mason

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Author name code: mason
ADS astronomy entries on 2022-09-14
author:"Mason, Helen E."

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Title: Multiwavelength Observations by XSM, Hinode, and SDO of an
Active Region. Chemical Abundances and Temperatures
Authors: Del Zanna, G.; Mondal, B.; Rao, Y. K.; Mithun, N. P. S.;
Vadawale, S. V.; Reeves, K. K.; Mason, H. E.; Sarkar, A.; Janardhan,
P.; Bhardwaj, A.
2022ApJ...934..159D Altcode: 2022ApJ...934..159Z; 2022arXiv220706879D
We have reviewed the first year of observations of the Solar X-ray
Monitor (XSM) on board Chandrayaan-2 and the available multiwavelength
observations to complement the XSM data, focusing on the Solar
Dynamics Observatory AIA and Hinode XRT and EIS observations. XSM has
provided disk-integrated solar spectra in the 1-15 keV energy range,
observing a large number of microflares. We present an analysis of
multiwavelength observations of AR 12759 during its disk crossing. We
use a new radiometric calibration of EIS to find that the quiescent
active region (AR) core emission during its disk crossing has a
distribution of temperatures and chemical abundances that does
not change significantly over time. An analysis of the XSM spectra
confirms the EIS results and shows that the low first ionization
potential (FIP) elements are enhanced compared to their photospheric
values. The frequent microflares produced by the AR did not affect the
abundances of the quiescent AR core. We also present an analysis of
one of the flares it produced, SOL2020-04-09T09:32. The XSM analysis
indicates isothermal temperatures reaching 6 MK. The lack of very
high-T emission is confirmed by AIA. We find excellent agreement
between the observed XSM spectrum and the one predicted using an AIA
DEM analysis. In contrast, the XRT Al-poly/Be-thin filter ratio gives
lower temperatures for the quiescent and flaring phases. We show that
this is due to the sensitivity of this ratio to low temperatures,
as the XRT filter ratios predicted with a DEM analysis based on EIS
and AIA give values in good agreement with the observed ones.

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Title: Diagnostics of non-Maxwellian electron distributions in solar
active regions from Fe XII lines observed by Hinode/EIS and IRIS
Authors: Del Zanna, G.; Polito, V.; Dudík, J.; Testa, P.; Mason,
H. E.; Dzifčáková, E.
2022arXiv220707026D Altcode:
We present joint Hinode/EIS and IRIS observations of Fe XII lines
in active regions, both on-disk and off-limb. We use an improved
calibration for the EIS data, and find that the 192.4 A / 1349 A
observed ratio is consistent with the values predicted by CHIANTI and
the coronal approximation in quiescent areas, but not in all active
region observations, where the ratio is often lower than expected
by up to a factor of about two. We investigate a number of physical
mechanisms that could affect this ratio, such as opacity and absorption
from cooler material. We find significant opacity in the EIS Fe XII
193 and 195 A lines, but not in the 192.4 A line, in agreement with
previous findings. As we cannot rule out possible EUV absorption by
H, He and He II in the on-disk observations, we focus on an off-limb
observation where such absorption is minimal. After considering these,
as well as possible non-equilibrium effects, we suggest that the most
likely explanation for the observed low Fe XII 192.4 A / 1349 A ratio
is the presence of non-Maxwellian electron distributions in the active
regions. This is in agreement with previous findings based on EIS and
IRIS observations independently.

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Title: Diagnostics of Non-Maxwellian Electron Distributions in
Solar Active Regions from Fe XII Lines Observed by the Hinode
Extreme Ultraviolet Imaging Spectrometer and Interface Region
Imaging Spectrograph
Authors: Del Zanna, G.; Polito, V.; Dudík, J.; Testa, P.; Mason,
H. E.; Dzifčáková, E.
2022ApJ...930...61D Altcode:
We present joint Hinode Extreme Ultraviolet Imaging Spectrometer
(EIS) and Interface Region Imaging Spectrograph (IRIS) observations
of Fe XII lines in active regions, both on-disk and off-limb. We use
an improved calibration for the EIS data, and find that the 192.4
Å/1349 Å observed ratio is consistent with the values predicted by
CHIANTI and the coronal approximation in quiescent areas, but not in
all active-region observations, where the ratio is often lower than
expected by up to a factor of about two. We investigate a number of
physical mechanisms that could affect this ratio, such as opacity and
absorption from cooler material. We find significant opacity in the EIS
Fe XII 193 and 195 Å lines, but not in the 192.4 Å line, in agreement
with previous findings. As we cannot rule out possible EUV absorption by
H, He, and He II in the on-disk observations, we focus on an off-limb
observation where such absorption is minimal. After considering these,
as well as possible nonequilibrium effects, we suggest that the most
likely explanation for the observed low Fe XII 192.4 Å/1349 Å ratio
is the presence of non-Maxwellian electron distributions in the active
regions. This is in agreement with previous findings based on EIS and
IRIS observations independently.

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Title: The centre-to-limb variation of non-thermal velocities using
IRIS Si IV
Authors: Rao, Yamini K.; Del Zanna, Giulio; Mason, Helen E.
2022MNRAS.511.1383R Altcode: 2022arXiv220107290R; 2022MNRAS.tmp..149R
We study the non-thermal velocities in the quiet Sun using various
high spatial, temporal, and spectral resolution observations from the
Interface Region Imaging Spectrograph (IRIS). We focus our analysis on
the transition region using the optically thin line (Si IV 1393.7 Å),
and select line profiles that are nearly Gaussian. We find evidence
of a centre-to-limb variation using different observations having
different exposure times, ranging from 5 to 30 s. The distribution of
non-thermal velocities close to the limb is observed to peak around
20 km s-1 while the disc observations show a peak around
15 km s-1. The distributions are also different. The
overall variation in the non-thermal velocities are correlated with
the intensity of the line, as found previously. The on-disc velocities
are smaller than most previous observations. In general, we find that
the non-thermal velocities are independent of the selected exposure
times. The Si IV lines did not seem to exhibit any significant opacity
effects. We conclude that these Doppler motions are mostly transverse
to the radial direction. The possibility of swaying/torsional motions
leading to such variations are validated from these IRIS observations.

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Title: Preliminary Results from the Marshall Grazing Incidence X-ray
Spectrometer (MaGIXS)
Authors: Winebarger, Amy; Savage, Sabrina; Kobayashi, Ken; Champey,
Patrick; Golub, Leon; Walsh, Robert; Athiray, P. S.; Bradshaw, Stephen;
Cheimets, Peter; Cirtain, Jonathan; DeLuca, Edward; Del Zanna, Giulio;
Mason, Helen; McKenzie, David; Ramsey, Brian; Reeves, Katharine;
Testa, Paola; Vigil, Genevieve; Warren, Harry
2021AGUFMSH51A..06W Altcode:
Coronal heating mechanisms are notoriously difficult to constrain with
current observations. We present new observations from an instrument
designed to measure a critical diagnostic of the frequency heating
events in active regions. The Marshall Grazing Incidence X-ray
Spectrometer (MaGIXS) is a sounding rocket mission that aims to
observe the soft x-ray solar spectrum (0.6 2.5 nm) with both spatial
and spectral resolution. This wavelength range has several high
temperature and abundance diagnostics that can be used to infer the
coronal heating frequency. MaGIXS will observe the Sun through a 12
x 33 slot, producing “overlappograms, where the spatial and spectral
information are overlapped and must be unfolded. In this presentation,
I will report on the MaGIXS launch and data collection and provide
preliminary analysis of MaGIXS observations.

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Title: Evolution of Elemental Abundances during B-Class Solar Flares:
Soft X-Ray Spectral Measurements with Chandrayaan-2 XSM
Authors: Mondal, Biswajit; Sarkar, Aveek; Vadawale, Santosh V.;
Mithun, N. P. S.; Janardhan, P.; Del Zanna, Giulio; Mason, Helen E.;
Mitra-Kraev, Urmila; Narendranath, S.
2021ApJ...920....4M Altcode: 2021arXiv210707825M
The Solar X-ray Monitor (XSM) payload on board Chandrayaan-2 provides
disk-integrated solar spectra in the 1-15 keV energy range with an
energy resolution of 180 eV (at 5.9 keV) and a cadence of 1 s. During
the period from 2019 September to 2020 May, covering the minimum of
Solar Cycle 24, it observed nine B-class flares ranging from B1.3 to
B4.5. Using time-resolved spectroscopic analysis during these flares,
we examined the evolution of temperature, emission measure, and absolute
elemental abundances of four elements-Mg, Al, Si, and S. These are
the first measurements of absolute abundances during such small flares
and this study offers a unique insight into the evolution of absolute
abundances as the flares evolve. Our results demonstrate that the
abundances of these four elements decrease toward their photospheric
values during the peak phase of the flares. During the decay phase,
the abundances are observed to quickly return to their preflare coronal
values. The depletion of elemental abundances during the flares is
consistent with the standard flare model, suggesting the injection
of fresh material into coronal loops as a result of chromospheric
evaporation. To explain the quick recovery of the so-called coronal
"First Ionization Potential bias" we propose two scenarios based on
the Ponderomotive force model.

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Title: Thermodynamic evolution of a sigmoidal active region with
associated flares
Authors: Mulay, Sargam M.; Tripathi, Durgesh; Mason, Helen
2021MNRAS.504.1201M Altcode: 2021MNRAS.tmp..832M; 2021arXiv210309561M
Active regions often show S-shaped structures in the corona called
sigmoids. These are highly sheared and twisted loops formed along
the polarity inversion line. They are considered to be one of the best
pre-eruption signatures for CMEs. Here, we investigate the thermodynamic
evolution of an on-disc sigmoid observed during 2015 December 24-28. For
this purpose, we have employed Emission Measure (EM) and filter-ratio
techniques on the observations recorded by the Atmospheric Imaging
Assembly (AIA) on-board the Solar Dynamics Observatory (SDO) and X-ray
Telescope (XRT) on-board Hinode. The EM analysis showed multithermal
plasma along the sigmoid and provided a peak temperature of ~10-12.5
MK for all observed flares. The sigmoidal structure showed emission
from Fe XVIII (93.93 Å) and Fe XXI (128.75 Å) lines in the AIA 94 and
131 Å channels, respectively. Our results show that the hot plasma is
often confined to very hot strands. The temperature obtained from the
EM analysis was found to be in good agreement with that obtained using
the XRT, AIA, and GOES filter-ratio methods. These results provide
important constraints for the thermodynamic modelling of sigmoidal
structures in the core of active regions. Moreover, this study also
benchmarks different techniques available for temperature estimation
in solar coronal structures.

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Title: High resolution soft X-ray spectroscopy and the quest for
the hot (5-10 MK) plasma in solar active regions
Authors: Del Zanna, Giulio; Andretta, Vincenzo; Cargill, Peter J.;
Corso, Alain J.; Daw, Adrian N.; Golub, Leon; Klimchuk, James A.;
Mason, Helen E.
2021FrASS...8...33D Altcode: 2021arXiv210306156D
We discuss the diagnostics available to study the 5--10 MK plasma in
the solar corona, which is key to understanding the heating in the
cores of solar active regions. We present several simulated spectra,
and show that excellent diagnostics are available in the soft X-rays,
around 100 Angstroms, as six ionisation stages of Fe can simultaneously
be observed, and electron densities derived, within a narrow spectral
region. As this spectral range is almost unexplored, we present an
analysis of available and simulated spectra, to compare the hot emission
with the cooler component. We adopt recently designed multilayers to
present estimates of count rates in the hot lines, with a baseline
spectrometer design. Excellent count rates are found, opening up
the exciting opportunity to obtain high-resolution spectroscopy of
hot plasma.

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Title: 'We love STEAM!'
Authors: Mason, Helen; Schell, Helen
2021A&G....62.1.26M Altcode:
Helen Mason and Helen Schell explain how the SunSpaceArt outreach
programme flourished in 2020, bringing art and science together for
pupils and teachers

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Title: Electron Densities in the Solar Corona Measured Simultaneously
in the Extreme Ultraviolet and Infrared
Authors: Dudík, Jaroslav; Del Zanna, Giulio; Rybák, Ján;
Lörinčík, Juraj; Dzifčáková, Elena; Mason, Helen E.; Tomczyk,
Steven; Galloy, Michael
2021ApJ...906..118D Altcode: 2020arXiv201109175D
Accurate measurements of electron density are critical for
determination of the plasma properties in the solar corona. We compare
the electron densities diagnosed from Fe XIII lines observed by the
Extreme-Ultraviolet Imaging Spectrometer (EIS) onboard the Hinode
mission with the near-infrared (NIR) measurements provided by the
ground-based Coronal Multichannel Polarimeter (CoMP). To do that, the
emissivity-ratio method based on all available observed lines of Fe
XIII is used for both EIS and CoMP. The EIS diagnostics is further
supplemented by the results from Fe XII lines. We find excellent
agreement, within 10%, between the electron densities measured from both
extreme-ultraviolet and NIR lines. In the five regions selected for
detailed analysis, we obtain electron densities of log(Ne
[cm-3]) = 8.2-8.6. Where available, the background
subtraction has a significant impact on the diagnostics, especially on
the NIR lines, where the loop contributes less than a quarter of the
intensity measured along the line of sight. For the NIR lines, we find
that the line center intensities are not affected by stray light within
the instrument, and recommend using these for density diagnostics. The
measurements of the Fe XIII NIR lines represent a viable method for
density diagnostics using ground-based instrumentation.

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Title: Study of the spatial association between an active region
jet and a nonthermal type~${\rm III}$ radio burst
Authors: Mulay, Sargam M.; Sharma, Rohit; Valori, Gherardo; Vásquez,
Alberto M.; Del Zanna, Giulio; Mason, Helen; Oberoi, Divya
2020arXiv200914581M Altcode:
We aim to investigate the spatial location of the source of an active
region (AR) jet and its relation with associated nonthermal type~III
radio emission. An emission measure (EM) method was used to study
the thermodynamic nature of the AR jet. The nonthermal type~{\rm III}
radio burst observed at meterwavelength was studied using the Murchison
Widefield Array (MWA) radio imaging and spectroscopic data. The local
configuration of the magnetic field and the connectivity of the source
region of the jet with open magnetic field structures was studied using
a nonlinear force-free field (NLFFF) extrapolation and potential field
source surface (PFSS) extrapolation respectively. The plane-of-sky
velocity of the AR jet was found to be $\sim$136~km/s. The EM analysis
confirmed the presence of low temperature 2~MK plasma for the spire,
whereas hot plasma, between 5-8 MK, was present at the footpoint region
which also showed the presence of Fe~{\sc xviii} emission. A lower limit
on the electron number density was found to be 1.4$\times$10$^{8}$
cm$^{-3}$ for the spire and 2.2$\times$10$^{8}$~cm$^{-3}$ for
the footpoint. A temporal and spatial correlation between the AR
jet and nonthermal type III burst confirmed the presence of open
magnetic fields. An NLFFF extrapolation showed that the photospheric
footpoints of the null point were anchored at the location of the
source brightening of the jet. The spatial location of the radio
sources suggests an association with the extrapolated closed and
open magnetic fields although strong propagation effects are also
present. The multi-scale analysis of the field at local, AR, and solar
scales confirms the interlink between different flux bundles involved
in the generation of the type III radio signal with flux transferred
from a small coronal hole to the periphery of the sunspot via null
point reconnection with an emerging structure.

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Title: Plasma Diagnostics from Active Region and Quiet-Sun Spectra
Observed by Hinode/EIS: Quantifying the Departures from a Maxwellian
Distribution
Authors: Lörinčík, Juraj; Dudík, Jaroslav; del Zanna, Giulio;
Dzifčáková, Elena; Mason, Helen E.
2020ApJ...893...34L Altcode: 2020arXiv200307091L
We perform plasma diagnostics, including that of the non-Maxwellian
κ-distributions, in several structures observed in the solar corona
by the Extreme-Ultraviolet Imaging Spectrometer (EIS) on board the
Hinode spacecraft. To prevent uncertainties due to the in-flight
calibration of EIS, we selected spectral atlases observed shortly
after the launch of the mission. One spectral atlas contains an
observation of an active region, while the other is an off-limb
quiet-Sun region. To minimize the uncertainties of the diagnostics,
we rely only on strong lines and average the signal over a spatial
area within selected structures. Multiple plasma parameters are
diagnosed, such as the electron density, the differential emission
measure, and the non-Maxwellian parameter κ. To do that, we use
a simple, well-converging iterative scheme based on refining the
initial density estimates via the differential emission measure
(DEM) and κ. We find that while the quiet-Sun spectra are consistent
with a Maxwellian distribution, the coronal loops and moss observed
within the active region are strongly non-Maxwellian with κ ⪅
3. These results were checked by calculating synthetic ratios using
DEMs obtained as a function of κ. Ratios predicted using the DEMs
assuming κ-distributions converged to the ratios observed in the
quiet Sun and coronal loops. To our knowledge, this work presents a
strong evidence of the presence of different electron distributions
between two physically distinct parts of the solar corona.

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Title: Study of the spatial association between an active region
jet and a nonthermal type III radio burst
Authors: Mulay, Sargam M.; Sharma, Rohit; Valori, Gherardo; Vásquez,
Alberto M.; Del Zanna, Giulio; Mason, Helen; Oberoi, Divya
2019A&A...632A.108M Altcode:
 Aims: We aim to investigate the spatial location of the source
of an active region (AR) jet and its relation with associated nonthermal
type III radio emission. Methods: An emission measure (EM) method
was used to study the thermodynamic nature of the AR jet. The nonthermal
type III radio burst observed at meterwavelength was studied using
the Murchison Widefield Array (MWA) radio imaging and spectroscopic
data. The local configuration of the magnetic field and the connectivity
of the source region of the jet with open magnetic field structures was
studied using a nonlinear force-free field (NLFFF) extrapolation and
potential field source surface (PFSS) extrapolation respectively. Results: The plane-of-sky velocity of the AR jet was found to be
∼136 km s-1. The EM analysis confirmed the presence of
low temperature 2 MK plasma for the spire, whereas hot plasma, between
5 and 8 MK, was present at the footpoint region which also showed the
presence of Fe XVIII emission. A lower limit on the electron number
density was found to be 1.4 × 108 cm-3 for the
spire and 2.2 × 108 cm-3 for the footpoint. A
temporal and spatial correlation between the AR jet and nonthermal
type III burst confirmed the presence of open magnetic fields. An NLFFF
extrapolation showed that the photospheric footpoints of the null point
were anchored at the location of the source brightening of the jet. The
spatial location of the radio sources suggests an association with the
extrapolated closed and open magnetic fields although strong propagation
effects are also present. Conclusions: The multi-scale analysis
of the field at local, AR, and solar scales confirms the interlink
between different flux bundles involved in the generation of the type
III radio signal with flux transferred from a small coronal hole to the
periphery of the sunspot via null point reconnection with an emerging
structure. The movie associated to Fig. 4 is available at <A
href="https://www.aanda.org/10.1051/0004-6361/201936369/olm">https://www.aanda.org</A>

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Title: Hinode EIS line widths in the quiet corona up to 1.5
R⊙
Authors: Del Zanna, G.; Gupta, G. R.; Mason, H. E.
2019A&A...631A.163D Altcode: 2019arXiv190509783D
We present an analysis of several Hinode Extreme-ultraviolet Imaging
Spectrometer (EIS) observations of coronal line widths in the quiet Sun,
up to 1.5 R⊙ radial distances. Significant variations are
found, which indicates no damping of Alfvén waves in the quiescent
corona. However, the uncertainties in estimating the instrumental
width mean that a firm conclusion cannot be reached. We present a
discussion of various EIS instrumental issues and suggest that the
strongest lines, from Fe XII at 193.5 Å and 195.1 Å, have anomalous
instrumental widths. We also show how line widths in EIS are uncertain
when the signal is low, and that the instrumental variation along
the slit is also uncertain. We also find an anomalous decrease (up
to 40%) in the intensities of these lines in many off-limb and active
region observations, and provide evidence that this is due to opacity
effects. We find that the most reliable measurements are obtained from
the weaker lines.

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Title: Exploring the damping of Alfvén waves along a long off-limb
coronal loop, up to 1.4 R⊙
Authors: Gupta, G. R.; Del Zanna, G.; Mason, H. E.
2019A&A...627A..62G Altcode: 2019arXiv190508194G
The Alfvén wave energy flux in the corona can be explored using the
electron density and velocity amplitude of the waves. The velocity
amplitude of Alfvén waves can be obtained from the non-thermal velocity
of spectral line profiles. Previous calculations of the Alfvén wave
energy flux with height in active regions and polar coronal holes have
provided evidence for the damping of Alfvén waves with height. We
present off-limb Hinode Extreme-ultraviolet Imaging Spectrometer (EIS)
observations of a long coronal loop up to 1.4 R⊙. We
obtained the electron density along the loop and found the loop to be
almost in hydrostatic equilibrium. We obtained the temperature using
the emission measure-loci (EM-loci) method and found the loop to be
isothermal across, as well as along, the loop with a temperature of
about 1.37 MK. We significantly improve the estimate of non-thermal
velocities over previous studies by using the estimated ion (equal to
electron) temperature. Estimates of electron densities are improved
using the significant updates of the CHIANTI v.8 atomic data. More
accurate measurements of propagating Alfvén wave energy along the
coronal loop and its damping are presented up to distances of 1.4
R⊙, further than have been previously explored. The
Alfvén wave energy flux obtained could contribute to a significant
part of the coronal losses due to radiation along the loop.

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Title: Signatures of the non-Maxwellian κ-distributions in optically
thin line spectra. II. Synthetic Fe XVII-XVIII X-ray coronal spectra
and predictions for the Marshall Grazing-Incidence X-ray Spectrometer
(MaGIXS)
Authors: Dudík, Jaroslav; Dzifčáková, Elena; Del Zanna, Giulio;
Mason, Helen E.; Golub, Leon L.; Winebarger, Amy R.; Savage, Sabrina L.
2019A&A...626A..88D Altcode: 2019arXiv190510356D
 Aims: We investigated the possibility of diagnosing the degree of
departure from the Maxwellian distribution using the Fe XVII-Fe XVIII
spectra originating in plasmas in collisional ionization equilibrium,
such as in the cores of solar active regions or microflares. 
Methods: The original collision strengths for excitation are integrated
over the non-Maxwellian electron κ-distributions characterized by a
high-energy tail. Synthetic X-ray emission line spectra were calculated
for a range of temperatures and κ. We focus on the 6-24 Å spectral
range to be observed by the upcoming Marshall Grazing-Incidence X-ray
Spectrometer MaGIXS. Results: We find that many line intensity
ratios are sensitive to both T and κ. Best diagnostic options are
provided if a ratio involving both Fe XVII and Fe XVIII is combined
with another ratio involving lines formed within a single ion. The
sensitivity of such diagnostics to κ is typically a few tens of per
cent. Much larger sensitivity, of about a factor of two to three, can
be obtained if the Fe XVIII 93.93 Å line observed by SDO/AIA is used
in conjuction with the X-ray lines. Conclusions: We conclude
that the MaGIXS instrument is well-suited for detection of departures
from the Maxwellian distribution, especially in active region cores.

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Title: Flare-related Recurring Active Region Jets: Evidence for Very
Hot Plasma
Authors: Mulay, Sargam M.; Matthews, Sarah; Hasegawa, Takahiro;
Del Zanna, Giulio; Mason, Helen; Shimizu, Toshifumi
2018SoPh..293..160M Altcode:
We present a study of two active region jets (AR jets) that are
associated with two C-class X-ray flares. The recurrent, homologous
jets originated from the northern periphery of a sunspot. We
confirm flare-like temperatures at the footpoints of these jets using
spectroscopic observations of Fe XXIII (263.76 Å) and Fe XXIV (255.11
Å) emission lines. The emission measure loci method was used to obtain
an isothermal temperature, and the results show a decrease (17.7 to 13.6
MK) in the temperature during the decay phase of the C 3.0 flare. The
electron number densities at the footpoints were found to range from
1.7 ×1010 to 2.0 ×1011cm−3 using
the Fe XIV line pair ratio. Nonthermal velocities were found to range
from 34 - 100 km/s for Fe XXIV and 51 - 89 km/s for Fe XXIII. The
plane-of-sky velocities were calculated to be 462 ±21 and 228 ±23
km/s for the two jets using the Atmospheric Imaging Assembly (AIA)
171 Å channel. The AIA light curves of the jet footpoint regions
confirmed the temporal and spatial correlation between the two X-ray
flares and the jet footpoint emission. The Gamma-ray Burst Monitor (GBM)
also confirmed superhot plasma of 27 (25) MK with a nonthermal energy
of 2.38 ×1026 (2.87 ×1027) ergs−1
in the jet footpoint region during the rise (peak) phase of one of the
flares. The temperatures of the jet footpoint regions obtained from
EIS agree very well (within an uncertainty of 20%) with temperatures
obtained from the Geostationary Environmental Operational Satellite
(GOES) flux ratios. These results provide clear evidence for very hot
plasma (&gt;10 MK) at the footpoints of the flare-related jets, and
they confirm the heating and cooling of the plasma during the flares.

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Title: Solar UV and X-ray spectral diagnostics
Authors: Del Zanna, Giulio; Mason, Helen E.
2018LRSP...15....5D Altcode: 2018arXiv180901618D
X-ray and ultraviolet (UV) observations of the outer solar atmosphere
have been used for many decades to measure the fundamental parameters
of the solar plasma. This review focuses on the optically thin
emission from the solar atmosphere, mostly found at UV and X-ray (XUV)
wavelengths, and discusses some of the diagnostic methods that have
been used to measure electron densities, electron temperatures,
differential emission measure (DEM), and relative chemical
abundances. We mainly focus on methods and results obtained from
high-resolution spectroscopy, rather than broad-band imaging. However,
we note that the best results are often obtained by combining imaging
and spectroscopic observations. We also mainly focus the review on
measurements of electron densities and temperatures obtained from single
ion diagnostics, to avoid issues related to the ionisation state of
the plasma. We start the review with a short historical introduction
on the main XUV high-resolution spectrometers, then review the basics
of optically thin emission and the main processes that affect the
formation of a spectral line. We mainly discuss plasma in equilibrium,
but briefly mention non-equilibrium ionisation and non-thermal electron
distributions. We also summarise the status of atomic data, which
are an essential part of the diagnostic process. We then review the
methods used to measure electron densities, electron temperatures,
the DEM, and relative chemical abundances, and the results obtained
for the lower solar atmosphere (within a fraction of the solar radii),
for coronal holes, the quiet Sun, active regions and flares.

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Title: The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS)
Authors: Winebarger, A. R.; Savage, S. L.; Kobayashi, K.; Champey,
P. R.; McKenzie, D. E.; Golub, L.; Testa, P.; Reeves, K.; Cheimets,
P.; Cirtain, J. W.; Walsh, R. W.; Bradshaw, S. J.; Warren, H.; Mason,
H. E.; Del Zanna, G.
2017AGUFMSH44A..06W Altcode:
For over four decades, X-ray, EUV, and UV spectral observations have
been used to measure physical properties of the solar atmosphere. At
wavelengths below 10 nm, however, observations of the solar corona
with simultaneous spatial and spectral resolution are limited,
and not since the late 1970's have spatially resolved solar X-ray
spectra been measured. Because the soft X-ray regime is dominated
by emission lines formed at high temperatures, X-ray spectroscopic
techniques yield insights to fundamental physical processes that are
not accessible by any other means. Using a novel implementation of
corrective optics, the Marshall Grazing Incidence X-ray Spectrometer
(MaGIXS) will measure, for the first time, the solar spectrum from 0.6-
2.4 nm with a 6 arcsec resolution over an 8 arcmin slit. The MaGIXS
mission will address on of the fundamental problems of coronal physics:
the nature of coronal heating. There are several observables in the
MaGIXS wavelength range that will constrain the heating frequency and
hence discriminate between competing coronal heating theories. In this
presentation, we will present the MaGIXS scientific motivation and
provide an update on instrument development. MaGIXS will be launched
from White Sands Missile Range in the summer of 2019.

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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
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.

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Title: Cool and hot emission in a recurring active region jet
Authors: Mulay, Sargam M.; Del Zanna, Giulio; Mason, Helen
2017A&A...606A...4M Altcode:
 Aims: We present a thorough investigation of the cool and hot
temperature components in four recurring active region jets observed
on July 10, 2015 using the Atmospheric Imaging Assembly (AIA),
X-ray Telescope (XRT), and Interface Region Imaging Spectrograph
(IRIS) instruments. Methods: A differential emission measure
(DEM) analysis was performed on areas in the jet spire and footpoint
regions by combining the IRIS spectra and the AIA observations. This
procedure better constrains the low temperature DEM values by adding
IRIS spectral lines. Plasma parameters, such as Doppler velocities,
electron densities, nonthermal velocities and a filling factor
were also derived from the IRIS spectra. Results: In the
DEM analysis, significant cool emission was found in the spire and
the footpoint regions. The hot emission was peaked at log T [K] =
5.6-5.9 and 6.5 respectively. The DEM curves show the presence of
hot plasma (T = 3 MK) in the footpoint region. We confirmed this
result by estimating the Fe XVIII emission from the AIA 94 Å channel
which was formed at an effective temperature of log T [K] = 6.5. The
average XRT temperatures were also found to be in agreement with log
T [K] = 6.5. The emission measure (EM) was found to be three orders
of magnitude higher in the AIA-IRIS DEM compared with that obtained
using only AIA. The O IV (1399/1401 Å) electron densities were found
to be 2.0×1010 cm-3 in the spire and 7.6 ×
1010 cm-3 in the footpoint. Different threads
along the spire show different plane-of-sky velocities both in the
lower corona and transition region. Doppler velocities of 32 km
s-1 (blueshifted) and 13 km s-1 (redshifted)
were obtained in the spire and footpoint, respectively from the
Si IV 1402.77 Å spectral line. Nonthermal velocities of 69 and 53
km s-1 were recorded in the spire and footpoint region,
respectively. We obtained a filling factor of 0.1 in the spire at
log T [K] = 5. Conclusions: The recurrent jet observations
confirmed the presence of significant cool emission co-spatial with the
coronal emission. The movie attached to Fig. 3 is available at <A
href="http://www.aanda.org/10.1051/0004-6361/201730429/olm">http://www.aanda.org</A>

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Title: Spectroscopy of Very Hot Plasma in Non-flaring Parts of a
Solar Limb Active Region: Spatial and Temporal Properties
Authors: Parenti, Susanna; del Zanna, Giulio; Petralia, Antonino;
Reale, Fabio; Teriaca, Luca; Testa, Paola; Mason, Helen E.
2017ApJ...846...25P Altcode: 2017arXiv170708445P
In this work we investigate the thermal structure of an off-limb
active region (AR) in various non-flaring areas, as it provides key
information on the way these structures are heated. In particular,
we concentrate on the very hot component (&gt; 3 {MK}) as it is a
crucial element to distinguish between different heating mechanisms. We
present an analysis using Fe and Ca emission lines from both the
Solar Ultraviolet Measurement of Emitted Radiation (SUMER) on board
the Solar and Heliospheric Observatory (SOHO) and the EUV Imaging
Spectrometer (EIS) on board Hinode. A data set covering all ionization
stages from Fe x to Fe xix has been used for the thermal analysis
(both differential emission measure and emission measure, EM). Ca
xiv is used for the SUMER-EIS radiometric cross calibration. We show
that the very hot plasma is present and persistent almost everywhere
in the core of the limb AR. The off-limb AR is clearly structured in
Fe xviii. Almost everywhere, the EM analysis reveals plasma at 10 MK
(visible in Fe xix emission), which is down to 0.1% of EM of the main
3 {MK} plasma. We estimate the power-law index of the hot tail of
the EM to be between -8.5 and -4.4. However, the question about the
possible existence of a small minor peak at around 10 {MK} remains
open. The absence in some part of the AR of the Fe xix and Fe xxiii
lines (which fall into our spectral range) enables us to determine
an upper limit on the EM at these temperatures. Our results include
a new Ca xiv 943.59 Å atomic model.

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Title: Nonequilibrium Processes in the Solar Corona, Transition
Region, Flares, and Solar Wind (Invited Review)
Authors: Dudík, Jaroslav; Dzifčáková, Elena; Meyer-Vernet, Nicole;
Del Zanna, Giulio; Young, Peter R.; Giunta, Alessandra; Sylwester,
Barbara; Sylwester, Janusz; Oka, Mitsuo; Mason, Helen E.; Vocks,
Christian; Matteini, Lorenzo; Krucker, Säm; Williams, David R.;
Mackovjak, Šimon
2017SoPh..292..100D Altcode: 2017arXiv170603396D
We review the presence and signatures of the non-equilibrium processes,
both non-Maxwellian distributions and non-equilibrium ionization, in
the solar transition region, corona, solar wind, and flares. Basic
properties of the non-Maxwellian distributions are described
together with their influence on the heat flux as well as on the
rates of individual collisional processes and the resulting optically
thin synthetic spectra. Constraints on the presence of high-energy
electrons from observations are reviewed, including positive detection
of non-Maxwellian distributions in the solar corona, transition
region, flares, and wind. Occurrence of non-equilibrium ionization
is reviewed as well, especially in connection to hydrodynamic and
generalized collisional-radiative modeling. Predicted spectroscopic
signatures of non-equilibrium ionization depending on the assumed
plasma conditions are summarized. Finally, we discuss the future
remote-sensing instrumentation that can be used for the detection of
these non-equilibrium phenomena in various spectral ranges.

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Title: Analysis and modelling of recurrent solar flares observed
with Hinode/EIS on March 9, 2012
Authors: Polito, V.; Del Zanna, G.; Valori, G.; Pariat, E.; Mason,
H. E.; Dudík, J.; Janvier, M.
2017A&A...601A..39P Altcode: 2016arXiv161203504P
Three homologous C-class flares and one last M-class flare were observed
by both the Solar Dynamics Observatory (SDO) and the Hinode EUV Imaging
Spectrometer (EIS) in the AR 11429 on March 9, 2012. All the recurrent
flares occurred within a short interval of time (less than 4 h),
showed very similar plasma morphology and were all confined, until the
last one when a large-scale eruption occurred. The C-class flares are
characterized by the appearance, at approximatively the same locations,
of two bright and compact footpoint sources of ≈3-10 MK evaporating
plasma, and a semi-circular ribbon. During all the flares, the
continuous brightening of a spine-like hot plasma (≈10 MK) structure
is also observed. Spectroscopic observations with Hinode/EIS are used to
measure and compare the blueshift velocities in the Fe xxiii emission
line and the electron number density at the flare footpoints for each
flare. Similar velocities, of the order of 150-200 km s-1,
are observed during the C2.0 and C4.7 confined flares, in agreement
with the values reported by other authors in the study of the last M1.8
class flare. On the other hand, lower electron number densities and
temperatures tend to be observed in flares with lower peak soft X-ray
flux. In order to investigate the homologous nature of the flares, we
performed a non-linear force-free field (NLFFF) extrapolation of the 3D
magnetic field configuration in the corona. The NLFFF extrapolation and
the Quasi-Separatrix Layers (QSLs) provide the magnetic field context
which explains the location of the kernels, spine-like hot plasma and
semi-circular brightenings observed in the (non-eruptive) flares. Given
the absence of a coronal null point, we argue that the homologous
flares were all generated by the continuous recurrence of bald patch
reconnection. The movie associated to Fig. 2 is available at <A
href="http://www.aanda.org/10.1051/0004-6361/201629703/olm">http://www.aanda.org</A>

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Title: Fan Loops Observed by IRIS, EIS, and AIA
Authors: Ghosh, Avyarthana; Tripathi, Durgesh; Gupta, G. R.; Polito,
Vanessa; Mason, Helen E.; Solanki, Sami K.
2017ApJ...835..244G Altcode: 2017arXiv170101617G
A comprehensive study of the physical parameters of active region fan
loops is presented using the observations recorded with the Interface
Region Imaging Spectrometer (IRIS), the EUV Imaging Spectrometer (EIS)
on board Hinode, and the Atmospheric Imaging Assembly (AIA) and the
Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics
Observatory (SDO). The fan loops emerging from non-flaring AR 11899
(near the disk center) on 2013 November 19 are clearly discernible in
AIA 171 Å images and in those obtained in Fe viii and Si vii images
using EIS. Our measurements of electron densities reveal that the
footpoints of these loops are at an approximately constant pressure
with electron densities of {log} {N}e=10.1 cm-3 at
{log} [T/K]=5.15 (O IV), and {log} {N}e=8.9 cm-3
at {log} [T/K]=6.15 (Si x). The electron temperature diagnosed
across the fan loops by means of EM-Loci suggest that two temperature
components exist at {log} [T/K]=4.95 and 5.95 at the footpoints. These
components are picked up by IRIS lines and EIS lines, respectively. At
higher heights, the loops are nearly isothermal at {log} [T/K]=5.95,
which remained constant along the loop. The measurement of the Doppler
shift using IRIS lines suggests that the plasma at the footpoints of
these loops is predominantly redshifted by 2-3 km s-1 in C
II, 10-15 km s-1 in Si IV, and 15-20 km s-1 in O
IV, reflecting the increase in the speed of downflows with increasing
temperature from {log} [T/K]=4.40 to 5.15. These observations can
be explained by low-frequency nanoflares or impulsive heating, and
provide further important constraints on the modeling of the dynamics
of fan loops.

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Title: Temperature and density structure of a recurring active
region jet
Authors: Mulay, Sargam M.; Del Zanna, Giulio; Mason, Helen
2017A&A...598A..11M Altcode: 2016arXiv160908472M
 Aims: We present a study of a recurring jet observed on
October 31, 2011 by the Atmosphereic Imaging Assembly (AIA) on
board the Solar Dynamic Observatory, the X-ray Telescope (XRT)
and EUV Imaging Spectrometer (EIS) on board Hinode. We discuss the
physical parameters of the jet that are obtained using imaging and
spectroscopic observations, such as density, differential emission
measure, peak temperature, velocity, and filling factor. Methods:
A differential emission measure (DEM) analysis was performed at the
region of the jet spire and the footpoint using EIS observations
and also by combining AIA and XRT observations. The resulting
EIS DEM curves were compared to those obtained with AIA-XRT. The
DEM curves were used to create synthetic spectra with the CHIANTI
atomic database. The predicted total count rates for each AIA channel
were compared with the observed count rates. The effects of varying
elemental abundances and the temperature range for the DEM inversion
were investigated. Spectroscopic diagnostics were used to obtain
an electron number density distribution for the jet spire and the
jet footpoint. Results: The plasma along the line of sight
in the jet spire and jet footpoint was found to be peak at 2.0 MK
(log T [K] = 6.3). We calculated electron densities using the Fe XII
(λ186/λ195) line ratio in the region of the spire (Ne
= 7.6 × 1010 cm-3) and the footpoint (1.1
× 1011 cm-3). The plane-of-sky velocity of
the jet is found to be 524 km s-1. The resulting EIS DEM
values are in good agreement with those obtained from AIA-XRT. The
synthetic spectra contributing to each AIA channel confirms the
multi-thermal nature of the AIA channels in both regions. There is
no indication of high temperatures, such as emission from Fe XVII
(λ254.87) (log T [K] = 6.75) seen in the jet spire. In the case of
the jet footpoint, synthetic spectra predict weak contributions from
Ca XVII (λ192.85) and Fe XVII (λ254.87). With further investigation,
we confirmed emission from the Fe XVIII (93.932 Å) line in the AIA
94 Å channel in the region of the footpoint. We also found good
agreement between the estimated and predicted Fe XVIII count rates. A
study of the temporal evolution of the jet footpoint and the presence
of high-temperature emission from the Fe XVIII (λ93.932) (log T [K]
= 6.85) line leads us to conclude that the hot component in the jet
footpoint was present initially and that the jet had cooled down by the
time EIS observed it. Two movies attached to Fig. 2 are available
at <A href="http://www.aanda.org">http://www.aanda.org</A>

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Title: Can the non-Maxwellian kappa-distributions be diagnosed in
the solar corona?
Authors: Dudík, J.; Dzifcakova, E.; Del Zanna, G.; Mackovjak, Š.;
Mason, H. E.
2016AGUFMSH21D2555D Altcode:
We report on the search of signatures of the non-Maxwellian
kappa-distributions in the emission line spectra of the solar
corona. A survey of coronal lines is performed for single-ion and
multi-ion diagnostics using ions spanning the temperature range of
0.5 - 6 MK. State-of-art excitation cross-sections are integrated
directly to obtain the corresponding non-Maxwellian excitation and
deexcitation rates. Ionization and recombination rates are obtained by
approximative methods. We find that there are only a few good diagnostic
options. This is due to majority of lines being formed from similar
energy levels. The best diagnostic options rely on lines formed at
different excitation tresholds, i.e., at different wavelengths. This
highlights the importance of absolute intensity calibration of
space-borne spectrometers. The applicability of these methods is
demonstrated on analysis of a dedicated extreme-ultraviolet observations
made in the Fe XI-XIII lines by the Hinode/EIS satellite during HOP
226. The observations are performed in an active region containing a
filament and several coronal loops. A transient coronal loop appears
at the foot of a filament and is preceded by activity within this
filament. EIS spectra are used to diagnose the electron density,
but also reveal that the transient loop is highly non-Maxwellian,
characterized by a kappa=2 distribution. We discuss the methods for
separation the non-Maxwellian effects from the effects of plasma
multi-thermality arising due to finite spatial resolution, as well
as the effect of kappa-distributions on the degree of multithermality
diagnosed in various observed coronal features.

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Title: Solar Coronal Jets: Observations, Theory, and Modeling
Authors: Raouafi, N. E.; Patsourakos, S.; Pariat, E.; Young, P. R.;
Sterling, A. C.; Savcheva, A.; Shimojo, M.; Moreno-Insertis, F.;
DeVore, C. R.; Archontis, V.; Török, T.; Mason, H.; Curdt, W.;
Meyer, K.; Dalmasse, K.; Matsui, Y.
2016SSRv..201....1R Altcode: 2016arXiv160702108R; 2016SSRv..tmp...31R
Coronal jets represent important manifestations of ubiquitous solar
transients, which may be the source of significant mass and energy
input to the upper solar atmosphere and the solar wind. While
the energy involved in a jet-like event is smaller than that of
"nominal" solar flares and coronal mass ejections (CMEs), jets
share many common properties with these phenomena, in particular,
the explosive magnetically driven dynamics. Studies of jets could,
therefore, provide critical insight for understanding the larger,
more complex drivers of the solar activity. On the other side of the
size-spectrum, the study of jets could also supply important clues on
the physics of transients close or at the limit of the current spatial
resolution such as spicules. Furthermore, jet phenomena may hint to
basic process for heating the corona and accelerating the solar wind;
consequently their study gives us the opportunity to attack a broad
range of solar-heliospheric problems.

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Title: Density diagnostics derived from the O iv and S iv
intercombination lines observed by IRIS
Authors: Polito, V.; Del Zanna, G.; Dudík, J.; Mason, H. E.; Giunta,
A.; Reeves, K. K.
2016A&A...594A..64P Altcode: 2016arXiv160705072P
The intensity of the O iv 2s2 2p
2P-2s2p24P and S iv 3 s2
3p 2P-3s 3p24 P intercombination lines
around 1400 Å observed with the Interface Region Imaging Spectrograph
(IRIS) provide a useful tool to diagnose the electron number density
(Ne) in the solar transition region plasma. We measure the
electron number density in a variety of solar features observed by
IRIS, including an active region (AR) loop, plage and brightening,
and the ribbon of the 22-June-2015 M 6.5 class flare. By using the
emissivity ratios of O iv and S iv lines, we find that our observations
are consistent with the emitting plasma being near isothermal
(logT[K] ≈ 5) and iso-density (Ne ≈ 1010.6
cm-3) in the AR loop. Moreover, high electron number
densities (Ne ≈ 1013 cm-3) are
obtained during the impulsive phase of the flare by using the S iv line
ratio. We note that the S iv lines provide a higher range of density
sensitivity than the O iv lines. Finally, we investigate the effects
of high densities (Ne ≳ 1011 cm-3)
on the ionization balance. In particular, the fractional ion
abundances are found to be shifted towards lower temperatures for
high densities compared to the low density case. We also explored the
effects of a non-Maxwellian electron distribution on our diagnostic
method. The movie associated to Fig. 3 is available at <A
href="http://www.aanda.org/10.1051/0004-6361/201628965/olm">http://www.aanda.org</A>

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Title: Multiwavelength study of 20 jets that emanate from the
periphery of active regions
Authors: Mulay, Sargam M.; Tripathi, Durgesh; Del Zanna, Giulio;
Mason, Helen
2016A&A...589A..79M Altcode: 2016arXiv160200151M
 Aims: We present a multiwavelength analysis of 20 EUV jets which
occurred at the periphery of active regions close to sunspots. We
discuss the physical parameters of the jets and their relation
with other phenomena such as Hα surges, nonthermal type-III radio
bursts and hard X-ray (HXR) emission. Methods: These jets
were observed between August 2010 and June 2013 by the Atmospheric
Imaging Assembly (AIA) instrument that is onboard the Solar Dynamic
Observatory (SDO). We selected events that were observed on the solar
disk within +/-60° latitude. Using AIA wavelength channels that
are sensitive to coronal temperatures, we studied the temperature
distribution in the jets using the line of sight (LOS) differential
emission measure (DEM) technique. We also investigated the role of the
photospheric magnetic field using the LOS magnetogram data from the
Helioseismic and Magnetic Imager (HMI) onboard SDO. Results:
It has been observed that most of the jets originated from the western
periphery of active regions. Their lifetimes range from 5 to 39 min
with an average of 18 min and their velocities range from 87 to 532
km s-1 with an average of 271 km s-1. All the
jets are co-temporally associated with Hα surges. Most of the jets
are co-temporal with nonthermal type-III radio bursts observed by the
Wind/WAVES spacecraft in the frequency range from 20 kHz to 13 MHz. We
confirm the source region of these bursts using the potential field
source surface (PFSS) technique. Using Reuven Ramaty High Energy Solar
Spectroscopic Imager (RHESSI) observations, we found that half of the
jets produced HXR emission and they often shared the same source region
as the HXR emission (6-12 keV). Ten out of 20 events showed that the
jets originated in a region of flux cancellation and six jets in a
region of flux emergence. Four events showed flux emergence and then
cancellation during the jet evolution. DEM analyses showed that for
most of the spires of the jets, the DEM peaked at around log T [K] =
6.2/6.3 (~2 MK). In addition, we derived an emission measure and a lower
limit of electron density at the location of the spire (jet 1: log EM =
28.6, Ne = 1.3 × 1010 cm-3; jet 2:
log EM = 28.0, Ne = 8.6 × 109 cm-3)
and the footpoint (jet 1 - log EM = 28.6, Ne = 1.1 ×
1010 cm-3; jet 2: log EM = 28.1, Ne =
8.4 × 109 cm-3). These results are in agreement
with those obtained earlier by studying individual active region
jets. Conclusions: The observation of flux cancellation, the
association with HXR emission and emission of nonthermal type-III
radio bursts, suggest that the initiation and therefore, heating
is taking place at the base of the jet. This is also supported by
the high temperature plasma revealed by the DEM analysis in the jet
footpoint (peak in the DEM at log T [K] = 6.5). Our results provide
substantial constraints for theoretical modeling of the jets and their
thermodynamic nature. Movies are available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201527473/olm">http://www.aanda.org</A>

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Title: Slipping Magnetic Reconnection, Chromospheric Evaporation,
Implosion, and Precursors in the 2014 September 10 X1.6-Class
Solar Flare
Authors: Dudík, Jaroslav; Polito, Vanessa; Janvier, Miho; Mulay,
Sargam M.; Karlický, Marian; Aulanier, Guillaume; Del Zanna, Giulio;
Dzifčáková, Elena; Mason, Helen E.; Schmieder, Brigitte
2016ApJ...823...41D Altcode: 2016arXiv160306092D
We investigate the occurrence of slipping magnetic reconnection,
chromospheric evaporation, and coronal loop dynamics in the 2014
September 10 X-class flare. Slipping reconnection is found to be present
throughout the flare from its early phase. Flare loops are seen to slip
in opposite directions toward both ends of the ribbons. Velocities
of 20-40 km s-1 are found within time windows where the
slipping is well resolved. The warm coronal loops exhibit expanding and
contracting motions that are interpreted as displacements due to the
growing flux rope that subsequently erupts. This flux rope existed and
erupted before the onset of apparent coronal implosion. This indicates
that the energy release proceeds by slipping reconnection and not via
coronal implosion. The slipping reconnection leads to changes in the
geometry of the observed structures at the Interface Region Imaging
Spectrograph slit position, from flare loop top to the footpoints in
the ribbons. This results in variations of the observed velocities of
chromospheric evaporation in the early flare phase. Finally, it is found
that the precursor signatures, including localized EUV brightenings as
well as nonthermal X-ray emission, are signatures of the flare itself,
progressing from the early phase toward the impulsive phase, with
the tether-cutting being provided by the slipping reconnection. The
dynamics of both the flare and outlying coronal loops is found to be
consistent with the predictions of the standard solar flare model in
three dimensions.

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Title: The CHIANTI atomic database
Authors: Young, P. R.; Dere, K. P.; Landi, E.; Del Zanna, G.; Mason,
H. E.
2016JPhB...49g4009Y Altcode: 2015arXiv151205620Y
The freely available CHIANTI atomic database was first released
in 1996 and has had a huge impact on the analysis and modeling of
emissions from astrophysical plasmas. It contains data and software
for modeling optically thin atom and positive ion emission from low
density (≲1013 cm-3) plasmas from x-ray to
infrared wavelengths. A key feature is that the data are assessed
and regularly updated, with version 8 released in 2015. Atomic data
for modeling the emissivities of 246 ions and neutrals are contained
in CHIANTI, together with data for deriving the ionization fractions
of all elements up to zinc. The different types of atomic data are
summarized here and their formats discussed. Statistics on the impact
of CHIANTI to the astrophysical community are given and examples of
the diverse range of applications are presented.

---------------------------------------------------------
Title: Simultaneous IRIS and Hinode/EIS Observations and Modelling
of the 2014 October 27 X2.0 Class Flare
Authors: Polito, V.; Reep, J. W.; Reeves, K. K.; Simões, P. J. A.;
Dudík, J.; Del Zanna, G.; Mason, H. E.; Golub, L.
2016ApJ...816...89P Altcode: 2015arXiv151206378P
We present a study of the X2-class flare which occurred on 2014 October
27 and was observed with the Interface Region Imaging Spectrograph
(IRIS) and the EUV Imaging Spectrometer (EIS) on board the Hinode
satellite. Thanks to the high cadence and spatial resolution of the IRIS
and EIS instruments, we are able to compare simultaneous observations
of the Fe xxi 1354.08 Å and Fe xxiii 263.77 Å high-temperature
emission (≳10 MK) in the flare ribbon during the chromospheric
evaporation phase. We find that IRIS observes completely blueshifted
Fe xxi line profiles, up to 200 km s-1 during the rise
phase of the flare, indicating that the site of the plasma upflows is
resolved by IRIS. In contrast, the Fe xxiii line is often asymmetric,
which we interpret as being due to the lower spatial resolution of
EIS. Temperature estimates from SDO/AIA and Hinode/XRT show that hot
emission (log(T[K]) &gt; 7.2) is first concentrated at the footpoints
before filling the loops. Density-sensitive lines from IRIS and
EIS give estimates of electron number density of ≳1012
cm-3 in the transition region lines and 1010
cm-3 in the coronal lines during the impulsive phase. In
order to compare the observational results against theoretical
predictions, we have run a simulation of a flare loop undergoing
heating using the HYDRAD 1D hydro code. We find that the simulated
plasma parameters are close to the observed values that are obtained
with IRIS, Hinode, and AIA. These results support an electron beam
heating model rather than a purely thermal conduction model as the
driving mechanism for this flare.

---------------------------------------------------------
Title: On the validity of the ICFT R-matrix method: Fe XIV
Authors: Del Zanna, G.; Badnell, N. R.; Fernández-Menchero, L.;
Liang, G. Y.; Mason, H. E.; Storey, P. J.
2015MNRAS.454.2909D Altcode:
Recently, Aggarwal &amp; Keenan published a Dirac R-matrix (DARC)
calculation for the electron-impact excitation of Fe XIV. A 136-level
configuration-interaction/close-coupling (CI/CC) expansion was
adopted. Comparisons with earlier calculations, obtained by Liang
et al. with the intermediate coupling frame transformation (ICFT)
R-matrix method, showed significant discrepancies. One of the main
differences was that the Liang et al. effective collision strengths
were consistently larger. Aggarwal &amp; Keenan suggested various
possible causes for the differences. We discuss them in detail here. We
have carried out an ICFT R-matrix calculation with the same 136-level
CI/CC expansion adopted by Aggarwal &amp; Keenan, and compared the
results with theirs and with those of Liang et al., which employed a
much larger CI/CC expansion. We find that the main differences arise
because of the different CC and CI expansions, and not because of the
use of the ICFT method, as suggested by Aggarwal &amp; Keenan. The
significant increase in the effective collision strengths obtained by
Liang et al. is mainly due to the extra resonances that are present
because of the larger target expansion.

---------------------------------------------------------
Title: CHIANTI - An atomic database for emission lines. Version 8
Authors: Del Zanna, G.; Dere, K. P.; Young, P. R.; Landi, E.; Mason,
H. E.
2015A&A...582A..56D Altcode: 2015arXiv150807631D
We present version 8 of the CHIANTI database. This version includes
a large amount of new data and ions, which represent a significant
improvement in the soft X-ray, extreme UV (EUV) and UV spectral
regions, which several space missions currently cover. New data for
neutrals and low charge states are also added. The data are assessed,
but to improve the modelling of low-temperature plasma the effective
collision strengths for most of the new datasets are not spline-fitted
as previously, but are retained as calculated. This required a change
of the format of the CHIANTI electron excitation files. The format
of the energy files has also been changed. Excitation rates between
all the levels are retained for most of the new datasets, so the data
can in principle be used to model high-density plasma. In addition,
the method for computing the differential emission measure used in
the CHIANTI software has been changed.

---------------------------------------------------------
Title: Slipping reconnection and chromospheric evaporation in the
10 September 2014 flare
Authors: Dudík, Jaroslav; Janvier, Miho; Polito, Vanessa; Mulay,
Sargam; Del Zanna, Giulio; Mason, Helen; Aulanier, Guillaume
2015IAUGA..2252237D Altcode:
We study the occurrence of slipping reconnection in the long-duration
X-class flare of 2014 September 10. From the start, the flare shows
apparent slippage of hot Fe XXI flare loops observed in the 131A
channel of SDO/AIA. Using the time-distance plots, we show that the
slipping motion of the flare loops proceeds in counter directions in
both flare ribbons. Simultaneous IRIS Fe XXI observations show the
occurrence of chromospheric evaporation at brightening kernels that are
involved in the slipping reconnection of AIA loops. This happens also
during a flux-rope breakout accompanied by a faint 'magnetic implosion'
of a coronal loop. Based on the 3D MHD flare model, we argue that the
'implosion' is caused by the erupting flux rope pushing the neighbouring
loops aside, with the low-lying loops being squeezed.

---------------------------------------------------------
Title: Imaging and Spectroscopic Observations of a Transient Coronal
Loop: Evidence for the Non-Maxwellian K Distributions
Authors: Dudík, Jaroslav; Mackovjak, Šimon; Dzifčáková, Elena;
Del Zanna, Giulio; Williams, David R.; Karlický, Marian; Mason,
Helen E.; Lörinčík, Juraj; Kotrč, Pavel; Fárník, František;
Zemanová, Alena
2015ApJ...807..123D Altcode: 2015arXiv150504333D
We report on the Solar Dynamics Observatory/Atmospheric Imaging Assembly
(AIA) and Hinode/EUV Imaging Spectrograph (EIS) observations of a
transient coronal loop. The loop brightens up in the same location after
the disappearance of an arcade formed during a B8.9-class microflare
3 hr earlier. EIS captures this loop during its brightening phase,
as observed in most of the AIA filters. We use the AIA data to study
the evolution of the loop, as well as to perform the differential
emission measure (DEM) diagnostics as a function of κ. The Fe xi-Fe
xiii lines observed by EIS are used to perform the diagnostics of
electron density and subsequently the diagnostics of κ. Using ratios
involving the Fe xi 257.772 Å self-blend, we diagnose κ ≲ 2,
i.e., an extremely non-Maxwellian distribution. Using the predicted
Fe line intensities derived from the DEMs as a function of κ, we
show that, with decreasing κ, all combinations of ratios of line
intensities converge to the observed values, confirming the diagnosed
κ ≲ 2. These results represent the first positive diagnostics of
κ-distributions in the solar corona despite the limitations imposed
by calibration uncertainties.

---------------------------------------------------------
Title: Joint High Temperature Observation of a Small C6.5 Solar
Flare With Iris/Eis/Aia
Authors: Polito, V.; Reeves, K. K.; Del Zanna, G.; Golub, L.; Mason,
H. E.
2015ApJ...803...84P Altcode:
We present the observation of a C6.5 class flare on 2014 February 3,
obtained with the Interface Region Imaging Spectrograph (IRIS) and
the EUV Imaging Spectrometer (EIS) on board HINODE. We follow the
details of the impulsive phase with IRIS and the gradual decay phase
with both IRIS and EIS. The IRIS Slit-Jaw Imager and Atmospheric
Imaging Assembly (AIA) are used to precisely co-align the two sets
of spectroscopic observations. Of particular interest is the Fe xxi
1354.08 Å spectral line, which is the highest temperature emission
(∼10 MK) observed in the IRIS wavelength range. We show the evolution
of the Fe xxi profiles during the impulsive phase of the flare at the
same ribbon location with a 75 s temporal cadence. Totally blueshifted
(∼82 km {{s}-1}) profiles are found at the very early
phase of the flare and gradually decrease in about 6 minutes. This
result is consistent with 1D model predictions during chromospheric
evaporation in flares. The blueshifted components also exhibit large
non-thermal broadening, which decreases simultaneously with the
blueshifted velocity. After the evaporation first occurs, the Fe xxi
intensity progressively moves from the footpoints to the top of the
hot flare loops seen in the AIA 131 Å images, where the emission is
observed to be at rest and thermal. Emission measure estimates from
IRIS/EIS/AIA observations during the gradual phase show isothermal loop
top structures cooling from about 13.5 to 12 MK with electron densities
of the order of ∼ 5-6× {{10}10} c{{m}-3}.

---------------------------------------------------------
Title: Spectroscopic Observations of a Coronal Loop: Basic Physical
Plasma Parameters Along the Full Loop Length
Authors: Gupta, G. R.; Tripathi, Durgesh; Mason, Helen E.
2015ApJ...800..140G Altcode: 2014arXiv1412.7428G
Coronal loops are the basic structures of the solar transition
region and corona. Understanding of the physical mechanisms behind
the loop heating, plasma flows, and filling are still considered a
major challenge in solar physics. The mechanism(s) should be able
to supply mass to the corona from the chromosphere and to heat the
plasma over 1 MK within a small distance of a few hundred kilometers
from the chromosphere to the corona. This problem makes coronal loops
an interesting target for detailed study. In this study, we focus on
spectroscopic observations of a coronal loop observed in its full length
in various spectral lines as recorded by the Extreme-ultraviolet Imaging
Spectrometer on board Hinode. We derive physical plasma parameters such
as electron density, temperature, pressure, column depth, and filling
factors along the loop length from one footpoint to the another. The
obtained parameters are used to infer whether the observed coronal loop
is overdense or underdense with respect to gravitational stratification
of the solar atmosphere. These new measurements of physical plasma
parameters, from one footpoint to another, provide important constraints
on the modeling of the mass and energy balance in coronal loops.

---------------------------------------------------------
Title: The evolution of the emission measure distribution in the
core of an active region
Authors: Del Zanna, Giulio; Tripathi, Durgesh; Mason, Helen;
Subramanian, Srividya; O'Dwyer, Brendan
2015A&A...573A.104D Altcode: 2014arXiv1411.0128D
We study the spatial distribution and evolution of the slope of the
emission measure (EM) between 1 MK and 3 MK in the core of the active
region (AR) NOAA 11193, first when it appeared near the central meridian
and then again when it reappeared after a solar rotation. We use
observations recorded by the Extreme-ultraviolet Imaging Spectrometer
(EIS) aboard Hinode, with a new radiometric calibration. We also use
observations from the Atmospheric Imaging Assembly (AIA) aboard the
Solar Dynamics Observatory (SDO). We present the first spatially
resolved maps of the EM slope in the 1-3 MK range within the core
of the AR using several methods, either from approximations or from
the differential emission measure (DEM). A significant variation of
the slope is found at different spatial locations within the active
region. We selected two regions that were not greatly affected by lower
temperature emission along the line of sight. We found that the EM
had a power law of the form EM ∝ Tb, with b = 4.4 ± 0.4,
and 4.6 ± 0.4, during the first and second appearance of the active
region, respectively. During the second rotation, line-of-sight effects
become more important, although difficult to estimate. We found that
the use of the ground calibration for Hinode/EIS and the approximate
method to derive the EM, used in previous publications, produce an
underestimation of the slopes. The EM distribution in active region
cores is generally found to be consistent with high frequency heating,
and does not change much during the evolution of the active region.

---------------------------------------------------------
Title: Emission Measure Distribution for Diffuse Regions in Solar
Active Regions
Authors: Subramanian, Srividya; Tripathi, Durgesh; Klimchuk, James A.;
Mason, Helen E.
2014ApJ...795...76S Altcode: 2014arXiv1409.1447S
Our knowledge of the diffuse emission that encompasses active regions
is very limited. In this paper we investigate two off-limb active
regions, namely, AR 10939 and AR 10961, to probe the underlying heating
mechanisms. For this purpose, we have used spectral observations from
Hinode/EIS and employed the emission measure (EM) technique to obtain
the thermal structure of these diffuse regions. Our results show that
the characteristic EM distributions of the diffuse emission regions peak
at log T = 6.25 and the coolward slopes are in the range 1.4-3.3. This
suggests that both low- as well as high-frequency nanoflare heating
events are at work. Our results provide additional constraints on the
properties of these diffuse emission regions and their contribution to
the background/foreground when active region cores are observed on-disk.

---------------------------------------------------------
Title: Signatures of the non-Maxwellian κ-distributions in optically
thin line spectra. I. Theory and synthetic Fe IX-XIII spectra
Authors: Dudík, J.; Del Zanna, G.; Mason, H. E.; Dzifčáková, E.
2014A&A...570A.124D Altcode: 2014arXiv1408.0950D
 Aims: We investigate the possibility of diagnosing the degree of
departure from the Maxwellian distribution using single-ion spectra
originating in astrophysical plasmas in collisional ionization
equilibrium. Methods: New atomic data for excitation of Fe ix
- Fe xiii are integrated under the assumption of a κ-distribution
of electron energies. Diagnostic methods using lines of a single
ion formed at any wavelength are explored. Such methods minimize
uncertainties from the ionization and recombination rates, as well as
the possible presence of non-equilibrium ionization. Approximations
to the collision strengths are also investigated. Results: The
calculated intensities of most of the Fe ix - Fe xiii EUV lines show
consistent behaviour with κ at constant temperature. Intensities
of these lines decrease with κ, with the vast majority of ratios
of strong lines showing little or no sensitivity to κ. Several of
the line ratios, especially involving temperature-sensitive lines,
show a sensitivity to κ that is of the order of several tens of per
cent, or, in the case of Fe ix, up to a factor of two. Forbidden
lines in the near-ultraviolet, visible, or infrared parts of the
spectrum are an exception, with smaller intensity changes or even
a reverse behaviour with κ. The most conspicuous example is the Fe
x 6378.26 Å red line, whose intensity incerases with κ. This line
is a potentially strong indicator of departures from the Maxwellian
distribution. We find that it is possible to perform density diagnostics
independently of κ, with many Fe xi, Fe xii, and Fe xiii line ratios
showing strong density-sensitivity and negligible sensitivity to κ
and temperature. We also tested different averaging of the collision
strengths. It is found that averaging over 0.01 interval in log(E [ Ryd
]) is sufficient to produce accurate distribution-averaged collision
strengths Υ(T,κ) at temperatures of the ion formation in ionization
equilibrium. Appendices are available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201424124/olm">http://www.aanda.org</A>

---------------------------------------------------------
Title: Atomic data for astrophysics: Ni XV
Authors: Del Zanna, G.; Storey, P. J.; Mason, H. E.
2014A&A...567A..18D Altcode:
We present the first R-matrix scattering calculation for electron
collisional excitation of Ni xv. The large-scale target includes
configurations up to n = 4. The calculations were carried out using
the intermediate-coupling frame transformation method. Significant
enhancements in the collision strengths, compared to previous
distorted-wave (DW) calculations, are found for several cases,
in particular the forbidden lines within the ground configuration
and the 3s2 3p 4s levels. We provide a complete set
of rates and a list of strongest lines that are observable in
astrophysical plasmas. Previous identifications are reviewed, and
a few new ones suggested. The new data can be used to accurately
measure electron densities for high-temperature (3 MK) plasmas, and
the nickel abundance. The full dataset (energies, transition
probabilities and rates) is available from our APAP website <A
href="http://www.apap-network.org">http://www.apap-network.org</A>,
and also at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/567/A18">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/567/A18</A>

---------------------------------------------------------
Title: VizieR Online Data Catalog: Ni XV electron collisional
excitation (Del Zanna+, 2014)
Authors: Del Zanna, G.; Storey, P. J.; Mason, H. E.
2014yCat..35670018D Altcode: 2014yCat..35679018D
We present the first R-matrix scattering calculation for electron
collisional excitation of NiXV. The large-scale target includes
configurations up to n=4. The calculations were carried out using the
intermediate-coupling frame transformation method (ICFT). Significant
enhancements in the collision strengths, compared to previous
distorted wave (DW) calculations, are found for several cases, in
particular the forbidden lines within the ground configuration and
the 3s2 3p 4s levels. We provide a complete set of rates
and a list of strongest lines that are observable in astrophysical
plasmas. Previous identifications are reviewed, and a few new ones
suggested. The new data can be used to accurately measure electron
densities for high-temperature (3MK) plasmas, and the nickel
abundance. (2 data files).

---------------------------------------------------------
Title: Atomic data for astrophysics: Fe IX
Authors: Del Zanna, G.; Storey, P. J.; Badnell, N. R.; Mason, H. E.
2014A&A...565A..77D Altcode:
We present the results of a new large-scale intermediate-coupling frame
transformation R-matrix scattering calculation for electron collisional
excitation of Fe ix. The target includes all the main configurations
up to n = 5, to improve our earlier R-matrix and distorted-wave (DW)
calculations for the n = 3,4 levels. Unlike similar calculations
which we carried out for the other coronal iron ions, in this case the
larger target does not significantly affect the collision strengths
of the strongest transitions to the n = 3,4 levels. Some differences
are however present for a few transitions, in particular for the 3d-4p
line at 197.86 Å. For the weaker transitions, significant enhancements
due to extra resonances resulting from this much bigger target are
found. Several new line identifications are suggested. We find excellent
agreement between predicted and observed line intensities in the EUV
(Hinode EIS) showing that Fe ix lines provide a reliable temperature
diagnostic. We also show that the visible forbidden lines are a good
diagnostic to measure electron densities. The full dataset
(energies, transition probabilities and rates) are also available
in electronic form at the APAP website (www.apap-network.org)
and are only available at the CDS via anonymous ftp to <A
href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/565/A77">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/565/A77</A>

---------------------------------------------------------
Title: Elemental abundances and temperatures of quiescent solar
active region cores from X-ray observations
Authors: Del Zanna, G.; Mason, H. E.
2014A&A...565A..14D Altcode:
A brief review of studies of elemental abundances and emission measures
in quiescent solar active region cores is presented. Hinode EUV Imaging
Spectrometer (EIS) observations of strong iron spectral lines have
shown sharply peaked distributions around 3 MK. EIS observations of
lines emitted by a range of elements have allowed good estimates of
abundances relative to iron. However, X-ray observations are required
to measure the plasma emission above 3 MK and the abundances of
oxygen and neon. We revisit, using up-to-date atomic data, older
X-ray observations obtained by a sounding rocket and by the Solar
Maximum Mission (SMM) Flat Crystal Spectrometer (FCS). We find that
the Fe/O and Fe/Ne ratios are normally increased by a factor of 3.2,
compared to the photospheric values. Similar results are obtained
from FCS observations of six quiescent active region cores. The FCS
observations also indicate that the emission measure above 3 MK has
a very steep negative slope, with very little plasma observed at 5
MK or above. Appendix A is available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201423471/olm">http://www.aanda.org</A>

---------------------------------------------------------
Title: Slipping Magnetic Reconnection during an X-class Solar Flare
Observed by SDO/AIA
Authors: Dudík, J.; Janvier, M.; Aulanier, G.; Del Zanna, G.;
Karlický, M.; Mason, H. E.; Schmieder, B.
2014ApJ...784..144D Altcode: 2014arXiv1401.7529D
We present SDO/AIA observations of an eruptive X-class flare of
2012 July 12, and compare its evolution with the predictions of a
three-dimensional (3D) numerical simulation. We focus on the dynamics of
flare loops that are seen to undergo slipping reconnection during the
flare. In the Atmospheric Imaging Assembly (AIA) 131 Å observations,
lower parts of 10 MK flare loops exhibit an apparent motion with
velocities of several tens of km s-1 along the developing
flare ribbons. In the early stages of the flare, flare ribbons consist
of compact, localized bright transition-region emission from the
footpoints of the flare loops. A differential emission measure analysis
shows that the flare loops have temperatures up to the formation of
Fe XXIV. A series of very long, S-shaped loops erupt, leading to a
coronal mass ejection observed by STEREO. The observed dynamics are
compared with the evolution of magnetic structures in the "standard
solar flare model in 3D." This model matches the observations well,
reproducing the apparently slipping flare loops, S-shaped erupting
loops, and the evolution of flare ribbons. All of these processes are
explained via 3D reconnection mechanisms resulting from the expansion
of a torus-unstable flux rope. The AIA observations and the numerical
model are complemented by radio observations showing a noise storm
in the metric range. Dm-drifting pulsation structures occurring
during the eruption indicate plasmoid ejection and enhancement of the
reconnection rate. The bursty nature of radio emission shows that the
slipping reconnection is still intermittent, although it is observed
to persist for more than an hour.

---------------------------------------------------------
Title: VizieR Online Data Catalog: Atomic data for FeIX (Del Zanna+,
2014)
Authors: Del Zanna, G.; Storey, P. J.; Badnell, N. R.; Mason, H. E.
2014yCat..35650077D Altcode: 2014yCat..35659077D
We present the results of a new large-scale intermediate-coupling frame
transformation R-matrix scattering calculation for electron collisional
excitation of Fe IX. The target includes all the main configurations
up to n=5, to improve our earlier R-matrix and distorted-wave (DW)
calculations for the n=3,4 levels. Unlike similar calculations which
we carried out for the other coronal iron ions, in this case the
larger target does not significantly affect the collision strengths
of the strongest transitions to the n=3,4 levels. Some differences
are however present for a few transitions, in particular for the 3d-4p
line at 197.86Å. For the weaker transitions, significant enhancements
due to extra resonances resulting from this much bigger target are
found. Several new line identifications are suggested. We find excellent
agreement between predicted and observed line intensities in the EUV
(Hinode EIS) showing that Fe IX lines provide a reliable temperature
diagnostic. We also show that the visible forbidden lines are a good
diagnostic to measure electron densities. (2 data files).

---------------------------------------------------------
Title: Diagnostics for the O IV and Si IV lines observed by IRIS
Authors: Dudik, Jaroslav; Mason, Helen; Del Zanna, Giulio; Golub,
Leon; Dzifcakova, Elena
2014cosp...40E.754D Altcode:
We investigate the formation of the IRIS O IV and Si IV lines under
non-Maxwellian conditions characterized by kappa-distributions. It is
found that the Si IV lines are always formed at lower temperatures
than the O IV lines. However, as the departure from the Maxwellian
increases, the peak formation temperatures are shifted progressively to
lower and lower temperatures. Coupled with the slope of the differential
emission measure (DEM), it is possible for the Si IV lines to be formed
very close to the solar chromosphere, with the majority of the O IV
intensities coming from a different, higher part of the transition
region. The predicted spectra for kappa-distributions exhibit very low O
IV intensities compared to Si IV, analogously to what is observed by the
IRIS spacecraft. Potential density diagnostics are discussed, as well
as the contribution of photoexcitation to the formation of these lines.

---------------------------------------------------------
Title: Chromospheric evaporation in recurrent flares
Authors: Polito, V.; Mason, Helen; Del Zanna, Giulio; Dudik, Jaroslav
2014cosp...40E2581P Altcode:
We present high-cadence (3 minutes) Hinode/EIS observations of small
recurrent flares and provide densities and velocities of the upflowing
plasma in the locations of the chromospheric evaporation. Lines formed
in the 2-10 MK range have significant blueshifts, of the order of
50 km/s or more. This upflowing plasma is the source of the 10 MK
plasma that emits strongly in EUV and X-ray lines after the impulsive
phases. We use the high-cadence and high-resolution SDO/AIA images
to describe the locations of the upflows, and magnetograms to locate
the ribbons. One interesting feature is that the recurrent flares are
confined, until the last one when a large-scale eruption occurs.

---------------------------------------------------------
Title: Response of Hinode XRT to quiet Sun, active region and
flare plasma
Authors: O'Dwyer, B.; Del Zanna, G.; Mason, H. E.
2014A&A...561A..20O Altcode:
 Aims: We examine the response of the Hinode X-Ray
Telescope (XRT), using simultaneous observations with the Hinode
Extreme-ultraviolet Imaging Spectrometer (EIS), for a flare, an active
region and a quiet Sun region. We also examine the relative intensity
calibration of EIS and XRT. Methods: EIS differential emission
measure distribution (DEM) curves were used to create synthetic spectra
with the CHIANTI atomic database. The contribution of spectral lines
and continuum emission to each of the XRT channels was determined from
the synthetic spectra, which were then convolved with the effective
area of each XRT channel. The predicted total count rates for each
channel were compared with the observed count rates. The effects
of varying elemental abundances and the temperature range for the
inversion were investigated. DEMs obtained from the XRT bands were
also computed and compared to those obtained with EIS. Results:
For the active region observations, the observed XRT count rates for
most of the channels are in reasonable agreement with those predicted
using EIS observations, but are dependent on the elemental abundances
chosen. Significant discrepancies between predicted and observed count
rates were found and are discussed for the adjacent quiet Sun region
and also for the flare. Synthetic spectra and continuum emission
contributing to the XRT channels are presented and discussed for the
active region, quiet Sun and flare observations.

---------------------------------------------------------
Title: Solar Transition Region Lines Observed by the Interface Region
Imaging Spectrograph: Diagnostics for the O IV and Si IV Lines
Authors: Dudík, J.; Del Zanna, G.; Dzifčáková, E.; Mason, H. E.;
Golub, L.
2014ApJ...780L..12D Altcode: 2013arXiv1311.6978D
The formation of the transition region O IV and Si IV lines observable
by the Interface Region Imaging Spectrograph (IRIS) is investigated
for both Maxwellian and non-Maxwellian conditions characterized by
a κ-distribution exhibiting a high-energy tail. The Si IV lines
are formed at lower temperatures than the O IV lines for all κ. In
non-Maxwellian situations with lower κ, the contribution functions
are shifted to lower temperatures. Combined with the slope of the
differential emission measure, it is possible for the Si IV lines to be
formed at very different regions of the solar transition region than the
O IV lines; possibly close to the solar chromosphere. Such situations
might be discernible by IRIS. It is found that photoexcitation can be
important for the Si IV lines, but is negligible for the O IV lines. The
usefulness of the O IV ratios for density diagnostics independently of
κ is investigated and it is found that the O IV 1404.78 Å/1399.77
Å ratio provides a good density diagnostics except for very low T
combined with extreme non-Maxwellian situations.

---------------------------------------------------------
Title: A Collaborative FP7 Effort towards the First European
Comprehensive SOLar Irradiance Data Exploitation (SOLID)
Authors: Haberreiter, Margit; Dasi, Maria; Delouille, Veronique; Del
Zanna, Giulio; Dudok de Wit, Thierry; Ermolli, Ilaria; Kretzschmar,
Matthieu; Krivova, Natalie; Mason, Helen; Qahwaji, Rami; Schmutz,
Werner; Solanki, Sami; Thuillier, Gerard; Tourpali, Kleareti; Unruh,
Yvonne; Verbeeck, Cis; Weber, Mark; Woods, Tom
2013EGUGA..1513079H Altcode:
Variations of solar irradiance are the most important natural factor
in the terrestrial climate and as such, the time dependent spectral
solar irradiance is a crucial input to any climate modelling. There
have been previous efforts to compile solar irradiance but it is
still uncertain by how much the spectral and total solar irradiance
changed on yearly, decadal and longer time scales. Observations of
irradiance data exist in numerous disperse data sets. Therefore, it
is important to bring together the European expertise in the field
to analyse and merge the complete set of European irradiance data,
complemented by archive data that include data from non-European
missions. We report on the initiation of a collaborative effort to unify
representatives from all European solar space experiments and European
teams specialized in multi-wavelength solar image processing. It is
intended to include the European groups involved in irradiance modelling
and reconstruction. They will work with two different state of the art
approaches to produce reconstructed spectral and total solar irradiance
data as a function of time. These results will be used to bridge
gaps in time and wavelength coverage of the observational data. This
will allow the proposing SOLID team to reduce the uncertainties in
the irradiance time series - an important requirement by the climate
community - and to provide uniform data sets of modelled and observed
solar irradiance data from the beginning of the space era to the
present including proper error and uncertainty estimates. Climate
research needs these data sets and therefore, the primary benefit
is for the climate community, but the stellar community, planetary,
lunar, and ionospheric researchers are also interested in having at
their disposition incident radiation of the Sun. The proposing team
plans to realize a wide international synergy in solar physics from
7 European countries, and collaborators from the US, complemented by
representatives from the climate community, who will accompany their
research work with wide dissemination activities.

---------------------------------------------------------
Title: Doppler Shifts in Active Region Moss Using SOHO/SUMER
Authors: Winebarger, Amy; Tripathi, Durgesh; Mason, Helen E.; Del
Zanna, Giulio
2013ApJ...767..107W Altcode:
The velocity of the plasma at the footpoint of hot loops in active
region cores can be used to discriminate between different heating
frequencies. Velocities on the order of a few kilometers per second
would indicate low-frequency heating on sub-resolution strands,
while velocities close to zero would indicate high-frequency (steady)
heating. To discriminate between these two values requires accurate
velocity measurements; previous velocity measurements suffer from
large uncertainties, mainly due to the lack of an absolute wavelength
reference scale. In this paper, we determine the velocity in the loop
footpoints using observations from Solar Ultraviolet Measurements of
Emitted Radiation (SUMER) on Solar and Heliospheric Observatory. We
use neutral spectral lines to determine the wavelength scale of the
observations with an uncertainty in the absolute velocity of &lt;3.5 km
s-1 and co-aligned Transition Region and Coronal Explorer
(TRACE) images to identify footpoint regions. We studied three
different active regions and found average redshifts in the Ne VIII
770 Å emission line (formed at 6 × 105 K) of 5.17 ± 5.37
km s-1 and average redshifts in the C IV 1548 and 1550 Å
emission lines (formed at 1 × 105 K) of 13.94 ± 4.93 km
s-1 and 14.91 ± 6.09 km s-1, respectively. We
find no correlation between the brightness in the spectral line and
the measured velocity, nor do we find correlation between the Ne VIII
and C IV velocities measured co-spatially and co-temporally. SUMER
scanned two of the active regions twice; in those active regions we
find positive correlation between the co-spatial velocities measured
during the first and second scans. These results provide definitive
and quantitative measurements for comparisons with simulations of
different coronal heating mechanisms.

---------------------------------------------------------
Title: CHIANTI 7.1: a new database release for SDO data analysis
Authors: Young, P. R.; Landi, E.; Del Zanna, G.; Dere, K. P.; Mason,
H. E.
2013enss.confE..58Y Altcode:
Version 7.1 of the CHIANTI atomic database was released in October 2012
and contains a number of improvements to better model data returned by
the AIA and EVE instruments on board SDO. Specifically the models for
the important iron ions Fe VIII to Fe XIV have been greatly expanded,
yielding many thousands of new transitions in the 50-170 angstrom
range that enable the irradiance spectra obtained by EVE to be modeled
more accurately. A lack of available atomic data meant that the AIA 94
angstrom channel was not well modeled at low temperatures in earlier
versions of CHIANTI. New data for Fe VIII, Fe X and Fe XIV added to
CHIANTI 7.1 give important contributions to the channel and greatly
improve comparisons with theory.

---------------------------------------------------------
Title: CHIANTI—An Atomic Database for Emission Lines. XIII. Soft
X-Ray Improvements and Other Changes
Authors: Landi, E.; Young, P. R.; Dere, K. P.; Del Zanna, G.; Mason,
H. E.
2013ApJ...763...86L Altcode:
The CHIANTI spectral code consists of two parts: an atomic database
and a suite of computer programs in Python and IDL. Together, they
allow the calculation of the optically thin spectrum of astrophysical
objects and provide spectroscopic plasma diagnostics for the analysis
of astrophysical spectra. The database includes atomic energy levels,
wavelengths, radiative transition probabilities, collision excitation
rate coefficients, ionization, and recombination rate coefficients,
as well as data to calculate free-free, free-bound, and two-photon
continuum emission. Version 7.1 has been released, which includes
improved data for several ions, recombination rates, and element
abundances. In particular, it provides a large expansion of the
CHIANTI models for key Fe ions from Fe VIII to Fe XIV to improve the
predicted emission in the 50-170 Å wavelength range. All data and
programs are freely available at http://www.chiantidatabase.org and
in SolarSoft, while the Python interface to CHIANTI can be found at
http://chiantipy.sourceforge.net.

---------------------------------------------------------
Title: The Sun as a Star
Authors: Del Zanna, Giulio; Mason, Helen
2013pss4.book...87D Altcode:
In this chapter we provide an overview of various observational and
theoreticalaspects about the Sun, paying more attention to global ones,
i.e., to thosewhere the Sun is considered as a star, so they can be
more or less directlyrelated to those studied for other stars. The
emphasis is on the processes bywhich energy is transferred to the
solar atmosphere and then flows fromthe Sun in the form of radiation
and particles. The chapter starts withan historical introduction,
and then discusses various subjects, startingwith a brief description
of the photosphere, the chromosphere, and thetransition region of
the Sun. The interior of the Sun is then introduced,with the standard
model and solar neutrinos, and with the observationsand theory of solar
oscillations. We present some important results fromhelioseismology,
and briefly discuss the problematics involved with theproduction and
regeneration of the solar magnetic fields during a solarcycle.

---------------------------------------------------------
Title: The spectroscopy of the dynamic Sun
Authors: Mason, Helen; Baker, Deb
2012A&G....53f..29M Altcode:
MEETING REPORT Helen Mason and Deb Baker celebrate the collaboration
between George Doschek and Tetsuya Watanabe that has uncovered so much
about the Sun's behaviour.

---------------------------------------------------------
Title: SDO AIA and EVE observations and modelling of solar flare loops
Authors: Petkaki, P.; Del Zanna, G.; Mason, H. E.; Bradshaw, S. J.
2012A&A...547A..25P Altcode:
We present imaging and spectroscopic observations of an isolated
C1-class solar flare, obtained with the Atmospheric Imaging Assembly
(AIA) and Extreme ultraviolet Variability Experiment (EVE) on the Solar
Dynamics Observatory (SDO). We obtain excellent agreement between the
peak flare temperatures estimated using the EVE spectra with those
obtained from GOES and, most importantly, from the ratio of the 94
Å and 131 Å AIA channels, which are found to be dominated by Fe
xviii and Fe xxi. These results confirm that these two AIA bands can
be reliably used to provide temperature diagnostics for the peak and
gradual phases of solar flares. The flare kernels, probable sources
of chromospheric evaporation, are seen as strong localised emission
in the AIA bands at the footpoints of flare loops. The flare loops
are close to isothermal during the gradual phase. We have run several
hydrodynamic simulations (using the HYDRAD code) to study the cooling
of the flare loops. We find good overall agreement between observed and
predicted electron temperatures and densities when a gradual increase
and decrease of the heating is assumed.

---------------------------------------------------------
Title: Atomic data for astrophysics: Fe xii soft X-ray lines
Authors: Del Zanna, G.; Storey, P. J.; Badnell, N. R.; Mason, H. E.
2012A&A...543A.139D Altcode:
We present new large-scale R-matrix (up to n = 4) and distorted-wave
(DW, up to n = 6) scattering calculations for electron collisional
excitation of Fe xii. The first aim is to provide accurate atomic data
for the soft X-rays, where strong decays from the n = 4 levels are
present. As found in previous work on Fe x, resonances attached to n =
4 levels increase the cross-sections for excitations from the ground
state to some n = 4 levels, when compared to DW calculations. Cascading
from higher levels is also important. We provide a number of models and
line intensities, and list a number of strong unidentified lines. The
second aim is to assess the effects of the large R-matrix calculation
on the n = 3 transitions. Compared to our previous (n = 3) R-matrix
calculation, we find overall excellent agreement to within a few
percent, however a few key density diagnostic EUV intensities differ
by about 60% at coronal densities. The new atomic data result in
lower electron densities, resolving previous discrepancies with solar
observations. The full dataset (energies, transition probabilities
and rates) are available in electronic form at our APAP website (<A
href="http://www.apap-network.org">http://www.apap-network.org</A>)
as well as at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/543/A139">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/543/A139</A>

---------------------------------------------------------
Title: Active Region Moss: Doppler Shifts from
Hinode/Extreme-ultraviolet Imaging Spectrometer Observations
Authors: Tripathi, Durgesh; Mason, Helen E.; Klimchuk, James A.
2012ApJ...753...37T Altcode: 2012arXiv1204.6550T
Studying the Doppler shifts and the temperature dependence of Doppler
shifts in moss regions can help us understand the heating processes
in the core of the active regions. In this paper, we have used an
active region observation recorded by the Extreme-ultraviolet Imaging
Spectrometer (EIS) on board Hinode on 2007 December 12 to measure the
Doppler shifts in the moss regions. We have distinguished the moss
regions from the rest of the active region by defining a low-density
cutoff as derived by Tripathi et al. in 2010. We have carried out a
very careful analysis of the EIS wavelength calibration based on the
method described by Young et al. in 2012. For spectral lines having
maximum sensitivity between log T = 5.85 and log T = 6.25 K, we find
that the velocity distribution peaks at around 0 km s-1
with an estimated error of 4-5 km s-1. The width of the
distribution decreases with temperature. The mean of the distribution
shows a blueshift which increases with increasing temperature and the
distribution also shows asymmetries toward blueshift. Comparing these
results with observables predicted from different coronal heating
models, we find that these results are consistent with both steady
and impulsive heating scenarios. However, the fact that there are a
significant number of pixels showing velocity amplitudes that exceed
the uncertainty of 5 km s-1 is suggestive of impulsive
heating. Clearly, further observational constraints are needed to
distinguish between these two heating scenarios.

---------------------------------------------------------
Title: VizieR Online Data Catalog: Fe XII soft X-ray lines (Del
Zanna+, 2012)
Authors: Del Zanna, G.; Storey, P. J.; Badnell, N. R.; Mason, H. E.
2012yCat..35430139D Altcode: 2012yCat..35439139D
We present new large-scale R-matrix (up to n=4) and distorted-wave (DW,
up to n=6) scattering calculations for electron collisional excitation
of Fe XII. The first aim is to provide accurate atomic data for the soft
X-rays, where strong decays from the n=4 levels are present. As found
in previous work on Fe X, resonances attached to n=4 levels increase the
cross-sections for excitations from the ground state to some n=4 levels,
when compared to DW calculations. Cascading from higher levels is also
important. We provide a number of models and line intensities,
and list a number of strong unidentified lines. The second aim
is to assess the effects of the large R-matrix calculation on the n=3
transitions. Compared to our previous (n=3) R-matrix calculation, we
find overall excellent agreement to within a few percent, however a few
key density diagnostic EUV intensities differ by about 60% at coronal
densities. The new atomic data result in lower electron densities,
resolving previous discrepancies with solar observations. (5
data files).

---------------------------------------------------------
Title: Observations of Plasma Upflow in a Warm Loop with Hinode/EIS
Authors: Tripathi, Durgesh; Mason, Helen E.; Del Zanna, Giulio;
Bradshaw, Steven
2012ApJ...754L...4T Altcode: 2012arXiv1206.3367T
A complete understanding of Doppler shift in active region loops can
help probe the basic physical mechanism involved into the heating
of those loops. Here, we present observations of upflows in coronal
loops detected in a range of temperatures (log T = 5.8-6.2). The loop
was not discernible above these temperatures. The speed of upflow
was strongest at the footpoint and decreased with height. The upflow
speed at the footpoint was about 20 km s-1 in Fe VIII, which
decreased with temperature, being about 13 km s-1 in Fe X,
about 8 km s-1 in Fe XII, and about 4 km s-1 in
Fe XIII. To the best of our knowledge, this is the first observation
providing evidence of upflow of plasma in coronal loop structures at
these temperatures. We interpret these observations as evidence of
chromospheric evaporation in quasi-static coronal loops.

---------------------------------------------------------
Title: VizieR Online Data Catalog: FeX soft X-ray lines (Del Zanna+,
2012)
Authors: Del Zanna, G.; Storey, P. J.; Badnell, N. R.; Mason, H. E.
2012yCat..35410090D Altcode: 2012yCat..35419090D
New atomic calculations for Fe X are presented. They focus on the need
to model the soft X-ray spectrum and in particular the line at 94.0Å
which is the dominant contribution to the Solar Dynamics Observatory
(SDO) Atmospheric Imaging Assembly (AIA) 94Å band in quiet Sun
conditions. This line, and others in the band, are due to strong
decays from n=4 levels. We present new large-scale R-matrix (up to
n=4) and distorted-wave (DW, up to n=6) scattering calculations for
electron collisional excitation and compare them to earlier work. We
find significant discrepancies with previous calculations. We show that
resonances significantly increase the cross-sections for excitations
from the ground state to some n=4 levels, in particular to those in
the 3s2 3p4 4s configuration. Cascading from
higher levels is also important. We suggest a new identification for
the 3s 3p6 2S1/2 - 3s 3p5
4s 2P3/2 transition, that has a predicted
intensity larger than the decays from the 3s2 3p4
4s levels which were identified by Edlen in 1936. The results presented
here are relevant to our understanding of transitions from n=4 levels
in a wide range of other ions. (5 data files).

---------------------------------------------------------
Title: Cross-Calibration of Hinode/EIS and SDO/AIA
Authors: O'Dwyer, B.; Zanna, G. D.; Mason, H. E.; Weber, M. A.;
Tripathi, D.
2012ASPC..455..369O Altcode:
We examine the contribution of spectral lines and continuum emission
to the EUV channels of the Atmospheric Imaging Assembly (AIA) on
the Solar Dynamics Observatory (SDO) in different regions of the
solar atmosphere (coronal hole, quiet Sun, active region, and flare
plasma). We highlight the contribution of particular spectral lines
which under certain conditions can affect the interpretation of SDO
AIA data. In addition we use simultaneous observations from the Hinode
Extreme-ultraviolet Imaging Spectrometer (EIS) and SDO/AIA to examine
their relative intensity calibration. Good agreement is found between
the two instruments for an active region observation.

---------------------------------------------------------
Title: Hinode Observations and Modeling of Small Flares
Authors: Zanna, G. D.; Mitra-Kraev, U.; Bradshaw, S. J.; Mason, H. E.;
Asai, A.
2012ASPC..455..295Z Altcode:
We present Hinode observations of a small B-class flare which occurred
on May 22, 2007, supplemented with X-ray, EUV, and radio data. We
found new signatures of chromospheric evaporation, strong (up to 170 km
s-1) blue-shifted emission in lines formed around 2-3 MK,
in a very narrow layer at the footpoints of a 10 MK flare loop. We
have found good agreement between the observed properties and those
predicted by a HYDRAD non-equilibrium hydrodynamic numerical simulation.

---------------------------------------------------------
Title: Atomic data for astrophysics: Fe x soft X-ray lines
Authors: Del Zanna, G.; Storey, P. J.; Badnell, N. R.; Mason, H. E.
2012A&A...541A..90D Altcode:
New atomic calculations for Fe x are presented. They focus on the need
to model the soft X-ray spectrum and in particular the line at 94.0 Å
which is the dominant contribution to the Solar Dynamics Observatory
(SDO) Atmospheric Imaging Assembly (AIA) 94 Å band in quiet Sun
conditions. This line, and others in the band, are due to strong decays
from n = 4 levels. We present new large-scale R-matrix (up to n =
4) and distorted-wave (DW, up to n = 6) scattering calculations for
electron collisional excitation and compare them to earlier work. We
find significant discrepancies with previous calculations. We show that
resonances significantly increase the cross-sections for excitations
from the ground state to some n = 4 levels, in particular to those
in the 3s2 3p4 4s configuration. Cascading from
higher levels is also important. We suggest a new identification for
the 3s 3p62S1/2-3s 3p5 4s
2P3/2 transition, that has a predicted intensity
larger than the decays from the 3s2 3p4 4s levels
which were identified by Edlén in 1936. The results presented here
are relevant to our understanding of transitions from n = 4 levels in a
wide range of other ions. The full dataset (energies, transition
probabilities and rates) are available in electronic form at our APAP
website (<A href="http://www.apap-network.org">www.apap-network.org</A>)
as well as at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/541/A90">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/541/A90</A>

---------------------------------------------------------
Title: Understanding Coronal Heating with Emission Measure
Distributions
Authors: Klimchuk, James A.; Tripathi, D.; Bradshaw, S. J.; Mason,
H. E.
2012AAS...22042302K Altcode:
It is widely believed that the cross-field spatial scale of coronal
heating is small, so that the fundamental plasma structures
(loop strands) are spatially unresolved. We therefore must
appeal to diagnostic techniques that are not strongly affected by
spatial averaging. One valuable observable is the emission measure
distribution, EM(T), which indicates how much material is present
at each temperature. Using data from the Extreme-ultraviolet Imaging
Spectrograph on the Hinode mission, we have determined emission measure
distributions in the cores of two active regions. The distributions have
power law slopes of approximately 2.4 coolward of the peak. We compare
these slopes, as well as the amount of emission measure at very high
temperature, with the predictions of a series of models. The models
assume impulsive heating (nanoflares) in unresolved strands and take
full account of nonequilibrium ionization.

---------------------------------------------------------
Title: VizieR Online Data Catalog: Atomic data for X-ray lines of
FeVIII and FeIX (O'Dwyer+, 2012)
Authors: O'Dwyer, B.; Del Zanna, G.; Badnell, N. R.; Mason, H. E.;
Storey, P. J.
2012yCat..35370022O Altcode: 2012yCat..35379022O
The distorted wave extension of the autostructure code has been used
to calculate energy levels, radiative transition probabilities and
collisional excitation rates of Fe VIII and Fe IX up to n=6 for Fe IX
and n=7 for Fe VIII. We have compared some of the data with previous
calculations, finding overall agreement for radiative transition
rates, but interesting differences for some collisional data. **************************************************************************
* * * Sorry, but the author(s) never supplied the
tabular material * * announced in the paper * * *
**************************************************************************

---------------------------------------------------------
Title: Spectroscopic Diagnostics and Heating of Active Region Cores
Authors: Tripathi, D.; Mason, H. E.; Klimchuk, J. A.
2012decs.confE..92T Altcode:
It is widely believed that we are still far from spatially resolving
the fundamental plasma structures in solar corona. Therefore,
we must use spectroscopic diagnostic techniques such as emission
measure distribution (EM(T)) and Doppler shifts that are not affected
by spatial averaging. Using observations recorded by the Extreme
ultraviolet Imaging Spectrometer we have studies emission measure (EM)
distribution and Doppler shift in the moss and inter-moss regions. The
EM distributions obtained for moss regions cab be reproduced by
considering strong coronal condensation scenario suggesting bulk
downflow of the plasma. Doppler shift measurements for the moss regions
show that almost all the moss regions are red-shifted with velocities
up to 15km/s with mean velocity of 5 km/s. However, the uncertainty
on the Doppler shift was large. The EM distributions obtained for
inter-moss regions have power law slopes of approximately 2.4 coolward
of the peak. We compare the EM for inter-moss region with that obtained
from nanoflare model using EBTEL (Enthalpy-Based Thermal Evolution of
Loops). Our results suggest that the EM distribution for both the moss
as well as inter-moss regions and Doppler shift in the moss regions can
be explained by nanoflare heating. IRIS will provide a better account
of the Doppler shift in the moss regions, which will dramatically
enhance our understanding of the heating of active region core.

---------------------------------------------------------
Title: Spectroscopic Diagnostics with IRIS
Authors: Mason, H. E.; Del Zanna, G.
2012decs.confE..47M Altcode:
This talk will review the spectroscopic diagnostics available in the
IRIS wavelength bands, built on the previous heritage of observations
in the 1330-1410A wavelength band. Consideration will be given to the
accuracy of available atomic data in CHIANTI and the relevant atomic
processes. Ways in which the IRIS data could be used to complement
observations from other observatories (SDO and Hinode) will be explored
with a view to probing the energy transport and dissipation in the
solar atmosphere.

---------------------------------------------------------
Title: CHIANTI—An Atomic Database for Emission Lines. XII. Version
7 of the Database
Authors: Landi, E.; Del Zanna, G.; Young, P. R.; Dere, K. P.; Mason,
H. E.
2012ApJ...744...99L Altcode:
The CHIANTI spectral code consists of an atomic database and
a suite of computer programs to calculate the optically thin
spectrum of astrophysical objects and carry out spectroscopic plasma
diagnostics. The database includes atomic energy levels, wavelengths,
radiative transition probabilities, collision excitation rate
coefficients, and ionization and recombination rate coefficients,
as well as data to calculate free-free, free-bound, and two-photon
continuum emission. Version 7 has been released, which includes
several new ions, significant updates to existing ions, as well as
Chianti-Py, the implementation of CHIANTI software in the Python
programming language. All data and programs are freely available at
http://www.chiantidatabase.org, while the Python interface to CHIANTI
can be found at http://chiantipy.sourceforge.net.

---------------------------------------------------------
Title: Velocity Measurements for a Solar Active Region Fan Loop from
Hinode/EIS Observations
Authors: Young, P. R.; O'Dwyer, B.; Mason, H. E.
2012ApJ...744...14Y Altcode: 2011arXiv1107.2362Y
The velocity pattern of a fan loop structure within a solar active
region over the temperature range 0.15-1.5 MK is derived using data from
the EUV Imaging Spectrometer (EIS) on board the Hinode satellite. The
loop is aligned toward the observer's line of sight and shows downflows
(redshifts) of around 15 km s-1 up to a temperature of 0.8
MK, but for temperatures of 1.0 MK and above the measured velocity
shifts are consistent with no net flow. This velocity result applies
over a projected spatial distance of 9 Mm and demonstrates that the
cooler, redshifted plasma is physically disconnected from the hotter,
stationary plasma. A scenario in which the fan loops consist of at
least two groups of "strands"—one cooler and downflowing, the other
hotter and stationary—is suggested. The cooler strands may represent
a later evolutionary stage of the hotter strands. A density diagnostic
of Mg VII was used to show that the electron density at around 0.8 MK
falls from 3.2 × 109 cm-3 at the loop base,
to 5.0 × 108 cm-3 at a projected height of
15 Mm. A filling factor of 0.2 is found at temperatures close to the
formation temperature of Mg VII (0.8 MK), confirming that the cooler,
downflowing plasma occupies only a fraction of the apparent loop
volume. The fan loop is rooted within a so-called outflow region that
displays low intensity and blueshifts of up to 25 km s-1 in
Fe XII λ195.12 (formed at 1.5 MK), in contrast to the loop's redshifts
of 15 km s-1 at 0.8 MK. A new technique for obtaining an
absolute wavelength calibration for the EIS instrument is presented and
an instrumental effect, possibly related to a distorted point-spread
function, that affects velocity measurements is identified.

---------------------------------------------------------
Title: Atomic data for the X-ray lines of Fe viii and Fe ix
Authors: O'Dwyer, B.; Del Zanna, G.; Badnell, N. R.; Mason, H. E.;
Storey, P. J.
2012A&A...537A..22O Altcode:
The distorted wave extension of the autostructure code has been used
to calculate energy levels, radiative transition probabilities and
collisional excitation rates of Fe viii and Fe ix up to n = 6 for Fe ix
and n = 7 for Fe viii. We have compared some of the data with previous
calculations, finding overall agreement for radiative transition
rates, but interesting differences for some collisional data. We have
merged our data for the higher energy levels with published R-matrix
collisional excitation rates for the lower ones to calculate spectral
line intensities and compare them with observations. In particular,
we have focused on the transitions from high energy levels of Fe
viii &amp; Fe ix which are present in the 93-95 Å region. A few new
identifications are tentatively provided. We find that Fe ix 5f-3d
and Fe viii 7f-3d transitions only comprise a small fraction of
the observed lines in the 93-95 Å region for quiet Sun conditions,
and thus their contribution to the Solar Dynamics Observatory (SDO)
Atmospheric Imaging Assembly (AIA) 94 Å band is expected to be
small. A complete list of calculated energies, radiative data
and thermally averaged collision strengths is only available at the
CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/537/A22">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/537/A22</A>

---------------------------------------------------------
Title: Understanding Coronal Heating with Emission Measure
Distributions
Authors: Klimchuk, J. A.; Tripathi, D.; Bradshaw, S. J.; Mason, H. E.
2011AGUFMSH43F..03K Altcode:
It is widely believed that the cross-field spatial scale of coronal
heating is small, so that the fundamental plasma structures
(loop strands) are spatially unresolved. We therefore must
appeal to diagnostic techniques that are not strongly affected by
spatial averaging. One valuable observable is the emission measure
distribution, EM(T), which indicates how much material is present
at each temperature. Using data from the Extreme-ultraviolet Imaging
Spectrograph on the Hinode mission, we have determined emission measure
distributions in the cores of two active regions. The distributions
have power law slopes of approximately 2.4 coolward of the peak. We
compare these slopes, as well as the amount of emission measure at
very high temperature, with the predictions of a series of models. The
models assume impulsive heating (nanoflares) in unresolved strands and
take full account of nonequilibrium ionization. A variety of nanoflare
properties and initial conditions are considered. We also comment on the
selection of spectral lines for upcoming missions like Solar Orbiter.

---------------------------------------------------------
Title: SDO AIA and Hinode EIS observations of "warm" loops
Authors: Del Zanna, G.; O'Dwyer, B.; Mason, H. E.
2011A&A...535A..46D Altcode:
We present simultaneous observations of active region "warm" (1 MK)
loops using the Solar Dynamics Observatory (SDO) Atmospheric Imaging
Assembly (AIA) and Hinode EUV Imaging Spectrometer (EIS). Sample EIS
spectra for a loop footpoint and a lop leg region are presented, and are
used to describe the spectral lines which contribute to the six AIA EUV
channels, both directly and predicted with DEM modeling. We find good
overall agreement between observed and predicted count rates for the 131
Å, 193 Å, and 335 Å bands, but highlight a number of problems, partly
to be ascribed to inter-calibration issues, partly due to the fact that
a large number of lines remain unidentified for the 94 Å, 171 Å, and
211 Å bands. We also found that the 335 Å band is severely affected by
cross-talk with the 131 Å band and by second order contributions. We
extend our previous work where we highlighted the multi-thermal nature
of the SDO AIA bands to show that emission from lines formed at typical
transition region temperatures (log T[K] = 5.0-5.8) can be significant
for all the EUV channels, and even dominant in some cases. We also
assess the possibility of deriving accurate emission measures from the
AIA observations. We have found that the inversion of the AIA data to
obtain a description of the thermal characteristics of warm loops is
unreliable. We highlight the need for further work on the relevant
atomic data before the AIA data can be reliably used for plasma
diagnostic purposes. Appendices A-C are available in electronic
form at <A href="http://www.aanda.org">http://www.aanda.org</A>

---------------------------------------------------------
Title: Emission Measure Distribution and Heating of Two Active
Region Cores
Authors: Tripathi, Durgesh; Klimchuk, James A.; Mason, Helen E.
2011ApJ...740..111T Altcode: 2011arXiv1107.4480T
Using data from the Extreme-ultraviolet Imaging Spectrometer aboard
Hinode, we have studied the coronal plasma in the core of two active
regions. Concentrating on the area between opposite polarity moss, we
found emission measure distributions having an approximate power-law
form EMvpropT 2.4 from log T = 5.5 up to a peak at log T
= 6.55. We show that the observations compare very favorably with
a simple model of nanoflare-heated loop strands. They also appear
to be consistent with more sophisticated nanoflare models. However,
in the absence of additional constraints, steady heating is also a
viable explanation.

---------------------------------------------------------
Title: The 22 May 2007 B-class flare: new insights from Hinode
observations
Authors: Del Zanna, G.; Mitra-Kraev, U.; Bradshaw, S. J.; Mason,
H. E.; Asai, A.
2011A&A...526A...1D Altcode:
We present multi-wavelength observations of a small B-class flare
which occurred on the Sun on 2007 May 22. The observations include
data from Hinode, GOES, TRACE and the Nobeyama Radioheliograph. We
obtained spatially and spectrally-resolved information from the Hinode
EUV Imaging Spectrometer (EIS) during this event. The temporal and
temperature coverage of the EIS observations provides new insights into
our understanding of chromospheric evaporation and cooling. The flare
showed many “typical” features, such as brightenings in the ribbons,
hot (10 MK) loop emission and subsequent cooling. We also observed
a new feature, strong (up to 170 km s-1) blue-shifted
emission in lines formed around 2-3 MK, located at the footpoints of
the 10 MK coronal emission and within the ribbons. Electron densities
at 2 MK in the kernels are high, of the order of 1011
cm-3, suggesting a very narrow layer where the chromospheric
evaporation occurs. We have run a non-equilibrium hydrodynamic numerical
simulation using the HYDRAD code to study the cooling of the 10 MK
plasma, finding good agreement between the predicted and observed
temperatures, densities and ion populations. Line blending for some
potentially useful diagnostic lines for flares, which are observed
with Hinode/EIS, is also discussed.

---------------------------------------------------------
Title: Hinode extreme-ultraviolet imaging spectrometer observations
of a limb active region
Authors: O'Dwyer, B.; Del Zanna, G.; Mason, H. E.; Sterling, A. C.;
Tripathi, D.; Young, P. R.
2011A&A...525A.137O Altcode:
 Aims: We investigate the electron density and temperature
structure of a limb active region. Methods: We have carried out
a study of an active region close to the solar limb using observations
from the Extreme-ultraviolet Imaging Spectrometer (EIS) and the X-ray
telescope (XRT) on board Hinode. The electron density and temperature
distributions of the coronal emission have been determined using
emission line intensity ratios. Differential emission measure (DEM)
analysis and the emission measure (EM) loci technique were used to
examine the thermal structure of the emitting plasma as a function
of distance from the limb. Results: The highest temperature
and electron density values are found to be located in the core of
the active region, with a peak electron number density value of 1.9
× 1010 cm-3 measured using the Fe XII 186.887
Å to 192.394 Å line intensity ratio. The plasma along the line of
sight in the active region was found to be multi-thermal at different
distances from the limb. The EIS and XRT DEM analyses appear to be
in agreement in the temperature interval from log T = 6.5-6.7. 
Conclusions: Our results provide new constraints for models of coronal
heating in active regions.

---------------------------------------------------------
Title: Science Objectives for an X-Ray Microcalorimeter Observing
the Sun
Authors: Laming, J. Martin; Adams, J.; Alexander, D.; Aschwanden, M;
Bailey, C.; Bandler, S.; Bookbinder, J.; Bradshaw, S.; Brickhouse,
N.; Chervenak, J.; Christe, S.; Cirtain, J.; Cranmer, S.; Deiker, S.;
DeLuca, E.; Del Zanna, G.; Dennis, B.; Doschek, G.; Eckart, M.; Fludra,
A.; Finkbeiner, F.; Grigis, P.; Harrison, R.; Ji, L.; Kankelborg,
C.; Kashyap, V.; Kelly, D.; Kelley, R.; Kilbourne, C.; Klimchuk, J.;
Ko, Y. -K.; Landi, E.; Linton, M.; Longcope, D.; Lukin, V.; Mariska,
J.; Martinez-Galarce, D.; Mason, H.; McKenzie, D.; Osten, R.; Peres,
G.; Pevtsov, A.; Porter, K. Phillips F. S.; Rabin, D.; Rakowski, C.;
Raymond, J.; Reale, F.; Reeves, K.; Sadleir, J.; Savin, D.; Schmelz,
J.; Smith, R. K.; Smith, S.; Stern, R.; Sylwester, J.; Tripathi, D.;
Ugarte-Urra, I.; Young, P.; Warren, H.; Wood, B.
2010arXiv1011.4052L Altcode:
We present the science case for a broadband X-ray imager with
high-resolution spectroscopy, including simulations of X-ray spectral
diagnostics of both active regions and solar flares. This is part of
a trilogy of white papers discussing science, instrument (Bandler et
al. 2010), and missions (Bookbinder et al. 2010) to exploit major
advances recently made in transition-edge sensor (TES) detector
technology that enable resolution better than 2 eV in an array that
can handle high count rates. Combined with a modest X-ray mirror, this
instrument would combine arcsecondscale imaging with high-resolution
spectra over a field of view sufficiently large for the study of
active regions and flares, enabling a wide range of studies such as
the detection of microheating in active regions, ion-resolved velocity
flows, and the presence of non-thermal electrons in hot plasmas. It
would also enable more direct comparisons between solar and stellar
soft X-ray spectra, a waveband in which (unusually) we currently have
much better stellar data than we do of the Sun.

---------------------------------------------------------
Title: Evidence of Impulsive Heating in Active Region Core Loops
Authors: Tripathi, Durgesh; Mason, Helen E.; Klimchuk, James A.
2010ApJ...723..713T Altcode: 2010arXiv1009.0663T
Using a full spectral scan of an active region from the
Extreme-Ultraviolet Imaging Spectrometer (EIS) we have obtained emission
measure EM(T) distributions in two different moss regions within the
same active region. We have compared these with theoretical transition
region EMs derived for three limiting cases, namely, static equilibrium,
strong condensation, and strong evaporation from Klimchuk et al. The
EM distributions in both the moss regions are strikingly similar and
show a monotonically increasing trend from log T[K] = 5.15-6.3. Using
photospheric abundances, we obtain a consistent EM distribution for
all ions. Comparing the observed and theoretical EM distributions,
we find that the observed EM distribution is best explained by the
strong condensation case (EMcon), suggesting that a downward
enthalpy flux plays an important and possibly dominant role in powering
the transition region moss emission. The downflows could be due to
unresolved coronal plasma that is cooling and draining after having
been impulsively heated. This supports the idea that the hot loops
(with temperatures of 3-5 MK) seen in the core of active regions are
heated by nanoflares.

---------------------------------------------------------
Title: SDO/AIA response to coronal hole, quiet Sun, active region,
and flare plasma
Authors: O'Dwyer, B.; Del Zanna, G.; Mason, H. E.; Weber, M. A.;
Tripathi, D.
2010A&A...521A..21O Altcode:
 Aims: We examine the contribution of spectral lines and continuum
emission to the EUV channels of the Atmospheric Imaging Assembly (AIA)
on the Solar Dynamics Observatory (SDO) in different regions of the
solar atmosphere. Methods: Synthetic spectra were obtained using
the CHIANTI atomic database and sample differential emission measures
for coronal hole, quiet Sun, active region and flare plasma. These
synthetic spectra were convolved with the effective area of each
channel, in order to determine the dominant contribution in different
regions of the solar atmosphere. Results: We highlight the
contribution of particular spectral lines which under certain conditions
can affect the interpretation of SDO/AIA data.

---------------------------------------------------------
Title: Evidence for magnetic flux cancelation leading to an ejective
solar eruption observed by Hinode, TRACE, STEREO, and SoHO/MDI
Authors: Sterling, A. C.; Chifor, C.; Mason, H. E.; Moore, R. L.;
Young, P. R.
2010A&A...521A..49S Altcode:
 Aims: We study the onset of a solar eruption involving a
filament ejection on 2007 May 20. Methods: We observe the
filament in Hα images from Hinode/SOT and in EUV with TRACE and
STEREO/SECCHI/EUVI. Hinode/XRT images are used to study the eruption in
soft X-rays. From spectroscopic data taken with Hinode/EIS we obtain
bulk-flow velocities, line profiles, and plasma densities in the
onset region. The magnetic field evolution was observed in SoHO/MDI
magnetograms. Results: We observed a converging motion between
two opposite polarity sunspots that form the primary magnetic polarity
inversion line (PIL), along which resides filament material before
eruption. Positive-flux magnetic elements, perhaps moving magnetic
features (MMFs) flowing from the spot region, appear north of the
spots, and the eruption onset occurs where these features cancel
repeatedly in a negative-polarity region north of the sunspots. An
ejection of material observed in Hα and EUV marks the start of the
filament eruption (its “fast-rise”). The start of the ejection is
accompanied by a sudden brightening across the PIL at the jet's base,
observed in both broad-band images and in EIS. Small-scale transient
brightenings covering a wide temperature range (Log Te =
4.8-6.3) are also observed in the onset region prior to eruption. The
preflare transient brightenings are characterized by sudden, localized
density enhancements (to above Log ne [ cm-3] =
9.75, in Fe XIII) that appear along the PIL during a time when pre-flare
brightenings were occurring. The measured densities in the eruption
onset region outside the times of those enhancements decrease with
temperature. Persistent downflows (red-shifts) and line-broadening
(Fe XII) are present along the PIL. Conclusions: The array of
observations is consistent with the pre-eruption sheared-core magnetic
field being gradually destabilized by evolutionary tether-cutting flux
cancelation that was driven by converging photospheric flows, and the
main filament ejection being triggered by flux cancelation between the
positive flux elements and the surrounding negative field. A definitive
statement however on the eruption's ultimate cause would require
comparison with simulations, or additional detailed observations of
other eruptions occurring in similar magnetic circumstances. The
video that accompanies Fig. 3 is only available in electronic form at
<A href="http://www.aanda.org">http://www.aanda.org</A>

---------------------------------------------------------
Title: Active region moss. Basic physical parameters and their
temporal variation
Authors: Tripathi, D.; Mason, H. E.; Del Zanna, G.; Young, P. R.
2010A&A...518A..42T Altcode: 2010arXiv1005.2220T
Context. Active region moss are transition region phenomena, first noted
in the images recorded by the Transition Region and Coronal Explorer
(TRACE) in λ171. Moss regions are thought to be the footpoints of
hot loops (3-5 MK) seen in the core of active regions. These hot
loops appear “fuzzy” (unresolved). Therefore, it is difficult to
study the physical plasma parameters in individual hot core loops and
hence their heating mechanisms. Moss regions provide an excellent
opportunity to study the physics of hot loops. In addition, they
allow us to study the transition region dynamics in the footpoint
regions. Aims: To derive the physical plasma parameters such as
temperature, electron density, and filling factors in moss regions and
to study their variation over a short (an hour) and a long time period
(5 consecutive days). Methods: Primarily, we have analyzed
spectroscopic observations recorded by the Extreme-ultraviolet Imaging
Spectrometer (EIS) aboard Hinode. In addition we have used supplementary
observations taken from TRACE and the X-Ray Telescope (XRT) aboard
Hinode. Results: The moss emission is strongest in the Fe XII
and Fe XIII lines. Based on analyses using line ratios and emission
measure we found that moss regions have a characteristic temperature
of log T[K] = 6.2. The temperature structure in moss region remains
almost identical from one region to another and it does not change
with time. The electron densities measured at different locations in
the moss regions using Fe XII ratios are about 1-3 × 1010
cm-3 and about 2-4 × 109 cm-3 using
Fe XIII and Fe XIV. The densities in the moss regions are similar in
different places and show very little variation over short and long
time scales. The derived electron density substantially increased (by
a factor of about 3-4 or even more in some cases) when a background
subtraction was performed. The filling factor of the moss plasma
can vary between 0.1-1 and the path length along which the emission
originates is from a few 100 to a few 1000 kms long. By combining the
observations recorded by TRACE, EIS and XRT, we find that the moss
regions correspond to the footpoints of both hot and warm loops.

---------------------------------------------------------
Title: VizieR Online Data Catalog: IRON project. LXVIII (Del Zanna+,
2010)
Authors: Del Zanna, G.; Storey, P. J.; Mason, H. E.
2010yCat..35140040D Altcode: 2010yCat..35149040D
**************************************************************************
* * * Sorry, but the author(s) never supplied the tabular
material * * (detailed tables) as announced in the paper. *
**************************************************************************

---------------------------------------------------------
Title: Plasma Flows in Coronal Loops
Authors: Young, Peter R.; Dwyer, B. O.; Mason, H. E.
2010AAS...21630004Y Altcode:
A survey of plasma flows in coronal loops is underway using data from
the Hinode/EIS instrument. The principal target is a study of flows
in 1 MK (so-called 'warm' loops). Using emission lines formed between
logT=5.6 and 6.2 it is possible to study the temperature dependence of
the flows, and also the density of the emitting material. The results
will be critical to making a definitive statement about whether apparent
motions seen in TRACE 171 movies are due to actual mass motion or wave
propagation. In addition we will also comment on the relation between
the flows in warm loops and those in the newly-discovered active region
outflow regions found by Hinode.

---------------------------------------------------------
Title: Atomic data from the IRON project. LXVIII. Electron impact
excitation of Fe xi
Authors: Del Zanna, G.; Storey, P. J.; Mason, H. E.
2010A&A...514A..40D Altcode:
A new R-matrix scattering calculation for electron collisional
excitation of Fe xi is presented and compared to earlier
calculations. The calculation includes 145 LS terms and 465
fine-structure levels and uses the intermediate-coupling frame
transformation method (ICFT). We discuss the strong interactions that
exist between three J = 1 levels in the 3s2 3p3
3d electron configuration. These levels give rise to strong lines
in the EUV spectrum and their energies and identifications have
been the source of much confusion in the literature. We show that
the oscillator and collision strengths linking these levels to
the ground levels of the ion are very sensitive to the choice of
configuration basis and argue that most earlier calculations have
failed to represent these levels adequately. Detailed tables
of the present data are available in electronic form at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via <A
href="http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/514/A40">http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/514/A40</A>

---------------------------------------------------------
Title: VizieR Online Data Catalog: IRON Project. LVIII. (Storey+,
2005)
Authors: Storey, P. J.; Del Zanna, G.; Mason, H. E.; Zeippen, C. J.
2010yCat..34330717S Altcode:
A new calculation of rate coefficients for electron collisional
excitation of Fe XII is presented and compared to earlier
calculations. Significant differences are found with all earlier work
due to the inclusion of resonance processes that have not previously
been considered and to the use of the intermediate coupling frame
transformation method. The resulting dataset of collision strengths
is shown to resolve many of the outstanding discrepancies between
theory and solar observations. In particular, density sensitive
line ratios in Fe XII now indicate electron densities close to
those derived from other ions of comparable ionization potential. **************************************************************************
* * * Sorry, but the author(s) never supplied the
tabular material * * announced in the paper * * *
**************************************************************************

---------------------------------------------------------
Title: Two types of magnetic flux cancelation in the solar eruption
of 2007 May 20
Authors: Sterling, Alphonse; Moore, Ronald; Mason, Helen
2010cosp...38.1946S Altcode: 2010cosp.meet.1946S
We study a solar eruption on 2007 May 20, in an effort to understand the
cWe study a solar eruption of 2007 May 20, in an effort to understand
the cause of the eruption's onset. The event produced a GOES class
B6.7 flare peaking at 05:56 UT, while ejecting a surge/filament and
producing a coronal mass ejection (CME). We examine several data
sets, including Hα images from the Solar Optical Telescope (SOT) on
Hinode, EUV images from TRACE, and line-of-sight magnetograms from
SoHO/MDI. Flux cancelation occurs among two different sets of flux
elements inside of the erupting active region: First, for several days
prior to eruption, opposite-polarity sunspot groups inside the region
move toward each other, leading to the cancelation of ∼ 1021 Mx
of flux over three days. Second, within hours prior to the eruption,
positive-polarity moving magnetic features (MMFs) flowing out of the
positive-flux spots at ∼ 1 km/s repeatedly cancel with field inside
a patch of negative-polarity flux located north of the sunspots. The
filament erupts as a surge whose base is rooted in the location where
the MMF cancelation occurs, while during the eruption that filament
flows out along the polarity inversion line between the converging spot
groups. We conclude that a plausible scenario is that the converging
spot fields brought the magnetic region to the brink of instability,
and the MMF cancelation pushed the system "over the edge," triggering
the eruption. This work was funded by NASA's Science Mission Directorate
thought the Living With a Star Targeted Research and Technology Program,
the Supporting Research and Program, and the Hinode project.

---------------------------------------------------------
Title: Diagnostics of Active Region Loops Observed with Hinode/EIS
Authors: Tripathi, D.; Mason, H. E.; Dwivedi, B. N.; Del Zanna, G.
2009ASPC..415..260T Altcode:
The Extreme Ultraviolet Imaging Spectrometer (EIS) on board Hinode
provides us with an excellent opportunity to study the physical
parameters in spatially resolved coronal structures. In this paper
we have carried out a study of active region loops using observations
from the EIS. The active region was observed on 2007 Ma 19 using the
1 arcsec slit of EIS. At coronal temperatures, we find that electron
densities measured from Fe XII and Si X line ratios decrease along
the loop length, being ≈10100 cm-3 at foot
point and ≈108.5 cm-3 at a height of about 75
Mm. However, the electron densities measured from the Mg VII line ratios
(at a transition region temperature) show significantly lower values
at the foot point. The electron temperature along the loop increases
with height from ≈0.8 MK (at foot point) to ≈1.5 MK (at a height
of 75 Mm). The temperature diagnostics using EM-loci at different
locations along the loop show that the loop is “nearly isothermal”
or “mildly multi-thermal” along the LOS. These measurements provide
important constraints on the theoretical modelling of coronal loops.

---------------------------------------------------------
Title: Multi-Instrument Campaigns to Observe the Off-Limb Corona
Authors: Del Zanna, G.; Andretta, V.; Poletto, G.; Teriaca, L.; Ko,
Y. -K.; Mason, H. E.; Vourdilas, A.; Bemporad, A.; Magri, M.
2009ASPC..415..315D Altcode:
We briefly describe two multi-instrument campaigns we coordinated to
observe the off-limb corona in 2007, with some preliminary results. The
first one (Hinode HOP 7) was a SOHO/Hinode/TRACE/STEREO/Ulysses
week-long campaign during the SOHO-Ulysses quadrature in 2007 May. We
could not achieve all of our goals, however we were very fortunate in
that the “Del Zanna” active region appeared on the Sun at the right
longitude, and that a filament eruption and a CME were observed. Of
particular significance is the finding of large (100 km s-1)
non-thermal broadenings in all coronal lines observed by Hinode/EIS
in the region where the filament was erupting. The second campaign
(Hinode HOP 44) involved SOHO (CDS, SUMER, UVCS), Hinode, and TRACE to
measure the physical parameters of plume/interplume regions in the polar
coronal holes from the low corona to 1.7 solar radii, on 30/10-4/11. We
obtained a good set of observations, however various instrumental
constraints and the lack of fully developed plumes limited our goals.

---------------------------------------------------------
Title: Temperature Tomography of a Coronal Sigmoid Supporting the
Gradual Formation of a Flux Rope
Authors: Tripathi, Durgesh; Kliem, Bernhard; Mason, Helen E.; Young,
Peter R.; Green, Lucie M.
2009ApJ...698L..27T Altcode: 2009arXiv0904.4782T
Multiwavelength observations of a sigmoidal (S-shaped) solar coronal
source by the EUV Imaging Spectrometer and the X-Ray Telescope
aboard the Hinode spacecraft and by the EUV Imager aboard STEREO are
reported. The data reveal the coexistence of a pair of J-shaped hot
arcs at temperatures T&gt;2 MK with an S-shaped structure at somewhat
lower temperatures (T ≈ 1-1.3 MK). The middle section of the S-shaped
structure runs along the polarity inversion line of the photospheric
field, bridging the gap between the arcs. Flux cancellation occurs
at the same location in the photosphere. The sigmoid forms in the
gradual decay phase of the active region, which does not experience
an eruption. These findings correspond to the expected signatures
of a flux rope forming, or being augmented, gradually by a topology
transformation inside a magnetic arcade. In such a transformation, the
plasma on newly formed helical field lines in the outer flux shell of
the rope (S-shaped in projection) is expected to enter a cooling phase
once the reconnection of their parent field line pairs (double-J shaped
in projection) is complete. Thus, the data support the conjecture that
flux ropes can exist in the corona prior to eruptive activity.

---------------------------------------------------------
Title: CHIANTI - an atomic database for emission lines. IX. Ionization
rates, recombination rates, ionization equilibria for the elements
hydrogen through zinc and updated atomic data
Authors: Dere, K. P.; Landi, E.; Young, P. R.; Del Zanna, G.; Landini,
M.; Mason, H. E.
2009A&A...498..915D Altcode:
Aims: The goal of the CHIANTI atomic database is to provide a set of
atomic data for the interpretation of astrophysical spectra emitted by
collisionally dominated, high temperature, optically thin sources. Methods: A complete set of ground level ionization and recombination
rate coefficients has been assembled for all atoms and ions of the
elements of H through Zn and inserted into the latest version of the
CHIANTI database, CHIANTI 6. Ionization rate coefficients are taken from
the recent work of Dere (2007, A&amp;A, 466, 771) and recombination
rates from a variety of sources in the literature. These new rate
coefficients have allowed the calculation of a new set of ionization
equilibria and radiative loss rate coefficients. For some ions, such
as Fe VIII and Fe IX, there are significant differences from previous
calculations. In addition, existing atomic parameters have been revised
and new atomic parameters inserted into the database. Results:
For each ion in the CHIANTI database, elemental abundances, ionization
potentials, atomic energy levels, radiative rates, electron and proton
collisional rate coefficients, ionization and recombination rate
coefficients, and collisional ionization equilibrium populations are
provided. In addition, parameters for the calculation of the continuum
due to bremsstrahlung, radiative recombination and two-photon decay are
provided. A suite of programs written in the Interactive Data Language
(IDL) are available to calculate line and continuum emissivities
and other properties. All data and programs are freely available at
http://wwwsolar.nrl.navy.mil/chianti

---------------------------------------------------------
Title: CHIANTI Version 6.0 - Inclusion of Ionization and Recombination
Rates
Authors: Dere, Kenneth P.; Landi, E.; Young, P.; Del Zanna, G.; Mason,
H.; Landini, M.
2009SPD....40.1504D Altcode:
A new version of the CHIANTI atomic database for astrophysical
spectroscopy is being prepared for imminent release. This will
constitute Version 6.0. The main focus of this release is the inclusion
of ionization cross-sections and rate coefficients from Dere (2007)
and recombination rate coefficients from the literature, in particular,
the calculations of Badnell and colleagues. A new set of ionization
equilibria have been calculated from these rate coefficients. These
show some significant differences from previous calculations. Atomic
data for many ions have been revised and new calculations are included
that enable the calculation of spectra of ions new to the CHIANTI
database. The radiative loss function has been calculated based on
the CHIANTI Version 6 database for both coronal and photospheric
abundances. A paper describing CHIANTI Version 6.0 in detail has
been accepted for publication in Astronomy and Astrophysics.

---------------------------------------------------------
Title: Active Region Loops: Hinode/Extreme-Ultraviolet Imaging
Spectrometer Observations
Authors: Tripathi, Durgesh; Mason, Helen E.; Dwivedi, Bhola N.;
del Zanna, Giulio; Young, Peter R.
2009ApJ...694.1256T Altcode: 2009arXiv0901.0095T
We have carried out a study of active region loops using observations
from the Extreme-ultraviolet Imaging Spectrometer (EIS) on board Hinode
using 1” raster data for an active region observed on 2007 May 19. We
find that active region structures which are clearly discernible in
cooler lines (≈1 MK) become "fuzzy" at higher temperatures (≈2
MK). The active region was comprised of redshifted emissions (downflows)
in the core and blueshifted emissions (upflows) at the boundary. The
flow velocities estimated in the two regions located near the footpoints
of coronal loop showed redshifted emission at transition region
temperature and blueshifted emission at coronal temperature. The upflow
speed in these regions increased with temperature. For more detailed
study we selected one particular well-defined loop. Downward flows are
detected along the coronal loop, being stronger in lower-temperature
lines (rising up to 60 km s-1 near the footpoint). The
downflow was localized toward the footpoint in transition region lines
(Si VII) and toward the loop top in high-temperature line (Fe XV). By
carefully accounting for the background emission we found that the
loop structure was close to isothermal for each position along the
loop, with the temperature rising from around 0.8 MK to 1.5 MK from
the close to the base to higher up toward the apex (≈75 Mm). We
derived electron density using well-established line ratio diagnostic
techniques. Electron densities along the active region loop were found
to vary from 1010 cm-3 close to the footpoint to
108.5 cm-3 higher up. A lower electron density,
varying from 109 cm-3 close to the footpoint to
108.5 cm-3 higher up, was found for the lower
temperature density diagnostic. Using these densities we derived filling
factors in along the coronal loop which can be as low as 0.02 near the
base of the loop. The filling factor increased with projected height
of the loop. These results provide important constraints on coronal
loop modeling.

---------------------------------------------------------
Title: Partially-erupting prominences: a comparison between
observations and model-predicted observables
Authors: Tripathi, D.; Gibson, S. E.; Qiu, J.; Fletcher, L.; Liu,
R.; Gilbert, H.; Mason, H. E.
2009A&A...498..295T Altcode: 2009arXiv0902.1228T
Aims: We investigate several partially-erupting prominences to
study their relationship with other CME-associated phenomena and
compare these observations with observables predicted by a model
of partially-expelled-flux-ropes (Gibson &amp; Fan 2006a, ApJ,
637, L65; 2006b, J. Geophys. Res., 111, 12103). Methods: We
studied 6 selected events with partially-erupting prominences using
multi-wavelength observations recorded by the Extreme-ultraviolet
Imaging Telescope (EIT), Transition Region and Coronal Explorer
(TRACE), Mauna Loa Solar Observatory (MLSO), Big Bear Solar Observatory
(BBSO), and Soft X-ray Telescope (SXT). The observational features
associated with partially-erupting prominences were then compared
with the predicted observables from the model. Results: The
partially-expelled-flux-rope (PEFR) model can explain the partial
eruption of these prominences, and in addition predicts a variety
of other CME-related observables that provide evidence of internal
reconnection during eruption. We find that all of the partially-erupting
prominences studied in this paper exhibit indirect evidence of internal
reconnection. Moreover, all cases showed evidence of at least one
observable unique to the PEFR model, e.g., dimmings external to the
source region and/or a soft X-ray cusp overlying a reformed sigmoid. Conclusions: The PEFR model provides a plausible mechanism to explain
the observed evolution of partially-erupting-prominence-associated
CMEs in our study.

---------------------------------------------------------
Title: Are Coronal Loops Isothermal or Multithermal?
Authors: Schmelz, J. T.; Nasraoui, K.; Rightmire, L. A.; Kimble,
J. A.; del Zanna, G.; Cirtain, J. W.; DeLuca, E. E.; Mason, H. E.
2009ApJ...691..503S Altcode: 2009arXiv0901.3281S
Surprisingly few solar coronal loops have been observed simultaneously
with TRACE and SOHO/Coronal Diagnostics Spectrometer (CDS), and even
fewer analyses of these loops have been conducted and published. The
SOHO Joint Observing Program 146 was designed in part to provide the
simultaneous observations required for in-depth temperature analysis of
active region loops and determine whether these loops are isothermal
or multithermal. The data analyzed in this paper were taken on 2003
January 17 of AR 10250. We used TRACE filter ratios, emission measure
loci, and two methods of differential emission measure analysis to
examine the temperature structure of three different loops. TRACE and
CDS observations agree that Loop 1 is isothermal with log T = 5.85,
both along the line of sight as well as along the length of the loop
leg that is visible in the CDS field of view. Loop 2 is hotter than
Loop 1. It is multithermal along the line of sight, with significant
emission between 6.2 &lt; log T&lt; 6.4, but the loop apex region
is out of the CDS field of view so it is not possible to determine
the temperature distribution as a function of the loop height. Loop
3 also appears to be multithermal, but a blended loop that is just
barely resolved with CDS may be adding cool emission to the Loop
3 intensities and complicating our results. So, are coronal loops
isothermal or multithermal? The answer appears to be yes.

---------------------------------------------------------
Title: Magnetic flux cancellation associated with a recurring solar
jet observed with Hinode, RHESSI, and STEREO/EUVI
Authors: Chifor, C.; Isobe, H.; Mason, H. E.; Hannah, I. G.; Young,
P. R.; Del Zanna, G.; Krucker, S.; Ichimoto, K.; Katsukawa, Y.;
Yokoyama, T.
2008A&A...491..279C Altcode:
Aims: We study the physical properties of a recurring solar active
region jet observed in X-rays and extreme-ultraviolet (EUV). Methods: Multi-wavelength data from all three instruments on
board Hinode were analysed. X-ray imaging and spectroscopy of the
microflaring emission associated with the jets was performed with the
Reuven Ramaty High Energy Spectroscopic Imager (RHESSI). Associated
EUV jets were observed with the Sun Earth Connection Coronal and
Heliospheric Investigation (SECCHI)/Extreme Ultraviolet Imager
(EUVI) on board STEREO. Results: We found a correlation between
recurring magnetic flux cancellation close to a pore, the X-ray jet
emission, and associated Ca II H ribbon brightenings. We estimated the
lower limit for the decrease in magnetic energy associated with the
X-ray jet emission at 3 × 1029 erg. The recurring plasma
ejection was observed simultaneously at EUV and X-ray temperatures,
associated with type III radio bursts and microflaring activity at the
jet footpoint. Conclusions: The recurring jet (EUV and X-ray)
emissions can be attributed to chromospheric evaporation flows due to
recurring coronal magnetic reconnection. In this process, the estimated
minimum loss in the magnetic energy is sufficient to account for the
total energy required to launch the jet. Movie of Fig. 3 is only
available in electronic form via http://www.aanda.org

---------------------------------------------------------
Title: Chapter 7: Active Region Diagnostics
Authors: Mason, H. E.; Tripathi, D.
2008psa..book..127M Altcode:
Active regions present us with complex and dynamic structures, which
look relatively simple, but are in fact very difficult to model and
explain. An active region is a region on the Sun where the magnetic
field breaks through the surface (photosphere and chromosphere) to
form giant arches of hot plasma. The magnetic field is stronger than
in surrounding regions and the plasma is hotter, so emits strongly
in UV and X-ray radiation. Figures 7.1 and 7.2 show UV images of the
Sun taken with the Transition Region and Coronal Explorer (TRACE)
spacecraft and the Extreme Ultraviolet Imaging Telescope (EIT) aboard
the Solar and Heliospheric Observatory (SOHO) spacecraft. The hot plasma
(around a million degree) traces out the magnetic field structures...

---------------------------------------------------------
Title: Active Region Microflares From Hinode and RHESSI
Authors: Chifor, C.; Hannah, I. G.; Mason, H. E.; Isobe, H.; Yokoyama,
T.; Young, P. R.; Tripathi, D.
2008ASPC..397..164C Altcode:
We are studying microflares (A, B-C class flares) in active regions
using coordinated observations from Hinode and RHESSI. Hinode/EIS
has unprecedented diagnostic power for small, transient activity
in the solar corona, providing temperature, density, and velocity
information. For this purpose, we designed and ran an EIS observing
sequence to provide high-cadence data at both transition region and
coronal temperatures. A preliminary analysis of these observations is
reported, with one data set given as an example.

---------------------------------------------------------
Title: Source Region Evolution of the Solar Wind Disappearance Event
of 11 May 1999
Authors: Janardhan, P.; Tripathi, D.; Mason, H. E.
2008ESPM...122.118J Altcode:
A recent, detailed study of the well known "solar wind disappearance
event" of 11 May 1999 traced its origin to a coronal hole lying adjacent
to a large active region, AR8525 in Carrington rotation 1949. The
active region was located at central meridian on 05 May 1999 when the
flows responsible for this event began. In this paper we examine the
evolution of the active region-coronal hole complex during 5-6 May 1999
to study the changes that apparently played a key role in causing this
disappearance event. To study the evolution of the solar source region
of the disappearance event of 11 May 1999 we have used images from the
Soft X-ray Telescope (SXT), the Extreme-ultraviolet Imaging Telescope
(EIT) and the Michelson Doppler Imager (MDI) to examine the evolution
of the coronal hole and active region complex at the source region of
the disappearance event. We find a dynamic evolution taking place in
the coronal hole-active region boundary at the source region of the
disappearance event of 11 May 1999. Based on the combined observations
it appears that the rapid evolution seen in the coronal hole is due to
reconnection's taking place between the newly emerging flux and the open
field regions from the coronal hole and the active region-coronal hole
boundary regions. This evolution, which is found to reduce the area of
the coronal hole, is accompanied by the formation of new loops in EUV
images which are spatially and temporally correlated with emerging flux
regions as seen in MDI data. As opposed to the well known drivers
of space weather phenomena like CME's or large flares, disappearance
events are not associated with explosive solar phenomena. However, they
do produce other observable effects that are not fully understood. In
the period leading up to the disappearance event of 11 May 1999, our
observations, during quiet solar conditions and in the absence of CMEs,
provide the first clear evidence for Sun-Earth connection originating
from an evolving active region-coronal hole region located at central
meridian. With the exception of corotating interacting regions, these
observations provide the first link between the Sun and space weather
effects at 1 AU, arising from non-explosive solar events.

---------------------------------------------------------
Title: Density Structure in Active Regions from Hinode/EIS
Authors: Tripathi, D.; Mason, H. E.; Young, P. R.; Chifor, C.; Del
Zanna, G.
2008ASPC..397...45T Altcode:
The Extreme-ultraviolet Imaging Spectrometer (EIS) on board Hinode
provides an excellent opportunity to study the physical plasma
parameters in spatially resolved coronal features. In this paper we
present the density structure in an active region at many different
temperatures. The active region was rastered on May 01, 2007 with the
2^{”} slit. We find that the electron density is highest in the core
of the active region where it exceeds log_{10} N_e = 10.5.

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Title: Nonthermal and thermal diagnostics of a solar flare observed
with RESIK and RHESSI
Authors: Dzifčáková, E.; Kulinová, A.; Chifor, C.; Mason, H. E.;
Del Zanna, G.; Sylwester, J.; Sylwester, B.
2008A&A...488..311D Altcode:
Aims: We aim to prove and diagnose the occurrence of nonthermal
electron distributions in solar flare plasma using X-ray spectral
observations. Methods: An M4.9 flare on 2003 January 7/8 was
observed with the RESIK instrument in the 3-6 Å wavelength range (2-4
keV) and with RHESSI at energies above 6 keV. The temporal behavior
of RESIK flare spectra has been analyzed for two different types of
velocity distributions - a thermal (Maxwellian) distribution and a
nonthermal plasma distribution of free electrons. The Si XIV, Si XIII,
and Si XIId satellite lines observed with RESIK in the 5-6 Å range
were used to determine the degree of deviation from Maxwellian, and
the equivalent non-Maxwellian pseudo-temperature, τ. The diagnostics
presented are sensitive to the shape of the distribution in the energy
range where the maximum of the electron distribution occurs (where
the bulk of electrons reside) and does not include the influence
of the shape of the high-energy tail of the distribution. Under
the assumption of a Maxwellian distribution of electron velocities,
the plasma temperature was determined from an emission measure (EM)
loci analysis and a differential emission measure (DEM) analysis of
RESIK spectra. The high-energy end of the flare radiative emission
was investigated through RHESSI spectral analysis. Results:
The nonthermal analysis of RESIK spectra has shown that the largest
deviations of the plasma electron distribution from Maxwellian appeared
during the impulsive phase of the flare. The decay phase spectra had
an almost isothermal character. The pseudo-temperature, τ, reached
its maximum around the peak time of the soft and hard X-ray fluxes. The
temporal behavior of the temperatures derived from the thermal analysis
was similar to the behavior of the nonthermal pseudo-temperature. The
values of the pseudo-temperature were consistent with the temperatures
obtained in both thermal analyses, but lower than the temperatures
derived from the slope of the RHESSI continua. In comparison with the
synthetic isothermal or multithermal spectra, the nonthermal synthetic
spectra fitted the observed Si XIId satellite lines much more closely
(the error is less than 10%). The fluxes in the Si XIId satellite lines
in isothermal or multithermal spectra have been underestimated by a
factor of three or more in comparison to the observed fluxes. The
value of this factor varies with time and it is different for the
different satellite lines. Conclusions: Evidence was found for
considerable deviations of the distribution of free electrons from
Maxwellian in the plasma during a solar flare. These occurred mainly
during the flare impulsive phase and can be diagnosed using existing
X-ray spectral observations.

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Title: The solar wind disappearance event of 11 May 1999: source
region evolution
Authors: Janardhan, P.; Tripathi, D.; Mason, H. E.
2008A&A...488L...1J Altcode: 2008arXiv0807.2697J
Context: A recent, detailed study of the well-known “solar wind
disappearance event” of 11 May 1999 traced its origin to a coronal
hole (CH) lying adjacent to a large active region (AR), AR8525 in
Carrington rotation 1949. The AR was located at central meridian on 05
May 1999 when the flows responsible for this event began. We examine
the evolution of the AR-CH complex during 5-6 May 1999 to study the
changes that apparently played a key role in causing this disappearance
event. Aims: To study the evolution of the solar source region
of the disappearance event of 11 May 1999. Methods: Using images
from the Soft X-ray Telescope (SXT), the Extreme-ultraviolet Imaging
Telescope (EIT) and the Michelson Doppler Imager (MDI) to examine
the evolution of the CH and AR complex at the source region of the
disappearance event. Results: We find a dynamic evolution taking
place in the CH-AR boundary at the source region of the disappearance
event of 11 May 1999. This evolution, which is found to reduce the
area of the CH, is accompanied by the formation of new loops in EUV
images that are spatially-and-temporally correlated with emerging flux
regions as seen in MDI data. Conclusions: In the period leading
up to the disappearance event of 11 May 1999, our observations,
during quiet solar conditions and in the absence of CMEs, provide
the first clear evidence for Sun-Earth connection originating from an
evolving AR-CH region located at central meridian. With the exception
of corotating interacting regions (CIR), these observations provide the
first link between the Sun and space weather effects at 1 AU, arising
from non-explosive solar events. 2 movies are only available in
electronic form at http://www.aanda.org

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Title: Magnetic Flux Cancelation Leading to the Eruption of a Coronal
Mass Ejection: Observations from Hinode, SOHO, TRACE, and STEREO
Authors: Sterling, A. C.; Chifor, C.; Mason, H.; Moore, R. L.
2008AGUSMSP23B..05S Altcode:
We study a solar eruption involving ejection of a filament on 2007 May
20, using instruments on Hinode, STEREO, TRACE, and SOHO. We observe
the filament in EUV from TRACE and STEREO, and in H-alpha from SOT on
Hinode. We also see the eruption in soft X-rays with XRT on Hinode,
and in several EUV lines from EIS on Hinode. SOHO/MDI magnetograms
show that converging motion between opposite-polarity sunspots in the
region result in expansion of large-scale loops overlying the region's
primary magnetic neutral line, along which sits filament material prior
to its eruption. The source location of an EUV filament's surge-like
ejection is a negative-polarity magnetic region that is north of the
interacting spots, and patches of magnetic field flow at ~ 0.5 km/s
from the positive converging spots into the negative region in the
north. Apparently, repeated episodes of flux cancelation occur where
the flowing positive flux collides with the northern negative flux,
and the source of the EUV filament's ejection is near this cancelation
site. Spectroscopic data from EIS are available for a portion of the
active region that includes the northern cancelation site, and from
these data we obtain bulk-flow velocities, line-broadening turbulent
velocities, and densities of plasma in the region. The array of
observations is consistent with the pre-eruption sheared-core magnetic
arcade being gradually destabilized by evolutionary tether-cutting
flux cancelation that was driven by converging photospheric flows.

---------------------------------------------------------
Title: Density structure of an active region and associated moss
using Hinode/EIS
Authors: Tripathi, D.; Mason, H. E.; Young, P. R.; Del Zanna, G.
2008A&A...481L..53T Altcode: 2008arXiv0802.3311T
Context: Studying the problem of active region heating requires precise
measurements of physical plasma parameters such as electron density,
temperature, etc. It is also important to understand the relationship
of coronal structures with the magnetic field. The Extreme-ultraviolet
Imaging Spectrometer (EIS) aboard Hinode provides a rare opportunity to
derive electron density simultaneously at different temperatures. Aims: We study the density structure and characterise plasma in
active regions and associated moss regions. In addition, we study its
relationship to the photospheric magnetic field. Methods: We used
data recorded by the EIS, together with magnetic field measurements
from the Michelson Doppler Imager (MDI) aboard SoHO and images recorded
with the Transition Region And Coronal Explorer (TRACE) and X-Ray
Telescope (XRT/Hinode). Results: We find that the hot core of
the active region is densest with values as high as 1010.5
cm-3. The electron density estimated in specific regions
in the active region moss decreases with increasing temperature. The
moss areas were located primarily on one side of the active region,
and they map the positive polarity regions almost exactly. The density
within the moss region was highest at log T=5.8{-}6.1, with a value
around 1010.0{-10.5} cm-3. The moss densities
were highest in the strong positive magnetic field region. However,
there was no such correlation for the negative polarity areas, where
there was a large sunspot.

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Title: An active region jet observed with Hinode
Authors: Chifor, C.; Young, P. R.; Isobe, H.; Mason, H. E.; Tripathi,
D.; Hara, H.; Yokoyama, T.
2008A&A...481L..57C Altcode:
Aims:We study the physical properties of an active region (AR) jet in
order to probe the mechanisms responsible for it. Methods: We
report 2007 January 15/16 observations of a recurring jet situated on
the west side of NOAA AR 10938. Multi-wavelength data from all three
instruments onboard Hinode were analysed. This paper focuses on one
instance of a jet observed with the Hinode/EUV Imaging Spectrometer
(EIS). Using EIS raster data we measured the temperatures, Doppler
shifts, density, and filling factor. Results: A strong
blue-shifted component and an indication of a weak red-shifted
component at the base of the jet was observed around Log Te
= 6.2. The up-flow velocities exceeded 150 km s-1. The
jet component was seen over a range of temperatures between 5.4 and
6.4 in Log T_e. Using Fe XII λ186 and λ195 line ratios, we measured
densities above Log Ne = 11 for the high-velocity up-flow
component. We found that the density of the high-velocity up-flow
increases with velocity. We estimate the filling factor in the jet
up-flow to be &lt;0.03. With the Hinode/Solar Optical Telescope (SOT),
we observed recurrent (quasi periodic) magnetic flux cancelations just
before the recurrent jet emission was seen in images taken with the
X-ray Telescope (XRT). Conclusions: The high-velocity up-flows,
together with the density dependence on velocity, support an evaporation
scenario for the acceleration of this jet. The high density and small
filling factor, coupled with the high Doppler velocities are strongly
suggestive of multiple small-scale magnetic reconnection events being
responsible for the production of both EUV and X-ray jets.

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Title: Computation of Non-Maxwellian Electron Excitation Rates for
Ions of Astrophysical Interest: Fe XV - A Test Case
Authors: Dzifčáková, Elena; Mason, Helen
2008SoPh..247..301D Altcode: 2008SoPh..tmp...14D
Dzifčáková previously developed a method for calculating the
influence of nonthermal electron-velocity distributions on the
intensities of spectral lines (Solar Phys.234, 243, 2006; In: Lacoste,
H., Ouwehand, L. (eds.) SOHO-17. 10 Years of SOHO and Beyond, SP-617,
ESA, Noordwijk, 89, 2006). Here, we study this method in detail for
the test case: Fe XV. It involves fitting a parametric form to the
electron-excitation data in the CHIANTI atomic database. We assess
the reliability of these fits by comparing them with the source atomic
data, both Upsilons (Maxwellian-averaged collision strengths) and the
original collision strengths. An accuracy for the method of better than
15% is deduced for all transitions, with a much higher accuracy than
this for the strong electric-dipole transitions. A κ-distribution,
which has an increased number of electrons in the high-energy tail
of the distribution, is considered as an example. The shape of the
κ-distribution affects the electron-excitation rate and thus the
relative intensities of the spectral lines. Since the shape of the
electron distribution function also influences the ionization balance of
Fe, both effects change the final intensities of the lines. Synthetic
spectra for Fe XV and Fe XVI in the wavelength range 50 - 80 Å are
presented for a κ-distribution and compared with solar observations.

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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
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: 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.
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.

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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
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.

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Title: Application of CHIANTI to Solar-B
Authors: Dere, K.; Landi, E.; Del Zanna, G.; Young, P.; Mason, H.;
Landini, M.
2007ASPC..369...35D Altcode:
CHIANTI (http://wwwsolar.nrl.navy.mil/chianti.html) has been developed
to support the interpretation of solar and astrophysical spectroscopic
measurements. The most recent release, version 5.0 (Landi et al. 2005)
presents an improvement over previous versions by including new
large scale datasets for Fe ions from Fe XVII to Fe XXIV for X-ray
emission and improved atomic data for EUV line emission. We will
demonstrate how this can be applied to the analysis of XRT and EIS
data, in particular. For example, new excitation rates for Fe XII have
resolved a long standing problem in the use of Fe XII line ratios as
accurate density diagnostics. Current work involves improvements to
ionization and recombination rates which will also be useful in the
interpretation of Solar-B data

---------------------------------------------------------
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.
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.

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Title: A bright coronal downflow seen in multi-wavelength
observations: evidence of a bifurcating flux-rope?
Authors: Tripathi, D.; Solanki, S. K.; Mason, H. E.; Webb, D. F.
2007A&A...472..633T Altcode: 2008arXiv0802.3616T
Aims:We study the origin and characteristics of a bright coronal
downflow seen after a coronal mass ejection associated with
erupting prominences on 5 March 2000. Methods: This study
extends that of Tripathi et al. (2006b, A&amp;A, 449, 369) based
on the Extreme-ultraviolet Imaging Telescope (EIT), the Soft X-ray
Telescope (SXT) and the Large Angle Spectrometric Coronagraph (LASCO)
observations. We combined those results with an analysis of the
observations taken by the Hα and the Mk4 coronagraphs at the Mauna Loa
Solar Observatory (MLSO). The combined data-set spans a broad range of
temperature as well as continuous observations from the solar surface
out to 30 R⊙. Results: The downflow started at
around 1.6 R⊙ and contained both hot and cold gas. The
downflow was observed in the Hα and the Mk4 coronagraphs as well as
the EIT and the SXT and was approximately co-spatial and co-temporal
providing evidence of multi-thermal plasma. The Hα and Mk4 images
show cusp-shaped structures close to the location where the downflow
started. Mk4 observations reveal that the speed of the downflow in
the early phase was substantially higher than the free-fall speed,
implying a strong downward acceleration near the height at which
the downflow started. Conclusions: The origin of the downflow
was likely to have been magnetic reconnection taking place inside
the erupting flux rope that led to its bifurcation. Movies are
available in electronic form at http://www.aanda.org

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Title: X-ray precursors to flares and filament eruptions
Authors: Chifor, C.; Tripathi, D.; Mason, H. E.; Dennis, B. R.
2007A&A...472..967C Altcode:
Aims:To study preflare X-ray brightenings as diagnostics of the
destabilisation of flare-associated erupting filaments/prominences. Methods: We combine new observations from the Transition Region
and Coronal Explorer (TRACE) and the Reuven Ramaty High Energy Solar
Spectroscopic Imager (RHESSI), as well as revisit events reported in the
literature to date, in order to scrutinise the preflare activity during
eight flare-associated filament eruptions. Results: The preflare
activity occurs in the form of discrete, localised X-ray brightenings
observed between 2 and 50 min before the impulsive phase of the flare
and filament acceleration. These transient preflare brightenings are
situated on or near (within 10{ arcsec} of) the polarity inversion
line (PIL), coincident with emerging and/or canceling magnetic
flux. The filaments begin to rise from the location of the preflare
brightenings. In five out of eight events, the preflare brightenings
were observed beneath the filament channel, close to the filament
footpoint first observed to rise. Both thermal and nonthermal hard
X-ray emissions during the preflare enhancement were detected with
RHESSI, suggesting that both plasma heating and electron acceleration
occurred at this time. The main energy release during the impulsive
phase of the flare is observed close to (within 50{ arcsec} of) the
preflare brightenings. The fast-rise phase of the filament eruption
starts at the same time as the onset of the main flare or up to 5 min
later. Conclusions: The preflare brightenings are precursors to
the flare and filament eruption. These precursors represent distinct,
localised instances of energy release, rather than a gradual energy
release prior to the main flare. The X-ray precursors represent clearly
observable signatures in the early stages of the eruption. Together with
the timing of the filament fast-rise at or after the main flare onset,
the X-ray precursors provide evidence for a tether-cutting mechanism
initially manifested as localised magnetic reconnection being a common
trigger for both flare emission and filament eruption. Movies and
Appendix A are only available in electronic form at http://www.aanda.org

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Title: Coronal Loops: Isothermal or Multithermal?
Authors: Kimble, Jason; Schmelz, J. T.; Nasraoui, K.; Cirtain, J. W.;
Del Zanna, G.; DeLuca, E. E.; Mason, H. E.
2007AAS...210.9120K Altcode: 2007BAAS...39..207K
The coronal loop data used for this analysis were taken on 2003 January
17 at 14:24:45 UT by the Coronal Diagnostic Spectrometer (CDS) aboard
the Solar and Heliospheric Observatory. We use the Chianti atomic
physics data base and the hybrid coronal abundances to determine
temperatures and densities for positions along several loops. The
traditional method used to create our differential emission measure
(DEM) curves has been forward folding, but we are now using both
emission measure loci plots and DEM automatic inversion to support
and confirm the original conclusions. In this poster, we will look
specifically at the emission measure loci analysis of three loops
visible in the CDS data set. We find different results for each of
these loops. One of the loops seems to be composed of isothermal
plasma with Log T = 5.8 MK. The temperature does not appear to change
with position, from the footpoint to the loop leg. Unfortunately,
the loop top is outside the CDS field of view. Each pixel examined in
the second loop seems to require a multithermal DEM distribution. For
the third loop, the temperature increases and the density appears
to decrease with loop height, reminiscent of traditional hydrostatic
loop models. Solar physics research at the University of Memphis is
supported by NSF ATM-0402729 and NASA NNG05GE68G.

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Title: SOHO-CDS: Thermal and Density Analysis of Coronal Loops
Authors: Rightmire, Lisa; Schmelz, J. T.; Cirtain, J. W.; Del Zanna,
G.; DeLuca, E. E.; Mason, H. E.
2007AAS...210.9121R Altcode: 2007BAAS...39..207R
Data was obtained using the Coronal Diagnostic Spectrometer (CDS)
instrument on the Solar and Heliospheric Observatory (SOHO). The goal
of this project is to analyze the data obtained by the CDS instrument
in order to determine the behavior of temperature and density of the
coronal loop progressing from the foot point and moving up the loop. The
loop being analyzed was observed by CDS on 2003 January 17 and the foot
point was located at solar coordinates (585,-472) arcsecs. A background
pixel and several pixels on the loop were selected. The background pixel
intensity was then subtracted from each loop pixel intensity in order to
isolate the emission from each loop pixel. The spectral line intensities
of each loop pixel were analyzed to determine which spectral lines
had any significant contribution to the loop intensity. The predicted
and observed intensities of these significant lines were then used to
create a differential emission measure (DEM) curve to best fit each
loop pixel emission. Comparison of the DEM curves for each loop pixel
indicates that the temperature increases and the density decreases,
while progressing up the loop. Solar physics research at the University
of Memphis is supported by NSF ATM-0402729 and NASA NNG05GE68G.

---------------------------------------------------------
Title: Are Coronal Loops Isothermal Or Multithermal? Yes!
Authors: Schmelz, Joan T.; Nasraoui, K.; Rightmire, L.; Garst, J.;
Kimble, J.; Cirtain, J.; DeLuca, E. E.; Del Zanna, G.; Mason, H.
2007AAS...210.9431S Altcode: 2007BAAS...39..222S
Analysis of loops observed with the Coronal Diagnostics Spectrometer
(CDS) and the Transition Region and Coronal Explorer (TRACE) reveal
examples of both isothermal and multithermal plasma. These data
were taken on 2003 January 17, and since the loops are on the disk,
a lot of work was done on the details of background subtraction. The
background-subtracted CDS intensities were analyzed using three
methods: (1) Emission Measure Loci, (2) Forward-Folding DEM, and (3)
Automatic-Inversion DEM. The first loop appears to be isothermal,
with Log T = 5.8 MK. The forward-folding DEM shows a spike at this
temperature and the EM Loci curves all intersect at this point. The
automatic-inversion DEM results are broadened, however, as a result
of the smoothing required for this method. This loop has a uniform
temperature along the segment visible in the CDS field of view,
and this result is confirmed using the TRACE data. The pixels along
the second loop do not appear to be isothermal. The EM Loci curves
do not intersect at a single point and both DEM methods show a broad
curve. Other loops in this data set as well as loop evolution will be
investigated if time permits. Solar physics research at the University
of Memphis is supported by NSF ATM-0402729 and NASA NNG05GE68G.

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Title: Differential Emission Measurements on Sparse Raster Data
from SOHO-CDS
Authors: Garst, Jennifer W.; Schmelz, J. T.; Nasraoui, K.; Cirtain,
J. W.; DeLuca, E. E.; Del Zanna, G.; Mason, H. E.
2007AAS...210.2517G Altcode: 2007BAAS...39..133G
Two types of rasters were taken on 2003 January 17 with the Solar and
Heliospheric Observatory’s Coronal Diagnostic Spectrometer. The
first type contains a continuous image of coronal loops under
investigation while the second, the ‘sparse raster,’ was taken at
spatial intervals in order to simulate enhanced time resolution. With
this technique, intensities in 14 passbands were collected at fixed
positions on the solar disk every 7 minutes. The start time for the
CDS observations was 06:51:27 UT and the observing sequences ran for
7 hours. The continuous rasters were interspersed with the sparse
rasters. All the rasters were then co-aligned and a loop pixel and a
background pixel were selected for detailed analysis. Differential
emission measure was performed on the background-subtracted CDS
intensities to determine the temporal evolution of the loop pixel
plasma. Solar physics research at the University of Memphis is supported
by NSF ATM-0402729 and NASA NNG05GE68G.

---------------------------------------------------------
Title: Coronal Diagnostics Spectrometer Observations of Coronal Loops
Authors: Nasraoui, Kaouther; Schmelz, J. T.; Cirtain, J. W.; Del Zanna,
G.; DeLuca, E. E.; Mason, H. E.
2007AAS...210.9122N Altcode: 2007BAAS...39..207N
Two side by side loops from the solar disk were analyzed. These two
loops were observed with the Coronal Diagnostics Spectrometer on
SOHO on 2003 January 17. The first loop was best seen in Mg IX at
a wavelength of 368 angstroms and a peak formation temperature of
Log T = 6.0. Seven pixels on the loop and one background pixel were
chosen. The intensity of the background pixel was subtracted from each
of the loop pixels. Only the lines that had a significant intensity
after background subtraction were considered. A differential emission
measure (DEM) curve was constructed for the background subtracted data
using the forward folding technique. The DEM for most of these pixels
had a spike shape at Log T equal to 5.85. This result shows that the
loop is isothermal at most of these pixels. The second loop was best
seen in Si XII at a wavelength of 520 angstroms and a peak formation
temperature of Log T = 6.3. The same procedure was followed for the
data analysis. After background subtraction only some hot lines had a
significant intensity and a DEM curve was constructed for each loop
pixel. This time the DEM is broader with a shape that shows that
the loop plasma is multithermal with a log temperature range of 6.1
to 6.5. Solar physics research at the University of Memphis is
supported by NSF ATM-0402729 and NASA NNG05GE68G.

---------------------------------------------------------
Title: Coronal Diagnostic Spectrometer Observations of Isothermal
and Multithermal Coronal Loops
Authors: Schmelz, J. T.; Nasraoui, K.; Del Zanna, G.; Cirtain, J. W.;
DeLuca, E. E.; Mason, H. E.
2007ApJ...658L.119S Altcode:
A data set obtained on 2003 January 17 with the Coronal Diagnostic
Spectrometer (CDS) shows two loops sitting side by side on the solar
disk. These loops are oriented along the CDS slit, so all pixels in
each loop were observed simultaneously. So, although the instrument
has a relatively slow time cadence, changes as a function of time
that may occur during the CDS raster buildup will not affect the loop
temperature results. Differential emission measure (DEM) analysis
using a forward-folding technique shows different results for the
two loops. For the first loop, the intensities of the lines that
remain after background subtraction are well fit with a DEM curve that
collapses to a single spike. In other words, the loop plasma at this
location is isothermal. This analysis is confirmed with an emission
measure loci method and agrees with the results obtained recently
by other authors that show that the moderate spatial resolution
of CDS can detect isothermal structures. For the second loop, the
background-subtracted line intensities require a broad DEM, not
consistent with isothermal plasma. This conclusion is confirmed with
an automatic-inversion DEM method. In this Letter, we specifically
address some of the concerns raised about CDS temperature analysis:
the slow CDS temporal resolution, the moderate CDS spatial resolution,
the inherent smoothing associated with DEM inversion, and line-of-sight
effects on the DEM distribution.

---------------------------------------------------------
Title: Active Region Loops: Temperature Measurements as a Function
of Time from Joint TRACE and SOHO CDS Observations
Authors: Cirtain, J. W.; Del Zanna, G.; DeLuca, E. E.; Mason, H. E.;
Martens, P. C. H.; Schmelz, J. T.
2007ApJ...655..598C Altcode:
In this paper, we aim to quantitatively investigate the structure
and time variation of quiescent active region loop structures. We
coordinated a joint program of observations (JOP 146) using TRACE, to
obtain high-cadence EUV images, and SOHO CDS, to obtain spectroscopic
data. Loop intensities are used to determine temperature as a function
of time for a single loop, taking full account of the background
emission. In many locations, the emission measure loci are consistent
with an isothermal structure. However, the results indicate significant
changes in the loop temperature (between 1 and 2 MK) over the 6 hr
observing period. It is possible that the loop structures are composed
of multiple, independently heated strands with sizes less than the
resolution of the imager and spectrometer.

---------------------------------------------------------
Title: A benchmark study for CHIANTI based on RESIK solar flare
spectra
Authors: Chifor, C.; Del Zanna, G.; Mason, H. E.; Sylwester, J.;
Sylwester, B.; Phillips, K. J. H.
2007A&A...462..323C Altcode:
Aims:To perform a benchmark analysis for the recent version of the
CHIANTI atomic database (v. 5.2) based on high-resolution solar
flare X-ray spectra in the range 3.4-6.1 Å from the RESIK crystal
spectrometer on the CORONAS-F spacecraft. Methods: A C5.8 flare
occurring on 2003 February 22 was chosen for analysis. RESIK spectra
of this flare include emission lines of He-like and H-like K, Ar,
S, and Si, with some dielectronic lines. Initially, two independent
plasma diagnostic techniques are employed: an emission measure
(EM) loci analysis using the line flux and the line contribution
function G(T_e, N_e), and a new method based on continuum fluxes and
contribution functions. We further apply a differential emission measure
(DEM) analysis, from which CHIANTI synthetic spectra are derived. The
continuum from RESIK spectra is checked against simultaneous RHESSI and
GOES observations. Comparisons of CHIANTI synthetic spectra with those
from the MEKAL code in the 3.4-6.1 Å range are also presented. Results: The emitting plasma appears multi-thermal, having one
dominant temperature component determined independently from the line
and continuum EM loci and DEM analyses. Consistency between line
and continuum emissions requires photospheric elemental abundances
(Asplund et al. 2005), with a depleted sulphur abundance. With the
exception of RESIK channel 4 (5.0-6.1 Å), we find overall very
good agreement between the calculated and observed intensities. From
comparisons with other instruments, RESIK's precision in the continuum
level is confirmed to be within the estimated 20% uncertainties in the
intensity calibration. We find general agreement between CHIANTI and
MEKAL isothermal spectra, but we note that the atomic data for the
Si xii and Si xiii ions contained in CHIANTI are more complete. Conclusions: .RESIK observations of both lines and continua are
suitable for characterising the properties of the flaring plasma such
as temperature, emission measure and elemental abundance. These spectra
can be used to evaluate any atomic database.

---------------------------------------------------------
Title: EIT and TRACE responses to flare plasma
Authors: Tripathi, D.; Del Zanna, G.; Mason, H. E.; Chifor, C.
2006A&A...460L..53T Altcode: 2008arXiv0802.3852T
Aims.To understand the contribution of active region and flare
plasmas to the λ195 channels of SOHO/EIT (Extreme-ultraviolet Imaging
Telescope) and TRACE (Transition Region and Coronal Explorer). 
Methods: .We have analysed an M8 flare simultaneously observed by
the Coronal Diagnostic Spectrometer (CDS), EIT, TRACE and RHESSI. We
obtained synthetic spectra for the flaring region and an outer region
using the differential emission measures (DEM) of emitting plasma based
on CDS and RHESSI observations and the CHIANTI atomic database. We
then predicted the EIT and TRACE count rates. Results: .For the
flaring region, both EIT and TRACE images taken through the λ195
filter are dominated by Fe XXIV (formed at about 20 MK). However,
in the outer region, the emission was primarily due to the Fe XII,
with substantial contributions from other lines. The average count
rate for the outer region was within 25% the observed value for EIT,
while for TRACE it was a factor of two higher. For the flare region,
the predicted count rate was a factor of two (in case of EIT) and
a factor of three (in case of TRACE) higher than the actual count
rate. Conclusions: .During a solar flare, both TRACE and EIT
λ195 channels are found to be dominated by Fe XXIV emission. Reasonable
agreement between predictions and observations is found, however some
discrepancies need to be further investigated.

---------------------------------------------------------
Title: The Gradual Phase of the X17 Flare on October 28, 2003
Authors: del Zanna, G.; Schmieder, B.; Mason, H.; Berlicki, A.;
Bradshaw, S.
2006SoPh..239..173D Altcode: 2006SoPh..239..173Z; 2006SoPh..tmp...74Z
We present SOHO/CDS observations taken during the gradual phase of
the X17 flare that occurred on October 28, 2003. The CDS data are
supplemented with TRACE and ground-based observations. The spectral
observations allow us to determine velocities from the Doppler
shifts measured in the flare loops and in the two ribbon kernels,
one hour and a half after the flare peak. Strong downflows (&gt;70 km
s-1) are observed along the loop legs at transition-region
temperatures. The velocities are close to those expected for free
fall. Observations and results from a hydrodynamic simulation are
consistent with the heating taking place for a short time near the
top of the arcade. Slight upflows are observed in the outer edges of
the ribbons (&lt;60 km s-1) in the EUV lines formed at log
T &lt; 6.3. These flows could correspond to the so-called “gentle
evaporation.” At “flare” temperatures (Fe xix, log T = 6.9),
no appreciable flows are observed. The observations are consistent
with the general standard reconnection models for two-ribbons flares.

---------------------------------------------------------
Title: The early phases of a solar prominence eruption and associated
flare: a multi-wavelength analysis
Authors: Chifor, C.; Mason, H. E.; Tripathi, D.; Isobe, H.; Asai, A.
2006A&A...458..965C Altcode:
Aims.We aim to examine the precursor phases and early evolution of a
prominence eruption associated with a M4-class flare and a partial
halo coronal mass ejection (CME) observed on 2005 July 27. Our
main goal is to investigate the precursor eruption signatures
observed in EUV, X-ray and microwave emission and their relation
to the prominence destabilisation. Methods: .We perform a
multi-wavelength study of the prominence morphology and motion using
high-cadence and spatial resolution EUV 171 Å images from the TRACE
satellite. The high-temperature flare radiative emission in soft
and hard X-rays are analysed through imaging and spectral modeling
with RHESSI. Complementary microwave images (17 GHz and 34 GHz)
from NoRH are also investigated. Results: .The activation
of the filament proceeds from one anchored footpoint. We observe
"pre-eruption" brightenings in X-ray and EUV images, close to the
erupting footpoint of the prominence, being temporally correlated to
the point when the prominence first enters a slow-rise phase, and then
an accelerated fast-rise phase. The brightness temperature (T_b) of the
prominence at 34 GHz is increasing during the eruption. We also find
very good correlation between the prominence height-time profile and
the spatially integrated soft X-ray (SXR) emission. Conclusions:
.We discuss the observed precursor brightenings with respect to possible
mechanisms that might be responsible for the prominence destabilisation
and acceleration. Our observations suggest that reconnection events
localised beneath the erupting footpoint may eventually destabilise
the entire prominence, causing the eruption.

---------------------------------------------------------
Title: Phosphorus distribution in calcite speleothems from solid-state
NMR and AFM
Authors: Mason, H. E.; Hausner, D.; Frisia, S.; Tang, Y.; Reeder,
R. J.; Strongin, D. R.; Phillips, B. L.
2006GeCAS..70Q.399M Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Multi-Wavelength Investigation of a Sigmoidal Active Region
Authors: Tripathi, D.; Mason, H. E.; Young, P. R.
2006ESASP.617E.148T Altcode: 2006soho...17E.148T
No abstract at ADS

---------------------------------------------------------
Title: Asymmetric Prominence Eruption: A "Domino Effect"?
Authors: Chifor, C.; Mason, H. E.; Tripathi, D.; Isobe, H.; Asai, A.
2006ESASP.617E.121C Altcode: 2006soho...17E.121C
No abstract at ADS

---------------------------------------------------------
Title: On the propagation of brightening after filament/prominence
eruptions, as seen by SoHO-EIT
Authors: Tripathi, D.; Isobe, H.; Mason, H. E.
2006A&A...453.1111T Altcode:
Aims.To study the relationship between the propagation of brightening
and erupting filaments/prominences in order to get some insight into
the three-dimensional picture of magnetic reconnection. Methods:
.Analysis of the observations taken with the EIT (Extreme-ultraviolet
Imaging Telescope) aboard SoHO (Solar and Heliospheric Observatory). Results: .When the prominences/filaments erupted having one point
fixed - asymmetric eruption - the brightening propagated along the
neutral line together with the expansion/separation from the polarity
inversion line (PIL) as expected from the standard models. However
in case of symmetric eruptions, the brightening propagated towards
both end points starting at the middle. When the prominence/filament
erupted faster then the speed of the propagating brightening was
faster and vice-versa. Conclusions: .Based on these observations
we conclude that the eruption and magnetic reconnection - propagation
(along the PIL) and separation (away from PIL) of the brightening - are
dynamically coupled phenomena. These observations can be explained by
a simple extension of the 2D models illustrating eruption and magnetic
reconnection to a 3D model.

---------------------------------------------------------
Title: SOHO/CDS Observations of Quiescent Active Region Loops
Authors: Del Zanna, G.; Mason, H. E.; Cirtain, J.
2006ESASP.617E..86D Altcode: 2006soho...17E..86D
No abstract at ADS

---------------------------------------------------------
Title: The Coronal Loop Controversy: Resolved!
Authors: Schmelz, Joan T.; Nasraoui, K.; Cirtain, J.; DeLuca, E.;
Del Zanna, G.; Mason, H.
2006SPD....37.1701S Altcode: 2006BAAS...38..245S
Critics have pointed out the shortcomings of CDS coronal loop
temperature analysis - the large pixel size and the slow time
cadence. It is these limitations, some say, that have produced
multithermal results for the loop observed with CDS on 1998 April
20, both along the line of sight and along the loop length. Analysis
of the CDS observations of AR 10250 from 2003 January 17, however,
seem to contradict these critics. Two loops sit side-by-side right
along the slit in this raster, so all pixels in each loop were
observed at the same time. As a result changes as a function of time
will not affect the temperature results. The first loop is observed
primarily in Mg IX (Log T = 6.0) and the second in Si XII (Log T =
6.3). Differential Emission Measure (DEM) analysis of background
subtracted line intensities of pixels in each loop show distinctly
different results. For the first loop, the intensities of the lines
that remain after background subtraction are well fit with a DEM that
collapses to a single spike. In other words, the loop plasma at this
location is isothermal. This proves that it is neither the DEM method
nor the CDS pixel size that produced the multithermal distributions
for the 1998 April 20 loop plasma. In addition the DEM distribution for
the second loop is similar to those produced for the 1998 April 20 loop
and is clearly inconsistent with isothermal plasma. Both distributions
change as a function of position along the loop, with the temperatures
increasing with loop height. Solar physics research at the University
of Memphis is supported by grants from NSF and NASA.

---------------------------------------------------------
Title: Exploring High Time Resolution Coronal Dynamics with the
Rapid Acquisition Imaging Spectrograph (RAISE) Sounding Rocket Program
Authors: Hassler, Donald W.; DeForest, C. E.; McIntosh, S.; Slater,
D.; Ayres, T.; Thomas, R.; Scheuhle, U.; Michaelis, H.; Mason, H.
2006SPD....37.3706H Altcode:
The Rapid Acquisition Imaging Spectrograph (RAISE) is a next-generation
high resolution imaging spectrograph to study the dynamics of the
solar chromosphere and corona on time scales as short as 100 ms. High
speed imaging from TRACE has shown that rapid motions and reconnection
are central to the physics of the transition region and corona, but
cannot resolve the differences between propagating phenomena and bulk
motion. SoHO/CDS and SoHO/SUMER have yielded intriguing measurements
of motion and heating in the solar atmosphere, and Solar-B/EIS will
capture EUV spectra of flares in progress; but no currently planned
instrument can capture spectral information in the chromosphere,
transition region, or cool corona on the 1-10 Hz time scale required for
few-second cadence spectral imaging or rapid wave motion studies. RAISE
is uniquely suited to exploring this hard-to-reach domain.The first
flight of RAISE is scheduled for October 24, 2006 (Flight 36.219 US)
and will focus on the study of high frequency, small-scale dynamics
of active region structures and the high frequency wave structure
associated with these active regions.

---------------------------------------------------------
Title: A Multi-Wavelength Study of the Compact M1 Flare on October
22, 2002
Authors: Zanna, G. Del; Berlicki, A.; Schmieder, B.; Mason, H. E.
2006SoPh..234...95Z Altcode:
In this paper we present a further study of the Ml class
flare observed on October 22, 2002. We focus on the SOHO Coronal
Diagnostic Spectrometer (CDS) spectral observations performed during a
multi-wavelength campaign with TRACE and ground-based instruments (VTT,
THEMIS). Strong blue-shifts are observed in the CDS coronal lines in
flare kernels during the impulsive phase of this flare. From a careful
wavelength calibration we deduce upflows of 140 km/s for the Fe XIX
flare emission, with a pattern of progressively smaller flows at lower
temperatures. Large line-widths were observed, especially for the Fe XIX
line, which indicate the existence of turbulent velocities. The strong
upflows correspond to full shifts of the line profiles. These flows
are observed at the initial phase of the flare, and correspond to the
"explosive evaporation". The regions of the blueshifted kernels, a few
arc seconds away from the flare onset location, could be explained by
the chain reaction of successive magnetic reconnections of growing
emerging field line with higher and higher overlying field. This
interpretation is evidenced by the analysis of the magnetic topology
of the active region using a linear force-free-field extrapolation of
THEMIS magnetograms.

---------------------------------------------------------
Title: A Multi-Wavelength Study of the Compact M1 Flare on October
22, 2002
Authors: del Zanna, G.; Berlicki, A.; Schmieder, B.; Mason, H. E.
2006SoPh..234...95D Altcode: 2006SoPh..234...95Z
In this paper we present a further study of the Ml class
flare observed on October 22, 2002. We focus on the SOHO Coronal
Diagnostic Spectrometer (CDS) spectral observations performed during a
multi-wavelength campaign with TRACE and ground-based instruments (VTT,
THEMIS). Strong blue-shifts are observed in the CDS coronal lines in
flare kernels during the impulsive phase of this flare. From a careful
wavelength calibration we deduce upflows of 140 km/s for the Fe XIX
flare emission, with a pattern of progressively smaller flows at lower
temperatures. Large line-widths were observed, especially for the Fe
XIX line, which indicate the existence of turbulent velocities. The
strong upflows correspond to full shifts of the line profiles. These
flows are observed at the initial phase of the flare, and correspond
to the “explosive evaporation”. The regions of the blueshifted
kernels, a few arc seconds away from the flare onset location, could be
explained by the chain reaction of successive magnetic reconnections of
growing emerging field line with higher and higher overlying field. This
interpretation is evidenced by the analysis of the magnetic topology
of the active region using a linear force-free-field extrapolation of
THEMIS magnetograms.

---------------------------------------------------------
Title: X-ray emission from PTT stars
Authors: Del Zanna, G.; Worters, H. L.; Bromage, G. E.; Foley, C. A.;
Mason, H. E.; Landini, M.; Whiting, A.
2006AdSpR..38.1475D Altcode:
We present preliminary results on an XMM-Newton observation dedicated to
Post-T-Tauri (PTT) stars. We observed the visual binary 2RE J0241-53 of
the Horologium association of nearby PTT stars. The XMM observations
have been complemented with ground-based optical spectroscopy and
photometry. Several flares have been observed. The X-ray spectrum of
the brightest star during quiescence indicates a rather cool corona
(with no emission at temperatures ⩾10 MK) more similar to that of the
Classical T-Tauri star TW Hya (observed with Chandra and XMM-Newton)
and at variance with that of another PTT Star (PZ Tel) observed with
Chandra. Approximate analysis shows large Ne/Fe, N/Fe, C/Fe abundances
(compared to solar photospheric values).

---------------------------------------------------------
Title: CHIANTI-An Atomic Database for Emission Lines. VII. New Data
for X-Rays and Other Improvements
Authors: Landi, E.; Del Zanna, G.; Young, P. R.; Dere, K. P.; Mason,
H. E.; Landini, M.
2006ApJS..162..261L Altcode:
The CHIANTI atomic database contains atomic energy levels, wavelengths,
radiative transition probabilities, and collisional excitation data for
a large number of ions of astrophysical interest. CHIANTI also includes
a suite of IDL routines to calculate synthetic spectra and carry out
plasma diagnostics. Version 5 has been released, which includes several
new features, as well as new data for many ions. The new features in
CHIANTI are as follows: the inclusion of ionization and recombination
rates to individual excited levels as a means to populate atomic
levels; data for Kα and Kβ emission from Fe II to Fe XXIV; new data
for high-energy configurations in Fe XVII to Fe XXIII; and a complete
reassessment of level energies and line identifications in the X-ray
range, multitemperature particle distributions, and photoexcitation
from any user-defined radiation field. New data for ions already in
the database, as well as data for ions not present in earlier versions
of the database, are also included. Version 5 of CHIANTI represents a
major improvement in the calculation of line emissivities and synthetic
spectra in the X-ray range and expands and improves theoretical spectra
calculations in all other wavelength ranges.

---------------------------------------------------------
Title: Dynamics of Active Region Loops: Temperature Measurements as
a function of Time
Authors: Cirtain, J. J.; del Zanna, G.; Mason, H.; Deluca, E.;
Martens, P.
2005AGUFMSH44A..03C Altcode:
The combination of moderate resolution EUV spectroscopy and high
resolution narrow band filter images provides the most accurate
measure of temperature and density for coronal loops to date. We will
demonstrate our technique for combining the data sets from the Coronal
Diagnostic Spectrometer on SoHO and the Transition Region and Coronal
Explorer. Background subtracted spectral intensities are used to
determine the temperature of coronal loops and the TRACE images help
determine the loop cross-section, temporal variability, and filling
factor. The resulting temperature profiles for multiple positions along
a loop leg are determined using the EM LOCI method, and a technique for
determining whether a single temperature can characterize the plasma is
also presented. We compare the results of our study to current models.

---------------------------------------------------------
Title: Flows and Heating of the Solar Atmosphere during Solar Flares
Authors: Schmieder, B.; Berlicki, A.; Li, H.; Del Zanna, G.; Mason, H.
2005ESASP.592..543S Altcode: 2005soho...16E.102S; 2005ESASP.592E.102S
No abstract at ADS

---------------------------------------------------------
Title: Recent developments of the CHIANTI database in the X-ray
wavelength range
Authors: Landi, E.; Dere, K. P.; Young, P. R.; del Zanna, G.; Mason,
H. E.; Landini, M.
2005AIPC..774..409L Altcode:
CHIANTI is a database of atomic data and transition probabilities that
allows the calculation of synthetic spectra and plasma diagnostics of
optically thin plasmas. It is primarily suited for wavelengths shorter
than 2000 Å but in principle can also be used at longer wavelengths. In
the present paper we illustrate the latest development of the CHIANTI
database, that include a huge expansion of the database in the X-ray
wavelength range, the renewal of several data in the EUV range, and
the inclusion of ionization and recombination in the level population
calculation. This enhanced database will constitute the Version 5
of CHIANTI.

---------------------------------------------------------
Title: EUV Observations of Active Region Dynamics
Authors: Deluca, E. E.; Cirtain, J. W.; del Zanna, G.; Mason, H. E.;
Martens, P. C.; Schmelz, J.; Golub, L.
2005AGUSMSP33A..03D Altcode:
Data collected during SoHO JOP 146, in collaboration with TRACE, is
used to investigate the physical characteristics of coronal active
region loops as a function of time and position along and across
loop structures. These data include TRACE images in all three EUV
passbands, and simultaneous CDS spectroscopic observations. Preliminary
measurements of the loop temperature both along the loop half-length
and loop cross-section are presented as a function of time. We will
show the temperature and density profiles of several structures as a
function of position, show changes in temperature and density with time
and characterize the coronal background emission. Questions raised
by these results will be greatly advanced with the high resolution
spectra available from the EIS on Solar-B.

---------------------------------------------------------
Title: Benchmarking atomic data for astrophysics: Fe XII
Authors: Del Zanna, G.; Mason, H. E.
2005A&A...433..731D Altcode:
We use recently calculated electron collisional data by [CITE] for
ion{Fe}{xii} (n=3 configurations) to build a model ion to compare
to spectroscopic observations of the solar corona and laboratory
measurements. We review all the line identifications of the brightest
lines, by comparing both wavelengths and line intensities. The
presence of blends in different plasma conditions is highlighted. A
large number of new energy levels and line identifications are
proposed. In particular, we identify the electric quadrupole
^4P{5/2}^e-^4F{9/2}e transition with the bright coronal
line observed at 592.6 Å, previously unidentified. This line, when
observed with the 1242.0, 1349.5 UV forbidden lines, is a good density
diagnostic over a large range of electron densities. We also indicate
the best spectral lines to be used for density diagnostics or instrument
calibration. From various combinations of lines we obtain electron
densities that are significantly different from those published in the
previous literature. Some examples are provided. The agreement between
theory and experimental data in terms of wavelengths, line intensities
and level lifetimes is excellent. The full datasets of energies
(Table 2) and radiative data (Table 3) are only available in electronic
form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5)
or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/433/731

---------------------------------------------------------
Title: Atomic data from the IRON Project
Authors: Storey, P. J.; Del Zanna, G.; Mason, H. E.; Zeippen, C. J.
2005A&A...433..717S Altcode:
A new calculation of rate coefficients for electron collisional
excitation of ion{Fe}{xii} is presented and compared to earlier
calculations. Significant differences are found with all earlier work
due to the inclusion of resonance processes that have not previously
been considered and to the use of the intermediate coupling frame
transformation method. The resulting dataset of collision strengths
is shown to resolve many of the outstanding discrepancies between
theory and solar observations. In particular, density sensitive
line ratios in ion{Fe}{xii} now indicate electron densities
close to those derived from other ions of comparable ionization
potential. Table 10 is only available in electronic form at the
CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/433/717

---------------------------------------------------------
Title: Multialtitude Observations of a Coronal Jet during the Third
Whole Sun Month Campaign
Authors: Ko, Y. -K.; Raymond, J. C.; Gibson, S. E.; Alexander, D.;
Strachan, L.; Holzer, T.; Gilbert, H.; Cyr, O. C. St.; Thompson, B. J.;
Pike, C. D.; Mason, H. E.; Burkepile, J.; Thompson, W.; Fletcher, L.
2005ApJ...623..519K Altcode:
On 1999 August 26, a coronal jet occurred at the northwest limb near
a sigmoid active region (AR 8668) that was the target for a joint
observation plan (SOHO joint observing program 106) during the third
Whole Sun Month Campaign. This jet was observed by several instruments
at the limb (SOHO/CDS, SOHO/EIT, TRACE, and Mauna Loa Solar Observatory
CHIP and PICS) and at 1.64 Rsolar (SOHO/UVCS). At the limb,
this jet event displayed both low- and high-temperature components. Both
high- and low-temperature components were evident during the early phase
(first 20 minutes) of the event. However, the low-temperature component
is maintained for ~1 hr after the higher temperature component is
gone. There is a second brightening (a possible second jet) seen by
EIT and TRACE about 50 minutes after the onset of the first jet. The
line-of-sight motion at the limb began with a 300 km s-1
redshift and evolved to a 200 km s-1 blueshift. At
1.64 Rsolar, the intensities of Lyα and Lyβ in the jet
increased by a factor of several hundred compared with the background
corona. The C III λ977 line also brightened significantly. This
indicates low-temperature [~(1-2)×105 K] emission in the
jet, while the intensities of O VI λ1032 and O VI λ1037 increased
by as much as a factor of 8. The UVCS data show evidence of heating at
the early phase of the event. The Doppler shift in the lines indicates
that the line-of-sight (LOS) velocity in the jet started from ~150
km s-1 in blueshift and ended at ~100 km s-1
in redshift. This LOS motion seen at 1.64 Rsolar was
apparently opposite to what was observed when the jet emerged from the
limb. The Doppler dimming analysis indicates that the radial outflow
speed correlates with the magnitude of the LOS speed. Interestingly,
UVCS observations at 2.33 and 2.66 Rsolar show no trace of
the jet and SOHO/LASCO observations also yield no firm detection. We
find that a simple ballistic model can explain most of the dynamical
properties of this jet, while the morphology and the thermal properties
agree well with reconnection-driven X-ray jet models.

---------------------------------------------------------
Title: Benchmarking atomic data for astrophysics: Fe XXIII
Authors: Del Zanna, G.; Chidichimo, M. C.; Mason, H. E.
2005A&A...432.1137D Altcode:
Recent scattering calculations for Fe XXIII are benchmarked against
laboratory and astrophysical observations. The collisional data are
supplemented by radiative data obtained with empirical adjustments
that take into account observed wavelengths. All previous line
identifications and energy levels are reviewed and assessed in light
of these new calculations. Most of the previous identifications,
in particular of the astrophysically-important spectral lines are
confirmed. However, some identification are rejected or questioned, and
new ones proposed. The agreement between theoretical and experimental
data in terms of wavelengths, line intensities and level lifetimes is
very good. Observations of Fe XXIII L-shell emission lines provide
a great opportunity to directly measure electron temperatures for
a wide range of astrophysical sources. Examples from solar (SMM,
SOLEX) and stellar (Chandra, EUVE) observations are provided. The full set of energies (cf. Table 2), wavelengths and A-values
(cf. Table 3) are available in electronic form at the CDS via
anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/432/1137 .

---------------------------------------------------------
Title: VizieR Online Data Catalog: Fe XXIII Benchmarking (Del
Zanna+, 2005)
Authors: Del Zanna, G.; Chidichimo, M. C.; Mason, H. E.
2005yCat..34321137D Altcode:
Recent scattering calculations for Fe XXIII are benchmarked against
laboratory and astrophysical observations. The collisional data are
supplemented by radiative data obtained with empirical adjustments
that take into account observed wavelengths. All previous line
identifications and energy levels are reviewed and assessed in light
of these new calculations. Most of the previous identifications,
in particular of the astrophysically-important spectral lines are
confirmed. However, some identification are rejected or questioned, and
new ones proposed. The agreement between theoretical and experimental
data in terms of wavelengths, line intensities and level lifetimes is
very good. Observations of Fe XXIII L-shell emission lines provide
a great opportunity to directly measure electron temperatures for
a wide range of astrophysical sources. Examples from solar (SMM,
SOLEX) and stellar (Chandra, EUVE) observations are provided. **************************************************************************
* * * Sorry, but the author(s) never supplied
the tabular material * * announced in the paper * * *
**************************************************************************
(1 data file).

---------------------------------------------------------
Title: VizieR Online Data Catalog: Atomic data from the IRON
Project. LVI. (Chidichimo+, 2005)
Authors: Chidichimo, M. C.; Del Zanna, G.; Mason, H. E.; Badnell,
N. R.; Tully, J. A.; Berrington, K. A.
2005yCat..34300331C Altcode:
Collision strengths for electron induced transitions in
the beryllium-like ion Fe+22 are calculated
using the intermediate coupling frame transformation
(ICFT) version of the R-matrix programs. Our target
has 98 fine structure states ls2 nl n'l'SLJ
corresponding to n=2 and n'=2, 3, 4. The present calculation
is for electron impact energies in the range 3.15 to 380Ry. **************************************************************************
* * * Sorry, but the author(s) never supplied
the tabular material * * announced in the paper * * *
**************************************************************************
(1 data file).

---------------------------------------------------------
Title: VizieR Online Data Catalog: Fe X Benchmarking atomic data
(Del Zanna+, 2004)
Authors: Del Zanna, G.; Berrington, K. A.; Mason, H. E.
2005yCat..34220731D Altcode:
This is the first in a series of papers in which we benchmark recent
atomic data available for astrophysical applications. We review various
issues related to the completeness and accuracy of both theoretical and
experimental data. In this paper, the available experimental and atomic
data for Fe X (n=3 configurations) are reviewed and assessed. New
collisional and radiative data are calculated to supplement
published data. The radiative calculations are done with empirical
adjustements that take into account observed wavelengths. Previous
line identifications are also reviewed and assessed. Our approach
focuses on the brightest spectral lines, and uses both wavelengths and
line intensities to assess the line identifications on a quantitative
basis. Although many previous line identifications are confirmed, some
are rejected (e.g. the coronal line observed at 1582.35{AA}). We confirm
previously suggested identifications (e.g. 257.262{AA},1028.02{AA}),
and we present new ones, (e.g. the lines of the 3s2
3p4 3d-3s 3p5 3d transition array). In addition,
we highlight the presence of blends and we review which spectral lines
are best for density diagnostics or for instrument calibration. The
theoretical data (line intensities and level lifetimes) are benchmarked
against well-calibrated spectroscopic observations of the solar corona
and laboratory measurements. The agreement between theoretical and
experimental data which we achieve with our new model ion is very
good. (3 data files).

---------------------------------------------------------
Title: The CHIANTI database
Authors: Landi, E.; Dere, K. P.; Young, P. R.; Landini, M.; Mason,
H. E.; Del Zanna, G.
2005HiA....13..653L Altcode:
CHIANTI is a database of atomic data and transition rates necessary for
calculating synthetic spectra and carrying out plasma diagnostics of
astrophysical sources in the X-ray EUV and UV wavelength ranges. CHIANTI
includes both line and continuum emission from all astrophysically
abundant elements in the universe. All data are taken from refereed
literature and are critically assessed. CHIANTI also includes a suite
of IDL programs that allow spectroscopic analysis to be carried
out. CHIANTI data and software are freely distributed over the
internet. In the present talk I will describe the contents of
the CHIANTI database its current status and the areas where CHIANTI
is being developed and I will also present a comparison of CHIANTI
predictions with the X-ray emission from astrophysical sources.

---------------------------------------------------------
Title: Atomic data from the IRON Project = 2, 3, 4 configurations.
LVI. Electron excitation of Be-like Fe XXIII for the n = 2,3,4
configurations
Authors: Chidichimo, M. C.; Del Zanna, G.; Mason, H. E.; Badnell,
N. R.; Tully, J. A.; Berrington, K. A.
2005A&A...430..331C Altcode:
Collision strengths for electron induced transitions in the
beryllium-like ion Fe+22 are calculated using the
intermediate coupling frame transformation (ICFT) version of
the R-matrix programs. Our target has 98 fine structure states
1s2 nl n'l' SLJ corresponding to n = 2 and n' = 2, 3,
4 . The present calculation is for electron impact energies in the
range 3.15 to 380 Ry. When T exceeds about ten million degrees one
needs to take account of contributions to the thermally averaged
collision strength Υ coming from electrons with energies in excess of
380 Ry. We discuss a way of allowing for these contributions. Values
of Υ for all the transitions between the ground state and the
excited states 1s2 2l n l n'l' S'L'J', with n'=2,3,4 are
tabulated as a function of log T. The temperature range 6.3 ≤log
T ≤8.1 is centred on log T = 7.1 which is approximately where
Fe+22 has maximum abundance in ionization equilibrium. To
the best of our knowledge these are the first R-matrix calculations
for Fe+22 for excitations to the n = 3,4 levels. Good
agreement with previous distored-wave calculations is found. However,
the resonance contributions have an important effect on the effective
collision strengths and in turn on the level populations. Full Tables 2, 4 and 6 are only available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5)
or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/430/331. The
full datasets of wavelengths and gf values (Table 4) and of
effective collision strengths (Table 7) are only available at
the same address. The same data are also available at the TIPbase
(http://vizier.u-strasbg.fr/tipbase/home.html) database and as an
`adf04' file at the Oak Ridge National Laboratory's database via
http://www-cfadc.phy.ornl.gov/

---------------------------------------------------------
Title: Spectral diagnostic capabilities of Solar-B EIS
Authors: Zanna, G. Del; Mason, H. E.
2005AdSpR..36.1503Z Altcode:
In this paper, we provide simulated intensities for Solar-B EIS to
aid in the scientific planning for Solar-B. These simulations are
obtained with the latest atomic data and EIS response functions. We
also report on our progress in reviewing and benchmarking atomic data
for the Fe coronal ions, that are of particular importance for spectral
and instrument calibration purposes. We highlight the most prominent
lines that can be used for plasma diagnostics.

---------------------------------------------------------
Title: VizieR Online Data Catalog: Fe XII Benchmarking atomic data
(Del Zanna+, 2005)
Authors: Del Zanna, G.; Mason, H. E.
2005yCat..34330731D Altcode:
We use recently calculated electron collisional data by Storey
et al. (2005A&amp;A...433..717S) for Fe XII (n=3 configurations)
to build a model ion to compare to spectroscopic observations of
the solar corona and laboratory measurements. We review all the line
identifications of the brightest lines, by comparing both wavelengths
and line intensities. The presence of blends in different plasma
conditions is highlighted. A large number of new energy levels and
line identifications are proposed. In particular, we identify the
electric quadrupole 4P5/2-4^F9/2
transition with the bright coronal line observed at 592.6{AA},
previously unidentified. This line, when observed with the 1242.0,
1349.5 UV forbidden lines, is a good density diagnostic over a large
range of electron densities. We also indicate the best spectral lines
to be used for density diagnostics or instrument calibration. From
various combinations of lines we obtain electron densities that
are significantly different from those published in the previous
literature. Some examples are provided. The agreement between theory
and experimental data in terms of wavelengths, line intensities and
level lifetimes is excellent. (2 data files).

---------------------------------------------------------
Title: Remote Sensing of Plasma Diagnostics Relating to Coronal
Heating
Authors: Mason, H. E.; Del Zanna, G.; Bradshaw, S.
2004ESASP.575..312M Altcode: 2004soho...15..312M
No abstract at ADS

---------------------------------------------------------
Title: Synthesised Radiative Emission from a Nanoflare Heated
Elemental Solar Loop
Authors: Bradshaw, S. J.; Del Zanna, G.; Mason, H. E.; Cargill, P. J.
2004ESASP.575..539B Altcode: 2004soho...15..539B
No abstract at ADS

---------------------------------------------------------
Title: On the consequences of a non-equilibrium ionisation balance
for compact flare emission and dynamics
Authors: Bradshaw, S. J.; Del Zanna, G.; Mason, H. E.
2004A&A...425..287B Altcode:
We carry out a hydrodynamic simulation of a compact flare and find
significant non-equilibrium distributions for the ionisation balance
during the impulsive and gradual phases, which can strongly alter the
radiative emission. This has major implications for attempts to derive
the theoretical intensities of emission lines used for spectroscopic
diagnostic analyses of the plasma properties. During the
impulsive phase we find that the emissivities of He I, He II and C IV
in the transition region can be strongly enhanced above their expected
equilibrium values, followed by a significant reduction which increases
the amount of chromospheric plasma ablated into the corona. Furthermore,
during the flare heating the overall charge state of the coronal
ions can be significantly lower than is suggested by an equilibrium
ionisation balance and, therefore, line ratio measurements will yield
plasma temperatures that are much greater than the formation temperature
of the emitting ion. During the gradual phase the emissivity at
transition region temperatures remains suppressed, compared with its
equilibrium value, with correspondingly reduced downflow velocities and
increased radiative cooling time-scales. Finally, we synthesise
the emission as it would be detected by TRACE in its 171 Å and 195 Å
wavelength bands, and find that the filter ratio technique can give
reasonably good estimates of the plasma temperature in quiescence,
though when the populations of Fe VIII, Fe IX, Fe X and Fe XII exhibit
departures from equilibrium the temperatures derived from filter ratio
measurements become unreliable. Figures \ref{fig4}-\ref{fig39}
are only available in electronic form at http://www.edpsciences.org

---------------------------------------------------------
Title: Benchmarking atomic data for astrophysics: Fe X
Authors: Del Zanna, G.; Berrington, K. A.; Mason, H. E.
2004A&A...422..731D Altcode:
This is the first in a series of papers in which we benchmark
recent atomic data available for astrophysical applications. We
review various issues related to the completeness and accuracy
of both theoretical and experimental data. In this paper, the
available experimental and atomic data for Fe X (n=3 configurations)
are reviewed and assessed. New collisional and radiative data are
calculated to supplement published data. The radiative calculations
are done with empirical adjustements that take into account observed
wavelengths. Previous line identifications are also reviewed and
assessed. Our approach focuses on the brightest spectral lines,
and uses both wavelengths and line intensities to assess the line
identifications on a quantitative basis. Although many previous line
identifications are confirmed, some are rejected (e.g. the coronal line
observed at 1582.35 Å). We confirm previously suggested identifications
(e.g. 257.262 Å, 1028.02 Å), and we present new ones, (e.g. the
lines of the 3s23p43d-3s 3p53d
transition array). In addition, we highlight the presence of blends
and we review which spectral lines are best for density diagnostics or
for instrument calibration. The theoretical data (line intensities and
level lifetimes) are benchmarked against well-calibrated spectroscopic
observations of the solar corona and laboratory measurements. The
agreement between theoretical and experimental data which we achieve
with our new model ion is very good. Table 1 and full Tables
3 and \ref{tab:lines} are only available in electronic form at the
CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/422/731 Appendix
is only available in electronic form at http://www.edpsciences.org

---------------------------------------------------------
Title: High Time Cadence Observations with the Rapid Acquisition
Imaging Spectrograph (RAISE) Rocket Program
Authors: Ayres, T. R.; Hassler, D. M.; Slater, D.; DeForest, C. E.;
Mason, H.; McIntosh, S.; Thomas, R. J.
2004AAS...204.9704A Altcode: 2004BAAS...36..828A
The Rapid Acquisition Imaging Spectrograph (RAISE) is a next-generation
high resolution imaging spectrograph scheduled to fly on a NASA sounding
rocket in 2006 to study the dynamics of the solar chromosphere and
corona on time scales as short as 100 ms. High speed imaging from
TRACE has shown that rapid motions and reconnection are central to the
physics of the transition region and corona, but cannot resolve the
differences between propagating phenomena and bulk motion. SoHO/CDS and
SoHO/SUMER have yielded intriguing measurements of motion and heating
in the solar atmosphere, and Solar-B/EIS will capture EUV spectra of
flares in progress; but no currently planned instrument can capture
spectral information in the chromosphere, transition region, or cool
corona on the ∼ 1-10 Hz time scale required for few-second cadence
spectral imaging or rapid wave motion studies. RAISE is uniquely suited
to exploring this hard-to-reach domain. This work is supported
by NASA Grant NNG04WC01G to the Southwest Research Institute.

---------------------------------------------------------
Title: Recent development of the CHIANTI database in the X-ray
wavelength range
Authors: Landi, E.; Dere, K. P.; Mason, H. E.; Del Zanna, G.; Landini,
M.; Young, P. R.
2004AAS...204.7310L Altcode: 2004BAAS...36R.801L
CHIANTI consists of a database of critically assessed atomic data
and transition rates to calculate line and continuum emission
from astrophysical plasmas. During the last year the CHIANTI
database has been substantially expanded in the X-ray wavelength
region by including a large number of new configurations and lines,
and by including ionization and recombination processes in the level
population calculations. We will describe these improvements,
the data we used, and illustrate examples of 1) their effects on
predicted emissivities and on plasma diagnostics 2) applications to
the study of flares in solar active regions

---------------------------------------------------------
Title: Spectral diagnostic capabilities of Solar-B EIS
Authors: del Zanna, G.; Mason, H. E.
2004cosp...35.3002D Altcode: 2004cosp.meet.3002D
We briefly review the main spectral diagnostics that will be available
with Solar-B EIS, and what kind of scientific questions could be best
addressed, based on our experience with SOHO/CDS observations. We then
report on our progress in reviewing and benchmarking atomic data for
the Fe coronal ions, that are of particular importance for spectral
and instrument calibration purposes.

---------------------------------------------------------
Title: Future Observations with the Rapid Acquisition Imaging
Spectrograph (RAISE)
Authors: Hassler, D. M.; Deforest, C. E.; Slater, D.; Ayres, T.;
Mason, H.; McIntosh, S.; Thomas, R.
2004cosp...35.2280H Altcode: 2004cosp.meet.2280H
The Rapid Acquisition Imaging Spectrograph (RAISE) is a next-generation
high resolution imaging spectrograph scheduled to fly on a NASA sounding
rocket in 2006 to study the dynamics of the solar chromosphere and
corona on time scales as short as 100 ms. High speed imaging from TRACE
has shown that rapid motions and reconnection are central to the physics
of the transition region and corona, but cannot resolve the differences
between propagating phenomena and bulk motion. SoHO/CDS and SoHO/SUMER
have yielded intriguing measurements of motion and heating in the
solar atmosphere, and Solar-B/EIS will capture EUV spectra of flares
in progress; but no currently planned instrument can capture spectral
information in the chromosphere, transition region, or cool corona
on the ~1-10 Hz time scale required for few-second cadence spectral
imaging or rapid wave motion studies. RAISE is uniquely suited to
exploring this hard-to-reach domain.

---------------------------------------------------------
Title: X-ray emission from PTT stars
Authors: del Zanna, G.; Bromage, G.; Foley, C.; Worters, H.; Mason,
H.; Landini, M.
2004cosp...35.2995D Altcode: 2004cosp.meet.2995D
We present preliminary results on new X-ray spectroscopic XMM/RGS
observations of the visual binary nicknamed `Horace Horologii' (2RE
J0241-53). The two stars are strong and very active X-ray emitters, and
are members of an association of Post-T-Tauri stars. A detailed study
(in particular in terms of chemical composition) is important for our
understanding of the evolution from the T-Tauri phase, and to explain
the origin of the X-ray emission in very young stars. The physical
characteristics of the quiescent X-ray emission are described, and
related to other stellar parameters such as photospheric abundances and
the rotational period. Simultaneous ground-based optical spectroscopy
and U-band photometric monitoring observations were obtained at the
South African Astronomical Observatory.

---------------------------------------------------------
Title: Spectroscopic observations of compact solar flares
Authors: del Zanna, G.; Mason, H. E.
2004cosp...35.2998D Altcode: 2004cosp.meet.2998D
We present SOHO/Coronal Diagnostic Spectrometer observations of
solar flares, complemented with data from other instruments (such
as high-resolution images from TRACE, magnetograms from SOHO/MDI,
and Yohkoh SXT). We show that CDS provides essential spectroscopic
information which adds complexity into our understanding of the dynamics
of solar flares. We give a description of the main observational
features, and what types of measurements (densities, temperatures,
flows) are obtained. These observations provide constraints for flare
modeling, and indications on what types of spectroscopic observations
future instruments should provide.

---------------------------------------------------------
Title: CHIANTI -- An Atomic Database for UV and X-ray Cool star
spectroscopy
Authors: Young, P. R.; Landi, E.; Bromage, G. E.; del Zanna, G.;
Dere, K. P.; Landini, M.; Mason, H. E.
2003csss...12.1119Y Altcode:
The CHIANTI atomic database was first released in 1996 and has since
become the standard resource for the interpretation of UV spectra
from the transition regions and coronae of the Sun and other cool
stars. We describe the contents of the most recent release (v.3)
and some of the uses that have been found for the database.

---------------------------------------------------------
Title: The radiative response of solar loop plasma subject to
transient heating
Authors: Bradshaw, S. J.; Mason, H. E.
2003A&A...407.1127B Altcode:
In Bradshaw &amp; Mason (\cite{Bradshaw2003}) we carried out a
hydrodynamic simulation of a cooling solar loop and investigated
the nonequilibrium response of the population of C VII ions to the
changing conditions in the plasma. We also compared equilibrium
and nonequilibrium calculations of the total plasma emissivity. In
this paper we present two simulations of a solar loop subject to a
transient heating process delivering energy on the nanoflare scale at
its apex. One simulation treats the ion populations and the energy
radiated from the loop plasma entirely as though the system were in
equilibrium and the other simulation performs a full nonequilibrium
treatment by coupling the time-dependent ion populations to the
hydrodynamic equations through the radiative energy loss. Our
radiative model accounts for the 15 most abundant elements of the
solar atmosphere including C, O, Ne, Mg, Si and Fe. We find some
pronounced differences between the populations of certain transition
region ions and the corresponding plasma emissivity curves in the
equilibrium and nonequilibrium simulations. Though the apex heating
event is relatively weak in comparison to energy released on the
microflare and flare scales, nonetheless a significant amount of energy
reaches the loop footpoint region to heat the plasma there and we find
a nonequilibrium spike in emissivity. However, more surprisingly we
find considerable differences between some of the coronal ions in the
equilibrium and nonequilibrium simulations, with important consequences
for the plasma emissivity curves. In particular, we find that the total
plasma emissivity calculated assuming equilibrium conditions is up to
a factor of 5 lower than the nonequilibrium emissivity and this is due
almost entirely to the response of the coronal Fe ions. Finally, we
suggest possible observational signatures of nonequilibrium ionisation
and ways in which one might identify it. This is important because
an invalid assumption of equilibrium ion populations may well lead
one to incorrect conclusions about the properties of the plasma in
both a broad-band and narrow-band/emission line based analysis. Figures 11 to 13 and Appendix A are only available in electronic
form at http://www.edpsciences.org

---------------------------------------------------------
Title: Solar active regions: SOHO/CDS and TRACE observations of
quiescent coronal loops
Authors: Del Zanna, G.; Mason, H. E.
2003A&A...406.1089D Altcode:
This study focuses on the diagnostic capabilities of the TRACE and
SOHO-CDS instruments to describe the physical characteristics of
quiescent solar active regions. In particular we concentrate on
the 1 MK loops, best seen in the TRACE EUV 173 Å passband. These
are high-lying structures which can remain stable over timescales
of hours to days. We present simultaneous observations of off-limb
active region 1 MK loops performed with TRACE (173 Å and 195 Å
bands) and the SOHO-CDS. The CDS spectral capabilities complement
the TRACE observations well and allow an in-depth study of the plasma
properties. Some important new results are presented here. In terms of
cross-field characteristics, we find that these loops are isothermal
and much cooler (T =~ 0.7-1.1 x 106 K) than the surrounding
diffuse high-lying active region emission (T =~ 2 x 106
K). We show that the diffuse background-foreground constitutes the
bulk of the high-lying quiescent active region emission. We explain
some of the discrepancies found by various authors (based on SOHO
and TRACE observations) with an overestimation of loop temperatures
and densities. This was caused by inaccurate or neglected background
subtraction in the data analysis. We studied the leg of a 1 MK loop and
found that along its length temperatures and densities have steeper
profiles compared to those derived from previous studies based on
TRACE observations. The observations are consistent with an element
abundance FIP effect of about 4, filling factors close to unity, and
a constant density across the loop. We find a remarkable consistency
between the CDS and TRACE observations, although we also find severe
limitations to the use of TRACE diagnostic techniques.

---------------------------------------------------------
Title: A self-consistent treatment of radiation in coronal loop
modelling
Authors: Bradshaw, S. J.; Mason, H. E.
2003A&A...401..699B Altcode:
We perform a hydrodynamic simulation of a cooling coronal loop and
calculate the time-dependent ion populations of the most abundant
elements of the solar atmosphere at each time-step. We couple the
time-dependent ion balance equations to the hydrodynamic equations in
order to treat the energy loss through radiation in a self-consistent
way by allowing for the emission from a potentially nonequilibrium ion
population. We present results for the response to the changing
conditions in the loop of the population of C VII ions and find
significant deviations from equilibrium in the coronal and footpoint
regions of the loop. The former is due to the tenuous nature of the
coronal plasma causing recombinations to be rare and the latter is
due to the strong downflows that develop as the loop cools, which
carry persistent C VII ions into the lower regions of the loop. We
also present a comparison between total plasma emissivity curves
calculated during this simulation and an almost identical simulation
that assumed an equilibrium ion population for the calculation of the
radiation term. As a result of the nonequilibrium ion populations
we find significant differences between the emissivity curves of
each simulation and the loop cooling times. We suggest that a
consideration of nonequilibrium ionisation and radiation might help
to (a) explain the thermal broadening observed in some emission lines
during explosive events, and (b) reconcile differences between theory
and observations relating to the longevity of some loops observed in
the TRACE filters.

---------------------------------------------------------
Title: Spectroscopic characteristics of polar plumes
Authors: Del Zanna, G.; Bromage, B. J. I.; Mason, H. E.
2003A&A...398..743D Altcode:
Extreme ultraviolet observations of plumes in polar coronal holes are
presented and their spectroscopic signatures discussed. The study
focuses on the base of plumes seen on the disk of the Sun with the
Coronal Diagnostic Spectrometer (CDS) on the Solar and Heliospheric
Observatory (SOHO) satellite. Spectroscopic diagnostic techniques are
applied to characterise the plumes in terms of density, temperature,
emission measure and element abundance. Attention is drawn to the
particular limitations of some of the techniques when applied to plume
structures. In particular, we revisit the Widing &amp; Feldman (1992)
findings of a plume having a large first ionization potential (FIP)
effect of 10, showing that instead the Skylab data are consistent
with no FIP effect. We present for the first time CDS-GIS (grazing
incidence spectrometer) observations of a plume. These observations
have been used to confirm the results obtained from normal incidence
(NIS) observations. We find that polar plumes exhibit the same
characteristics as the Elephant's Trunk equatorial plume. The
most striking characteristic of the plume bases is that they are
near-isothermal with a peak emission measure at transition region
temperatures =~ 8 x 105 K. At these temperatures, plumes have
averaged densities Nlo {e} =~ 1.2 x 109 cm-3,
about twice the value of the surrounding coronal hole region. Element
abundances in the plumes are found to be close to photospheric, with the
exception of neon which appears to be depleted by 0.2 dex relative to
oxygen. The absence of a significant FIP effect in plumes is consistent
with fast solar wind plasma, although it is not sufficient to prove
a link between the two. Finally, we present a comparison between GIS
spectra and the SOHO EIT (EUV Imaging Telescope) broad-band images,
showing that temperatures derived from the EIT ratio technique are
largely overestimated, for plumes and coronal holes. This is partly
due to the fact that the so called “Fe XII 195 Å” and “Fe XV
284 Å” filters are not isothermal, and in coronal holes and plumes
lower-temperature lines dominate the EIT signal.

---------------------------------------------------------
Title: CHIANTI-An Atomic Database for Emission Lines. VI. Proton
Rates and Other Improvements
Authors: Young, P. R.; Del Zanna, G.; Landi, E.; Dere, K. P.; Mason,
H. E.; Landini, M.
2003ApJS..144..135Y Altcode: 2002astro.ph..9493Y
The CHIANTI atomic database contains atomic energy levels, wavelengths,
radiative transition probabilities, and electron excitation data for
a large number of ions of astrophysical interest. Version 4 has been
released, and proton excitation data are now included, principally
for ground configuration levels that are close in energy. The fitting
procedure for excitation data, both electrons and protons, has been
extended to allow nine-point spline fits in addition to the previous
five-point spline fits. This allows higher quality fits to data from
close-coupling calculations where resonances can lead to significant
structure in the Maxwellian-averaged collision strengths. The effects
of photoexcitation and stimulated emission by a blackbody radiation
field in a spherical geometry on the level balance equations of
the CHIANTI ions can now be studied following modifications to the
CHIANTI software. With the addition of H I, He I, and N I, the first
neutral species have been added to CHIANTI. Many updates to existing
ion data sets are described, while several new ions have been added
to the database, including Ar IV, Fe VI, and Ni XXI. The two-photon
continuum is now included in the spectral synthesis routines, and a
new code for calculating the relativistic free-free continuum has been
added. The treatment of the free-bound continuum has also been updated.

---------------------------------------------------------
Title: CHIANTI - An Atomic Database for XUV Emission Lines
Authors: Landi, Enrico; Dere, Ken P.; Landini, Massimo; Young, Peter
R.; Mason, Helen E.; del Zanna, Giulio
2003IAUJD..17E..10L Altcode:
CHIANTI is a database of atomic data and transition rates necessary for
calculating synthetic spectra and carrying out plasma diagnostics of
astrophysical sources in the X-ray EUV and UV wavelength ranges. CHIANTI
includes both line and continuum emission from all astrophysically
abundant elements in the universe. All data are taken from refereed
literature and are critically assessed. CHIANTI also includes a suite
of IDL programs that allow spectroscopic analysis to be carried
out. CHIANTI data and software are freely distributed over the
internet. In the present talk I will describe the contents of
the CHIANTI database its current status and the areas where CHIANTI
is being developed and I will also present a comparison of CHIANTI
predictions with the X-ray emission from astrophysical sources.

---------------------------------------------------------
Title: Active Region Studies with SOHO-CDS
Authors: Mason, H. E.; Del Zanna, G.
2002ASPC..277...37M Altcode: 2002sccx.conf...37M
No abstract at ADS

---------------------------------------------------------
Title: EUV spectral observations of active region flares
Authors: Del Zanna, G.; Mason, H. E.; Foley, C.
2002ESASP.506..585D Altcode: 2002svco.conf..585D; 2002ESPM...10..585D
We present EUV spectral observations of C-M class flares performed
with the Coronal Diagnostic Spectrometer (CDS) onboard SOHO during the
Cambridge active region (AR) campaigns in 1999 and 2001. With the CDS
spectral data, complemented by other space observations (mainly TRACE,
YOHKOH SXT), we investigate the physical properties of ARs, and study
the development of small-scale flares. We discuss the importance of
spectral observations in relation to the correct interpretation of
broad band images. In particular, we present co-spatial simultaneous
YOHKOH SXT and CDS flare observations and discuss the validity of the
temperatures derived from the SXT filter ratios. In addition, we present
sample results that can only be obtained with spectral data, such as
measurements of densities, elemental abundances and post-flare flows,
associated with slow chromospheric evaporation. All these results are
important observational constraints for flare modeling.

---------------------------------------------------------
Title: Solar and stellar high-resolution X-ray spectra: plasma
diagnostics with the CHIANTI atomic database
Authors: Del Zanna, G.; Mason, H. E.
2002ASPC..277..333D Altcode: 2002sccx.conf..333D
No abstract at ADS

---------------------------------------------------------
Title: The Structure and Evolution of a Sigmoidal Active Region
Authors: Gibson, S. E.; Fletcher, L.; Del Zanna, G.; Pike, C. D.;
Mason, H. E.; Mandrini, C. H.; Démoulin, P.; Gilbert, H.; Burkepile,
J.; Holzer, T.; Alexander, D.; Liu, Y.; Nitta, N.; Qiu, J.; Schmieder,
B.; Thompson, B. J.
2002ApJ...574.1021G Altcode:
Solar coronal sigmoidal active regions have been shown to be precursors
to some coronal mass ejections. Sigmoids, or S-shaped structures,
may be indicators of twisted or helical magnetic structures, having
an increased likelihood of eruption. We present here an analysis of a
sigmoidal region's three-dimensional structure and how it evolves in
relation to its eruptive dynamics. We use data taken during a recent
study of a sigmoidal active region passing across the solar disk
(an element of the third Whole Sun Month campaign). While S-shaped
structures are generally observed in soft X-ray (SXR) emission, the
observations that we present demonstrate their visibility at a range of
wavelengths including those showing an associated sigmoidal filament. We
examine the relationship between the S-shaped structures seen in SXR
and those seen in cooler lines in order to probe the sigmoidal region's
three-dimensional density and temperature structure. We also consider
magnetic field observations and extrapolations in relation to these
coronal structures. We present an interpretation of the disk passage
of the sigmoidal region, in terms of a twisted magnetic flux rope
that emerges into and equilibrates with overlying coronal magnetic
field structures, which explains many of the key observed aspects of
the region's structure and evolution. In particular, the evolving flux
rope interpretation provides insight into why and how the region moves
between active and quiescent phases, how the region's sigmoidicity is
maintained during its evolution, and under what circumstances sigmoidal
structures are apparent at a range of wavelengths.

---------------------------------------------------------
Title: Spectroscopic diagnostics of stellar transition regions and
coronae in the XUV: AU Mic in quiescence
Authors: Del Zanna, G.; Landini, M.; Mason, H. E.
2002A&A...385..968D Altcode:
In this paper we review the spectroscopic diagnostic techniques that
can be applied to XUV observations of active stars. In particular, we
discuss methods for the determination of electron densities, emission
measures and the chemical composition of the stellar transition regions
and coronae. We pay particular attention to the atomic data used and
we revise several previous analyses with the most recent atomic data
(from CHIANTI). We find severe limitations to some of the commonly used
methods and atomic data and we obtain results which are significantly
different from other authors. We illustrate this with a number of
examples. We analyse a combined set of multi-wavelength observations
(EUVE, HST/STIS, FUSE) for the quiescent phase of the dMe star AU Mic. A
major conclusion of this paper is that the use of spectral lines from
the Li and Na isoelectronic sequences, common in previous literature,
produces erroneous results in the determination of emission measures,
elemental abundances and transition region densities.

---------------------------------------------------------
Title: EUV Spectroscopic Observations of Spray Ejecta from an X2 Flare
Authors: Pike, C. D.; Mason, H. E.
2002SoPh..206..359P Altcode:
An X2.3 class flare was reported on 10 April 2001 in AR 9415. A halo
coronal mass ejection (CME) was associated with this flare. The Coronal
Diagnostic Spectrometer (CDS) on board the Solar and Heliospheric
Observatory (SOHO), which was running in its daily synoptic mode,
recorded a very high-velocity ejection of plasma associated with
this activity. The spatial scanning and spectral capabilities
of CDS allow the measurement of both transverse and line-of-sight
velocities. Components of the plasma, as seen in emission from O v at
around 2.5×105 K, reached transverse velocities in excess
of 800 km s−1. The nature of the spectral line profiles
suggests that a rotational motion of ± 350 km s−1 was
superimposed upon the general outward expansion of approximately 150
km s−1. The ejection detected using CDS was found to have
a constant acceleration and is thought to be a spray of plasma with
a helical structure driven by the magnetic topology.

---------------------------------------------------------
Title: SOHO-CDS Observations of an X2 Flare Spray Injection
Authors: Mason, H. E.; Pike, C. D.
2002mwoc.conf...89M Altcode:
Spectral observations with SOHO-CDS provide an opportunity to study the
development of active region structures. In particular, it is possible
to determine the plasma properties: temperature and electron density
distribution, elemental abundances and mass motions. The nature of
enhancements in the transition region emission is investigated.

---------------------------------------------------------
Title: Sigmoidal diagnostics with SOHO/CDS
Authors: Del Zanna, G.; Gibson, S. E.; Mason, H. E.; Pike, C. D.;
Mandrini, C. H.
2002AdSpR..30..551D Altcode:
During the third Whole Sun Month Campaign (August 18 - September 14,
1999), the evolution of the active region NOAA 8668 was followed
during its meridian passage and at the limb (Sigmoid JOP 106),
with simultaneous observations with the Solar and Heliospheric
Observatory (SOHO), and with other instruments, both satellite
and ground-based. On August 21st, a small flare, associated with
a brightening of the sigmoidal structure, occurred. SOHO Coronal
Diagnostic Spectrometer (CDS) observations of this small flare are
presented. Coronal temperatures and densities of the sigmoid are
estimated. High transition region densities (in the range 2.5-7 × 10
11 cm -3), obtained using O IV, are present in
the brightenings associated with the flare. At coronal level, high
temperatures of at least 8 MK were reached, as shown by strong Fe
XIX emission. After this small flare, relatively strong blue-shifts
(⋍ 30 km/s) are observed in coronal lines, located at the two ends
of a small loop system associated with the sigmoid.

---------------------------------------------------------
Title: The CHIANTI Atomic Database and Instrument Calibration:
a Symbiosis
Authors: Mason, H. E.; Del Zanna, G.; Dere, K. P.; Landi, E.; Landini,
M.; Young, P. R.
2002ISSIR...2..271M Altcode: 2002ESASR...2..271M; 2002rcs..conf..271M
The CHIANTI atomic database comprises a comprehensive, accurate and
up-to-date database of atomic parameters, necessary for emission-line
spectroscopy. The suite of user-friendly software allows plasma
diagnostics to be carried out. Since its release in 1996, CHIANTI has
become a standard resource for the analysis of solar spectra. Accurate
atomic data can provide the foundation for in-flight instrument
calibrations. Conversely, an accurate instrument calibration can provide
a check on atomic parameters. The internal consistency of spectral-line
intensities can be used to highlight specific anomalies. In this paper,
we illustrate how CHIANTI has been used to validate the calibration of
solar EUV instruments: SOHO-CDS, -SUMER, -EIT and SERTS. In addition,
we show how anomalous spectral-line intensities indicate the need for
more accurate atomic calculations.

---------------------------------------------------------
Title: A Relationship Between Transition Region Brightenings,
Abundances, and Magnetic Topology
Authors: Fletcher, Lyndsay; López Fuentes, Marcelo C.; Mandrini,
Cristina H.; Schmieder, Brigitte; Démoulin, Pascal; Mason, Helen E.;
Young, Peter R.; Nitta, Nariaki
2001SoPh..203..255F Altcode:
We present multi-instrument observations of active region (AR) 8048,
made between 3 June and 5 June 1997, as part of the SOHO Joint Observing
Program 33. This AR has a sigmoid-like global shape and undergoes
transient brightenings in both soft X-rays and transition region
(TR) lines. We compute a magneto-hydrostatic model of the AR magnetic
field, using as boundary condition the photospheric observations of
SOHO/MDI. The computed large-scale magnetic field lines show that the
large-scale sigmoid is formed by two sets of coronal loops. Shorter
loops, associated with the core of the SXT emission, coincide with
the loops observed in the hotter CDS lines. These loops reveal a
gradient of temperature, from 2 MK at the top to 1 MK at the ends. The
field lines most closely matching these hot loops extend along the
quasi-separatrix layers (QSLs) of the computed coronal field. The TR
brightenings observed with SOHO/CDS can also be associated with the
magnetic field topology, both QSL intersections with the photosphere,
and places where separatrices issuing from bald patches (sites where
field lines coming from the corona are tangent to the photosphere)
intersect the photosphere. There are, furthermore, suggestions that
the element abundances measured in the TR may depend on the type
of topological structure present. Typically, the TR brightenings
associated with QSLs have coronal abundances, while those associated
with BP separatrices have abundances closer to photospheric values. We
suggest that this difference is due to the location and manner in which
magnetic reconnection occurs in two different topological structures.

---------------------------------------------------------
Title: Elemental abundances of the low corona as derived from
SOHO/CDS observations
Authors: Del Zanna, G.; Bromage, B. J. I.; Mason, H. E.
2001AIPC..598...59D Altcode: 2001sgc..conf...59D
No abstract at ADS

---------------------------------------------------------
Title: A comparison between theoretical and solar FeXII UV line
intensity ratios UV line intensity ratios
Authors: Binello, A. M.; Landi, E.; Mason, H. E.; Storey, P. J.;
Brosius, J. W.
2001A&A...370.1071B Altcode:
A new set of radiative and electron collisional data for Fe XII
was presented in two earlier papers. In the present work, we derive
level populations and theoretical line intensities for a range of
plasma densities and temperatures. Observations of Fe XII lines
obtained with the Solar EUV Rocket Telescope and Spectrograph are
analysed both as a check the quality of the new atomic data and
to determine the electron density in active regions and the quiet
Sun. The discrepancy between the electron density values determined
from Fexii line intensity ratios and those obtained from other ions
is investigated. Tables 2-5 are also available in electronic form
at the CDS via anonymous ftp to cdarc.u-strasbg.fr (130.79.128.5)
or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/370/1071}

---------------------------------------------------------
Title: VizieR Online Data Catalog: Fe XII UV line intensity ratios
(Binello+, 2001)
Authors: Binello, A. M.; Landi, E.; Mason, H. E.; Storey, P. J.;
Brosius, J. W.
2001yCat..33701071B Altcode:
A new set of radiative and electron collisional data for Fe XII
was presented in two earlier papers. In the present work, we derive
level populations and theoretical line intensities for a range of
plasma densities and temperatures. Observations of Fe XII lines
obtained with the Solar EUV Rocket Telescope and Spectrograph are
analysed both as a check on the quality of the new atomic data and
to determine the electron density in active regions and the quiet
Sun. The discrepancy between the electron density values determined
from Fe XII line intensity ratios and those obtained from other ions
is investigated. (2 data files).

---------------------------------------------------------
Title: CDS UV Brightenings Explained by Quasi-separatrices and Bald
Patches in an S-shape active region
Authors: Schmieder, B.; Démoulin, P.; Fletcher, L.; López Fuentes,
M. C.; Mandrini, C. H.; Mason, H. E.; Young, P. R.; Nitta, N.
2001IAUS..203..314S Altcode:
We present multi-instrument observations of AR 8048, made between
June 3 and June5 1997 as part of SoHO JOP033. This active region
has a sigmoid-like global shape and undergoes transient erupting
phenomena which releases the stored energy. Using a force free
field approach, we defined coronal magnetic field lines which fit
with the observations. The large-scale magnetic field lines confirms
the sigmoid characteristics of the active region. The study in 3D of
the configuration explained where and how the energy is released at
different places. The Ne VI brightenings correspond to the location
of tangent to the photosphere field lines, named "bald patch", they
are localized in the low transition region and represent feet of field
lines. The Si XII brightenings at coronal temperature are at the top
of coronal loops joining quasi-separatrices.

---------------------------------------------------------
Title: Solar Spectroscopy and Diagnostics
Authors: Mason, H.
2000eaa..bookE1985M Altcode:
Solar spectroscopy and diagnostics provide the opportunity for
determining the physical parameters in different parts of the solar
atmosphere....

---------------------------------------------------------
Title: Solar Spectroscopy: Atomic Processes
Authors: Mason, H.
2000eaa..bookE2229M Altcode:
A Greek philosopher called DEMOCRITUS (c. 460-370 BC) first introduced
the concept of atoms (which means indivisible). His atoms do not
precisely correspond to our atoms of today, which are not indivisible,
but made up of a nucleus (protons with positive charge and neutrons
which have no charge) and orbiting electrons (with negative
charge). Indeed, in the solar atmosphere, the temperature is suc...

---------------------------------------------------------
Title: Seeking the magnetic roots of a sample of SOHO coronal
bright points.
Authors: Saba, J. L. R.; Zamkoff, E. B.; Mason, H. E.; Pike, C. D.;
Moses, J. D.; Covington, J. F.
2000BAAS...32..808S Altcode:
No abstract at ADS

---------------------------------------------------------
Title: SUMER observations of transition region fine structures
Authors: Landi, E.; Mason, H. E.; Lemaire, P.; Landini, M.
2000A&A...357..743L Altcode:
The SUMER (Solar Ultraviolet Measurements of Emitted Radiation)
instrument on SOHO (Solar and Heliospheric Observatory) provides an
opportunity to observe and study the solar transition region with
high spatial and spectral resolution. We present new evidence to
confirm that the emission from the quiet Sun at 2x 105 K
is dominated by cool loop-like fine structures which cluster across
the chromospheric network boundaries. The electron density of these
structures is found to be around 1010 cm-3. The
red-shifts in spectral line profiles and the non-thermal widths from
lines formed at this temperature are found to be correlated with
intensity. The properties of explosive events with irregular profiles
are explored. A large jet-like structure is analysed. The results of
our analysis are compared with recent predictions from numerical models.

---------------------------------------------------------
Title: Seeking the Magnetic Roots of a Sample of SOHO Coronal
Bright Points
Authors: Saba, J. L. R.; Zamkoff, E. B.; Mason, H. E.; Pike, C. D.;
Moses, J. D.; Covington, J. F.
2000SPD....31.0143S Altcode:
As part of an ongoing study of X-ray/EUV bright points (XBPs)
in synoptic data from the Coronal Diagnostic Spectrometer (CDS)
on the Solar and Heliospheric Observatory (SoHO), we consider six
CDS XBP detections for which there are concurrent high-cadence,
high-spatial-resolution magnetogram data from the SoHO Michelson Doppler
Imager (MDI). All six cases occurred at solar minimum or in the early
rise phase of solar cycle 23 (Jul 1996 - Jan 1998). They sample a factor
of 10 range in size of XBPs as detected by CDS in an Fe XVI coronal
emission line, with peak formation temperature of about 2.5 MK. MDI
data are available for over 1.5 hr leading up to each CDS observation,
and for at least 0.4 hr after; this allows a detailed study of the
magnetic field evolution under the XBP site, including detection of flux
emergence or cancellation. EIT data are used to monitor the evolution
and persistence of these XBPs in the corona before and after the CDS
detections. The nature of the jointly observed XBPs is investigated,
in particular the relationship of the plasma parameters and size found
with CDS, and the timescales for coronal evolution inferred from EIT,
to the character of the underlying magnetic field and its changes
as observed with MDI. This work was supported by the SOI/MDI project
at Stanford and LMSAL (grant NAG5-3077). HEM and CDP acknowledge the
financial support of PPARC.

---------------------------------------------------------
Title: SunBlock '99- An Educational Resource
Authors: Pike, C. D.; Mason, H. E.; Walsh, R. W.
2000ASPC..205..141P Altcode: 2000ltse.conf..141P
SunBlock `99 is a web-based Public Understanding of Science and
educational project which presents the very latest solar research as
seen through the eyes of young British scientists. It seeks both to
increase public awareness of solar physics and to provide an educational
resource for use in the classroom.

---------------------------------------------------------
Title: Dynamics in Restructuring Active Regions Observed During
Soho/Yohkoh/Gbo Campaigns
Authors: Schmieder, B.; Deng, Y.; Mandrini, C. H.; Rudawy, P.; Nitta,
N.; Mason, H.; Fletcher, L.; Martens, P.; Brynildsen, N.
2000AdSpR..25.1879S Altcode:
JOP17 and JOP 33 are SOHO Joint Observing Programs in collaboration
with Yohkoh/SXT and ground based observatories (GBO's), dedicated to
observe dynamical events through the atmosphere. During runs of these
programs we observed in restructuring active regions (ARs), surges,
subflares, bright knots, but not large flares and jets. From these
observations we have been able to derive some of the responses of the
coronal and chromospheric plasma to the evolution of the photospheric
magnetic field. Emerging flux in an AR led to the formation of Arch
Filament Systems in the chromosphere, hot loops and knots in the
transition region, and X-ray loops. Frequent surges have been observed
in relation to parasitic or mixed polarities, but coronal jets have not
yet been found. We discuss the possible mechanisms acting during the
restructuring of the active regions (reconnection or “sea-serpent”
geometries)

---------------------------------------------------------
Title: Atomic data from the IRON Project. XL. Electron impact
excitation of the Fe XIV EUV transitions
Authors: Storey, P. J.; Mason, H. E.; Young, P. R.
2000A&AS..141..285S Altcode:
We calculate collision strengths and thermally averaged collision
strengths for electron excitation between the forty energetically
lowest levels of Fe13+. The scattering calculation is more
complete than any previous work on this ion and significant differences
are found in the excitation rates for many of the extreme ultra-violet
(EUV) transitions, compared to earlier work. A detailed comparison
is made between predicted line intensity ratios and those observed in
solar coronal spectra which shows that several outstanding discrepancies
are resolved by the new atomic data.

---------------------------------------------------------
Title: Commission 14: Atomic and Molecular Data: (Donnees Atomiques
et Moleculaires)
Authors: Rostas, F.; Smith, P. L.; Berrington, K. A.; Feautrier, N.;
Grevesse, N.; Johansson, S.; Jørgensen, U. G.; Martin, W. C.; Mason,
H.; Parkinson, W.; Tchang-Brillet, W. -Ü. L.
2000IAUTA..24..380R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: CHIANTI: A database for astrophysical emission line
spectroscopy
Authors: Del-Zanna, Giulio; Young, Peter; Dere, Ken; Landini, Massimo;
Landi, Enrico; Mason, Helen
1999ascl.soft11004D Altcode:
CHIANTI consists of a critically evaluated set of atomic data necessary
to calculate the emission line spectrum of astrophysical plasmas. The
data consists of atomic energy levels, atomic radiative data such as
wavelengths, weighted oscillator strengths and A values, and electron
collisional excitation rates. A set of programs that use these data to
calculate the spectrum in a desired wavelength range as a function of
temperature and density are also provided. These programs have been
written in Interactive Data Language (IDL) and descriptions of these
various programs are provided on the website.

---------------------------------------------------------
Title: Temperature and density in a polar plume - measurements
from CDS/SOHO
Authors: Young, P. R.; Klimchuk, J. A.; Mason, H. E.
1999A&A...350..286Y Altcode:
A detailed analysis of a particularly intense polar plume observed
on the 25th of October, 1996, by the Coronal Diagnostic Spectrometer
(CDS) on board the Solar and Heliospheric Observatory (SOHO) is
presented. Above the limb, emission measure distributions derived for
both the plume and a section of coronal hole background are found to
be sharply peaked at approximately 1.0-1.1 million degrees in both
regions. The temperature rises with height in the background, but no
evidence is found for a rising temperature in the plume. The density
of the background is approximately 10(8) electrons/cm(3) and falls
with height. In the plume the density is between 3.8 and 9.5x 10(8)
electrons/cm(3) , and exhibits no decrease with height up to 70 000
km. The plume base is visible on the solar surface and shows a strong
brightening lying directly below the main body of the plume. This
brightening has a temperature of 2 000 000 K, and a density of
2.5-5.6x 10(9) electrons/cm(3) . Images from lines formed at different
temperatures suggest that the morphology of the base is consistent with
an emerged bipole in a region of unipolar magnetic flux. A measurement
of the Mg/Ne relative abundance is made at two transition region
brightenings at the base of the plume. An enhancement of only 1.5 is
found over the photospheric value. Considerations of the geometry of
both the high temperature brightening at the base of the plume and
the off-limb section give filling factors of 0.5 and 1.0, respectively.

---------------------------------------------------------
Title: Variation of Thermal Structure with Height of a Solar Active
Region Derived from SOHO CDS and YOHKOH BCS Observations
Authors: Sterling, Alphonse C.; Pike, C. D.; Mason, Helen E.; Watanabe,
Tetsuya; Antiochos, Spiro K.
1999ApJ...524.1096S Altcode:
We present observations of NOAA solar Active Region 7999 when it was
near the west solar limb on 1996 December 2 and 3, using data from
the Coronal Diagnostic Spectrometer (CDS) experiment on the SOHO
satellite. Ratios of intensities of 2 MK material (as observed in
CDS Fe XVI images) to 1 MK material (from CDS Mg IX images) indicate
that there is a drop in the ratio of the hotter to the cooler material
with height in the region, up to an altitude of about 105
km. At low altitudes the relative amount of 2 MK emission measure to
1 MK emission measure ranges from 8 to 10, while the ratio is minimum
near 105 km, ranging from 1.3 to 3.5. The decrease with
height of the CDS ratio qualitatively resembles the decrease in S
XV election temperature with height (measurable up to ~85,000 km) in
the same active region obtained from the Bragg crystal spectrometer
instrument on Yohkoh. The CDS images indicate that the highest S
XV temperatures and largest CDS ratios correspond to regions of
microflares, and somewhat lower S XV temperatures and CDS ratios
correspond to diffuse regions. Above 105 km, the trend of
the CDS ratios changes, either increasing or remaining approximately
constant with height. At these altitudes the CDS images show faint,
large-scale diffuse structures.

---------------------------------------------------------
Title: SunBlock '99: Young Scientists Investigate the Sun
Authors: Walsh, R. W.; Pike, C. D.; Mason, H.; Young, P.; Ireland,
J.; Galsgaard, K.
1999ESASP.446..693W Altcode: 1999soho....8..693W
SunBlock `99 is a Web-based Public Understanding of Science and
educational project which seeks to present the very latest solar
research as seen through the eyes of young British scientists. These
“solar guides” discuss not only their scientific interests, but also
their extra-curricular activities and the reasons they chose scientific
careers; in other words the human face of scientific research. The
SunBlock '99 pages gather a range of solar images and movies from
current solar space observatories and discuss the underlying physics
and its relationship to the school curriculum. The instructional level
is pitched at UK secondary school children (aged 13-16 years). It is
intended that the material should not only provide a visually appealing
introduction to the study of the Sun, but that it should help bridge
the often wide gap between classroom science lessons and the research
scientist `out in the field'. SunBlock '99 is managed by a team from
the Rutherford Appleton Laboratory and the Universities of St Andrews
and Cambridge, together with educational consultants. The production
has, in part, been sponsored by PPARC and the Millennium Mathematics
Project. Web site addresss: http://www.sunblock99.org.uk

---------------------------------------------------------
Title: Searching for Sigmoids in SOHO/CDS
Authors: Gibson, Sarah; Mason, Helen; Pike, Dave; Young, Peter
1999ESASP.446..331G Altcode: 1999soho....8..331G
Sigmoidal structures observed in X-rays have been shown to be precursors
to CMEs, existing in some cases for several days before an eruption
(Sterling and Hudson 1997,ApJ,491,L55; Canfield et al, 1999, GRL, 26,
6, 627). While these S-shaped structures are most apparent in X-ray
active region observations, they may be manifestations of a more general
helical magnetic structure having observational signatures at other
wavelengths. We will present preliminary results of a survey search for
sigmoidal structures and other CME tracers in archived SOHO/CDS data
for a series of active regions known to contain erupting sigmoidal
structures in X-ray observations. We are particularly interested in
determining the relative locations and temperatures of these tracers,
and will see to what extent the data answers questions such as,
if S shapes are observed at different wavelengths do they line up,
or is there a spatial displacement and/or rotation of angle of S that
corresponds with height/temperature variation ? How does the appearance
of the region vary over the lifetime of the observed x-ray sigmoidal
structure ? After an eruption, how much if any of the S shape remains,
and at what spatial and spectral locations ? We will use the results of
this comparison survey to consider what the implications are for the
underlying magnetic field structure, and the location and variation
of heating throughout it.

---------------------------------------------------------
Title: Electron density and temperature structure of two limb active
regions observed by SOHO-CDS
Authors: Mason, H. E.; Landi, E.; Pike, C. D.; Young, P. R.
1999SoPh..189..129M Altcode:
The analysis of two active regions on the limb using observations from
SOHO-CDS allows us to determine the electron density and temperature
distribution of the coronal emission. We find that the active regions
have hot cores (3×106 K) with larger cooler (106
K) loop structures extending above the limb. The electron number
density, determined using the Si X diagnostic line ratio, is found to
be highest in the active region core (greater than 2.3×109
cm−3). Electron number density values are determined for a
range of spectral lines from different ions and are found to increase
with temperature between 0.8 and 2.5×106 K. These results
are consistent with recent models of enhanced heating along the compact
core of active regions, where the magnetic field shear is strongest.

---------------------------------------------------------
Title: CHIANTI - an atomic database for emission lines. III. Continuum
radiation and extension of the ion database
Authors: Landi, E.; Landini, M.; Dere, K. P.; Young, P. R.; Mason,
H. E.
1999A&AS..135..339L Altcode:
CHIANTI provides a database of atomic energy levels, wavelengths,
radiative transition probabilities and electron excitation data for a
large number of ions of astrophysical interest. This database allows
the calculation of theoretical line emissivities necessary for the
analysis of optically thin emission line spectra, and includes also
a suite of IDL (Interactive Data Language) programs to calculate
optically thin synthetic spectra and to perform spectral analysis and
plasma diagnostics. The first version (1.0) of the CHIANTI database was
released in 1996 te[(Dere et al. 1997)]{Der97} and has been extensively
used for analysis of line spectra from astrophysical sources by the
scientific community. The present paper describes the first major update
to the CHIANTI database which will subsequently be labeled version
2.0. The update consists of the addition of a large number of new ions,
the revision of existing data for some ions and the inclusion of an
IDL procedure to calculate the continuum. The CHIANTI atomic database
and supporting IDL routines are freely available through the internet.

---------------------------------------------------------
Title: Solar Wind Outflow and the Chromospheric Magnetic Network
Authors: Hassler, Donald M.; Dammasch, Ingolf E.; Lemaire, Philippe;
Brekke, Pal; Curdt, Werner; Mason, Helen E.; Vial, Jean-Claude;
Wilhelm, Klaus
1999Sci...283..810H Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Calentamiento de arcos coronales en una región activa por
reconfiguración topológica del campo magnético.
Authors: López Fuentes, M.; Mandrini, C. H.; Démoulin, P.; Schmieder,
B.; Fletcher, L.; Mason, H.
1999BAAA...43...24L Altcode:
We study the active region (AR) 8048 observed on June 1997 in several
wavelenghts. The combined observations obtained using CDS (SOHO)
and SXT (Yohkoh) show the heating of the coronal magnetic loops at
different atmospheric altitudes. Extrapolating the magnetic field in the
corona from longitudinal magnetograms from MDI (SOHO), we determine the
location of Bald Patches in the surroundings of the leading spot. This
magnetic feature, the emergence of parasitic magnetic polarities and
the observed photospheric motions provide the conditions to explain
the observed heating.

---------------------------------------------------------
Title: SOHO - Where has the Quiet Sun gone?
Authors: Mason, H. E.
1999ASPC..158..348M Altcode: 1999ssa..conf..348M
No abstract at ADS

---------------------------------------------------------
Title: Working Group 4 Report: Composition and Elemental Abundance
Variations in the Solar Atmosphere and Solar Wind
Authors: Mason, Helen E.; Bochsler, Peter
1999SSRv...87..105M Altcode:
This paper contains a summary of the topics treated in the working
group on abundance variations in the solar atmosphere and in the solar
wind. The FIP bias (overabundance of particles with low First Ionization
Potentials over photospheric abundances) in coronal holes and coronal
hole associated solar wind amounts to values between 1 and 2. The FIP
bias in the slow solar wind is typically a factor 4, consistent with
optical observations in streamers. In order to distinguish between
different theoretical models which make an attempt to explain the FIP
bias, some observable parameters must be provided. Unfortunately,
many models are deficient in this respect. In addition to FIP
fractionation, gravitational settling of heavy elements has been
found in the core of long lived streamers. The so-called electron
'freeze in' temperatures derived from in situ observed ionization
states of minor ions in the fast wind are significantly higher than
the electron temperatures derived from diagnostic line ratios observed
in polar coronal holes. The distinction between conditions in plumes
and interplume lanes needs to be further investigated. The 'freeze in'
temperatures for the slow solar wind are consistent with the electron
temperatures derived for streamers.

---------------------------------------------------------
Title: Observation of Transition Region Fine Structures with
Soho/Sumer
Authors: Landi, E.; Mason, H. E.; Landini, M.
1999SSRv...87..241L Altcode:
We present a preliminary analysis of two quiet Sun transition
region areas observed with the SOHO/SUMER spectrometer, using lines
from oxygen, nitrogen and silicon. The average quiet Sun physical
parameters are studied as a function of line intensity. Systematic
variations of line position and width with increasing intensity are
found. A large number of small-scale active points have been observed,
and preliminary analysis of the physical properties and dynamics of
these active features is presented. A jet-like structure, found in an
active point, is also investigated and its velocity along the line of
sight determined.

---------------------------------------------------------
Title: Rotating Transition Region Features Observed with the SOHO
Coronal Diagnostic Spectrometer
Authors: Pike, C. D.; Mason, H. E.
1998SoPh..182..333P Altcode:
Strong evidence has been found from SOHO-CDS (Solar and Heliospheric
Observatory - Coronal Diagnostic Spectrometer) observations to support
the hypothesis that rotation plays a major role in the dynamics of
transition region features. A comprehensive survey of the CDS daily
synoptic rasters has been carried out to select dynamic events by
searching for spectral line shifts in the O v emission line at 629.73 Å
(formed at a temperature of 2.5×105 K). Unique CDS observations of a
macrospicule were reported by Pike and Harrison (1997), and several more
macrospicule-like solar features have now been identified in the polar
regions both on the limb and disk. These show blue- and red-shifted
emission on either side of an axis stretching above the limb from
a footpoint region on the disk. These observations are interpreted
as indicating the presence of a rotating plasma, a sort of solar
tornado. In the examples studied, the rotation velocities increase
with height. The implications for coronal heating models are discussed.

---------------------------------------------------------
Title: Atomic data from the IRON project. XXXI. Electron impact
excitation of optically allowed and intercombination electric dipole
transitions in Fe XII
Authors: Binello, A. M.; Mason, H. E.; Storey, P. J.
1998A&AS..131..153B Altcode:
A new, accurate set of electron impact collisional data is presented,
relating to all electric dipole fine-structure transitions between
the ground {3s(2) 3p(3) } and the first two excited {3s 3p(4) },
{3s(2) 3p(2) 3d} configurations in {Fe xii} (Fe(11+) ). Theoretical
energies have been obtained with a multi-configuration atomic structure
calculation. The {R-matrix} method, coupled with the {Coulomb-Bethe}
(CBe) approximation for the high partial wave contributions to the
collision strengths, has been employed in the Fe(11+) - e(-) scattering
problem. The data presented in this paper form part of the IRON Project
effort to provide the most accurate atomic data available to date
for all the iron ions (Hummer et al. 1993). Tables 1 to 9 are also
available in electronic form at the CDS via ftp to cdsarc.u-strasbg.fr
(130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html

---------------------------------------------------------
Title: A new perspective on the sun from SOHO-challenges for atomic
physics
Authors: Dere, Kenneth; Mason, Helen
1998AIPC..434..213D Altcode: 1998amda.conf..213D
The Solar and Heliospheric Observatory (SOHO) carries several
ultraviolet spectrometers to diagnose the plasma conditions of
the solar atmosphere in order to address several outstanding
questions in solar research: why is the corona hot and how is the
solar wind accelerated. Diagnostic techniques for determining the
magnetohydrodynamic state (magnetic field, density, temperature,
velocity) are discussed. We describe the CHIANTI database which has been
designed to provide the necessary spectroscopic diagnostics for these
data as well as for other spectroscopic missions. The database is built
on 3 main files for each ion: atomic energy levels, radiative data,
and electron collisional data. The electron collision strengths are
assessed and scaled using the Burgess and Tully scaling laws. Analyses
of EUV line intensities often reveal discrepancies between observed
and predicted line intensities of about of 2 when considering lines of
the same ion. A more recent analysis has shown that it is possible to
arrive at a subset of EUV spectral lines where the line intensities
are reproducible to within about 25%. For X-ray lines, as will be
observed by AXAF, there is still considerable need for energy levels,
radiative data and collision strengths, particularly for the Δn&gt;=1
transitions.

---------------------------------------------------------
Title: Atomic Physics for Atmospheric Composition Measurements
Authors: Young, P. R.; Mason, H. E.
1998SSRv...85..315Y Altcode:
The atomic physics relevant to the interpretation of solar spectra
produced by plasmas at temperatures ≳ 105 K are discussed. Methods
for determining relative abundance ratios are presented and examples
provided from the Coronal Diagnostic Spectrometer on board SOHO. In
particular, the Fe/Si ratio in the corona is found to be close to
photospheric; the Mg/Ne ratio in the transition region is found to
vary by an order of magnitude in different solar features. The Mg/Ne
ratios in supergranule cell centres and the network are separated for
the first time, although no significant differences are found.

---------------------------------------------------------
Title: VizieR Online Data Catalog: IRON Project XXXI. Fe XII electron
excitation (Binello+ 1998)
Authors: Binello, A. M.; Mason, H. E.; Storey, P. J.
1998yCat..41310153B Altcode:
The following tables list energy levels and electron excitation data for
the lowest 41 levels of Fe XII (configurations 3s2 3p^3, 3s
3p4 and 3s2 3p2 3d). The table numbers
correspond to the numbering given in the paper (8 data files).

---------------------------------------------------------
Title: Atomic data from the IRON Project. XXV. Electron impact
excitation of fine-structure transitions in the ground configuration
of Fe XII
Authors: Binello, A. M.; Mason, H. E.; Storey, P. J.
1998A&AS..127..545B Altcode:
In the framework of the IRON Project we have performed new, fully
quantum mechanical atomic calculations for the Fexii (Fe(11+) )
coronal ion. Energy levels, oscillator strengths and spontaneous decay
transition probabilities have been computed by including extensive
configuration interaction (CI) and relativistic effects in the
solution of the atomic structure problem. The R-matrix approach has
been employed to solve the electron scattering problem and generate
a new set of collisional atomic data. Results are discussed for the
ten fine-structure forbidden transitions in the 3s(23p^3) ground
configuration of Fexii, and compared with previous calculations.

---------------------------------------------------------
Title: Atomic Physics for Atmospheric Composition Measurements
Authors: Young, P. R.; Mason, H. E.
1998sce..conf..315Y Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Surges and filaments in active regions during SOHO campaigns
Authors: Schmieder, B.; Deng, Y.; Rudawy, P.; Nitta, N.; Mandrini,
C. H.; Fletcher, L.; Martens, P.; Innes, D.; Young, P.; Mason, H.
1998ESASP.421..323S Altcode: 1998sjcp.conf..323S
No abstract at ADS

---------------------------------------------------------
Title: Dynamic features observed with SOHO-CDS
Authors: Mason, H.
1998ESASP.421...95M Altcode: 1998sjcp.conf...95M
No abstract at ADS

---------------------------------------------------------
Title: CHIANTI - an Atomic Database For Emission Lines Paper I:
Wavelengths Greater than 50 Angstroms
Authors: Dere, K. P.; Landi, E.; Mason, H. E.; Fossi, B. C. M.; Young,
P. R.
1998ASPC..143..390D Altcode: 1998sigh.conf..390D
No abstract at ADS

---------------------------------------------------------
Title: Plasma Diagnostics for the Solar Atmosphere
Authors: Mason, Helen E.
1998LNP...507..143M Altcode: 1998sspt.conf..143M
Superb observations are now being obtained with the ESA/NASA Solar
Heliospheric Observatory (SOHO). In these lectures, I discuss the
spectroscopic diagnostic techniques used to analyse ultraviolet and
X-ray spectra. Intensities of the spectral emission lines can be used
to determine the electron density and temperature structure, element
abundances and dynamic nature of different features in the solar
transition region and corona. To ensure that these techniques are
accurate it is necessary to model all the important atomic processes
with the best available atomic data calculations. I discuss the
analysis of SOHO spectra and look towards other astrophysical UV and
X-ray observations.

---------------------------------------------------------
Title: New Results from the Coronal Diagnostic Spectrometer
Authors: Mason, H. E.; Pike, C. D.
1998ASPC..154..431M Altcode: 1998csss...10..431M
The Coronal Diagnostic Spectrometer (CDS) on SOHO has provided
some exciting new results on the nature of the solar transition
region and corona. CDS has as a scientific goal the determination
of the physical parameters of the solar plasma, using spectroscopic
diagnostic techniques. Intensity ratios of the EUV spectral emission
lines (150-785A) have been used to obtain information on the electron
density and temperature structure, element abundance and the dynamic
nature of various solar features. An overview of these CDS results is
presented here.

---------------------------------------------------------
Title: Solar Active Region Movies seen by the SOHO Extreme-ultraviolet
Telescope
Authors: Newmark, J. S.; Thompson, B.; Gurman, J. B.; Delaboudiniere,
J. P.; Aschwanden, Markus; Mason, Helen
1997AAS...191.7307N Altcode: 1997BAAS...29.1321N
The Extreme-ultraviolet Imaging Telescope (EIT) on board the SOHO (SOlar
and Heliospheric Observatory) satellite provides wide-field images of
the corona and transition region on the solar disc and up to 1.4 solar
radii above the limb. Its normal incidence multilayer-coated optics
select spectral emission lines from FeIX (171 Ang), FeXII (195 Ang),
FeXV (284 Ang), and HeII (304 Ang) with 2.6 arcsecond resolution which
allow us to describe Solar activity over a wide temperature range. EIT
is providing unique EUV observations of the structure and evolution of
active regions. Here we show movies of active region 8059 from July
3-10, 1997. The high temporal variability of the AR loops is very
evident. Initial temperature and density diagnostics are explored as
well as a comparison with diagnostics from the SOHO-CDS instrument.

---------------------------------------------------------
Title: Active Regions Observed in Extreme Ultraviolet Light by the
Coronal Diagnostic Spectrometer on SOHO
Authors: Fludra, A.; Brekke, P.; Harrison, R. A.; Mason, H. E.; Pike,
C. D.; Thompson, W. T.; Young, P. R.
1997SoPh..175..487F Altcode:
We present observations of five active regions made by the Coronal
Diagnostic Spectrometer (CDS) on the Solar and Heliospheric Observatory
(SOHO). CDS observes the Sun in the extreme ultraviolet range 150-780
Å. Examples of active region loops seen in spectral lines emitted at
various temperatures are shown. Several classes of loops are identified:
those that are seen in all temperatures up to 2 x 106 K;
loops seen at 106 K but not reaching 1.6 x 106
K; those at temperatures 2- 4 x 10-5 K and occasionally at
6 x 10-5 K but not reaching 106 K. An increasing
loop size with temperature and the relationship between the cool and
hot structures is discussed. CDS observations reveal the existence of
loops and other unresolved structures in active regions, at temperatures
between 1.5- 4 x 10-5 K, which do not have counterparts in
lines emitted above 8 x 10-5 K. Bright compact sources only
seen in the transition region lines are investigated. These sources can
have lifetimes of up to several days and are located in the vicinity
of sunspots. We study the variability of active region sources on time
scales from 30 sec to several days. We find oscillatory behaviour of Hei
and Ov line intensities in an active region on time scales of 5-10 min.

---------------------------------------------------------
Title: CHIANTI - an atomic database for emission lines
Authors: Dere, K. P.; Landi, E.; Mason, H. E.; Monsignori Fossi,
B. C.; Young, P. R.
1997A&AS..125..149D Altcode:
A comprehensive set of accurate atomic data is required for analyses of
astrophysical and solar spectra. CHIANTI provides a database of atomic
energy levels, wavelengths, radiative data and electron excitation
data for ions which are abundant in cosmic plasmas. The most recent
electron excitation data have been assessed and stored following
the method of \cite[Burgess \&amp; Tully (1992)]{bur92}. The current
version is essentially complete for specifying the emission spectrum
at wavelengths greater than 50 Angstroms. A list of observed lines in
the spectral region between 50 and 1100 Angstroms has been compiled
and compared with the lines predicted by the CHIANTI database. The
CHIANTI database reproduces the vast majority of lines observed at
these wavelengths. CHIANTI includes IDL (Interactive Data Language)
routines to calculate optically thin synthetic spectra for equilibrium
conditions. IDL routines to calculate theoretical line intensities
required for electron density or temperature diagnostics and emission
measure studies are also included. The CHIANTI atomic database and
supporting IDL routines are available by anonymous FTP.

---------------------------------------------------------
Title: Soho Cds nis in-flight intensity calibration using a plasma
diagnostic method
Authors: Landi, E.; Landini, M.; Pike, C. D.; Mason, H. E.
1997SoPh..175..553L Altcode:
The internal intensity calibration of the Coronal Diagnostic
Spectrometer (CDS) - Normal Incidence Spectrometer (NIS) is studied
using the Arcetri diagnostic method. A large number of spectral lines
observed by the CDS-NIS 1 and NIS 2 windows in a solar active region
is analysed in order to determine the intensity calibration curve for
both channels.

---------------------------------------------------------
Title: The Mg/Ne abundance ratio in a recently emerged flux region
observed by CDS
Authors: Young, P. R.; Mason, H. E.
1997SoPh..175..523Y Altcode:
Evidence for the existence of the FIP-effect in the transition region is
presented here based on recent observations from the Coronal Diagnostic
Spectrometer (CDS) on-board the Solar and Heliospheric Observatory
(SOHO). Observations of an emerging flux region in lines of Mgv-vii and
Nevi-vii reveal differences in the relative Mg/Ne abundance of a factor
of 9.2 between two transition region brightenings separated by less
than 1 arc min on the Sun. The lower abundance ratio is approximately
equal to the photospheric Mg/Ne value and is associated with a small
loop-like feature in the central, hottest part of the active region. The
higher abundance ratio is found in spike-like structures at the edge
of the active region. A density diagnostic of Oiv is used to derive
an electron number density of 1011.3 cm-3 for
the low Mg/Ne brightening, while a Mgvii diagnostic gives a density
of 109.2 cm for the high Mg/Ne brightening.

---------------------------------------------------------
Title: The Ar/Ca relative abundance in solar coronal plasma.
Authors: Young, P. R.; Mason, H. E.; Keenan, F. P.; Widing, K. G.
1997A&A...323..243Y Altcode:
The relative abundances of elements with low and high first
ionisation potentials (FIP) is a subject of much recent debate. In
situ measurements of the solar wind reveal a clear pattern of low
FIP enhancement that has been followed up with various spectroscopic
measurements of the solar corona. Argon is unique amongst the more
abundant high FIP elements in retaining several of its electrons at
the high temperatures seen in flares. This allows emission lines of
different ions to be compared with more confidence than for, say,
hydrogen-like high FIP ions such as OVIII and NeX. In this paper we
look at emission lines of the boron-like ion ArXIV; in particular,
the optical line at 4412Å, seen in eclipse observations, is compared
to the CaXIII 4086Å and CaXV 5445Å &amp; 5694Å lines to yield an
Ar/Ca abundance of 0.85+/- 0.20. In the extreme ultra-violet (EUV),
the ArXIV lines at 187.94Å and 194.41Å can be compared with CaXIV
193.87 Å - flare data from Skylab giving values of 1.10+/-0.25 and
0.55+/-0.21. Analysis of previous work indicates a photospheric Ar/Ca
abundance of 1.31+/-0.30, hence supporting the conclusion that elements
with high FIP have lower coronal abundances.

---------------------------------------------------------
Title: VizieR Online Data Catalog: CHIANTI - An Atomic Database For
Emission Lines I. (Dere+ 1997)
Authors: Dere, K. P.; Landi, E.; Mason, H. E.; Monsignori Fossi,
B. C.; Young, P. R.
1997yCat..41250149D Altcode:
A comprehensive set of accurate atomic data is required for analyses of
astrophysical and solar spectra. CHIANTI provides a database of atomic
energy levels, wavelengths, radiative data and electron excitation
data for ions which are abundant in cosmic plasmas. The most recent
electron excitation data have been assessed and stored following
the method of Burgess &amp; Tully (1992A&amp;A...254..436B). The
current version is essentially complete for specifying the emission
spectrum at wavelengths greater than 50Å. A list of observed lines
in the spectral region between 50 and 1100Å has been compiled
and compared with the lines predicted by the CHIANTI database. The
CHIANTI database reproduces the vast majority of lines observed at
these wavelengths. CHIANTI includes IDL (Interactive Data Language)
routines to calculate optically thin synthetic spectra for equilibrium
conditions. IDL routines to calculate theoretical line intensities
required for electron density or temperature diagnostics and emission
measure studies are also included. The CHIANTI atomic database and
supporting IDL routines are available by anonymous FTP. (1 data file).

---------------------------------------------------------
Title: UV and soft X-ray lines from Fe XVI observed in solar and
stellar spectra.
Authors: Cornille, M.; Dubau, J.; Mason, H. E.; Blancard, C.; Brown,
W. A.
1997A&A...320..333C Altcode:
The ion Fe XVI is abundant in solar active regions and flares. Strong
spectral lines from this ion have been observed over a wide wavelength
range. The transitions 3s-3p and 3p-3d fall between 250 and 365Å and
lines from transitions between n=3 to n=4, n=3 to n=5 fall between
30 and 80Å. In this paper, we present distorted wave results for
the electron scattering collision strengths from the ground level to
all the other levels and discuss previous calculations. We compare
our theoretical intensity ratios with solar observations and show
that the strongest spectral lines in the X-ray wavelength range do
not correspond to the dipole transitions, 3s-4p, 3s-5p, as might be
expected. We comment on the approximations which have been generally
used in synthetic spectrum programs to simulate the Fe XVI spectral
line intensities and the consequences for analyses of solar and
stellar spectra.

---------------------------------------------------------
Title: Spectral Line Intensities for n = 3-3 EUV Transitions in Fe XV
Authors: Bhatia, A. K.; Mason, H. E.
1997ADNDT..66..119B Altcode:
Transition rates and collision strengths between the
fine-structure levels of Fe XV have been calculated using
the configurations 3s2, 3s3p, 3p2,
3s3d, 3p3d, and 3d2and are compared here with other
calculations. The present calculations were carried out using the
Superstructure and distorted-wave programs developed at University
College, London. Level populations and line intensity ratios
are calculated for three temperatures with logTe(K)
= 6.2, 6.4, and 6.6 and for electron densitiesNe=
108-1012cm-3. Calculated intensity
ratios of the emission lines are compared with those observed by
the Solar EUV Rocket Telescope and Spectrograph (SERTS) in an active
region of sun. The present results should also be useful in analyzing
observations from the Solar Heliospheric Observatory (SOHO).

---------------------------------------------------------
Title: New atomic data for the FeXII coronal ion
Authors: Binello, A. M.; Mason, H. E.; Storey, P. J.
1997AdSpR..20.2263B Altcode:
Various FeXII spectroscopic lines in the UV and EUV range have been
proved to be ideal diagnostic tools for measuring electron temperature,
density and iron abundance in the solar corona. In the framework of the
“IRON PROJECT” we have provided improved theoretical calculations
of the atomic data required to analyse the intensity of these lines
and to apply the results to SOHO (Solar Heliospheric Observatory)
observations. Extensive configuration interaction and relativistic
effects have been allowed for in the atomic structure computations which
have provided energy levels and an extensive set of radiative data. The
e-FeXII collisional problem has been tackled with the multichannel
R-matrix method, a close-coupling calculation for the determination
of electron impact collision strengths. Final results are presented
for FeXII thermally averaged collision strengths, for fine-structure
forbidden transitions within the ground configuration.

---------------------------------------------------------
Title: Application of Spectroscopic Diagnostics to Early Observations
with the SOHO Coronal Diagnostic Spectrometer
Authors: Mason, H. E.; Young, P. R.; Pike, C. D.; Harrison, R. A.;
Fludra, A.; Bromage, B. J. I.; Del Zanna, G.
1997SoPh..170..143M Altcode:
The Coronal Diagnostic Spectrometer (CDS) has as a scientific goal
the determination of the physical parameters of the solar plasma
using spectroscopic diagnostic techniques. Absolute intensities and
intensity ratios of the EUV spectral emission lines can be used to
obtain information on the electron density and temperature structure,
element abundances, and dynamic nature of different features in the
solar atmosphere. To ensure that these techniques are accurate it is
necessary to interface solar analysis programs with the best available
atomic data calculations. Progress is reported on this work in relation
to CDS observations.

---------------------------------------------------------
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.
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: High Coronal Electron Densities in a Solar Flare from Fe XXI
and Fe XXII X-Ray Line Measurements
Authors: Phillips, K. J. H.; Bhatia, A. K.; Mason, H. E.; Zarro, D. M.
1996ApJ...466..549P Altcode:
New calculations of the intensities of the Fe XXI 2p2-2p4l
X-ray lines using the distorted wave method are described and compared
with observations made by a crystal spectrometer on the Solar Maximum
Mission about 6 minutes after the peak of a very intense flare. The
comparison enables the electron density of the flare to be derived,
the value being about 2 or 3 × 1012 cm-3. Some
nearby Fe XXII X-ray lines, scanned 1 minute after flare peak, give an
even higher value, 1013 cm-3. This is the first
time corroborated values of such high densities have been obtained
from ions emitted at temperatures as high as ∼10 MK. They imply very
rapid radiation cooling rates and have other important consequences
for flare models.

---------------------------------------------------------
Title: CHIANTI - an Atomic Database for Emission Line Spectroscopy:
Version 1 - Wavelengths greater than 50 Angstroms
Authors: Dere, K. P.; Monsignori-Fossi, B. C.; Landi, E.; Mason,
H. E.; Young, P. R.
1996AAS...188.8501D Altcode: 1996BAAS...28..961D
A comprehensive set of accurate atomic data is required for analyses of
astrophysical and solar spectra. CHIANTI provides an atomic database of
energy levels (wavelengths), radiative data and electron excitation data
for ions which are abundant in astrophysical plasmas. The most recent
electron excitation data have been assessed and stored following the
method of Burgess and Tully (1992). CHIANTI includes IDL (Interactive
Data Language) routines to produce optically thin synthetic spectra
for lambda &gt; 50 Angstroms, assuming equilibrium conditions. It also
includes IDL routines to calculate theoretical line intensities required
for electron density or temperature diagnostics and emission measure
studies. The CHIANTI atomic database and supporting IDL routines are
available by anonymous FTP.

---------------------------------------------------------
Title: Atomic data from the IRON Project. XIV. Electron
impact excitation of the Fe XIV fine-structure transition
^2^P^o^_1/2_-^2^P^o^_3/2_
Authors: Storey, P. J.; Mason, H. E.; Saraph, H. E.
1996A&A...309..677S Altcode:
We calculate collision strengths and collision rates for electron
excitation of the ^2^P^o^_1/2_-^2^P^o^_3/2_ ground term fine-structure
transition in Fe xiv, the coronal green line at 5303A. The collision
strength for the green line is found to be strongly enhanced by
resonances for the first 4 Rydberg above the excitation threshold, and
as a result the collision rates are found to be significantly larger
than other recently published results, even at coronal temperatures. The
calculations are carried out using the R-matrix formulation of the
close-coupling approximation.

---------------------------------------------------------
Title: New atomic data for the FeXII coronal ion
Authors: Binello, A. M.; Mason, H. E.; Storey, P. J.; Kohl, J.
1996ASPC..109..251B Altcode: 1996csss....9..251B
No abstract at ADS

---------------------------------------------------------
Title: EUV density diagnostics in solar and stellar spectra
Authors: Young, P. R.; Mason, H. E.
1996ASPC..109..301Y Altcode: 1996csss....9..301Y
No abstract at ADS

---------------------------------------------------------
Title: EUV Line Intensities of Fe X
Authors: Young, P. R.; Mason, H. E.; Bhatia, A. K.; Doschek, G. A.;
Thomas, R. J.
1996aeu..conf..583Y Altcode: 1996IAUCo.152..583Y
No abstract at ADS

---------------------------------------------------------
Title: Plasma Emission Codes: Comparisons and Critiques
Authors: Mason, Helen E.
1996aeu..conf..561M Altcode: 1996IAUCo.152..561M
No abstract at ADS

---------------------------------------------------------
Title: High coronal electron densities in a solar flare from Fe XXI
and Fe XXII X-ray line ratios.
Authors: Phillips, K. J. H.; Bhatia, A. K.; Mason, H. E.; Zarro, D. M.
1996uxsa.conf...75P Altcode: 1996uxsa.coll...75P
New distorted-wave calculations of the intensities of the Fe XXI
2p2 - 2p4l X-ray lines are described and compared with
observations made during an unusually intense flare. The density
sensitivity of some of the lines implies that Ne is between
1012 and 1013cm-3. An even higher value
(1013cm-3) is obtained from nearby Fe XXII 2p -
4d lines. This is the first time such high densities have been measured
from ions emitted at temperatures as high as ≡107K. They
imply very rapid radiation cooling rates, and have other important
consequences for flare models.

---------------------------------------------------------
Title: Atomic data for solar VUV spectroscopy (SOHO).
Authors: Mason, H. E.
1996uxsa.conf..213M Altcode: 1996uxsa.coll..213M
A great deal of effort in recent years has gone into the development of
spectroscopic techniques to probe the physical parameters of the solar
atmosphere. One aspect of this work is the calculation of new atomic
data and the development of plasma emission codes to study spectral
lines. This work is being carried out in preparation for the SOHO
(Solar Heliospheric Observatory). In this paper, the author presents
an overview of the atomic processes involved and an assessment of
the accuracy of the parameters which are required for spectroscopic
diagnostics in the EUV and UV wavelength ranges.

---------------------------------------------------------
Title: The Coronal Diagnostic Spectrometer for the Solar and
Heliospheric Observatory
Authors: Harrison, R. A.; Sawyer, E. C.; Carter, M. K.; Cruise,
A. M.; Cutler, R. M.; Fludra, A.; Hayes, R. W.; Kent, B. J.; Lang,
J.; Parker, D. J.; Payne, J.; Pike, C. D.; Peskett, S. C.; Richards,
A. G.; Gulhane, J. L.; Norman, K.; Breeveld, A. A.; Breeveld, E. R.; Al
Janabi, K. F.; Mccalden, A. J.; Parkinson, J. H.; Self, D. G.; Thomas,
P. D.; Poland, A. I.; Thomas, R. J.; Thompson, W. T.; Kjeldseth-Moe,
O.; Brekke, P.; Karud, J.; Maltby, P.; Aschenbach, B.; Bräuninger,
H.; Kühne, M.; Hollandt, J.; Siegmund, O. H. W.; Huber, M. C. E.;
Gabriel, A. H.; Mason, H. E.; Bromage, B. J. I.
1995SoPh..162..233H Altcode:
The Coronal Diagnostic Spectrometer is designed to probe the solar
atmosphere through the detection of spectral emission lines in the
extreme ultraviolet wavelength range 150 - 800 å. By observing
the intensities of selected lines and line profiles, we may derive
temperature, density, flow and abundance information for the plasmas
in the solar atmosphere. Spatial and temporal resolutions of down to
a few arcseconds and seconds, respectively, allow such studies to be
made within the fine-scale structure of the solar corona. Futhermore,
coverage of large wavelength bands provides the capability for
simultaneously observing the properties of plasmas across the wide
temperature ranges of the solar atmosphere.

---------------------------------------------------------
Title: The application of atomic physics to the study of solar
abundances and their variations
Authors: Mason, H. E.
1995AdSpR..15g..53M Altcode: 1995AdSpR..15R..53M
The determination of elemental abundances in the solar atmosphere
depends critically on the accuracy of the atomic physics assumed
in the models. Uncertainties in the electron-ion excitation rates,
ionisation and recombination rates or other atomic processes can lead
to variations in the derived relative abundance values. In this paper,
the different methods used in the analyses of UV and X-ray spectra are
explored. Particular attention is paid to the accuracy of the atomic
parameters and the assumptions made in the atomic model. A summary is
given of the most recent theoretical and laboratory work. Implications
for analyses of existing solar datasets and proposed observations
(SOHO) are discussed.

---------------------------------------------------------
Title: Atomic data and coronal diagnostics
Authors: Mason, H. E.
1995HiA....10..303M Altcode:
No abstract at ADS

---------------------------------------------------------
Title: EUV and infra-red lines of FE XIII
Authors: Young, P. R.; Mason, H. E.; Thomas, R. J.
1994ESASP.373..417Y Altcode: 1994soho....3..417Y
No abstract at ADS

---------------------------------------------------------
Title: Spectroscopic diagnostics in the VUV for solar and stellar
plasmas
Authors: Mason, H. E.; Fossi, B. C. Monsignori
1994A&ARv...6..123M Altcode:
The VUV emission spectra from the solar atmosphere and stellar
atmospheres have been intensively studied during the past 25 years
with several major space programs. In this review we discuss the
spectroscopic diagnostic techniques used to study astrophysical plasmas,
the atomic processes involved, the recent observations and the plans
for future space missions.

---------------------------------------------------------
Title: Spectroscopic diagnostics for CDS and SUMER
Authors: Mason, Helen E.
1994SSRv...70..111M Altcode:
The CDS and SUMER instruments will make extensive use of spectroscopic
diagnostics to determine the physical parameters of the solar transition
region and corona. A great deal of effort is going into the development
of these techniques to ensure that they are accurate. This requires
interfacing solar analysis programs with the best available atomic
data calculations. Recent developments in this work will be presented,
with specific examples of useful spectral line ratios.

---------------------------------------------------------
Title: An Assessment of Theoretical Electron Excitation Data for Fe
IX-Fe XIV
Authors: Mason, H. E.
1994ADNDT..57..305M Altcode:
The available theoretical electron excitation data for Fe IX-Fe
XIV are assessed and recommendations are made for improvement in
future work. The averaged collision strengths are obtained using
the interactive, graphical programs of Burgess and Tully. Accurate
calculations for these ions are very difficult to carry out because
of the complexity of the n = 3 target wave functions. It is evident
that a substantial amount of work is still required for some of the
ions to obtain results with a high accuracy.

---------------------------------------------------------
Title: A New Synthetic XUV Spectrum
Authors: Dere, K. P.; Mason, H. E.; Fossi, B. C. Monsignori; Waljeski,
K. H.
1993AAS...18311203D Altcode: 1993BAAS...25.1459D
We have begun a program to develop a synthetic XUV spectrum for the
70 - 2500 /AA wavelength region based on a critical analysis of the
most recent calculations of atomic parameters, in particular, atomic
collision strengths and their thermal averages. Ultraviolet spectra
returned by the EUVE and HST instruments demonstrate a continued need
for the most accurate atomic parameters in order to determine the
physical conditions in the emitting plasmas. Most previous synthetic
spectra has relied heavily on the gaunt factor approximation which can
predict excitation rates only for dipole transitions and only to within
a factor of 2 to 3. In many cases, direct calculations of the collision
strengths are now available. Burgess and Tully (1992) have developed
a technique for critically evaluating collision strength calculations
and scaling and compacting the data. Different scalings are available
for resonance, intercombination and forbidden excitations. This method
will be applied in the construction of our spectrum. In the end, we
intend to produce a set of critically evaluated atomic parameters
from which the nearly optically thin spectrum of a low density
astrophysical plasma can be calculated, together with the programs
necessary to perform these calculations. We will include the ability
to prescribe elemental abundances and to correct for optical depth
and populations of metastable levels as a function of density. The
data sets and programs will be made available by anonymous ftp.

---------------------------------------------------------
Title: Nonthermal Velocities in the Solar Transition Zone Observed
with the High-Resolution Telescope and Spectrograph
Authors: Dere, K. P.; Mason, H. E.
1993SoPh..144..217D Altcode:
Data obtained during the first rocket flight of the NRL High Resolution
Telescope and Spectrograph (HRTS) have been used to study nonthermal
velocities for spectral lines primarily covering the temperature
range 104 to 2 × 106 K. The high spectral and
spatial resolution, combined with an enhanced dynamic intensity range
of the reduced data, has enabled us to study the distribution of the
nonthermal velocities for quiet and active regions. Average values
of the nonthermal velocities peak at about 27 km s−1
at 105 K for the quiet regions, with a wide distribution
of nonthermal velocities for each line. The active region nonthermal
velocities have a narrower distribution which is weighted towards higher
values. The SiIV and C IV line profiles are not well described by a
single Gaussian, indicating that high-velocity components (above 30 km
s−1) are present in the quiet-Sun spectra. The radiative
losses for all plasma above l05 K have been calculated for
the quiet Sun, an active region and a coronal hole. These have been
compared with the acoustic wave flux inferred from the nonthermal line
widths. There appears to be a sufficient flux of waves to heat these
regions of the atmosphere.

---------------------------------------------------------
Title: Atomic data for the SOHO mission.
Authors: Burgess, A.; Mason, H. E.; Tully, J. A.
1993uxrs.conf...97B Altcode: 1993uxsa.conf...97B
An interactive computer program has been developed by Burgess and Tully
(1992) to assess and store electron excitation collision rates. The
program is being used to prepare atomic data which is required to
analyse solar and astrophysical spectra. In this paper, the authors
present work in progress on several solar ions with spectral lines in
the UV wavelength region. These will be observed by the CDS and SUMER
instruments to be flown on the SOHO mission.

---------------------------------------------------------
Title: Abundance determination in the quiet corona.
Authors: Mason, Helen E.
1992ESASP.348..297M Altcode: 1992cscl.work..297M
A study is made of the determination of element abundances in the quiet
regions of the solar transition zone and corona. The early work with EUV
spectral lines, which is cited in the paper by Meyer (1985), is reviewed
together with subsequent analyses of Skylab observations. The intention
of this paper is to question some of the assumptions which have been
made in these analyses and to look critically at the accuracy of past
and present atomic data. The overall aim is to assess what further work
is required to adapt these methods for use as diagnostic techniques
with the SOHO instruments, in particular CDS and SUMER. Mention is
also made of the importance of studying the coronal forbidden lines
in the visible and infra-red wavelength regions.

---------------------------------------------------------
Title: Atomic Physics Calculations Relevant to Solar Flare Spectra
Authors: Mason, Helen E.
1991RSPTA.336..471M Altcode:
Solar flare spectra in the ultraviolet and X-ray wavelength regions
are rich in emission lines from highly ionized ions, formed at
temperatures around 107 K. These lines can be used as
valuable diagnostics for probing the physical conditions in solar
flares. Such analyses require accurate atomic data for excitation,
ionization and recombination processes. In this paper, we present
a review of work which has already been carried out, in particular
for the Solar Maximum Mission observations, and we look to future
requirements for Solar-A.

---------------------------------------------------------
Title: A Critical Assessment of Electron Excitation between the 2s
22p 2 and 2s2p 3 Configurations of MG +6
Authors: Burgess, A.; Mason, H. E.; Tully, J. A.
1991ApJ...376..803B Altcode:
Using the programs RMATRX and DSTWAV, which are based, respectively,
on the close coupling and distorted wave approximations, we
compute and compare partial collision strengths for the optically
allowed transitions between the 2s22p2
and 2s2p3 configurations of Mg+6. From this
investigation we conclude that the differences between the published
results of Mason and Bhatia (DSTWAV) and Aggarwal (RMATRX) arise not
simply because they used different target wave functions, but also
because the method used by Aggarwal for treating the outer region in
his close coupling calculation is inadequate for optically allowed
transitions.

---------------------------------------------------------
Title: Nonthermal Velocities in the Solar Transition Region
Authors: Dere, K. P.; Mason, H. E.
1991BAAS...23Q1028D Altcode:
No abstract at ADS

---------------------------------------------------------
Title: IR Line Radiation : A Program for Interpolating Atomic
Collision Data
Authors: Burgess, A.; Chidichimo, M. C.; Mason, H. E.; Tully, J. A.
1991isrs.conf..105B Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Atomic physics calculations relevant to solar flare spectra.
Authors: Mason, H. E.
1991psf..conf..471M Altcode:
Solar flare spectra in the ultraviolet and X-ray wavelength
regions are rich in emission lines from highly ionized ions, formed
at temperatures around 107K. These lines can be used as
valuable diagnostics for probing the physical conditions in solar
flares. Such analyses require accurate atomic data for excitation,
ionization and recombination processes. The author presents a review
of work which has already been carried out, in particular for the
Solar Maximum Mission observations.

---------------------------------------------------------
Title: Collision Strengths and Oscillator Strengths for Fe IX
Authors: Fawcett, B. C.; Mason, H. E.
1991ADNDT..47...17F Altcode:
Collision strengths and oscillator strengths are calculated for
Fe IX. The three configurations 3 s23 p6, 3
s23 p53 d, and 3 s23 p54
s were included in the computations. The data can be applied to
the analysis of spectral lines in the solar spectrum and laboratory
sources. The collision calculations were executed with the DISTORTED
WAVE collision code and SUPERSTRUCTURE atomic-structure code
interfaced via transformation code JAJOM. These codes were written
at University College London. As reported in a previous publication,
the codes were adapted to enable the adjustment of Slater parameters
leading to improved energy levels and eigenvectors. The Cowan suite
of atomic-structure codes was used to generate the adopted optimized
parameters and also to compute oscillator strenghts. Possible
application of the method to more complex atomic structures was
investigated.

---------------------------------------------------------
Title: Density measurements in the corona
Authors: Mason, Helen E.
1991AdSpR..11a.293M Altcode: 1991AdSpR..11..293M
A knowledge of the electron density in the solar atmosphere is
fundamental to our understanding of the dominant physical processes. The
field of spectroscopic diagnostics is therefore an area of major
interest in the analysis of space observations. In this paper, we
review techniques which are used for determining the electron density
in the corona, with reference to UV and X-ray observations. Particular
attention is given to the accuracy of the methods, including an
assessment of the atomic parameters. Future projects are discussed,
such as the CDS and SUMER instruments on SOHO which will make extensive
use of spectroscopic diagnostics.

---------------------------------------------------------
Title: The Interpretation of the Spectral Line Intensities from the
Chase Spectrometer on SPACELAB-2
Authors: Lang, J.; Mason, H. E.; McWhirter, R. W. P.
1990SoPh..129...31L Altcode:
In this paper we analyse the solar spectral intensities observed
with the CHASE grazing incidence telescope and spectrometer flown
on NASA's Spacelab 2 Mission in 1985. Our main purpose has been to
investigate the sources of error that arise in the application of the
differential emission measure technique used to analyse such data. We
suggest methods by which these sources of error may be investigated.

---------------------------------------------------------
Title: Spectroscopic diagnostics for ions observed in solar and
cosmic plasmas
Authors: Mason, Helen E.
1990hrxr.conf...11M Altcode: 1990IAUCo.115...11M
The X-ray wavelength region (1-200 A) is rich in spectral lines
from highly ionized systems. Spectra from the solar atmosphere have
been studied extensively with various instruments covering different
wavelength regions. The solar spectral line emission with particular
reference to iron ions and helium-like ions observed during solar
flares is discussed. The atomic processes involved in the calculation of
theoretical intensities for low-density plasmas are outlined together
with the diagnostic properties of the emission lines. Comparisons are
made with available cosmic X-ray spectra and predicted spectra for
future projects, such as AXAF.

---------------------------------------------------------
Title: UV and EUV Spectroscopy of the Upper Solar Atmosphere
Authors: Mason, H. E.
1990PDHO....7..232M Altcode: 1990dysu.conf..232M; 1990ESPM....6..232M
The UV and EUV wavelength regions are rich in emission lines from the
transition region and the corona. Spectroscopic diagnostic techniques
have been used extensively to determine the physical conditions in the
solar atmosphere for such diverse phenomena as coronal holes, active
regions surges, flares. The author reviews diagnostic techniques which
have been used in the analyses of space observations (eg Skylab, SMM,
HRTS, CHASE) and looks to future projects such as the CDS and SUMER
instruments on SOHO which cover the UV and EUV wavelength regions
and will provide a wealth of observations with excellent spatial,
spectral and temporal resolution.

---------------------------------------------------------
Title: A comparison of theoretical and solar-flare intensity ratios
for the Fe XIX X-ray lines
Authors: Bhatia, A. K.; Fawcett, B. C.; Phillips, K. J. H.; Lemen,
J. R.; Mason, H. E.
1989MNRAS.240..421B Altcode:
Atomic data including energy levels, gf-values, and wavelengths are
given for the Fe XIX transitions that give rise to lines in solar-flare
and active-region X-ray spectra. Collision strengths and theoretical
intensity ratios are presented for lines which occur in the 13.2-14.3-A
range. Observed spectra are found to be consistent with those derived
from the present Fe XIX atomic data. For the case of spectra in which
the Fe XIX lines are very strong, such as those at the maxima of hot
flares, two observed line features due to Fe XIX are shown to have
larger intensities than calculated. The calculated Fe XIX and Ne IX line
spectra are used to determine electron densities from Ne IX line ratios.

---------------------------------------------------------
Title: Solar Astrophysics SIG
Authors: Mason, Helen
1989StarB...4....9M Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Coronal Mg(9+) - Collisional excitation of the 2s-2p multiplet
Authors: Burgess, A.; Mason, H. E.; Tully, J. A.
1989A&A...217..319B Altcode:
Electron impact excitation of the astrophysically important 2s-2p
multiplet in lithium-like Mg(9+) is discussed. The collision strength
for this optically allowed transition is computed using a two state
model ion with the close coupling approximation. At high impact energies
a distorted wave approximation is used. The contribution from distant
encounters is determined by the Coulomb Bethe approximation. The
Burgess-Tully method is used to interpolate the results and to
evaluate the thermally averaged collision strength from which the rate
coefficient is readily obtained.

---------------------------------------------------------
Title: A Slater Parameter Optimization Method Applied to the
Computation of Collision Strengths for Fe XIII
Authors: Fawcett, B. C.; Mason, H. E.
1989ADNDT..43..245F Altcode:
Details of a new computational method for calculating collision
strengths are presented through an application to Fe XIII. The method,
which enables the computation of collision strengths for complex ions,
is adapted from long-established optimization techniques previously
used for the calculation of atomic energy levels and oscillator
strengths. The procedure involves the adjustment of Slater parameters
and average energies of configurations so that they result in improved
energy levels and eigenvectors. These improved values can then provide
a basis for collision strength calculations in ions where ab initio
computations break down or result in unnecessarily large errors. The
present application is implemented through modifications of the
DISTORTED WAVE collision code and SUPERSTRUCTURE atomic-structure
code interfaced via a transformation code JAJOM, which also processes
their output; these atomic codes were written at University College
London. It should be feasible to make similar adaptions to other
collision codes. The Cowan suite of atomic-structure codes generated
the optimized parameters. Fe XIII collision strengths are tabulated for
3 s23 p2-3 s3 p3 and 3 s23
p2-3 s23 p3 d transitions. Six configurations,
3 s23 p2, 3 p4, 3 s3 p3,
3 s23 p3 d, 3 s3 p3 d2, and 3 p33 d,
were included in these computations.

---------------------------------------------------------
Title: Solar Astrophysics
Authors: Mason, Helen
1988StarB...2....8M Altcode:
No abstract at ADS

---------------------------------------------------------
Title: A New Aid for Interpolating and Assessing Collision Strengths
and Rate Coefficients
Authors: Burgess, A.; Mason, H. E.; Tully, J. A.
1988JPhys..49..107B Altcode: 1988IAUCo.102..107B
No abstract at ADS

---------------------------------------------------------
Title: Spectroscopic techniques for determining electron densities
in the solar atmosphere.
Authors: Mason, H. E.
1988JPhys..49...13M Altcode: 1988IAUCo.102...13M
An overview is given of the methods used for determining electron
densities in the solar atmosphere. This includes a discussion of the
accuracy of the atomic parameters required in such analyses. Several
different approximations are used to calculate electron scattering
cross-sections. These are outlined and their accuracy for individual
ions is assessed. A lot of effort has gone into the determination
of the electron densities in solar flares, particularly during the
impulsive phase. Such studies are crucial to distinguish between various
theoretical flare models. These problems are discussed in relation to
analyses of spectral data from SKYLAB, HRTS, SMM, SOLEX and XSST and
with a view to future projects such as SOHO.

---------------------------------------------------------
Title: Spectral Line Profiles of Fe XXI 1354.1 Angstrom from the
Solar Maximum Mission
Authors: Mason, H. E.; Shine, R. A.; Gurman, J. B.; Harrison, R. A.
1986ApJ...309..435M Altcode:
Observations of the Fe XXI 1354.1 A line were obtained for several
flares using the SMM-UVSP instrument with varying spectral and spatial
resolution. Of special interest are spectral line profiles from the
footpoints of flare loops taken during the impulsive phase. These
data show blueshifted Fe XXI profiles coincident and cospatial with
the impulsive brightening of chromospheric material. The present
analysis supports the hypothesis that the blueshifted component of the
high temperature emission is an integral part of the flare, possibly
associated with chromospheric evaporation.

---------------------------------------------------------
Title: Further atomic calculations for Fe XXIII
Authors: Bhatia, A. K.; Mason, H. E.
1986A&A...155..413B Altcode:
Electron collision strengths for Fe XXIII have been obtained using the
'distorted wave' approximation. Previous results (Bhatia and Mason,
1981) were obtained including the configurations 2s(2), 2s2p, 2p(2),
2s3s, 2s3p, and 2s3d. In this paper, the correlation configurations
2p3s, 2p3p and 2p3d have also been included in the solution of the
electron scattering problem.

---------------------------------------------------------
Title: Electron Density Diagnostics in the 10--100 Angstrom Interval
for a Solar Flare
Authors: Brown, W. A.; Bruner, M. E.; Acton, L. W.; Mason, H. E.
1986ApJ...301..981B Altcode:
Electron density measurements from spectral-line diagnostics are
reported for a solar flare on July 13, 1982, 1627 UT. The spectrogram,
covering the 10-95 A interval, contained usable lines of helium-like
ions C V, N VI, O VII, and Ne IX which are formed over the temperature
interval 0.7-3.5 x 10 to the 6th K. In addition, spectral-line ratios of
Si IX, Fe XIV, and Ca XV were compared with new theoretical estimates
of their electron density sensitivity to obtain additional electron
density diagnostics. An electron density of 3 x 10 to the 10th/cu
cm was obtained. The comparison of these results from helium-like
and other ions gives confidence in the utility of these tools for
solar coronal analysis and will lead to a fuller understanding of the
phenomena observed in this flare.

---------------------------------------------------------
Title: Theoretical intensity ratios for the X-ray lines from CA XV
Authors: Bhatia, A. K.; Mason, H. E.
1986A&A...155..417B Altcode:
Electron collision strengths for Ca XV have been obtained using
the 'distorted wave' approximation. Previous results (Mason,
1975; Dere et al., 1979) were obtained for the configurations
2s22p2, 2s2p3, 2p4. The
authors present results for transitions 2s22p2
→ 2s22p3s, 2s22p3d which give rise to lines
in the X-ray spectra of solar active regions and flares.

---------------------------------------------------------
Title: Interpretation of EUV spectra from loop structures in an
active region at the limb
Authors: Doyle, J. G.; Mason, H. E.; Vernazza, J. E.
1985A&A...150...69D Altcode:
EUV spectral scans and rasters of an active region observed at
the limb are analyzed. These were obtained with the Harvard EUV
spectroheliometer on the Apollo Telescope Mount. The spectra were
taken following a small flare and an H-alpha surge. Diagnostic line
ratios are used to determine electron densities and temperatures from
the spectral scans. An electron pressure of 10 to the 15th/cu cm K
is derived at 200,000 K. The temperatures derived from the diagnostic
ratios indicate that the plasma is in ionization equilibrium, although
mass flows of a few kilometers per s could be present. Rasters of
the active region taken later show well defined loop structures. The
parameters derived from the low temperature lines (100,000 K) and the
rasters are inconsistent with those inferred from scaling laws based
on static loop models. However, better agreement between the derived
parameters and the models is achieved if use is made of the electron
density derived from the emission measure of Mg X, and it is assumed
that it remains constant up to 5-million K.

---------------------------------------------------------
Title: Multiwavelength Analysis of a Well Observed Flare from Solar
Maximum Mission
Authors: MacNeice, P.; Pallavicini, R.; Mason, H. E.; Simnett, G. M.;
Antonucci, E.; Shine, R. A.; Rust, D. M.; Jordan, C.; Dennis, B. R.
1985SoPh...99..167M Altcode:
We describe and analyse observations of an M1.4 flare which began at 17:
00 UT on 12 November, 1980. Ground based Hα and magnetogram data have
been combined with EUV, soft and hard X-ray observations made with
instruments on-board the Solar Maximum Mission (SMM) satellite. The
preflare phase was marked by a gradual brightening of the flare site
in Ov and the disappearance of an Hα filament. Filament ejecta were
seen in Ov moving southward at a speed of about 60 km s−1,
before the impulsive phase. The flare loop footpoints brightened in Hα
and the CaXIX resonance line broadened dramatically 2 min before the
impulsive phase. Non-thermal hard X-ray emission was detected from the
loop footpoints during the impulsive phase while during the same period
blue-shifts corresponding to upflows of 200-250 km s−1
were seen in Ca XIX. Evidence was found for energy deposition in both
the chromosphere and corona at a number of stages during the flare. We
consider two widely studied mechanisms for the production of the high
temperature soft X-ray flare plasma in the corona, i.e. chromospheric
evaporation, and a model in which the heating and transfer of material
occurs between flux tubes during reconnection.

---------------------------------------------------------
Title: Fe XIX transitions within the N = 2 complex
Authors: Loulergue, M.; Mason, H. E.; Nussbaumer, H.; Storey, P. J.
1985A&A...150..246L Altcode:
The authors calculate the atomic data necessary for the interpretation
of the Fe XIX spectra emitted by solar flare and tokamak plasmas. They
consider the transitions between the 2s22p4,
2s2p5,and 2p6 configurations. Some of the Fe
XIX lines are potentially useful for determining electron density, and
for one XUV flare spectrum they find evidence to indicate an electron
density in excess of 1013cm-3.

---------------------------------------------------------
Title: Flare Electron Densities Using X-ray Line Ratios
Authors: Brown, W. A.; Bruner, M. E.; Acton, L. W.; Mason, H. E.
1985BAAS...17R.629B Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Diagnostic Application of Highly Ionised Iron Lines in the
Extreme Ultraviolet Spectrum of a Solar Flare
Authors: Mason, H. E.; Bhatia, A. K.; Kastner, S. O.; Neupert, W. M.;
Swartz, M.
1984SoPh...92..199M Altcode:
Recent atomic data have been used to analyze a solar flare spectrum
obtained with the Goddard Space Flight Center's grating spectrometer
on the OSO-5 satellite. There exist in the wavelength region 90-200 Å
strong lines from each of the ions Fe XVIII-Fe XXIV. The Fe XXI lines
can be used as an electron density diagnostic for the 107
K plasma. From our analysis of a particular flare, we find a steep
positive slope in the emission measure between 106.5 and
107.2 K and an electron density of ∼4 × 1011
cm−3 at 107 K. We emphasise the need for high
spectral and spatial resolution observations of solar flares in this
wavelength region, which has to date been largely neglected.

---------------------------------------------------------
Title: Evidence for Chromospheric Evaporation in Solar Flares from
UV Observations
Authors: Shine, R. A.; Mason, H. E.
1984BAAS...16..543S Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Atomic Calculations for the Highly Ionized Iron Ions Produced
in Solar Flares
Authors: Mason, H. E.; Bhatia, A. K.
1984uxsa.coll..141M Altcode: 1984uxsa.conf..141M; 1984IAUCo..86..141M
No abstract at ADS

---------------------------------------------------------
Title: Atomic calculations for the Fe XX X-ray lines
Authors: Mason, H. E.; Bhatia, A. K.
1983A&AS...52..181M Altcode:
The atomic data presented here and in Bhatia and Mason (1980) allow
the calculation of theoretical intensity ratios for all the EUV, UV,
and X-ray lines from Fe XX. Tabulations are presently given for the
transitions between levels in the 2s2 2p3, 2s2 2p2 3s, and 2s2 2p2
3d configurations of Fe(19+), and electron collision strengths are
calculated by means of the 'distorted wave' approximation. In addition
to the theoretical X-ray line intensity ratios, new spectral line
identifications from a solar flare are presented.

---------------------------------------------------------
Title: Atomic calculations for CA XVII - UV and X-ray lines
Authors: Bhatia, A. K.; Mason, H. E.
1983A&AS...52..115B Altcode:
Doschek et al. (1977) have pointed out the importance of the Ca XVII
UV lines as an electron density diagnostic. Energy levels, transition
probabilities, and collision strengths, are presently obtained
for the 2s2, 2s 2p, 2p2, 2s 3s, 2s 3p, and 2s 3d configurations
of Ca XVII, and the theoretical intensity ratios for the UV and
X-ray lines are compared with observed intensities in solar flare
spectra. Inconsistencies are indicated in the analysis of UV data,
and discrepancies between observed and theoretical intensity ratios
indicate that further studies are required. New identifications are
suggested in the X-ray wavelength region.

---------------------------------------------------------
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.
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: Solar physics
Authors: Gabriel, A. H.; Mason, H. E.
1982aacp....1..345G Altcode:
A review is presented of the two major aspects of the interaction
between atomic and solar physics. The first aspect is related to the way
in which the various atomic collision processes determine the physical
behavior of the plasma, and, thereby, the physical properties of the
sun. The second aspect is concerned with diagnostics, taking into
account the way in which the spectra emitted are determined by the
atomic processes occurring in the observed plasma. Aspects of solar
physics involving atomic collisions are examined, giving attention to
radial structure, active regions, solar flares, element abundances,
and spectroscopic diagnostics. Questions of impact excitation are
considered along with ionization and recombination, absolute spectral
intensities, and radiation effects.

---------------------------------------------------------
Title: Solar Physics
Authors: Gabriel, Alan H.; Mason, Helen E.
1982aacp....1..346G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Atomic calculation for Fe XXIII, UV, and X-ray lines.
Authors: Bhatia, A. K.; Mason, H. E.
1981A&A...103..324B Altcode:
Electron-ion scattering data have been obtained for the configurations
22, 2s2p, 2p2, 2s3s, 2s3p, and 2s3d of Fe
XXIII in the "distorted wave" approximation. Oscillator and collision
strengths are compared with other calculations. Wavelengths for various
UV and X-ray lines are compared with laboratory measurements. New
identifications are given for recent solar spectra based on intensity
estimates. A line at 11.737 Å is identified as the strongest Fe XXIII
line in the solar X-ray spectrum.

---------------------------------------------------------
Title: Spectroscopic diagnostics of the active region: transition
zone and corona.
Authors: Dere, K. P.; Mason, H. E.
1981sars.work..129D Altcode:
Techniques currently used in the analysis of X-ray and UV spectroscopic
data on solar features are reviewed with particular emphasis on
those used for studies of active regions in the transition zone
and corona. Attention is given to temperature and emission measure
diagnostics by the use of line emission from a low-density plasma,
broadband X-ray diagnostics, and diagnostics specific to various
active region structures, and to electron density diagnostics based
on metastable levels and the ratio of emission measure to the volume
derived from spatially resolved images. Methods used for calculating
atomic structure, electron and proton scattering, the ionization
equilibrium and the effects on it of diffusion and flows, and the line
profiles and optical depths are also considered.

---------------------------------------------------------
Title: Atomic Data for the Interpretation of EUV Astrophysical Plasmas
Authors: Mason, H. E.
1981ebas.conf...81M Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Development of Flares Observed in the Spectral Lines OV
1371 Å, FeXXI 1354 Å, and in Hard X-Rays
Authors: Woodgate, B. E.; Bruner, E. C.; Cheng, C. C.; Dennis, B. R.;
Gurman, J. B.; Frost, K. J.; Hyder, C. L.; Kiplinger, A.; Mason,
H. E.; Orwig, L. E.; Poland, A. I.; Schoolman, S. A.; Shine, R. A.;
Tandberg-Hanssen, E. A.
1980BAAS...12..911W Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Atomic data for Fe XXII
Authors: Mason, H. E.; Storey, P. J.
1980MNRAS.191..631M Altcode:
Intermediate coupling energy levels, oscillator strengths and electron
collision strengths in the distorted wave approximation have been
computed for Fe XXII. Results are tabulated for the configurations
2s22p, 2s 2p2, 2s23s, 2s23d, 2s 2p 3p, 2s24s, 2s24d, 2s 2p 4p. The
level population of the excited level in the ground configuration is
given as a function of electron density together with theoretical
intensity ratios for the strongest transitions from the excited
configurations. The theoretical results are compared to available
solar flare observations. The intensity ratios observed correspond to
electron densities of less than 10 to the 13 per cu cm.

---------------------------------------------------------
Title: Theoretical atomic structure and electron scattering data
for ions in the nitrogen isoelectronic sequence - MG VI, SI VIII,
S X, A XII and CA XIV
Authors: Bhatia, A. K.; Mason, H. E.
1980MNRAS.190..925B Altcode:
Intermediate coupling energy levels, oscillator strengths and
electron collision strengths have been computed for the configurations
2s22p3, 2s2p4 of Mg VI, Si VIII, S X,
Ax II and Ca XIV. The electron scattering problem was solved using the
"distorted wave" approximation. The statistical equilibrium equations
for level populations were solved including all relevant excitation
and de-excitation mechanisms. The level populations for the ground
configuration and theoretical intensity ratios for the UV spectral
lines are tabulated for conditions appropriate to the solar atmosphere.

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Title: New atomic data for Fe/+19/
Authors: Bhatia, A. K.; Mason, H. E.
1980A&A....83..380B Altcode:
New atomic data are tabulated for Fe(+19). The electron collision
strengths are calculated using the 'distorted wave' approximation
and results are presented for several energies of the exciting
electron. The populations of the ground levels are calculated as a
function of electron density under conditions appropriate to solar
flares and tokamak plasmas. Theoretical intensity ratios are tabulated
for the UV lines.

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Title: EUV limb spectra of a surge observed from Skylab.
Authors: Doschek, G. A.; Feldman, U.; Mason, H. E.
1979A&A....78..342D Altcode:
The EUV spectra of a surge observed at plus 8 in. and plus 20
in. above the white light limb from Skylab are examined. The shape of
the differential emission measure determined at 8 in. and 20 in. is
nearly the same as for a quiet Sun spectrum at 8 in., but the emission
measure of the surge at 8 in. is about an order of magnitude greater
than for the quiet Sun. At 20 in. the emission measure of the surge is
initially close to the quiet Sun distribution, but decreases by a factor
of 4 within 6 min. The optically thin lines formed near 10 to the 5th
power K show nonthermal broadening at 8 in., and electron densities near
this temperature are derived from intersystem to resonance ratios. The
volume of the emitting plasma at 8 in. above the limb was determined,
concluding that a continuous energy input is required to explain the
observations.

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Title: XUV electron density diagnostics for solar flares.
Authors: Dere, K. P.; Mason, H. E.; Widing, K. G.; Bhatia, A. K.
1979ApJS...40..341D Altcode:
Potential electron-density diagnostics for the high-temperature
component of solar flares are studied with reference to the wavelength
region from 171 to 630 A. The specific ions discussed include Fe
IX through Fe XV, Ni XI through Ni XVII, and ions in the beryllium,
boron, carbon, and nitrogen isoelectronic sequences. Line ratios that
could be useful as density indicators under solar-flare conditions
are indicated, available data for the ions considered are reviewed,
and several theoretical intensity ratios are plotted. The results are
employed to determine the electron-density distribution as a function
of electron temperature for several spectra from two flares. For these
flares it is found that the electron density increases from 10 billion
to 500 billion per cu cm for a temperature increase from 1 million to
10 million K.

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Title: Fe XXI as an electron density diagnostic in solar flares.
Authors: Mason, H. E.; Bhatia, A. K.; Doschek, G. A.; Feldman, U.
1979A&A....73...74M Altcode:
Atomic data have been calculated for Fe XXI, and the theoretical
intensity ratios for many transitions are tabulated. Fe XXI lines in
wavelength regions 1-25 A, 90-200 A, and 300-2500 A are discussed with
reference to presently available solar and laboratory spectra. It is
found that Fe XXI is an excellent density diagnostic for solar-flare
and tokamak plasmas, when densities are in the range from 10 to the
11th to 10 to the 15th per cu cm. The theoretical calculations are
applied to flare spectra obtained from OSO 5, and an electron density
of less than 10 to the 13th per cu cm is deduced for a temperature
of 10,000,000 K. The results are somewhat ambiguous in several cases
because of the limited spectral and temporal resolution of these
earlier spectrometers. However, the calculations will be important
for forthcoming solar projects, such as the Solar Maximum Mission.

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Title: Electron densities in the solar corona from density-sensitive
line ratios in the N I isoelectronic sequence.
Authors: Feldman, U.; Doschek, G. A.; Mariska, J. T.; Bhatia, A. K.;
Mason, H. E.
1978ApJ...226..674F Altcode:
Electron densities are derived in the solar inner corona from forbidden
lines of S x near 1100 A. The density-sensitive line ratio considered
is (4S0312-2D0312)/(4S0312-2D0612). The ratio is calculated as a
function of density for four ions of the N I isoelectronic sequence,
i.e., Mg VI, Si VIII, S x, and Ar XII. The variation of the ratio
(4S0312-2P0312)/(4S0312-2D0312) with density is also calculated. The
results are applied to off-limb spectra recorded by the NRL Skylab
spectrograph. Densities were found to be the same in five quiet Sun
regions and four active regions observed at heights &gt; 8" outside
the white-light limb. The average density derived from the S x lines
for all regions considered is 1.0 x 10 cm -3. This result applies to
plasma at the temperature of formation of S x, i.e., 1.3 x 106 K. At
heights greater than 20" outside the limb the average density is 7.7 x
108 cm -3, and between 8" and 12" above the limb the average density is
1.0 x 10 cm 3, for both quiet Sun and active regions. Subject heading:
Sun: corona

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Title: Density sensitivity of the solar EUV emission from boron-like
ions.
Authors: Vernazza, J. E.; Mason, H. E.
1978ApJ...226..720V Altcode:
The paper investigated the level populations and the line emission
arising from ions of the boron isoelectronic sequence from C II to Ca
XVI. It is found that, under conditions present in the solar corona,
some of these ions have pairs of emission lines having intensity
ratios which are density-sensitive. The boron-like lines observed in
the solar spectrum between 300 and 1350 A are analyzed, and densities
for quiet and active regions, coronal holes, sunspots, and flares
are derived. Some aspects of the differences in the behavior of the
emission from the lithium and boron sequences are also discussed.

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Title: Densities in the quiet sun and polar coronal holes from EUV
line ratios involving O III (1666.15 Å).
Authors: Doschek, G. A.; Feldman, U.; Bhatia, A. K.; Mason, H. E.
1978ApJ...226.1129D Altcode:
The EUV line intensity ratios C iii (1908.73 A)/o iii (1666.15 A), 0 iii
(1666.15 A)/Si iv (1402.77 A), and C iii (1908.73 A)ISi iv (1402.77 A)
are shown to be sensitive to variations in the electron density at
densities typical of the quiet Sun ( 1010 cm - at 6 x 10 K). Using
the 0 iii line, the above ratios can be normalized to observational
data and densities in quiet-Sun regions and coronal holes can be
determined. The average value of the density determined for three
quiet-Sun regions is 1.9 x 1010 cm - . The densities determined from
several observations of the north and south polar coronal holes are
about the same as in the quiet Sun, with the exception of one set of
observations of the north polar hole that indicates a density about
a factor of 2 less than that of the quiet Sun. Subject headings: Sun:
corona - Sun: spectra - ultraviolet: spectra

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Title: Theoretical intensity ratios for the UV lines of Mg VII,
Si IX and S XI.
Authors: Mason, H. E.; Bhatia, A. K.
1978MNRAS.184..423M Altcode:
Energy levels, oscillator strengths, and electron collision strengths
have been computed for the configurations 2s2 2p2, 2s 2p3, 2p4 of Mg
VII, Si IX, and S XI. Level populations for the ground configuration and
theoretical intensity ratios for the UV lines are tabulated for electron
densities and temperatures appropriate to the solar atmosphere. The
identification of the Mg VII, Si IX, and S XI UV lines is discussed.

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Title: Limb-brightening observations from the OSO-7
satellite. III. Comparison of EUV line intensities of Fe XII, Fe XI,
Fe XV, Si X and S XII, Si IX and S XI with predictions.
Authors: Kastner, S. O.; Mason, H. E.
1978A&A....67..119K Altcode:
Continuing a study of heliocentric dependence of EUV emission line
intensities observed by the Goddard OSO-7 spectroheliograph in 1972,
the variation of lines of the ions Fe XII, Fe XI, Fe XV, Si X and S XII,
Si IX and S XI is compared with the results of individual calculations
for these ions, including theoretical intensities presented for Fe XII
and Fe XI. Agreement is found to be good for Fe XII and reasonable
for some of the lines of the other ions which in general are weaker
in intensity. Several apparent anomalies are found however which may
be due to unknown line components near the wavelengths observed.

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Title: On the unidentified forbidden coronal lines.
Authors: Mason, H. E.; Nussbaumer, H.
1977A&A....54..547M Altcode:
Approximately one quarter of the forbidden coronal lines observed
in the visual and EUV regions of the solar spectrum are still
unidentified. Evidence is presented showing that some of these
unidentified lines originate from Fe X and Fe XI. Population densities
of metastable levels in excited configurations of these ions are
determined, and emissivities are calculated for transitions from these
levels. Based on examination of emissivity ratios, it is proposed that
the forbidden coronal lines observed at 4312, 3454, 1918.27, 1603.31,
and 1428.76 be attributed to Fe X and that the lines at 5539, 4566,
and 264 A be attributed to Fe XI.

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Title: Density-Sensitive Lines in the EUV Region.
Authors: Vernazza, J. E.; Mason, H. E.
1977uxsa.coll...15V Altcode: 1977IAUCo..43...15V
No abstract at ADS

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Title: The interpretation of the forbidden emission lines from a
coronal condensation.
Authors: Mason, H. E.
1975MNRAS.171..119M Altcode:
Theoretical emission rates have recently been computed (Mason) for
six lines observed in the visible spectrum of the solar corona. These
rates are used to analyse the spectra of a coronal condensation
observed by Lyot and Aly at the 1952 eclipse (Aly et al.). Average
electron density and temperature conditions for the condensation are
deduced and a specific model is proposed, in which electron density
and temperature estimates are defined as a function of position within
the condensation. Since continuum measurements were also recorded,
abundance estimates for iron and calcium relative to hydrogen are
obtained. The structure of the model is seen to be consistent with
other solar observation.

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Title: The excitation of several iron and calcium lines in the
visible spectrum of the solar corona.
Authors: Mason, H. E.
1975MNRAS.170..651M Altcode:
New atomic data have been obtained for the coronal ions Fe X, Fe
XI, Fe XIV, Ca XII, Ca XIII and Ca XV, using a computer. Energy
levels and radiative transition probabilities have been computed
allowing for configuration interaction and relativistic effects. The
electron scattering problem has been solved using the distorted
wave approach. All radiative and collisional processes contributing
to the equilibrium equations for the ground configuration were
considered, including cascade via the excited configurations and the
effect of autoionizing levels on the electron collisional excitation
rate. Wherever possible, the accuracy of the atomic parameters has been
estimated and the results compared to those of previous authors. The
atomic data, level populations and emission rates for the ions studied,
are tabulated for various physical conditions appropriate to the
solar corona.

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Title: The interpretation of the forbidden emission lines from a
coronal condensation
Authors: Mason, Helen Elizabeth
1974PhDT.......256M Altcode:
No abstract at ADS

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Title: Spectrographic Examination of Chromatographic Columns
Authors: Dunabin, J. E.; Mason, H.; Seyfang, A. P.; Woodman, F. J.
1949Natur.164..916D Altcode:
IN the determination of metallic traces, insufficient attention has been
paid either to the advantages of direct spectrography of chromatographic
columns, or to the chromatographic behaviour of organic metal complexes,
although in the latter sphere the use of oxine1 and of
violuric acid2 has been reported.