IX resonance lines the
electron temperature and emission measure of the individual emitting
regions are derived on the basis of two models, one (a) in which the
region is assumed to be isothermal and another (b) in which the emission
measure decreases exponentially with increasing temperature. The
latter model, which is the most adequate of the two, yields for the
electron temperature of the time-varying feature 2-3 × 106
K, for the other active regions 1.5-2.5 × 106 K, and for
the general corona 1.3-1.7 × 106 K. The Ne IX emitting
regions are about 1.5 times as hot as the O VII regions. The emission
measure ranges from 0.4-2.3 × 1048 cm−3 for
all active regions and is about 2 × 1049 cm−3
for one hemisphere of the general corona above 106 K. From
an analysis of the ratio, R, of the forbidden and intersystem lines
of O VII we conclude that none of the regions producing these lines
at the time of the rocket flight had electron densities exceeding
about 3 × 109 cm−3. Our data demonstrate
a dependence of R upon temperature in agreement with the theory of
Blumenthal et al. (1971). The wavelengths for the intersystem, the
1s22s2Se−1s2p2s2P0
satellite, and the forbidden transition show in the case of Ne IX
improved agreement with predictions. The observed strength of the
satellite lines for both O VII and Ne IX agrees with the predictions
of Gabriel's (1972) theory, which attributes their formation to
dielectronic recombination.
Title: Mapping the Solar Corona in X-Ray Lines of O VII and NE IX
Authors: Catura, R. C.; Acton, L. W.; Meyerott, A. J.; Culhane, J. L.
Bibcode: 1972SSRv...13..742C
Altcode: 1972IAUCo..14..742C
No abstract at ADS
Title: Analysis of X-Ray Line Emission from Individual Solar Active
Regions
Authors: Catura, R. C.; Acton, L. W.; Wolfson, C. J.; Culhane, J. L.
Bibcode: 1972BAAS....4R.379C
Altcode:
No abstract at ADS
Title: Origin of the Low Energy Diffuse Cosmic X-Ray Flux
Authors: Culhane, J. L.; Fabian, A. C.
Bibcode: 1972Natur.237..379C
Altcode:
While only the gross features of the low energy diffuse flux have been
observed, it seems that a galactic component of diffuse soft X-rays is
required. Forces of this flux should be distributed about the galactic
plane with a scale height similar to that of the hydrogen.
Title: Circuits for Pulse Rise Time Discrimination in Proportional
Counters
Authors: Culhane, J. L.; Fabian, A. C.
Bibcode: 1972ITNS...19..569C
Altcode:
No abstract at ADS
Title: The Cosmic X-Ray Experiments Selected for Oso-J
Authors: Culhane, J. L.
Bibcode: 1972xanf.conf..105C
Altcode:
No abstract at ADS
Title: Helium-like Line Emission from Coronal Features
Authors: Acton, L. W.; Catura, R. C.; Meyerott, A. J.; Culhane, J. L.
Bibcode: 1971NPhS..233...75A
Altcode: 1971Natur.233...75A
SINCE Gabriel and Jordan1 proposed the theory
relating the relative intensity of the inter-system
(3P-1S0) and forbidden
(3S1 - 1S0) lines of
helium-like ions to the electron density of the emitting volume there
has been growing interest in using this type of information to determine
electron densities in the solar corona2-5. We present here
the preliminary results of a rocket experiment designed to study the
OVII and NeIX line emission from discrete coronal features. These
results indicate that electron densities in normal, non-flare, coronal
features are below the low density limits (6 × 109 and 1
× 1011 cm-3 respectively) given by Freeman et
al.5 for these particular ions.
Title: A Comment on Solar Flare Iron Line Emission at 1.9 Å
Authors: Phillips, K. J. H.; Culhane, J. L.
Bibcode: 1971SoPh...16..469P
Altcode:
No abstract at ADS
Title: A Rocket-Borne X-Ray Spectrometer Monochromator System for
Mapping the Solar Corona
Authors: Action, L. W.; Catura, R. C.; Culhane, J. L.; Meyerott, A. J.
Bibcode: 1971IAUS...41..181A
Altcode:
No abstract at ADS
Title: Gradual rise and fall X-ray bursts aboard OSO-4.
Authors: Phillips, K. J. H.; Culhane, J. L.; Sanford, P. W.
Bibcode: 1971spre.conf.1351P
Altcode:
No abstract at ADS
Title: The Cooling of Flare Produced Plasmas in the Solar Corona
Authors: Culhane, J. L.; Vesecky, J. F.; Phillips, K. J. H.
Bibcode: 1970SoPh...15..394C
Altcode:
Solar flare X-rays, at energies less than 10 keV, are emitted by
hot plasmas located in the corona. Three plasma cooling models are
examined in detail. The cooling of the electrons by Coulomb collisions
with ions at a lower temperature would require the observed material
to occupy very large volumes. Cooling could take place by conduction
or by radiation and observations are proposed which would allow the
dominant cooling mechanism to be established.
Title: The Cooling of Flare-Produced Plasmas in the Solar Corona
Authors: Culhane, J. L.; Phillips, K. J. H.; Vesecky, J. F.
Bibcode: 1970BAAS....2R.306C
Altcode:
No abstract at ADS
Title: Simultaneous Rocket and Satellite Observations of the Solar
X-Ray Spectrum in the 3-15-keV Range
Authors: Culhane, J. L.; Acton, L. W.; Catura, R. C.
Bibcode: 1970BAAS....2Q.307C
Altcode:
No abstract at ADS
Title: X-Ray Line Emission from Scorpius X-1
Authors: Acton, L. W.; Catura, R. C.; Culhane, J. L.; Fisher, P. C.
Bibcode: 1970ApJ...161L.175A
Altcode:
Observations of the Sco X-1 source with a large-area proportional
counter suggest the presence of iron-line emission in the spectrum of
the source at an energy of 6.6 + 0.2 keV. The counts due to the line
are in excess of the continuum and background counts by 6 standard
deviations. A comparison of the observed line-to-continuum ratio with
calculations yields a value consistent with a normal cosmic abundance
of iron in the source.
Title: Iron Line Emission at 1.9 Å during Solar Flares
Authors: Culhane, J. L.; Phillips, K. J. H.
Bibcode: 1970ApJ...160..309C
Altcode:
Solar X-ray spectra have been obtained with a proportional-counte
spectrometer on board the Orbiting Sotar Observatory 4. Observations
of an iron line at around t.9 A are presented which suggest that the
line is nonthermally excited.
Title: A simplified thermal continuum functionfor the X-ray emission
from coronal plasmas
Authors: Culhane, J. L.; Acton, L. W.
Bibcode: 1970MNRAS.151..141C
Altcode:
At temperatures below x io6 0K, the free-bound process makes an
increasingly significant contribution to the total continuum flux. While
the free-free spectrum may be represented by a relatively simple
expression, a detailed calculation of the spectrum requires a lengthy
summation process over all the ionization stages and levels of the
abundant coronal ions. A simple empirical expression is presented which
gives the magnitude and spectral slope of the free-bound contribution
over the energy interval - for the temperature range 4 2ooxIo60K. This
expression gives results that agree to better than 15 per cent with
more detailed calculations of the thermal continuous spectrum.
Title: Techniques for Improving the Sensitivity of Proportional
Counters Used in X-Ray Astronomy
Authors: Sanford, P. W.; Cruise, A. M.; Culhane, J. L.
Bibcode: 1970IAUS...37...35S
Altcode:
No abstract at ADS
Title: Solar X-Ray Bursts at Energies Less than 10 keV Observed
with OSO-4
Authors: Culhane, J. L.; Phillips, K. J. H.
Bibcode: 1970SoPh...11..117C
Altcode:
Using data from a proportional counter spectrometer, sensitive in the
wavelength range 1-20 Å, on OSO-4, X-ray bursts in the energy band 3.0
to 4.5 keV have been studied. 150 events have been identified between
October 27, 1967 and May 8, 1968, mostly of an impulsive nature. Some
gradual rise and fall bursts occur, but there is a selection bias
against such long-enduring events. A study of the profiles of these
events reveals no basis for identifying different types of impulsive
event.
Title: Soft X-Ray Observations from OSO-4
Authors: Culhane, J. L.; Sanford, P. W.; Phillips, K. J. H.
Bibcode: 1969S&T....37..287C
Altcode:
No abstract at ADS
Title: A study of the solar soft X-ray spectrum
Authors: Culhane, J. L.; Sanford, P. W.; Shaw, M. L.; Phillips,
K. J. H.; Willmore, A. P.; Bowen, P. J.; Pounds, K. A.; Smith, D. G.
Bibcode: 1969MNRAS.145..435C
Altcode:
A proportional counter X-ray spectrometer, sensitive in the
wavelength ranges 1-20 A and o A, was placed in orbit on the
Orbiting Solar Observatory -4. The instrument began to acquire data
on 1967 October 23. The spectrometer and its operation are briefly
described. Its performance and the method of data analyses are also
discussed. Preliminary studies have been made of the slowly varying
component of solar X-radiation, the nature of the X-ray active regions
in the solar corona and the characteristics of impulsive X-ray events.
Title: Thermal continuum radiation from coronal plasmas at soft
X-ray wavelengths
Authors: Culhane, J. L.
Bibcode: 1969MNRAS.144..375C
Altcode:
The continuous spectra, arising from the and transitions of electrons
in coronal plasmas, are calculated for wavelengths in the range IA
to 3oA and at temperatures in the range 106 K to 106 K. The effect of
variations in the element abundances is investigated. Estimates of the
continuum flux from the solar corona are presented and the observed
line to continuum ratios discussed.
Title: Observations of solar X-ray activity with a proportional
counter spectrometer on OSO-IV
Authors: Culhane, J. L.; Sanford, P. W.; Shaw, M. L.; Pounds, K. A.;
Smith, D. G.
Bibcode: 1969sfsr.conf..131C
Altcode:
No abstract at ADS
Title: Prelimiary Results of Soalr X-Ray Studies With a Proportionall
Counter Spectrometer on OSO-IV
Authors: Culhane, J. L.; Sanford, P. W.; Shaw, M. L.
Bibcode: 1968AJS....73S..58C
Altcode:
No abstract at ADS
Title: A measurement of the solar X-ray flux in the wavelength range
below 5 Å
Authors: Bowles, J. A.; Culhane, J. L.; Sanford, P. W.; Shaw, M. L.;
Cooke, B. A.; Pounds, K. A.
Bibcode: 1967P&SS...15..931B
Altcode:
Two beryllium windowed proportional counters were used to measure the
solar X-ray flux in the wavelength band below 5 Å. They were flown on
a Centaure rocket launched from a site near Karystos in Greece. The
counters and their associated electronics are briefly described. The
shape of the spectrum is estimated by considering the variation
in counting rate as the rocket ascended through the atmosphere. A
comparison of the present result with other measurements suggests that
the spectral slope and intensity are extremely variable in this part
of the spectrum.
Title: X-ray astronomy of the Sun
Authors: Culhane, J. L.
Bibcode: 1966PhDT.......114C
Altcode:
This thesis is concerned with the study of soft X-radiation from
the Sun. The properties of the Solar Corona are briefly reviewed
and possible mechanisms for the production of X-rays in the Corona
are critically discussed. The proportional counter is used as a
spectrometer throughout the work so the operation of this detector is
considered in detail. In particular its energy resolution and limits
of proportionality are examined. The continuous X-ray spectrum
of the Sun has been calculated and compared with proportional counter
observations under both quiet and disturbed Solar conditions. Finally two new experiments are described. One is a rocket experiment
designed to study the radiation from the Sun in the 20 - 70A band,
while the other is a satellite experiment which is designed to study
the Solar radiation in the 1 - 20A band in considerable detail.
Title: Variability of the solar X-ray spectrum below 15 A
Authors: Culhane, J. L.; Willmore, A. P.; Pounds, K. A.; Sanford, P. W.
Bibcode: 1964spre.conf..741C
Altcode:
No abstract at ADS