kucera-therese

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Author name code: kucera-therese
ADS astronomy entries on 2022-09-14
author:"Kucera, Therese A."

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Title: Abundance diagnostics in active regions with Solar
Orbiter/SPICE
Authors: Giunta, Alessandra; Peter, Hardi; Parenti, Susanna; Buchlin,
Eric; Thompson, William; Auchere, Frederic; Kucera, Therese; Carlsson,
Mats; Janvier, Miho; Fludra, Andrzej; Hassler, Donald M.; Grundy,
Timothy; Sidher, Sunil; Guest, Steve; Leeks, Sarah; Fredvik, Terje;
Young, Peter
2022cosp...44.2583G Altcode:
With the launch of Solar Orbiter in February 2020, we are now able to
fully explore the link between the solar activity on the Sun and the
inner heliosphere. Elemental abundance measurements provide a key tracer
to probe the source regions of the solar wind and to track it from the
solar surface and corona to the heliosphere. Abundances of elements
with low first ionisation potential (FIP) are enhanced in the corona
relative to high-FIP elements, with respect to the photosphere. This is
known as the FIP effect, which is measured as abundance bias (FIP bias)
of low and high FIP elements. This effect is vital for understanding the
flow of mass and energy through the solar atmosphere. The comparison
between in-situ and remote sensing composition data, coupled with
modelling, will allow us to trace back the source of heliospheric
plasma. Solar Orbiter has a unique combination of in-situ and remote
sensing instruments that will help to make such a comparison. In
particular, the SPICE (Spectral Imaging of the Coronal Environment)
EUV spectrometer records spectra in two wavelength bands, 70.4-79.0
nm and 97.3-104.9 nm. SPICE is designed to provide spectroheliograms
using a core set of emission lines arising from ions of both low-FIP
and high-FIP elements such as C, N, O, Ne, Mg, S and Fe. These lines
are formed over a wide range of temperatures from 20,000 K to over 1
million K, enabling the analysis of the different layers of the solar
atmosphere. SPICE spectroheliograms can be processed to produce FIP
bias maps, which can be compared to in-situ measurements of the solar
wind composition of the same elements. During the Solar Orbiter Cruise
Phase, SPICE observed several active regions. We will present some of
these observations and discuss the SPICE diagnostic potential to derive
relative abundances (e.g., Mg/Ne) and the FIP bias in those regions.

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Title: The SPICE spectrograph on Solar Orbiter: an introduction and
results from the first Orbits
Authors: Auchère, Frédéric; Peter, Hardi; Parenti, Susanna; Buchlin,
Eric; Thompson, William; Auchere, Frederic; Teriaca, Luca; Kucera,
Therese; Carlsson, Mats; Janvier, Miho; Fludra, Andrzej; Giunta,
Alessandra; Schuehle, Udo; Hassler, Donald M.; Grundy, Timothy;
Sidher, Sunil; Fredvik, Terje; Plowman, Joseph; Aznar Cuadrado, Regina
2022cosp...44.1338A Altcode:
The Spectral Imaging of the Coronal Environment (SPICE) instrument is
the EUV imaging spectrometer on board the Solar Orbiter mission. With
its ability to derive physical properties of the coronal plasma,
SPICE is a key component of the payload to establish the connection
between the source regions and the in-situ measurements of the solar
wind. The spacecraft was successfully launched in February 2020 and
completed its cruise phase in December 2021. During this period,
the remote sensing instruments were mostly operated during limited
periods of time for 'checkout' engineering activities and synoptic
observations. Nonetheless, several of these periods provided enough
opportunities already to obtain new insights on coronal physics. During
the march 2022 perihelion - close to 0.3 AU - SPICE will provide
its highest spatial resolution data so far. Coordinated observations
between the remote sensing and in-situ instruments will provide the
first opportunity to use the full potential of the Solar Orbiter
mission. We will review the instrument characteristics and present
initial results from the cruise phase and first close encounter.

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Title: The Multiview Observatory for Solar Terrestrial Science (MOST)
Authors: Gopalswamy, Nat; Kucera, Therese; Leake, James; MacDowall,
Robert; Wilson, Lynn; Kanekal, Shrikanth; Shih, Albert; Christe,
Steven; Gong, Qian; Viall, Nicholeen; Tadikonda, Sivakumar; Fung,
Shing; Yashiro, Seiji; Makela, Pertti; Golub, Leon; DeLuca, Edward;
Reeves, Katharine; Seaton, Daniel; Savage, Sabrina; Winebarger, Amy;
DeForest, Craig; Desai, Mihir; Bastian, Tim; Lazio, Joseph; Jensen,
P. E., C. S. P., Elizabeth; Manchester, Ward; Wood, Brian; Kooi,
Jason; Wexler, David; Bale, Stuart; Krucker, Sam; Hurlburt, Neal;
DeRosa, Marc; Pevtsov, Alexei; Tripathy, Sushanta; Jain, Kiran;
Gosain, Sanjay; Petrie, Gordon; Kholikov, Shukirjon; Zhao, Junwei;
Scherrer, Philip; Woods, Thomas; Chamberlin, Philip; Kenny, Megan
2021AGUFMSH12A..07G Altcode:
The Multiview Observatory for Solar Terrestrial Science (MOST) is a
comprehensive mission concept targeting the magnetic coupling between
the solar interior and the heliosphere. The wide-ranging imagery and
time series data from MOST will help understand the solar drivers and
the heliospheric responses as a system, discerning and tracking 3D
magnetic field structures, both transient and quiescent in the inner
heliosphere. MOST will have seven remote-sensing and three in-situ
instruments: (1) Magnetic and Doppler Imager (MaDI) to investigate
surface and subsurface magnetism by exploiting the combination of
helioseismic and magnetic-field measurements in the photosphere; (2)
Inner Coronal Imager in EUV (ICIE) to study large-scale structures
such as active regions, coronal holes and eruptive structures by
capturing the magnetic connection between the photosphere and the
corona to about 3 solar radii; (3) Hard X-ray Imager (HXI) to image
the non-thermal flare structure; (4) White-light Coronagraph (WCOR) to
seamlessly study transient and quiescent large-scale coronal structures
extending from the ICIE field of view (FOV); (5) Faraday Effect
Tracker of Coronal and Heliospheric structures (FETCH), a novel radio
package to determine the magnetic field structure and plasma column
density, and their evolution within 0.5 au; (6) Heliospheric Imager
with Polarization (HIP) to track solar features beyond the WCOR FOV,
study their impact on Earth, and provide important context for FETCH;
(7) Radio and Plasma Wave instrument (M/WAVES) to study electron beams
and shocks propagating into the heliosphere via passive radio emission;
(8) Solar High-energy Ion Velocity Analyzer (SHIVA) to determine spectra
of electrons, and ions from H to Fe at multiple spatial locations
and use energetic particles as tracers of magnetic connectivity; (9)
Solar Wind Magnetometer (MAG) to characterize magnetic structures at
1 au; (10) Solar Wind Plasma Instrument (SWPI) to characterize plasma
structures at 1 au. MOST will have two large spacecraft with identical
payloads deployed at L4 and L5 and two smaller spacecraft ahead of L4
and behind L5 to carry additional FETCH elements. MOST will build upon
SOHO and STEREO achievements to expand the multiview observational
approach into the first half of the 21st Century.

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Title: First observations from the SPICE EUV spectrometer on Solar
Orbiter
Authors: Fludra, A.; Caldwell, M.; Giunta, A.; Grundy, T.; Guest,
S.; Leeks, S.; Sidher, S.; Auchère, F.; Carlsson, M.; Hassler, D.;
Peter, H.; Aznar Cuadrado, R.; Buchlin, É.; Caminade, S.; DeForest,
C.; Fredvik, T.; Haberreiter, M.; Harra, L.; Janvier, M.; Kucera, T.;
Müller, D.; Parenti, S.; Schmutz, W.; Schühle, U.; Solanki, S. K.;
Teriaca, L.; Thompson, W. T.; Tustain, S.; Williams, D.; Young, P. R.;
Chitta, L. P.
2021A&A...656A..38F Altcode: 2021arXiv211011252F
 Aims: We present first science observations taken during the
commissioning activities of the Spectral Imaging of the Coronal
Environment (SPICE) instrument on the ESA/NASA Solar Orbiter
mission. SPICE is a high-resolution imaging spectrometer operating at
extreme ultraviolet (EUV) wavelengths. In this paper we illustrate
the possible types of observations to give prospective users a
better understanding of the science capabilities of SPICE. 
Methods: We have reviewed the data obtained by SPICE between April
and June 2020 and selected representative results obtained with
different slits and a range of exposure times between 5 s and 180
s. Standard instrumental corrections have been applied to the raw
data. Results: The paper discusses the first observations
of the Sun on different targets and presents an example of the full
spectra from the quiet Sun, identifying over 40 spectral lines from
neutral hydrogen and ions of carbon, oxygen, nitrogen, neon, sulphur,
magnesium, and iron. These lines cover the temperature range between
20 000 K and 1 million K (10 MK in flares), providing slices of the
Sun's atmosphere in narrow temperature intervals. We provide a list
of count rates for the 23 brightest spectral lines. We show examples
of raster images of the quiet Sun in several strong transition region
lines, where we have found unusually bright, compact structures in the
quiet Sun network, with extreme intensities up to 25 times greater
than the average intensity across the image. The lifetimes of these
structures can exceed 2.5 hours. We identify them as a transition
region signature of coronal bright points and compare their areas and
intensity enhancements. We also show the first above-limb measurements
with SPICE above the polar limb in C III, O VI, and Ne VIII lines, and
far off limb measurements in the equatorial plane in Mg IX, Ne VIII,
and O VI lines. We discuss the potential to use abundance diagnostics
methods to study the variability of the elemental composition that can
be compared with in situ measurements to help confirm the magnetic
connection between the spacecraft location and the Sun's surface,
and locate the sources of the solar wind. Conclusions: The
SPICE instrument successfully performs measurements of EUV spectra
and raster images that will make vital contributions to the scientific
success of the Solar Orbiter mission.

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Title: Observations and 3D MHD Modeling of Small-scale Solar
Prominence Oscillations
Authors: Ofman, L.; Kucera, T.; DeVore, C. R.
2021AAS...23810607O Altcode:
Small scale oscillations were recently observed in prominences with
high resolution Hinode/SOT and IRIS SJI in unprecedented detail and
identified as fast magnetosonic waves. The high-resolution observations
provide evidence of flows of cool material, fluid instabilities
such as Kelvin-Helmholtz and Rayleigh-Taylor, and the spectroscopic
information provides evidence of Doppler shifts, heating, and cooling
of the prominence material. Recently nonlinear fast magnetosonic
waves were observed with periods in the range of 5-11 minutes and
wavelengths in the plane of the sky (POS) of ~ 2000 km and flows,
and the flows in narrow threads with POS speed ∼16-46 km/s. The
nonlinear fast magnetosonic waves and flows were modeled using 2.5D MHD
(Ofman &amp; Kucera 2020). Here, we extend the study of the nonlinear
fast magnetosonic waves using more realistic 3D MHD model. The model
includes the 3D structure of the density and the magnetic field as well
as mode coupling and demonstrate the propagating density compressions
associated with the nonlinear fast magnetosonic waves, as well as the
guided modes in the pillar. The 3D MHD modeling improve understanding
of the POS effects in limb prominence oscillations observations. The
results of the modeling are useful for coronal seismology of the
prominence structure.

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Title: Magnetic Field Curvature In A Filament Channel Derived From
Oscillation Measurements And MHD Modeling
Authors: Kucera, T. A.; Luna, M.; Torok, T.; Muglach, K.; Downs, C.;
Sun, X.; Thompson, B.; Karpen, J.; Gilbert, H.
2021AAS...23811306K Altcode:
We have used measurements of repeated large amplitude longitudinal
oscillations (LALOs) in an active region filament to diagnose the
curvature of the magnetic field in the filament channel and compared the
results with predictions of an MHD flux-rope model based on magnetograms
of the region. In May and June of 2014 Active Region 12076 exhibited a
complex of filaments undergoing repeated oscillations over the course
of twelve days. The central filament channel exhibited emerging and then
canceling magnetic flux that resulted in multiple activations, filament
eruptions, and eight oscillation events, which we analyzed using GONG
H-alpha data. Luna and Karpen (2012) model LALOs as oscillations of
magnetized filament plasma moving along dipped magnetic field lines
with gravity as a restoring force. Under this model the period of these
oscillations can be used to estimate the curvature of the magnetic
field in the location of the filament threads. Utilizing this, we find
that the measured periods in the central filament ranging from 34-74
minutes should correspond to magnetic field curvatures of about 30-136
Mm. We also derive radii of curvature for the central filament channel
using a flux-rope model that is based on an SDO/HMI magnetogram of the
region. The rope is constructed using the analytic expressions by Titov
et al. (2018) and then numerically relaxed towards a force-free state in
the zero-beta MHD approximation, where gravity and thermal pressure are
neglected. For comparison, we also employ a nonlinear force-free field
(NLFFF) extrapolation of the active region. We compare the results
of these different ways of attempting to determine the field in the
filament channel.

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Title: The Magnetic Skeleton of the Solar Corona Over Several Solar
Rotations: Features, Analysis, and Community Availability
Authors: Malanushenko, A. V.; Gibson, S. E.; Kucera, T. A.; McKenzie,
D. E.
2020AGUFMSH041..02M Altcode:
The magnetic field in the solar corona is thought to be the main
driver for solar eruptive events, such as flares and coronal mass
ejections. The coronal magnetic field is therefore important to study,
but it is difficult to measure directly. Usually, it is studied through
extrapolations based on photospheric magnetograms. As the corona is
thought to be mostly in a state of equilibrium, equations of low-beta
equilibria are often used in order to study the structure of the
field, or to estimate the magnetic energy. One of the complications
that arise from this approach is that the solar photosphere itself is
not a low-beta equilibrium. Images of the solar corona in extreme
ultraviolet (EUV) do not directly measure the magnetic field; however,
they do reveal structures from which information about magnetic field
can be inferred. For example, coronal loops are thought to trace
out magnetic field lines, coronal cavities are bounded by magnetic
surfaces, coronal holes are areas of magnetic flux that is open to
the heliosphere, and plasma flows are also thought to follow lines
of magnetic field. In other wavelengths, coronal spectropolarimetry
(SP) can provide us with proxies for magnetic field strength and
reveal plasma flows along the line of sight, off the limb. The EUV
images and SP data are frequently used to validate magnetic field
models. Additionally, new models are emerging which can use these data
directly as additional constraints. We aggregate available relevant
features seen in EUV and SP data for several solar rotations. We
apply existing techniques to infer 3D constraints on the magnetic
field from these data. The result is an interactive 3D model based on
these constraints for a full rotation, or a "magnetic skeleton". It
is modular, so individual constraints can be easily added, or only
selected constraints can be used. The features could be exported in
either graphical or numerical form. The possible uses of our approach
include validation of magnetic models that are based on extrapolations
alone. Some models allow for using additional coronal constraints
directly. These 'skeletons' can also be used in non-magnetic-modeling
applications, as a simple, interactive reference for features seen in
a given rotation. We make the models available to the community and
show how to obtain and use them.

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Title: Relative coronal abundance diagnostics with Solar Orbiter/SPICE
Authors: Zambrana Prado, N.; Buchlin, E.; Peter, H.; Young, P. R.;
Auchere, F.; Carlsson, M.; Fludra, A.; Hassler, D.; Aznar Cuadrado,
R.; Caminade, S.; Caldwell, M.; DeForest, C.; Fredvik, T.; Harra,
L.; Janvier, M.; Kucera, T. A.; Giunta, A. S.; Grundy, T.; Müller,
D.; Parenti, S.; Schmutz, W. K.; Schühle, U.; Sidher, S.; Teriaca,
L.; Thompson, W. T.; Williams, D.
2020AGUFMSH038..09Z Altcode:
Linking solar activity on the surface and in the corona to the inner
heliosphere is one of Solar Orbiter's main goals. Its UV spectrometer
SPICE (SPectral Imaging of the Coronal Environment) will provide
relative abundance measurements which will be key in this quest
as different structures on the Sun have different abundances as a
consequence of the FIP (First Ionization Potential) effect. Solar
Orbiter's unique combination of remote sensing and in-situ instruments
coupled with observation from other missions such as Parker Solar
Probe will allow us to compare in-situ and remote sensing composition
data. With the addition of modeling, these new results will allow us
to trace back the source of heliospheric plasma. As high telemetry
will not always be available with SPICE, we have developed a method
for measuring relative abundances that is both telemetry efficient
and reliable. Unlike methods based on Differential Emission Measure
(DEM) inversion, the Linear Combination Ratio (LCR) method does not
require a large number of spectral lines. This new method is based
on linear combinations of UV spectral lines. The coefficients of
the combinations are optimized such that the ratio of two linear
combinations of radiances would yield the relative abundance of two
elements. We present some abundance diagnostics tested on different
combinations of spectral lines observable by SPICE.

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Title: Dynamics and thermal structure in the quiet Sun seen by SPICE
Authors: Peter, H.; Aznar Cuadrado, R.; Schühle, U.; Teriaca, L.;
Auchere, F.; Carlsson, M.; Fludra, A.; Hassler, D.; Buchlin, E.;
Caminade, S.; Caldwell, M.; DeForest, C.; Fredvik, T.; Harra, L. K.;
Janvier, M.; Kucera, T. A.; Giunta, A. S.; Grundy, T.; Müller, D.;
Parenti, S.; Schmutz, W. K.; Sidher, S.; Thompson, W. T.; Williams,
D.; Young, P. R.
2020AGUFMSH038..03P Altcode:
We will present some of the early data of the Spectral Imaging of the
Coronal Environment (SPICE) instrument on Solar Orbiter. One of the
unique features of SPICE is its capability to record a wide range of
wavelengths in the extreme UV with the possibility to record spectral
lines giving access to a continuous plasma temperature range from 10.000
K to well above 1 MK. The data taken so far were for commissioning
purposes and they can be used for a preliminary evaluation of the
science performance of the instrument. Here we will concentrate on
sample spectra covering the whole wavelength region and on the early
raster maps acquired in bright lines in the quiet Sun close to disk
center. Looking at different quiet Sun features we investigate the
thermal structure of the atmosphere and flow structures. For this
we apply fits to the spectral profiles and check the performance in
terms of Doppler shifts and line widths to retrieve the structure of
the network in terms of dynamics. While the amount of data available
so far is limited, we will have a first look on how quiet Sun plasma
responds to heating events. For this, we will compare spectral lines
forming at different temperatures recorded at strictly the same time.

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Title: First Results From SPICE EUV Spectrometer on Solar Orbiter
Authors: Fludra, A.; Caldwell, M.; Giunta, A. S.; Grundy, T.; Guest,
S.; Sidher, S.; Auchere, F.; Carlsson, M.; Hassler, D.; Peter, H.;
Aznar Cuadrado, R.; Buchlin, E.; Caminade, S.; DeForest, C.; Fredvik,
T.; Harra, L. K.; Janvier, M.; Kucera, T. A.; Leeks, S.; Mueller,
D.; Parenti, S.; Schmutz, W. K.; Schühle, U.; Teriaca, L.; Thompson,
W. T.; Tustain, S.; Williams, D.; Young, P. R.
2020AGUFMSH038..02F Altcode:
SPICE (Spectral Imaging of Coronal Environment) is one of the remote
sensing instruments onboard Solar Orbiter. It is an EUV imaging
spectrometer observing the Sun in two wavelength bands: 69.6-79.4 nm
and 96.6-105.1 nm. SPICE is capable of recording full spectra in these
bands with exposures as short as 1s. SPICE is the only Solar Orbiter
instrument that can measure EUV spectra from the disk and low corona
of the Sun and record all spectral lines simultaneously. SPICE uses
one of three narrow slits, 2"x11', 4”x11', 6”x11', or a wide slit
30”x14'. The primary mirror can be scanned in a direction perpendicular
to the slit, allowing raster images of up to 16' in size. We
present an overview of the first SPICE data taken on several days
during the instrument commissioning carried out by the RAL Space team
between 2020 April 21 and 2020 June 14. We also include results from
SPICE observations at the first Solar Orbiter perihelion at 0.52AU,
taken between June 16-21st. We give examples of full spectra
from the quiet Sun near disk centre and provide a list of key spectral
lines emitted in a range of temperatures between 10,000 K and over 1
million K, from neutral hydrogen and ions of carbon, oxygen, nitrogen,
neon, sulphur and magnesium. We show examples of first raster images
in several strong lines, obtained with different slits and a range
of exposure times between 5s and 180s. We describe the temperature
coverage and density diagnostics, determination of plasma flows, and
discuss possible applications to studies of the elemental abundances
in the corona. We also show the first off-limb measurements with SPICE,
as obtained when the spacecraft pointed at the limb.

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Title: Calibrating optical distortions in the Solar Orbiter SPICE
spectrograph
Authors: Thompson, W. T.; Schühle, U.; Young, P. R.; Auchere, F.;
Carlsson, M.; Fludra, A.; Hassler, D.; Peter, H.; Aznar Cuadrado, R.;
Buchlin, E.; Caldwell, M.; DeForest, C.; Fredvik, T.; Harra, L. K.;
Janvier, M.; Kucera, T. A.; Giunta, A. S.; Grundy, T.; Müller, D.;
Parenti, S.; Caminade, S.; Schmutz, W. K.; Teriaca, L.; Williams,
D.; Sidher, S.
2020AGUFMSH0360029T Altcode:
The Spectral Imaging of the Coronal Environment (SPICE) instrument on
Solar Orbiter is a high-resolution imaging spectrometer operating
at extreme ultraviolet (EUV) wavelengths from 70.4-79.0 nm and
97.3-104.9 nm. A single-mirror off-axis paraboloid focuses the solar
image onto the entrance slit of the spectrometer section. A Toroidal
Variable Line Space (TVLS) grating images the entrance slit onto a
pair of MCP-intensified APS detectors. Ray-tracing analysis prior
to launch showed that the instrument was subject to a number of
small image distortions which need to be corrected in the final data
product. We compare the ray tracing results with measurements made in
flight. Co-alignment with other telescopes on Solar Orbiter will also
be examined.

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Title: First results from the EUI and SPICE observations of Alpha
Leo near Solar Orbiter first perihelion
Authors: Buchlin, E.; Teriaca, L.; Giunta, A. S.; Grundy, T.; Andretta,
V.; Auchere, F.; Peter, H.; Berghmans, D.; Carlsson, M.; Fludra, A.;
Harra, L.; Hassler, D.; Long, D.; Rochus, P. L.; Schühle, U.; Aznar
Cuadrado, R.; Caldwell, M.; Caminade, S.; DeForest, C.; Fredvik, T.;
Gissot, S.; Heerlein, K.; Janvier, M.; Kraaikamp, E.; Kucera, T. A.;
Müller, D.; Parenti, S.; Schmutz, W. K.; Sidher, S.; Smith, P.;
Stegen, K.; Thompson, W. T.; Verbeeck, C.; Williams, D.; Young, P. R.
2020AGUFMSH0360024B Altcode:
On June 16th 2020 Solar Orbiter made a dedicated observing campaign
where the spacecraft pointed to the solar limb to allow some of the
high resolution instruments to observe the ingress (at the east limb)
and later the egress (west limb) of the occultation of the star Alpha
Leonis by the solar disk. The star was chosen because its luminosity and
early spectral type ensure high and stable flux at wavelengths between
100 and 122 nanometers, a range observed by the High Resolution EUI
Lyman alpha telescope (HRI-LYA) and by the long wavelength channel
of the SPICE spectrograph. Star observations, when feasible, allow
to gather a great deal of information on the instrument performances,
such as the radiometric performance and the instrument optical point
spread function (PSF). We report here the first results from the
above campaign for the two instruments.

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Title: Spectroscopic Constraints on the Dimension of Active Region
Loops Along the Line of Sight
Authors: Kucera, T. A.; Young, P. R.; Klimchuk, J. A.; DeForest, C.
2020AGUFMSH041..05K Altcode:
Understanding the cross sections of coronal loops and how they vary
along the loop is important both for understanding coronal heating
and how the loops are shaped by the coronal magnetic field. To better
address this question we have developed a new method to constrain the
dimension of loops along the line of sight by utilizing spectroscopic
observations. We apply this method to a cool (5.5&lt;logT&lt;6.2)
loop using data from the Hinode/EUV Imaging Spectrometer (EIS) with
supporting data from Solar Dynamic Observatory (SDO) and the Solar
TErrestrial RElations Observatory (STEREO), and discuss the results and
their limitations. Our results are consistent with circular loop cross
sections, but could also be consistent with aspect ratios of 2 or 3.

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Title: Using SDO/AIA to Understand the Thermal Evolution of Solar
Prominence Formation
Authors: Viall, Nicholeen M.; Kucera, Therese A.; Karpen, Judith T.
2020ApJ...905...15V Altcode:
We investigated the thermal properties of prominence formation using
time series analysis of Solar Dynamics Observatory's Atmospheric
Imaging Assembly (SDO/AIA) data. Here, we report the first time-lag
measurements derived from SDO/AIA observations of a prominence and its
cavity on the solar limb, made possible by AIA's different wave bands
and high time resolution. With our time-lag analysis, which tracks
the thermal evolution using emission formed at different temperatures,
we find that the prominence cavity exhibited a mixture of heating and
cooling signatures. This is in contrast to prior time-lag studies of
multiple active regions that chiefly identified cooling signatures
and very few heating signatures, which is consistent with nanoflare
heating. We also computed time lags for the same pairs of SDO/AIA
channels using output from a one-dimensional hydrodynamic model of
prominence material forming through thermal nonequilibrium (TNE). We
demonstrate that the SDO/AIA time lags for flux tubes undergoing TNE
are predicted to be highly complex, changing with time and location
along the flux tube, and are consistent with the observed time-lag
signatures in the cavity surrounding the prominence. Therefore, the
time-lag analysis is a sensitive indicator of the heating and cooling
processes in different coronal regions. The time lags calculated for
the simulated prominence flux tube are consistent with the behavior
deduced from the AIA data, thus supporting the TNE model of prominence
formation. Future investigations of time lags predicted by other models
for the prominence mass could be a valuable method for discriminating
among competing physical mechanisms.

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Title: First results from combined EUI and SPICE observations of
Lyman lines of Hydrogen and He II
Authors: Teriaca, L.; Aznar Cuadrado, R.; Giunta, A. S.; Grundy, T.;
Parenti, S.; Auchere, F.; Vial, J. C.; Fludra, A.; Berghmans, D.;
Carlsson, M.; Harra, L.; Hassler, D.; Long, D.; Peter, H.; Rochus,
P. L.; Schühle, U.; Buchlin, E.; Caldwell, M.; Caminade, S.; DeForest,
C.; Fredvik, T.; Gissot, S.; Heerlein, K.; Janvier, M.; Kraaikamp,
E.; Kucera, T. A.; Mueller, D.; Schmutz, W. K.; Sidher, S.; Smith, P.;
Stegen, K.; Thompson, W. T.; Verbeeck, C.; Williams, D.; Young, P. R.
2020AGUFMSH0360003T Altcode:
The Solar Orbiter spacecraft carries a powerful set of remote
sensing instruments that allow studying the solar atmosphere with
unprecedented diagnostic capabilities. Many such diagnostics require
the simultaneous usage of more than one instrument. One example of that
is the capability, for the first time, to obtain (near) simultaneous
spatially resolved observations of the emission from the first three
lines of the Lyman series of hydrogen and of He II Lyman alpha. In fact,
the SPectral Imaging of the Coronal Environment (SPICE) spectrometer
can observe the Lyman beta and gamma lines in its long wavelength
(SPICE-LW) channel, the High Resolution Lyman Alpha (HRI-LYA) telescope
of the Extreme Ultraviolet Imager (EUI) acquires narrow band images in
the Lyman alpha line while the Full Disk Imager (FSI) of EUI can take
images dominated by the Lyman alpha line of ionized Helium at 30.4 nm
(FSI-304). Being hydrogen and helium the main components of our star,
these very bright transitions play an important role in the energy
budget of the outer atmosphere via radiative losses and the measurement
of their profiles and radiance ratios is a fundamental constraint to
any comprehensive modelization effort of the upper solar chromosphere
and transition region. Additionally, monitoring their average ratios
can serve as a check out for the relative radiometric performance of
the two instruments throughout the mission. Although the engineering
data acquired so far are far from ideal in terms of time simultaneity
(often only within about 1 h) and line coverage (often only Lyman beta
was acquired by SPICE and not always near simultaneous images from all
three telescopes are available) the analysis we present here still
offers a great opportunity to have a first look at the potential of
this diagnostic from the two instruments. In fact, we have identified
a series of datasets obtained at disk center and at various positions
at the solar limb that allow studying the Lyman alpha to beta radiance
ratio and their relation to He II 30.4 as a function of the position
on the Sun (disk center versus limb and quiet Sun versus coronal holes).

---------------------------------------------------------
Title: Untangling the global coronal magnetic field with
multiwavelength observations
Authors: Gibson, S. E.; Malanushenko, A.; de Toma, G.; Tomczyk, S.;
Reeves, K.; Tian, H.; Yang, Z.; Chen, B.; Fleishman, G.; Gary, D.;
Nita, G.; Pillet, V. M.; White, S.; Bąk-Stęślicka, U.; Dalmasse,
K.; Kucera, T.; Rachmeler, L. A.; Raouafi, N. E.; Zhao, J.
2020arXiv201209992G Altcode:
Magnetism defines the complex and dynamic solar corona. Coronal
mass ejections (CMEs) are thought to be caused by stresses, twists,
and tangles in coronal magnetic fields that build up energy and
ultimately erupt, hurling plasma into interplanetary space. Even the
ever-present solar wind possesses a three-dimensional morphology shaped
by the global coronal magnetic field, forming geoeffective corotating
interaction regions. CME evolution and the structure of the solar
wind depend intimately on the coronal magnetic field, so comprehensive
observations of the global magnetothermal atmosphere are crucial both
for scientific progress and space weather predictions. Although some
advances have been made in measuring coronal magnetic fields locally,
synoptic measurements of the global coronal magnetic field are not yet
available. We conclude that a key goal for 2050 should be comprehensive,
ongoing 3D synoptic maps of the global coronal magnetic field. This will
require the construction of new telescopes, ground and space-based,
to obtain complementary, multiwavelength observations sensitive
to the coronal magnetic field. It will also require development of
inversion frameworks capable of incorporating multi-wavelength data,
and forward analysis tools and simulation testbeds to prioritize and
establish observational requirements on the proposed telescopes.

---------------------------------------------------------
Title: The Solar Orbiter SPICE instrument. An extreme UV imaging
spectrometer
Authors: SPICE Consortium; Anderson, M.; Appourchaux, T.; Auchère, F.;
Aznar Cuadrado, R.; Barbay, J.; Baudin, F.; Beardsley, S.; Bocchialini,
K.; Borgo, B.; Bruzzi, D.; Buchlin, E.; Burton, G.; Büchel, V.;
Caldwell, M.; Caminade, S.; Carlsson, M.; Curdt, W.; Davenne, J.;
Davila, J.; Deforest, C. E.; Del Zanna, G.; Drummond, D.; Dubau,
J.; Dumesnil, C.; Dunn, G.; Eccleston, P.; Fludra, A.; Fredvik, T.;
Gabriel, A.; Giunta, A.; Gottwald, A.; Griffin, D.; Grundy, T.; Guest,
S.; Gyo, M.; Haberreiter, M.; Hansteen, V.; Harrison, R.; Hassler,
D. M.; Haugan, S. V. H.; Howe, C.; Janvier, M.; Klein, R.; Koller,
S.; Kucera, T. A.; Kouliche, D.; Marsch, E.; Marshall, A.; Marshall,
G.; Matthews, S. A.; McQuirk, C.; Meining, S.; Mercier, C.; Morris,
N.; Morse, T.; Munro, G.; Parenti, S.; Pastor-Santos, C.; Peter, H.;
Pfiffner, D.; Phelan, P.; Philippon, A.; Richards, A.; Rogers, K.;
Sawyer, C.; Schlatter, P.; Schmutz, W.; Schühle, U.; Shaughnessy,
B.; Sidher, S.; Solanki, S. K.; Speight, R.; Spescha, M.; Szwec, N.;
Tamiatto, C.; Teriaca, L.; Thompson, W.; Tosh, I.; Tustain, S.; Vial,
J. -C.; Walls, B.; Waltham, N.; Wimmer-Schweingruber, R.; Woodward,
S.; Young, P.; de Groof, A.; Pacros, A.; Williams, D.; Müller, D.
2020A&A...642A..14S Altcode: 2019arXiv190901183A; 2019arXiv190901183S
 Aims: The Spectral Imaging of the Coronal Environment (SPICE)
instrument is a high-resolution imaging spectrometer operating at
extreme ultraviolet wavelengths. In this paper, we present the concept,
design, and pre-launch performance of this facility instrument on the
ESA/NASA Solar Orbiter mission. Methods: The goal of this paper
is to give prospective users a better understanding of the possible
types of observations, the data acquisition, and the sources that
contribute to the instrument's signal. Results: The paper
discusses the science objectives, with a focus on the SPICE-specific
aspects, before presenting the instrument's design, including optical,
mechanical, thermal, and electronics aspects. This is followed by a
characterisation and calibration of the instrument's performance. The
paper concludes with descriptions of the operations concept and data
processing. Conclusions: The performance measurements of the
various instrument parameters meet the requirements derived from the
mission's science objectives. The SPICE instrument is ready to perform
measurements that will provide vital contributions to the scientific
success of the Solar Orbiter mission.

---------------------------------------------------------
Title: Fast Magnetosonic Waves and Flows in a Solar Prominence Foot:
Observations and Modeling
Authors: Ofman, Leon; Kucera, Therese A.
2020ApJ...899...99O Altcode: 2020arXiv200605885O
We study recent observations of propagating fluctuations in a prominence
foot with Hinode Solar Optical Telescope (SOT) high-resolution
observations in Ca II and Hα emission, which we identify as nonlinear
fast magnetosonic waves. Here we analyze further the observations of
propagating waves and flows with Interface Region Imaging Spectrograph
Mg II slit jaw images, in addition to Hinode/SOT Ca II images. We find
that the waves have typical periods in the range of 5-11 minutes and
wavelengths in the plane of the sky (POS) of about 2000 km, while the
flows in narrow threads have a typical speed in the POS of ∼16-46
km s-1. We also detect apparent kink oscillations in the
threads with flowing material, and apply coronal seismology to estimate
the magnetic field strength in the range of 5-17 G. Using 2.5D MHD we
model the combined effects of nonlinear waves and flows on the observed
dynamics of the prominence material, and reproduce the propagating and
refracting fast magnetosonic waves, as well as standing kink-mode waves
in flowing material along the magnetic field. The modeling results are
in good qualitative agreement with the observations of the various
waves and flows in the prominence foot, further confirming coronal
seismology analysis and improving the understanding of the fine-scale
dynamics of the prominence material.

---------------------------------------------------------
Title: Filament Oscillations in Active Region 12076
Authors: Kucera, T. A.; Muglach, K.; Luna Bennasar, M.; Karpen, J.;
Thompson, B.; Gilbert, H.
2020AAS...23633004K Altcode:
We present an analysis of repeated large amplitude longitudinal
oscillations (LALO) in filaments in Active Region 12076 in May
and June of 2014. Most of the oscillations were associated with a
region of emerging and then canceling magnetic flux that resulted
in multiple activations and filament eruptions. We analyze twelve
separate oscillations that occur in a complex of filaments in the
active region over twelve days. Luna and Karpen (2012) model LALO
in filaments oscillations of magnetized filament plasma moving along
dipped magnetic field lines with gravity as a restoring force. Under
this model the period of these oscillations can be used to estimate
the curvature of the magnetic field in the location of the filament,
providing observationally derived values to compare with models of the
magnetic field in the active region corona. Periods ranged from 26-74
minutes, corresponding to magnetic field curvatures of about 20-130 Mm.

---------------------------------------------------------
Title: Spectroscopic Constraints on the Cross-sectional Asymmetry
and Expansion of Active Region Loops
Authors: Kucera, T. A.; Young, P. R.; Klimchuk, J. A.; DeForest, C. E.
2019ApJ...885....7K Altcode:
We explore the constraints that can be placed on the dimensions of
coronal loops out of the plane of the sky by utilizing spectroscopic
observations from the Hinode/EUV Imaging Spectrometer (EIS). The
usual assumption is that loop cross sections are circular. Changes in
intensity are assumed to be the result of changing density, filling
factor, and/or point of view. In this work we instead focus on the
possibility that the loop dimensions may be changing along the line of
sight while the filling factor remains constant. We apply these ideas
to two warm (5.5≲ {log}T({{K}})&lt; 6.2) loops observed by EIS in
Active Region 11150 on 2011 February 6 with supporting observations
from Solar Dynamics Observatory's Atmospheric Imaging Assembly and
the Solar TErrestrial RElations Observatory-A's Extreme Ultraviolet
Imager. Our results are generally consistent with nonexpanding loops
but could also allow linear expansions of up to a factor of 2.5 along
a 40 Mm section of one loop and up to a factor of 3.9 in another loop,
both under the assumption that the filling factor is constant along
the loop. Expansions in the plane of the sky over the same sections of
the loops are 1.5 or less. For a filling factor of 1, the results of
the analysis are consistent with circular cross sections but also with
aspect ratios of 2 or greater. Count rate statistics are an important
part of the uncertainties, but the results are also significantly
dependent on radiometric calibration of EIS and the selection of the
loop backgrounds.

---------------------------------------------------------
Title: Constraints from Hinode/EIS on the Expansion of Active Region
Loops Along the Line of Sight
Authors: Kucera, Therese A.; Young, Peter R.; Klimchuk, James A.;
DeForest, Craig
2019AAS...23411706K Altcode:
We explore the constraints that can be placed on the dimensions of
coronal loops out of the plane of the sky by utilizing spectroscopic
observations from the Hinode/EUV Imaging Spectrometer (EIS). The
usual assumption is that loop cross sections are circular. Changes
in intensity not constant with the measured width are assumed to be
the result of changing density and/or filling factor. Here we instead
focus on the possibility that the loop dimensions may be changing along
the line of sight while the filling factor remains constant. We apply
these ideas to two cool (5.5&lt;logT&lt;6.2) loops observed by EIS with
supporting observations from Solar Dynamics Observatory's Atmospheric
Imaging Assembly (SDO/AIA) and the Solar TErrestrial RElations
Observatory-A's Extreme Ultraviolet Imager (STEREO-A/EUVI). Our
results are generally consistent with non-expanding loops, but allow
for line-of-sight expansion factors up to 3-4. The uncertainties are
sizable and are driven by count rate statistics, radiometric calibration
of EIS, and the selection of the loop backgrounds.

---------------------------------------------------------
Title: Using SDO/AIA to Understand the Thermal Evolution of Solar
Prominence Formation
Authors: Viall, Nicholeen; Kucera, Therese; Karpen, Judith
2018csc..confE.124V Altcode:
We investigate prominence formation using time series analysis of
Solar Dynamics Observatory's Atmospheric Imaging Assembly (SDO/AIA)
data. We examine the thermal properties of forming prominences by
analyzing observed light curves using the same technique that we have
already successfully applied to active regions to diagnose heating
and cooling cycles. This technique tracks the thermal evolution using
emission formed at different temperatures, made possible by AIA's
different wavebands and high time resolution. We also compute the
predicted light curves in the same SDO/AIA channels of a hydrodynamic
model of thermal nonequilibrium formation of prominence material,
an evaporation-condensation model. In these models of prominence
formation, heating at the foot-points of sheared coronal flux-tubes
results in evaporation of material of a few MK into the corona followed
by catastrophic cooling of the hot material to form cool ( 10,000 K)
prominence material. We investigate prominences from different viewing
angles to evaluate possible line of sight effects. We demonstrate
that the SDO/AIA light curves for flux tubes undergoing thermal
nonequilibrium vary at different locations along the flux tube,
especially in the region where the condensate forms, and we compare
the predicted light curves with those observed.

---------------------------------------------------------
Title: "Building a Magnetic Skeleton of the Solar Corona: Towards
Better 3-D Constraints on the Coronal Magnetic Field
Authors: Malanushenko, Anna; Gibson, Sarah; Kucera, Therese; McKenzie,
David
2018cosp...42E2139M Altcode:
The energy stored in the solar magnetic field is what is powering many
violent explosive events in the solar atmosphere, or the corona. Some
of these events result in the coronal mass ejections (CME's) released
into the interplanetary space. The magnetic field in the solar corona
is therefore very important to know, yet it is very difficult to
measure. Most of the time it is modeled with the magnetic maps at
the solar surface used as boundary conditions. The magnetic maps on
the surface are therefore also important to know, yet the full vector
of the field on the surface is also difficult to measure. Once such
measurements are made, constructing a model capable of predicting
eruptive potential of a given region is on its own a complicated
task. One of the problems arising is that that the equations for
low-beta equilibria, which are often used to describe the coronal
field, do not, strictly speaking, work for the solar surface. In
short, we need better inputs to model the solar corona. The use of
non-magnetic and non-surface constraints on the magnetic field becomes
increasingly popular. For example, the paths of filaments can be used
to guide flux rope trajectories; the loops of active regions, seen
in extreme ultraviolet (EUV) can be used to obtain 3-D trajectories
of magnetic field lines and estimate electric currents flowing along
them. We are currently exploring ways to use other sources of data,
such as flows in prominences and coronal spectropolarimetric data, in a
similar fashion. I will talk about this work, and about our project of
aggregating many different sources of non-magnetic 3-D constraints on
the magnetic field. The resulting 'skeleton' can be used to constraint
global field models, or to validate models obtained in traditional
ways. We intend to develop a pipeline and assemble several skeletons
for several instances in time of the Sun, which we will then release
to community.

---------------------------------------------------------
Title: Motions in Prominence Barbs Observed on the Solar Limb
Authors: Kucera, T. A.; Ofman, L.; Tarbell, T. D.
2018ApJ...859..121K Altcode:
We analyze and discuss an example of prominence barbs observed on the
limb on 2016 January 7 by the Hinode/Solar Optical Telescope in Ca
II and Hα, the Interface Region Imaging Spectrograph, with slit jaw
images and Mg II spectral data, and the Solar Dynamics Observatory’s
Atmospheric Imaging Assembly. In the recent literature there has
been a debate concerning whether these features, sometimes referred
to as “tornadoes,” are rotating. Our data analysis provides no
evidence for systematic rotation in the barbs. We do find line-of-sight
motions in the barbs that vary with location and time. We also discuss
observations of features moving along the barbs. These moving features
are elongated parallel to the solar limb and tend to come in clusters
of features moving along the same or similar paths in the plane of
the sky during a period of 10 minutes to an hour, moving toward or
away from the limb. The motion may have a component along the line
of sight as well. The spectral data indicate that the features are
Doppler shifted. We discuss possible explanations for these features.

---------------------------------------------------------
Title: GONG Catalog of Solar Filament Oscillations Near Solar Maximum
Authors: Luna, M.; Karpen, J.; Ballester, J. L.; Muglach, K.; Terradas,
J.; Kucera, T.; Gilbert, H.
2018ApJS..236...35L Altcode: 2018arXiv180403743L
We have cataloged 196 filament oscillations from the Global Oscillation
Network Group Hα network data during several months near the maximum
of solar cycle 24 (2014 January-June). Selected examples from the
catalog are described in detail, along with our statistical analyses of
all events. Oscillations were classified according to their velocity
amplitude: 106 small-amplitude oscillations (SAOs), with velocities
&lt;10 {km} {{{s}}}-1, and 90 large-amplitude oscillations
(LAOs), with velocities &gt;10 {km} {{{s}}}-1. Both SAOs
and LAOs are common, with one event of each class every two days on the
visible side of the Sun. For nearly half of the events, we identified
their apparent trigger. The period distribution has a mean value of
58 ± 15 minutes for both types of oscillations. The distribution
of the damping time per period peaks at τ/P = 1.75 and 1.25 for
SAOs and LAOs, respectively. We confirmed that LAO damping rates
depend nonlinearly on the oscillation velocity. The angle between the
direction of motion and the filament spine has a distribution centered
at 27° for all filament types. This angle agrees with the observed
direction of filament-channel magnetic fields, indicating that most
of the cataloged events are longitudinal (i.e., undergo field-aligned
motions). We applied seismology to determine the average radius of
curvature in the magnetic dips, R ≈ 89 Mm, and the average minimum
magnetic field strength, B ≈ 16 G. The catalog is available to the
community online and is intended to be expanded to cover at least 1
solar cycle.

---------------------------------------------------------
Title: Motions in Prominence Barbs Observed on the Solar Limb
Authors: Kucera, Therese Ann; Ofman, Leon; Tarbell, Theodore D.
2018tess.conf21059K Altcode:
We analyze and discuss an example of prominence barbs observed on the

---------------------------------------------------------
Title: Large-amplitude Longitudinal Oscillations Triggered by the
Merging of Two Solar Filaments: Observations and Magnetic Field
Analysis
Authors: Luna, M.; Su, Y.; Schmieder, B.; Chandra, R.; Kucera, T. A.
2017ApJ...850..143L Altcode: 2017arXiv171101038L
We follow the eruption of two related intermediate filaments observed in
Hα (from GONG) and EUV (from Solar Dynamics Observatory SDO/Atmospheric
Imaging assembly AIA) and the resulting large-amplitude longitudinal
oscillations of the plasma in the filament channels. The events occurred
in and around the decayed active region AR12486 on 2016 January 26. Our
detailed study of the oscillation reveals that the periods of the
oscillations are about one hour. In Hα, the period decreases with
time and exhibits strong damping. The analysis of 171 Å images shows
that the oscillation has two phases: an initial long-period phase and
a subsequent oscillation with a shorter period. In this wavelength,
the damping appears weaker than in Hα. The velocity is the largest
ever detected in a prominence oscillation, approximately 100 {km}
{{{s}}}-1. Using SDO/HMI magnetograms, we reconstruct
the magnetic field of the filaments, modeled as flux ropes by using
a flux-rope insertion method. Applying seismological techniques,
we determine that the radii of curvature of the field lines in which
cool plasma is condensed are in the range 75-120 Mm, in agreement with
the reconstructed field. In addition, we infer a field strength of
≥7 to 30 Gauss, depending on the electron density assumed, that
is also in agreement with the values from the reconstruction (8-20
Gauss). The poloidal flux is zero and the axis flux is on the order
of 1020 to 1021 Mx, confirming the high shear
existing even in a non-active filament.

---------------------------------------------------------
Title: Constraints on Nonuniform Expansion in Coronal Loops
Authors: Kucera, Therese A.; DeForest, Craig; Klimchuk, James A.;
Young, Peter R.
2017SPD....4810608K Altcode:
We use measurements of coronal loop properties to constrain the
hypothesis that coronal loops expand differently in different
directions. A long standing problem in understanding coronal loops is
that although the magnetic field is expected to expand with altitude
and does indeed seem to do so on scales of active regions, individual
loops seem to have fairly uniform diameters along the length of the
loop. Malanushenko &amp; Schrijver (2013) have suggested that loops
may be expanding, but with a non-circular cross section. In this
scenario a loop might have a constant width in the plane of the sky,
but expand along the line of sight. Furthermore, such loops might be
easier to see from the point of view that does not show expansion. We
use Hinode/EIS and SDO/AIA data to measure loop intensities, electron
densities, temperatures and dimensions in order to determine the extent
to which loops may be expanding along the line of sight.

---------------------------------------------------------
Title: Probing Prominence Formation with Time Series Analysis of
Models and AIA Data
Authors: Kucera, T. A.; Viall, N. M.; Karpen, J. T.
2016AGUFMSH43C2583K Altcode:
We present a observational and modeling study of the formation and
dynamics of prominence plasma, using a time series analysis of data
from the Solar Dynamic Observatory's Atmospheric Imaging Assembly
(SDO/AIA). The analysis consists of a diagnosis of heating and cooling
events by comparing the time profiles of emission formed at different
temperatures and observed by different AIA bands. We apply this
analysis both to prominences observed by AIA and to model runs from
the thermal non-equilibrium model in which heating at the foot-points
of sheared coronal flux-tubes results in evaporation of hot (a few MK)
material into the corona and subsequent catastrophic cooling of the
hot material to form the cool ( 10,000 K) prominence material. We find
that both the data and model show characteristic heating and cooling
signatures that are significantly different from those seen in active
regions. Supported by NASA's Living with a Star program.

---------------------------------------------------------
Title: New Capabilities for Adaptive Mesh Simulation Use within
FORWARD
Authors: Mathews, N.; Flyer, N.; Gibson, S. E.; Kucera, T. A.;
Manchester, W.
2016AGUFMSM32A..05M Altcode:
The multiscale nature of the solar corona can pose challenges to
numerical simulations. Adaptive meshes are often used to resolve
fine-scale structures, such as the chromospheric-coronal interface
found in prominences and the transition region as a whole. FORWARD is
a SolarSoft IDL package designed as a community resource for creating
a broad range of synthetic coronal observables from numerical models
and comparing them to data. However, to date its interface with
numerical simulations has been limited to regular grids. We will
present a new adaptive-grid interface to FORWARD that will enable
efficient synthesis of solar observations. This is accomplished
through the use of hierarchical IDL structures designed to enable
finding nearest-neighbor points quickly for non-uniform grids. This
facilitates line-of-sight integrations that can adapt to the unequally
spaced mesh. We will demonstrate this capability for the Alfven-Wave
driven SOlar wind Model (AWSOM), part of the Space Weather Modeling
Framework (SWMF). In addition, we will use it in the context of a
prominence-cavity model, highlighting new capabilities in FORWARD that
allow treatment of continuum absorbtion as well as EUV line emission
via dual populations (chromosphere-corona).

---------------------------------------------------------
Title: Large-Amplitude Oscillations as a Probe of Solar Prominences
Authors: Luna Bennasar, M.; Karpen, J. T.; Gilbert, H. R.; Kucera,
T. A.; Muglach, K.
2016AGUFMSH41E..01L Altcode:
Large-amplitude oscillations in prominences are among the most
spectacular phenomena of the solar atmosphere. Such an oscillations
involve motions with velocities above 20 km/s, and large portions
of the filament that move in phase. These are triggered by energetic
disturbances as flares and jets. These oscillations are an excellent
tool to probe the not directly measurable filament morphology. In
addition, the damping of these motions can be related with the process
of evaporation of chromospheric plasma associated to coronal heating. In
these talk I will show recent observational and theoretical progress
on large-amplitude seismology on prominences.

---------------------------------------------------------
Title: Motions in Prominence Barbs as observed by Hinode/SOT and IRIS
Authors: Kucera, Therese A.; Ofman, Leon; Tarbell, Theodore D.
2016SPD....47.0316K Altcode:
We discuss observations of prominence barb dynamics as observed by
Hinode/SOT and IRIS. Prominence barbs extend outwards to the side of the
main prominence spine and downwards towards the chromosphere. Their
properties, including the structure of their magnetic field and
the nature of the motions observed in them are a subject of current
debate. We use a combination of high cadence, high resolution imaging,
H-alpha Doppler, and Mg II line profile data to analyze and understand
waves and flows in barbs and discuss their ramifications in terms of
a model of the barb magnetic field as collection of dipped field lines.

---------------------------------------------------------
Title: FORWARD: A toolset for multiwavelength coronal magnetometry
Authors: Gibson, Sarah; Kucera, Therese; White, Stephen; Dove,
James; Fan, Yuhong; Forland, Blake; Rachmeler, Laurel; Downs, Cooper;
Reeves, Katharine
2016FrASS...3....8G Altcode:
Determining the 3D coronal magnetic field is a critical, but extremely
difficult problem to solve. Since different types of multiwavelength
coronal data probe different aspects of the coronal magnetic field,
ideally these data should be used together to validate and constrain
specifications of that field. Such a task requires the ability to create
observable quantities at a range of wavelengths from a distribution
of magnetic field and associated plasma -- i.e., to perform forward
calculations. In this paper we describe the capabilities of the FORWARD
SolarSoft IDL package, a uniquely comprehensive toolset for coronal
magnetometry. FORWARD is a community resource that may be used both
to synthesize a broad range of coronal observables, and to access and
compare synthetic observables to existing data. It enables forward
fitting of specific observations, and helps to build intuition into
how the physical properties of coronal magnetic structures translate to
observable properties. FORWARD can also be used to generate synthetic
test beds from MHD simulations in order to facilitate the development
of coronal magnetometric inversion methods, and to prepare for the
analysis of future large solar telescope data.

---------------------------------------------------------
Title: Nonlinear MHD Waves in a Prominence Foot
Authors: Ofman, L.; Knizhnik, K.; Kucera, T.; Schmieder, B.
2015ApJ...813..124O Altcode: 2015arXiv150907911O
We study nonlinear waves in a prominence foot using a 2.5D MHD model
motivated by recent high-resolution observations with Hinode/Solar
Optical Telescope in Ca ii emission of a prominence on 2012 October
10 showing highly dynamic small-scale motions in the prominence
material. Observations of Hα intensities and of Doppler shifts show
similar propagating fluctuations. However, the optically thick nature
of the emission lines inhibits a unique quantitative interpretation
in terms of density. Nevertheless, we find evidence of nonlinear wave
activity in the prominence foot by examining the relative magnitude of
the fluctuation intensity (δI/I ∼ δn/n). The waves are evident as
significant density fluctuations that vary with height and apparently
travel upward from the chromosphere into the prominence material
with quasi-periodic fluctuations with a typical period in the range
of 5-11 minutes and wavelengths &lt;2000 km. Recent Doppler shift
observations show the transverse displacement of the propagating
waves. The magnetic field was measured with the THEMIS instrument
and was found to be 5-14 G. For the typical prominence density the
corresponding fast magnetosonic speed is ∼20 km s-1,
in qualitative agreement with the propagation speed of the detected
waves. The 2.5D MHD numerical model is constrained with the typical
parameters of the prominence waves seen in observations. Our numerical
results reproduce the nonlinear fast magnetosonic waves and provide
strong support for the presence of these waves in the prominence
foot. We also explore gravitational MHD oscillations of the heavy
prominence foot material supported by dipped magnetic field structure.

---------------------------------------------------------
Title: Investigating the Thermal Evolution of Solar Prominence
Formation
Authors: Kucera, Therese A.; Viall, Nicholeen M.; Karpen, Judith T.
2015TESS....120315K Altcode:
We present a study of prominence formation using time series analysis of
Solar Dynamics Observatory’s Atmospheric Imaging Assembly (SDO/AIA)
data. In evaporation-condensation models of prominence formation,
heating at the foot-points of sheared coronal flux-tubes results in
evaporation of hot (a few MK) material into the corona and subsequent
catastrophic cooling of the hot material to form the cool (~10,000 K)
prominence material. We present the results of a time-lag analysis
that tracks the thermal evolution using emission formed at different
temperatures. This analysis is made possible by AIA's many wavebands
and high time resolution, and it allows us to look for signs of the
evaporation-condensation process and to study the heating time scales
involved. Supported by NASA’s Living with a Star program.

---------------------------------------------------------
Title: Observations and Implications of Large-Amplitude Longitudinal
Oscillations in a Solar Filament
Authors: Karpen, J. T.; Luna Bennasar, M.; Knizhnik, K. J.; Muglach,
K.; Gilbert, H. R.; Kucera, T. A.; Uritsky, V. M.; Asfaw, T. T.
2014AGUFMSH51C4171K Altcode:
On 20 August 2010 an energetic disturbance triggered large-amplitude
longitudinal oscillations in a large fraction of a nearby filament. The
triggering mechanism appears to be episodic jets connecting the
energetic event with the filament threads. We analyzed this periodic
motion to characterize the underlying physics of the oscillation as
well as the filament properties. The results support our previous
theoretical conclusions that the restoring force of large-amplitude
longitudinal oscillations is solar gravity, and the damping mechanism
is the ongoing accumulation of mass onto the oscillating threads. Based
on our previous work, we used the fitted parameters to determine the
magnitude and radius of curvature of the dipped magnetic field along
the filament, as well as the mass accretion rate onto the filament
threads. These derived properties are nearly uniform along the filament,
indicating a remarkable degree of homogeneity throughout the filament
channel. Moreover, the estimated mass accretion rate implies that the
footpoint heating responsible for the thread formation, according to
the thermal nonequilibrium model, agrees with previous coronal heating
estimates. We also estimated the magnitude of the energy released in
the nearby event by studying the dynamic response of the filament
threads, and concluded that the initiating event is likely to be a
microflare. Using a nonlinear force-free field extrapolation of the
photospheric magnetogram to estimate the coronal magnetic structure,
we determined the possible connectivity between the jet source and the
oscillating prominence segments. We will present the results of this
investigation and discuss their implications for filament structure
and heating. This work was supported by NASA's H-SR program.

---------------------------------------------------------
Title: Open questions on prominences from coordinated observations
by IRIS, Hinode, SDO/AIA, THEMIS, and the Meudon/MSDP
Authors: Schmieder, B.; Tian, H.; Kucera, T.; López Ariste, A.;
Mein, N.; Mein, P.; Dalmasse, K.; Golub, L.
2014A&A...569A..85S Altcode: 2014arXiv1407.3171S
Context. A large prominence was observed by multiple instruments on the
ground and in space during an international campaign on September 24,
2013, for three hours (12:12 UT -15:12 UT). Instruments used in the
campaign included the newly launched (June 2013) Interface Region
Imaging Spectrograph (IRIS), THEMIS (Tenerife), the Hinode Solar
Optical Telescope (SOT), the Solar Dynamic Observatory's Atmospheric
Imaging Assembly (SDO/AIA), and the Multichannel Subtractive Double
Pass spectrograph (MSDP) in the Meudon Solar Tower. The movies obtained
in 304 Å with the EUV imager SDO/AIA, and in Ca II line by SOT show
the dynamic nature of the prominence. Aims: The aim of this
work is to study the dynamics of the prominence fine structures in
multiple wavelengths to understand their formation. Methods:
The spectrographs IRIS and MSDP provided line profiles with a high
cadence in Mg II h (2803.5 Å) and k (2796.4 Å) lines along four
slit positions (IRIS), and in Hα in a 2D field of view (MSDP). The
spectropolarimetry of THEMIS (Tenerife) allowed us to derive the
magnetic field of the prominence using the He D3 line
depolarization (Hanle effect combined with the Zeeman effect). 
Results: The magnetic field is found to be globally horizontal with
a relatively weak field strength (8-15 Gauss). On the other hand,
the Ca II movie reveals turbulent-like motion that is not organized in
specific parts of the prominence. We tested the addition of a turbulent
magnetic component. This model is compatible with the polarimetric
observations at those places where the plasma turbulence peaks. On the
other hand, the Mg II line profiles show multiple peaks well separated
in wavelength. This is interpreted by the existence of small threads
along the line of sight with a large dispersion of discrete values of
Doppler shifts, from 5 km s-1 (a quasi-steady component) to
60-80 km s-1. Each peak corresponds to a Gaussian profile,
and not to a reversed profile as was expected by the present non-LTE
radiative transfer modeling. This is a very surprising behavior for
the Mg II line observed in prominences. Conclusions: Turbulent
fields on top of the macroscopic horizontal component of the magnetic
field supporting the prominence give rise to the complex dynamics of
the plasma. The plasma with the high velocities (70 km s-1 to
100 km s-1 if we take into account the transverse velocities)
may correspond to condensation of plasma along more or less horizontal
threads of the arch-shape structure visible in 304 Å. The steady
flows (5 km s-1) would correspond to a more quiescent plasma
(cool and prominence-corona transition region) of the prominence packed
into dips in horizontal magnetic field lines. The very weak secondary
peaks in the Mg II profiles may reflect the turbulent nature of parts
of the prominence. Movies are available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201423922/olm">http://www.aanda.org</A>

---------------------------------------------------------
Title: Mass Flows in a Prominence Spine as Observed in EUV
Authors: Kucera, T. A.; Gilbert, H. R.; Karpen, J. T.
2014ApJ...790...68K Altcode:
We analyze a quiescent prominence observed by the Solar Dynamics
Observatory's Atmospheric Imaging Assembly (AIA) with a focus on
mass and energy flux in the spine, measured using Lyman continuum
absorption. This is the first time this type of analysis has been
applied with an emphasis on individual features and fluxes in a
quiescent prominence. The prominence, observed on 2010 September
28, is detectable in most AIA wavebands in absorption and/or
emission. Flows along the spine exhibit horizontal bands 5”-10” wide
and kinetic energy fluxes on the order of a few times 105
erg s-1cm-2, consistent with quiet sun coronal
heating estimates. For a discrete moving feature we estimate a mass
of a few times 1011 g. We discuss the implications of our
derived properties for a model of prominence dynamics, the thermal
non-equilibrium model.

---------------------------------------------------------
Title: Observations and Implications of Large-Amplitude
LongitudinalOscillations in a Solar Filament
Authors: Karpen, Judith T.; Luna, Manuel; Knizhnik, Kalman J.; Muglach,
Karin; Gilbert, Holly; Kucera, Therese A.; Uritsky, Vadim
2014AAS...22411106K Altcode:
On 20 August 2010 an energetic disturbance triggered large-amplitude
longitudinal oscillations in a large fraction of a nearby filament. The
triggering mechanism appears to be episodic jets connecting the
energetic event with the filament threads. We analyzed this periodic
motion to characterize the underlying physics of the oscillation as
well as the filament properties. The results support our previous
theoretical conclusions that the restoring force of large-amplitude
longitudinal oscillations is solar gravity, and the damping mechanism
is the ongoing accumulation of mass onto the oscillating threads. Based
on our previous work, we used the fitted parameters to determine the
magnitude and radius of curvature of the dipped magnetic field along
the filament, as well as the mass accretion rate onto the filament
threads. These derived properties are nearly uniform along the filament,
indicating a remarkable degree of homogeneity throughout the filament
channel. Moreover, the estimated mass accretion rate implies that the
footpoint heating responsible for the thread formation, according to
the thermal nonequilibrium model, agrees with previous coronal heating
estimates. We also estimated the magnitude of the energy released in
the nearby event by studying the dynamic response of the filament
threads, and concluded that the initiating event is likely to be a
microflare. We will present the results of this investigation and
discuss their implications for filament structure and heating. This
work was supported by NASA’s H-SR program.

---------------------------------------------------------
Title: Mass Flows in a Prominence Spine as Observed in EUV
Authors: Kucera, Therese A.; Gilbert, Holly; Karpen, Judith T.
2014AAS...22440804K Altcode:
We analyze a quiescent prominence observed by the Solar Dynamics
Observatory's Atmospheric Imaging Assembly with a focus on mass
and energy flows in the spine measured using Lyman continuum
absorption. This is the first time this sort of analysis has been
applied with an emphasis on individual features and flows in a quiescent
prominence. The prominence, observed on 2010 Sept. 28, is detectable in
most AIA wavebands in absorption and/or emission. Flows along the spine
exhibit horizontal bands 5-10 arcsec wide and kinetic energy fluxes
consistent with quiet sun coronal heating estimates. For a discrete
moving feature we estimate a mass of a few times 10^11 g. We discuss
the implications of our derived properties for models of prominence
dynamics, in particular the thermal non-equilibrium model. This project
was supported by NASA's LWS TR&amp;T program.

---------------------------------------------------------
Title: FORWARD: Forward modeling of coronal observables
Authors: Gibson, Sarah E.; Kucera, Therese A.; Casini, Roberto; Dove,
James; Forland, Blake; Judge, Philip; Rachmeler, Laurel
2014ascl.soft05007G Altcode: 2014ascl.soft05007F
FORWARD forward models various coronal observables and can access
and compare existing data. Given a coronal model, it can produce
many different synthetic observables (including Stokes polarimetry),
as well as plots of model plasma properties (density, magnetic field,
etc.). It uses the CHIANTI database (ascl:9911.004) and CLE polarimetry
synthesis code, works with numerical model datacubes, interfaces with
the PFSS module of SolarSoft (ascl:1208.013), includes several analytic
models, and connects to the Virtual Solar Observatory for downloading
data in a format directly comparable to model predictions.

---------------------------------------------------------
Title: Observations and Implications of Large-amplitude Longitudinal
Oscillations in a Solar Filament
Authors: Luna, M.; Knizhnik, K.; Muglach, K.; Karpen, J.; Gilbert,
H.; Kucera, T. A.; Uritsky, V.
2014ApJ...785...79L Altcode: 2014arXiv1403.0381L
On 2010 August 20, an energetic disturbance triggered large-amplitude
longitudinal oscillations in a nearby filament. The triggering mechanism
appears to be episodic jets connecting the energetic event with the
filament threads. In the present work, we analyze this periodic motion
in a large fraction of the filament to characterize the underlying
physics of the oscillation as well as the filament properties. The
results support our previous theoretical conclusions that the restoring
force of large-amplitude longitudinal oscillations is solar gravity,
and the damping mechanism is the ongoing accumulation of mass onto
the oscillating threads. Based on our previous work, we used the
fitted parameters to determine the magnitude and radius of curvature
of the dipped magnetic field along the filament, as well as the mass
accretion rate onto the filament threads. These derived properties are
nearly uniform along the filament, indicating a remarkable degree of
cohesiveness throughout the filament channel. Moreover, the estimated
mass accretion rate implies that the footpoint heating responsible
for the thread formation, according to the thermal nonequilibrium
model, agrees with previous coronal heating estimates. We estimate the
magnitude of the energy released in the nearby event by studying the
dynamic response of the filament threads, and discuss the implications
of our study for filament structure and heating.

---------------------------------------------------------
Title: Erratum: "Propagating Waves Transverse to the Magnetic Field
in a Solar Prominence" <A href="/abs/2013ApJ...777..108S">(2013,
ApJ, 777, 108)</A>
Authors: Schmieder, B.; Kucera, T. A.; Knizhnik, K.; Luna, M.;
Lopez-Ariste, A.; Toot, D.
2014ApJ...781..129S Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Propagating waves transverse to the magnetic field in a
solar prominence
Authors: Kucera, Therese; Schmieder, Brigitte; Knizhnik, Kalman;
Lopez-Ariste, Arturo; Luna, Manuel; Toot, David
2014IAUS..300..435K Altcode:
We have observed a quiescent prominence with the Hinode Solar Optical
Telescope (SOT) (Ca II and Hα lines), Sacramento Peak Dunn Solar
Telescope using the Universal Birefringent Filter (DST/UBF, in Hα,
Hβ and Sodium-D lines), THEMIS (Télescope Héliographique pour l
Etude du Magnétisme et des Instabilités Solaires/MTR (Multi Raies)
spectromagnetograph (He D3), and the Solar Dynamics
Observatory Atmospheric Imaging Assembly (SDO/AIA) in EUV over a 4
hour period on 2012 October 10. The small fields of view of the SOT,
DST, and MTR are centered on a large prominence footpoint extending
towards the surface. This feature appears in the larger field of view
of the AIA/304 Å filtergram as a large, quasi-vertical pillar with
loops on each side. The THEMIS/MTR data indicate that the magnetic
field in the pillar is essentially horizontal and the observations in
the optical domain show a large number of horizontally aligned features
in the pillar. The data are consistent with a model of cool prominence
plasma trapped in the dips of horizontal field lines. The SOT and DST
data show what appear to be moving wave pulses. These pulses, which
include a Doppler signature, move vertically, perpendicular to the
field direction, along quasi-vertical columns of horizontal threads in
the pillar. The pulses have a velocity of propagation of about 10 km/s,
a wavelength about 2000 km in the plane of the sky, and a period about
280 sec. We interpret these waves in terms of fast magnetosonic waves.

---------------------------------------------------------
Title: Dynamics of a prominence observed in Mg II lines by IRIS
Authors: Schmieder, Brigitte; Mein, Pierre; Dalmasse, Kévin; Tian,
Hui; Kucera, Therese; Lopez-Ariste, Arturo
2014cosp...40E2927S Altcode:
In September 2013 several prominences were observed with the IRIS
spectrograph during a 60 day-long international program. We will present
one set of observations obtained using multiple instruments on September
24. SDO/AIA and IRIS slit jaws provided images of the prominence
corresponding to different physical conditions of the transition
region between the cool plasma and the corona. The vector magnetic
field was derived from THEMIS (Tenerife) observations using the He D3
depolarisation due to the magnetic field. The inversion code (CPA) takes
into account the Hanle and the Zeeman effects. Movies from SDO/AIA in
304 A and Hinode/SOT in Ca II show the dynamics of the fine structures
in the plane of the sky. From Mg II and Si IV line spectra observed by
IRIS and H-alpha observed by the Multi-channel subtractive spectrograph
(MSDP) in the Meudon solar tower we derived the Dopplershifts of the
fine structures. The profiles of the Mg II lines are narrow (FHWM =0.15
A) and not reversed, contrary to the predictions of the theoretical
models (Paletou et al 1993). We could resolve the velocity of several
structures along the LOS with Dopplershifts as high as 60 km/s.

---------------------------------------------------------
Title: Large-amplitude longitudinal oscillations in solar prominences
Authors: Luna, Manuel; Karpen, Judith; Díaz, Antonio; Knizhnik,
Kalman; Muglach, Karin; Gilbert, Holly; Kucera, Therese
2014IAUS..300..155L Altcode:
Large-amplitude longitudinal (LAL) prominence oscillations consist of
periodic mass motions along a filament axis. The oscillations appear
to be triggered by an energetic event, such as a microflare, subflare,
or small C-class flare, close to one end of the filament. Observations
reveal speeds of several tens to 100 km/s, periods of order 1 hr,
damping times of a few periods, and displacements equal to a significant
fraction of the prominence length. We have developed a theoretical model
to explain the restoring force and the damping mechanism. Our model
demonstrates that the main restoring force is the projected gravity in
the flux tube dips where the threads oscillate. Although the period
is independent of the tube length and the constantly growing mass,
the motions are strongly damped by the steady accretion of mass onto
the threads. We conclude that the LAL movements represent a collective
oscillation of a large number of cool, dense threads moving along
dipped flux tubes, triggered by a nearby energetic event. Our model
yields a powerful seismological method for constraining the coronal
magnetic field strength and radius of curvature at the thread locations.

---------------------------------------------------------
Title: The solar physics FORWARD codes: Now with widgets!
Authors: Forland, Blake; Gibson, Sarah; Dove, James; Kucera, Therese
2014IAUS..300..414F Altcode:
We have developed a suite of forward-modeling IDL codes (FORWARD)
to convert analytic models or simulation data cubes into coronal
observables, allowing a direct comparison with observations. Observables
such as extreme ultraviolet, soft X-ray, white light, and polarization
images from the Coronal Multichannel Polarimeter (CoMP) can be
reproduced. The observer's viewpoint is also incorporated in the FORWARD
analysis and the codes can output the results in a variety of forms in
order to easily create movies, Carrington maps, or simply observable
information at a particular point in the plane of the sky. We present
a newly developed front end to the FORWARD codes which utilizes IDL
widgets to facilitate ease of use by the solar physics community. Our
ultimate goal is to provide as useful a tool as possible for a broad
range of scientific applications.

---------------------------------------------------------
Title: Observational Study of Large Amplitude Longitudinal
Oscillations in a Solar Filament
Authors: Knizhnik, Kalman; Luna, Manuel; Muglach, Karin; Gilbert,
Holly; Kucera, Therese; Karpen, Judith
2014IAUS..300..428K Altcode: 2013arXiv1310.7657K
On 20 August 2010 an energetic disturbance triggered damped
large-amplitude longitudinal (LAL) oscillations in almost an entire
filament. In the present work we analyze this periodic motion in
the filament to characterize the damping and restoring mechanism of
the oscillation. Our method involves placing slits along the axis
of the filament at different angles with respect to the spine of the
filament, finding the angle at which the oscillation is clearest, and
fitting the resulting oscillation pattern to decaying sinusoidal and
Bessel functions. These functions represent the equations of motion
of a pendulum damped by mass accretion. With this method we determine
the period and the decaying time of the oscillation. Our preliminary
results support the theory presented by Luna and Karpen (2012) that
the restoring force of LAL oscillations is solar gravity in the tubes
where the threads oscillate, and the damping mechanism is the ongoing
accumulation of mass onto the oscillating threads. Following an earlier
paper, we have determined the magnitude and radius of curvature of
the dipped magnetic flux tubes hosting a thread along the filament,
as well as the mass accretion rate of the filament threads, via the
fitted parameters.

---------------------------------------------------------
Title: Nonlinear MHD waves in a Prominence Foot: Observations
and Models
Authors: Ofman, Leon; Schmieder, Brigitte; Kucera, Therese; Knizhnik,
Kalman
2014cosp...40E2338O Altcode:
Recent high-resolution observations with Hinode/SOT in Ca II emission
of a prominence on October 12, 2012 show highly dynamic small-scale
motions in the prominence material. Observations in Hα and of Doppler
shifts show similar propagating fluctuations. However the optically
thick nature of the emission lines inhibits unique quantitative
interpretation in terms of density. Nevertheless, we find evidence of
nonlinear wave activity in the prominence foot by examining the relative
magnitude of the fluctuation intensity (dI/I~ dn/n). The waves are
evident as significant density fluctuations (dn/n~O(1)) with weak height
dependence, and apparently travel upward from the chromosphere into the
prominence material with quasi-periodic fluctuations on the order of 5
minutes, and wavelengths ~&lt;2000 km. Doppler shift observations show
the transverse displacement of the propagating waves. The magnetic
field is measured with THEMIS and is found to be 5-14 G. For the
typical prominence density the corresponding fast magnetosonic speed
is ~20 km/s in qualitative agreement with the propagation speed of
the detected wave. We use 2D and 3D MHD numerical models to reproduce
the nonlinear magnetosonic waves with the typical parameters of the
prominence guided by observations. We investigate the parameter range
of the model that fits the observed properties of the waves in order
confirm the identification of the wave nature of these observations.

---------------------------------------------------------
Title: Propagating Waves Transverse to the Magnetic Field in a
Solar Prominence
Authors: Schmieder, B.; Kucera, T. A.; Knizhnik, K.; Luna, M.;
Lopez-Ariste, A.; Toot, D.
2013ApJ...777..108S Altcode: 2013arXiv1309.1568S
We report an unusual set of observations of waves in a large prominence
pillar that consist of pulses propagating perpendicular to the
prominence magnetic field. We observe a huge quiescent prominence with
the Solar Dynamics Observatory Atmospheric Imaging Assembly in EUV on
2012 October 10 and only a part of it, the pillar, which is a foot or
barb of the prominence, with the Hinode Solar Optical Telescope (SOT;
in Ca II and Hα lines), Sac Peak (in Hα, Hβ, and Na-D lines), and
THEMIS ("Télescope Héliographique pour l' Etude du Magnétisme et des
Instabilités Solaires") with the MTR (MulTi-Raies) spectropolarimeter
(in He D3 line). The THEMIS/MTR data indicates that
the magnetic field in the pillar is essentially horizontal and the
observations in the optical domain show a large number of horizontally
aligned features on a much smaller scale than the pillar as a whole. The
data are consistent with a model of cool prominence plasma trapped in
the dips of horizontal field lines. The SOT and Sac Peak data over
the four hour observing period show vertical oscillations appearing
as wave pulses. These pulses, which include a Doppler signature,
move vertically, perpendicular to the field direction, along thin
quasi-vertical columns in the much broader pillar. The pulses have
a velocity of propagation of about 10 km s-1, a period of
about 300 s, and a wavelength around 2000 km. We interpret these waves
in terms of fast magnetosonic waves and discuss possible wave drivers.

---------------------------------------------------------
Title: Propagating Waves Transverse to the Magnetic Field in a
Solar Prominence
Authors: Kucera, Therese A.; Knizhnik, K.; Lopez Ariste, A.; Luna
Bennasar, M.; Schmieder, B.; Toot, D.
2013SPD....4410403K Altcode:
We have observed a quiescent prominence with the Hinode Solar Optical
Telescope (SOT, in Ca II and H-alpha lines), Sacramento Peak Observatory
(in H-alpha, H-beta and Sodium-D lines), and THEMIS/MTR (Télescope
Héliographique pour l'Étude du Magnétisme et des Instabilités
Solaires/MulTi Raies, providing vector magnetograms), and SDO/AIA (Solar
Dynamics Observatory Atmospheric Imaging Assembly, in EUV) over a 4 hour
period on 2012 October 10. The small fields of view of SOT, Sac Peak
and THEMIS are centered on a large pillar-like prominence footpoint
extending towards the surface. This feature appears in the larger
field of view of the 304 Å band, as a large, quasi-vertical column
with material flowing horizontally on each side. The THEMIS/MTR data
indicate that the magnetic field in the pillar is essentially horizontal
and the observations in the optical wavelengths show a large number of
horizontally aligned features on a much smaller scale than the pillar
as a whole. The data are consistent with a model of cool prominence
plasma trapped in the dips of horizontal field lines. The SOT and Sac
Peak data show what appear to be moving wave pulses. These pulses,
which include a Doppler signature, move vertically, perpendicular to
the field direction, along quasi-vertical columns. The pulses have
a velocity of propagation of about 10 km/s, a period about 260 sec,
and a wavelength around 2000 km. We interpret these waves in terms of
fast magneto-sonic waves and discuss possible wave drivers.

---------------------------------------------------------
Title: Morphology and Temperature of a Hot Prominence Cavity Observed
with SDO
Authors: Weber, Mark A.; Reeves, K.; Gibson, S.; Kucera, T. A.
2013SPD....44...39W Altcode:
Prominence cavities appear as circularly shaped voids in coronal
emission over polarity inversion lines where a prominence channel
is straddling the solar limb. The presence of chromospheric material
suspended at coronal altitudes is a common but not necessary feature
within these cavities. These voids are observed to change shape as
a prominence feature rotates around the limb. We apply temperature
diagnostics to SDO data to investigate the thermal structure. We find
significant evidence that the prominence cavity is hotter than the
corona immediately outside the cavity boundary. This investigation
follows upon “Thermal Properties of A Solar Coronal Cavity Observed
with the X-ray Telescope on Hinode” by Reeves et al., 2012, ApJ, in
press. M. Weber and K.K. Reeves are supported under contract NNM07AB07C
from NASA to SAO. T. Kucera is supported by an award from the NASA
SHP Program.

---------------------------------------------------------
Title: FORWARD Codes: Now with Widget!
Authors: Gibson, Sarah; Forland, B.; Kucera, T. A.
2013SPD....44...49G Altcode:
The FORWARD suite of SolarSoft IDL codes converts an analytic
or simulation data cube into a form directly comparable to
observations. Observables such as extreme ultraviolet, soft X-ray,
white light, and polarization images from the Coronal Multichannel
Polarimeter (CoMP) can be reproduced. The observer's viewpoint is
also incorperated in the forward analysis and the codes can output
the results in a variety of forms in order to easily create movies,
Carrington maps, or simply plasma properties at a particular point
in the plane of the sky. We present a newly developed front end to
the FORWARD codes which utilizes IDL widgets. Our ultimate goal is to
provide as useful a tool as possible for a broad range of scientific
applications.Abstract (2,250 Maximum Characters): The FORWARD suite
of SolarSoft IDL codes converts an analytic or simulation data cube
into a form directly comparable to observations. Observables such as
extreme ultraviolet, soft X-ray, white light, and polarization images
from the Coronal Multichannel Polarimeter (CoMP) can be reproduced. The
observer's viewpoint is also incorperated in the forward analysis and
the codes can output the results in a variety of forms in order to
easily create movies, Carrington maps, or simply plasma properties at a
particular point in the plane of the sky. We present a newly developed
front end to the FORWARD codes which utilizes IDL widgets. Our ultimate
goal is to provide as useful a tool as possible for a broad range of
scientific applications.

---------------------------------------------------------
Title: FORWARD Codes: Now with Widgets!
Authors: Forland, B.; Gibson, S. E.; Kucera, T. A.
2013AGUSMSH51A..02F Altcode:
The FORWARD suite of SolarSoft IDL codes converts an analytic
model or simulation data cube into a form directly comparable to
observations. Observables such as extreme ultra violet, soft X-ray,
white light, and polarization images from the Coronal Multichannel
Polarimeter (CoMP) can be reproduced. The observer's viewpoint is
also incorporated in the forward analysis and the codes can output
the results in a variety of forms in order to easily create movies,
Carrington maps, or simply observable information at a particular point
in the plane of the sky. We present a newly developed front end to the
FORWARD codes which utilizes IDL widgets to facilitate ease of use by
the solar physics community. Our ultimate goal is to provide as useful
a tool as possible for a broad range of scientific applications.

---------------------------------------------------------
Title: Mass Flows in a Prominence Spine as Observed in EUV
Authors: Kucera, T. A.; Gilbert, H. R.
2013enss.confE..54K Altcode:
We analyze flows in the spine of a quiescent prominence observed by
SDO/AIA. We discuss the appearance of the prominence in absorption and
emission and estimate quantities including the mass of material flowing
in the spine, measured by analyzing Lyman absorption, velocities and
sizes of moving features, and lifetimes of flows. These quantities
provide constraints on models of prominence formation and dynamics such
as the thermal non-equilibrium model of prominence condensation. This
work is funded by NASA's LWS program

---------------------------------------------------------
Title: Temperature and Extreme-ultraviolet Intensity in a Coronal
Prominence Cavity and Streamer
Authors: Kucera, T. A.; Gibson, S. E.; Schmit, D. J.; Landi, E.;
Tripathi, D.
2012ApJ...757...73K Altcode:
We analyze the temperature and EUV line emission of a coronal cavity and
surrounding streamer in terms of a morphological forward model. We use a
series of iron line ratios observed with the Hinode Extreme-ultraviolet
Imaging Spectrograph (EIS) on 2007 August 9 to constrain temperature
as a function of altitude in a morphological forward model of the
streamer and cavity. We also compare model predictions to the EIS EUV
line intensities and polarized brightness (pB) data from the Mauna
Loa Solar Observatory (MLSO) Mark 4 K-coronameter. This work builds
on earlier analysis using the same model to determine geometry of
and density in the same cavity and streamer. The fit to the data
with altitude-dependent temperature profiles indicates that both
the streamer and cavity have temperatures in the range 1.4-1.7
MK. However, the cavity exhibits substantial substructure such
that the altitude-dependent temperature profile is not sufficient to
completely model conditions in the cavity. Coronal prominence cavities
are structured by magnetism so clues to this structure are to be found
in their plasma properties. These temperature substructures are likely
related to structures in the cavity magnetic field. Furthermore,
we find that the model overestimates the EUV line intensities by a
factor of 4-10, without overestimating pB. We discuss this difference
in terms of filling factors and uncertainties in density diagnostics
and elemental abundances.

---------------------------------------------------------
Title: Morphology Of A Hot Prominence Cavity Observed With Hinode/XRT
And SDO/AIA
Authors: Weber, Mark A.; Reeves, K. K.; Gibson, S. E.; Kucera, T. A.
2012AAS...22020205W Altcode:
Prominence cavities appear as circularly shaped voids in coronal
emission over polarity inversion lines where a prominence channel
is straddling the solar limb. The presence of chromospheric material
suspended at coronal altitudes is a common but not necessary feature
within these cavities. These voids are observed to change shape as a
prominence feature rotates around the limb. We use a morphological
model projected in cross-sections to fit the cavity emission in
Hinode/XRT passbands, and then apply temperature diagnostics to
XRT and SDO/AIA data to investigate the thermal structure. We find
significant evidence that the prominence cavity is hotter than the
corona immediately outside the cavity boundary. This investigation
follows upon “Thermal Properties of A Solar Coronal Cavity Observed
with the X-ray Telescope on Hinode” by Reeves et al., 2012, ApJ, in
press. M. Weber and K.K. Reeves are supported under contract NNM07AB07C
from NASA to SAO. T. Kucera is supported by an award from the NASA
SHP Program.

---------------------------------------------------------
Title: Temperature Structure of a Coronal Cavity and Streamer
Authors: Kucera, Therese A.; Gibson, S. E.; Schmit, D. J.; Landi,
E.; Tripathi, D.
2012AAS...22052113K Altcode:
We analyze the temperature and EUV line emission of a coronal cavity and
surrounding streamer in terms of a morphological forward model. We use a
series of iron line ratios observed with the Hinode Extreme-ultraviolet
Imaging Spectrograph (EIS) on 2007 Aug. 9 to constrain temperature
as a function of altitude in a morphological forward model of the
streamer and cavity. We also compare model prediction of the EIS EUV
line intensities and polarized brightness (pB) data from the Mauna Loa
Solar Observatory (MLSO) MK4. This work builds on earlier analysis using
the same model to determine geometry of and density in the same cavity
and streamer (Gibson et al. 2010 and Schmit and Gibson 2011). The fit
to the data with altitude dependent temperature profiles indicates that
both the streamer and cavity have temperatures in the range 1.4-1.7
MK. However, the cavity exhibits substantial substructure such that the
altitude dependent temperature profile is not sufficient to completely
model conditions in the cavity. This work is supported in part by the
NASA SHP program

---------------------------------------------------------
Title: Morphology of a Hot Prominence Cavity Observed with XRT and AIA
Authors: Weber, Mark; Reeves, Katherine K.; Gibson, Sarah E.; Kucera,
Therese A.
2012decs.confE..56W Altcode:
Prominence cavities appear as circularly shaped voids in coronal
emission over polarity inversion lines where a prominence channel
is straddling the solar limb. The presence of chromospheric material
suspended at coronal altitudes is a common but not necessary feature
within these cavities. These voids are observed to change shape as
a prominence feature rotates around the limb. We use a morphological
model projected in cross-sections to fit the cavity emission in XRT
passbands, and then apply temperature diagnostics to XRT and AIA data
to investigate the thermal structure. We find significant evidence that
the prominence cavity is hotter than the corona immediately outside the
cavity boundary. This investigation follows upon “Thermal Properties
of A Solar Coronal Cavity Observed with the X-ray Telescope on Hinode”
by Reeves et al., 2012, ApJ, in press. M. Weber and K.K. Reeves are
supported under contract NNM07AB07C from NASA to SAO. T. Kucera is
supported by an award from the NASA SHP Program.

---------------------------------------------------------
Title: Thermal Properties of a Solar Coronal Cavity Observed with
the X-Ray Telescope on Hinode
Authors: Reeves, Katharine K.; Gibson, Sarah E.; Kucera, Therese A.;
Hudson, Hugh S.; Kano, Ryouhei
2012ApJ...746..146R Altcode:
Coronal cavities are voids in coronal emission often observed above
high latitude filament channels. Sometimes, these cavities have areas of
bright X-ray emission in their centers. In this study, we use data from
the X-ray Telescope (XRT) on the Hinode satellite to examine the thermal
emission properties of a cavity observed during 2008 July that contains
bright X-ray emission in its center. Using ratios of XRT filters, we
find evidence for elevated temperatures in the cavity center. The area
of elevated temperature evolves from a ring-shaped structure at the
beginning of the observation, to an elongated structure two days later,
finally appearing as a compact round source four days after the initial
observation. We use a morphological model to fit the cavity emission,
and find that a uniform structure running through the cavity does not
fit the observations well. Instead, the observations are reproduced
by modeling several short cylindrical cavity "cores" with different
parameters on different days. These changing core parameters may be
due to some observed activity heating different parts of the cavity
core at different times. We find that core temperatures of 1.75 MK,
1.7 MK, and 2.0 MK (for July 19, July 21, and July 23, respectively)
in the model lead to structures that are consistent with the data,
and that line-of-sight effects serve to lower the effective temperature
derived from the filter ratio.

---------------------------------------------------------
Title: Ion-neutral Coupling in Solar Prominences
Authors: Gilbert, H. R.; DeVore, C. R.; Karpen, J. T.; Kucera, T. A.;
Antiochos, S. K.; Kawashima, R.
2011AGUFMSH13B1953G Altcode:
Coupling between ions and neutrals in magnetized plasmas is
fundamentally important to many aspects of heliophysics, including our
ionosphere, the solar chromosphere, the solar wind interaction with
planetary atmospheres, and the interface between the heliosphere and
the interstellar medium. Ion-neutral coupling also plays a major role
in the physics of solar prominences. By combining theory, modeling,
and observations we are working toward a better understanding of the
structure and dynamics of partially ionized prominence plasma. Two
key questions are addressed in the present work: 1) what physical
mechanism(s) sets the cross-field scale of prominence threads? 2)
Are ion-neutral interactions responsible for the vertical flows and
structure in prominences? We present initial results from a study
investigating what role ion-neutral interactions play in prominence
dynamics and structure. This research was supported by NASA.

---------------------------------------------------------
Title: Viewing The Entire Sun With STEREO And SDO
Authors: Thompson, William T.; Gurman, J. B.; Kucera, T. A.; Howard,
R. A.; Vourlidas, A.; Wuelser, J.; Pesnell, D.
2011SPD....42.1835T Altcode: 2011BAAS..43S.1835T
On 6 February 2011, the two Solar Terrestrial Relations Observatory
(STEREO) spacecraft were at 180 degrees separation. This allowed the
first-ever simultaneous view of the entire Sun. Combining the STEREO
data with corresponding images from the Solar Dynamics Observatory
(SDO) allows this full-Sun view to continue for the next eight years. We
show how the data from the three viewpoints are combined into a single
heliographic map. Processing of the STEREO beacon telemetry allows
these full-Sun views to be created in near-real-time, allowing tracking
of solar activity even on the far side of the Sun. This is a valuable
space-weather tool, not only for anticipating activity before it rotates
onto the Earth-view, but also for deep space missions in other parts of
the solar system. Scientific use of the data includes the ability to
continuously track the entire lifecycle of active regions, filaments,
coronal holes, and other solar features. There is also a significant
public outreach component to this activity. The STEREO Science Center
produces products from the three viewpoints used in iPhone/iPad and
Android applications, as well as time sequences for spherical projection
systems used in museums, such as Science-on-a-Sphere and Magic Planet.

---------------------------------------------------------
Title: Temperature Structure of a Coronal Cavity
Authors: Kucera, Therese A.; Gibson, S. E.; Schmit, D. J.
2011SPD....42.1833K Altcode: 2011BAAS..43S.1833K
We analyze the temperature structure of a coronal cavity observed in
Aug. 2007. Coronal cavities are long, low-density structures located
over filament neutral lines and are often seen as dark elliptical
features at the solar limb in white light, EUV and X-rays. When
these structures erupt they form the cavity portions of CMEs. It is
important to establish the temperature structure of cavities in order
to understand the thermodynamics of cavities in relation to their
three-dimensional magnetic structure. To analyze the temperature
we compare temperature ratios of a series of iron lines observed by
the Hinode/EUV Imaging Spectrometer (EIS). We also use those lines
to constrain a forward model of the emission from the cavity and
streamer. The model assumes a coronal streamer with a tunnel-like
cavity with elliptical cross-section and a Gaussian variation of height
along the tunnel length. Temperature and density can be varied as
a function of altitude both in the cavity and streamer. The general
cavity morphology and the cavity and streamer density have already
been modeled using data from STEREO's SECCHI/EUVI and Hinode/EIS
(Gibson et al 2010 and Schmit &amp; Gibson 2011).

---------------------------------------------------------
Title: Comparing Spatial Distributions of Solar Prominence Mass
Derived from Coronal Absorption
Authors: Gilbert, Holly; Kilper, Gary; Alexander, David; Kucera,
Therese
2011ApJ...727...25G Altcode:
In a previous study, Gilbert et al. derived the column density and total
mass of solar prominences using a new technique, which measures how much
coronal radiation in the Fe XII (195 Å) spectral band is absorbed by
prominence material, while considering the effects of both foreground
and background radiation. In the present work, we apply this method
to a sample of prominence observations in three different wavelength
regimes: one in which only H0 is ionized (504 Å &lt; λ
&lt; 911 Å), a second where both H0 and He0 are
ionized (228 Å &lt; λ &lt; 504 Å), and finally at wavelengths where
H0, He0, and He+ are all ionized (λ
&lt; 228 Å). This approach, first suggested by Kucera et al., permits
the separation of the contributions of neutral hydrogen and helium to
the total column density in prominences. Additionally, an enhancement
of the technique allowed the calculation of the two-dimensional (2D)
spatial distribution of the column density from the continuum absorption
in each extreme-ultraviolet observation. We find the total prominence
mass is consistently lower in the 625 Å observations compared to lines
in the other wavelength regimes. There is a significant difference in
total mass between the 625 Å and 195 Å lines, indicating the much
higher opacity at 625 Å is causing a saturation of the continuum
absorption and thus, a potentially large underestimation of mass.

---------------------------------------------------------
Title: Three-dimensional morphology of a coronal prominence cavity
Authors: Gibson, S. E.; Kucera, T. A.; Rastawicki, D.; Dove, J.; de
Toma, G.; Hao, J.; Hill, S. M.; Hudson, H. S.; Marque, C.; McIntosh,
P. S.; Rachmeler, L.; Reeves, K. K.; Schmieder, B.; Schmit, D. J.;
Sterling, A.; Tripathi, D.; Williams, D. R.; Zhang, M.
2010AGUFMSH51A1667G Altcode:
We present a three-dimensional density model of coronal prominence
cavities, and a morphological fit that has been tightly constrained
by a uniquely well-observed cavity. Observations were obtained as part
of an International Heliophysical Year campaign by instruments from a
variety of space- and ground-based observatories, spanning wavelengths
from radio to soft-X-ray to integrated white light. From these data
it is clear that the prominence cavity is the limb manifestation of
a longitudinally-extended polar-crown filament channel, and that
the cavity is a region of low density relative to the surrounding
corona. As a first step towards quantifying density and temperature
from campaign spectroscopic data, we establish the three-dimensional
morphology of the cavity. This is critical for taking line-of-sight
projection effects into account, since cavities are not localized in the
plane of the sky and the corona is optically thin. We have augmented
a global coronal streamer model to include a tunnel-like cavity with
elliptical cross-section and a Gaussian variation of height along
the tunnel length. We have developed a semi-automated routine that
fits ellipses to cross-sections of the cavity as it rotates past the
solar limb, and have applied it to Extreme Ultraviolet Imager (EUVI)
observations from the two Solar Terrestrial Relations Observatory
(STEREO) spacecraft. This defines the morphological parameters of our
model, from which we reproduce forward-modeled cavity observables. We
find that cavity morphology and orientation, in combination with the
viewpoints of the observing spacecraft, explains the observed variation
in cavity visibility for the east vs. west limbs.

---------------------------------------------------------
Title: Three-dimensional Morphology of a Coronal Prominence Cavity
Authors: Gibson, S. E.; Kucera, T. A.; Rastawicki, D.; Dove, J.; de
Toma, G.; Hao, J.; Hill, S.; Hudson, H. S.; Marqué, C.; McIntosh,
P. S.; Rachmeler, L.; Reeves, K. K.; Schmieder, B.; Schmit, D. J.;
Seaton, D. B.; Sterling, A. C.; Tripathi, D.; Williams, D. R.;
Zhang, M.
2010ApJ...724.1133G Altcode:
We present a three-dimensional density model of coronal prominence
cavities, and a morphological fit that has been tightly constrained
by a uniquely well-observed cavity. Observations were obtained as part
of an International Heliophysical Year campaign by instruments from a
variety of space- and ground-based observatories, spanning wavelengths
from radio to soft X-ray to integrated white light. From these data
it is clear that the prominence cavity is the limb manifestation of
a longitudinally extended polar-crown filament channel, and that the
cavity is a region of low density relative to the surrounding corona. As
a first step toward quantifying density and temperature from campaign
spectroscopic data, we establish the three-dimensional morphology
of the cavity. This is critical for taking line-of-sight projection
effects into account, since cavities are not localized in the plane of
the sky and the corona is optically thin. We have augmented a global
coronal streamer model to include a tunnel-like cavity with elliptical
cross-section and a Gaussian variation of height along the tunnel
length. We have developed a semi-automated routine that fits ellipses
to cross-sections of the cavity as it rotates past the solar limb, and
have applied it to Extreme Ultraviolet Imager observations from the
two Solar Terrestrial Relations Observatory spacecraft. This defines
the morphological parameters of our model, from which we reproduce
forward-modeled cavity observables. We find that cavity morphology
and orientation, in combination with the viewpoints of the observing
spacecraft, explain the observed variation in cavity visibility for
the east versus west limbs.

---------------------------------------------------------
Title: Space Based Observations of Coronal Cavities in Conjunction
with the Total Solar Eclipse of July 2010
Authors: Kucera, T. A.; Berger, T. E.; Boerner, P.; Dietzel, M.;
Druckmuller, M.; Gibson, S. E.; Habbal, S. R.; Morgan, H.; Reeves,
K. K.; Schmit, D. J.; Seaton, D. B.
2010AGUFMSH51A1666K Altcode:
In conjunction with the total solar eclipse on July 11, 2010 we
coordinated a campaign between ground and space based observations. Our
specific goal was to augment the ground based measurement of coronal
prominence cavity temperatures made using iron lines in the IR (Habbal
et al. 2010 ApJ 719 1362) with measurements performed by space based
instruments. Included in the campaign were Hinode/EIS, XRT and SOT,
PROBA2/SWAP, SDO/AIA, SOHO/CDS and STEREO/SECCHI/EUVI, in addition
to the ground based IR measurements. We plan to use a combination of
line ratio and forward modeling techniques to investigate the density
and temperature structure of the cavities at that time.

---------------------------------------------------------
Title: Morphology of a hot coronal cavity core as observed by
Hinode/XRT
Authors: Reeves, K. K.; Gibson, S. E.; Kucera, T. A.; Hudson, H. S.
2010AGUFMSH51A1669R Altcode:
We follow a coronal cavity that was observed by Hinode/XRT during the
summer of 2008. This cavity has a persistent area of relatively bright
X-ray emission in its center. We use multifilter data from XRT to
study the thermal emission from this cavity, and find that the bright
center is hotter than the surrounding cavity plasma with temperatures
of about 1.6 MK. We follow the morphology of this hot feature as the
cavity structure rotates over the limb during the several days between
July 19 - 23 2008. We find that the hot structure at first looks fairly
circular, then appears to expand and elongate, and then shrinks again
to a compact circular shape. We interpret this apparent change in shape
as being due to the morphology of the filament channel associated with
the cavity, and the change in viewing angle as the structure rotates
over the limb of the Sun.

---------------------------------------------------------
Title: Density Diagnostics in Cavities: Incorporating and Bypassing
Projection Effects
Authors: Schmit, D. J.; Gibson, S. E.; Kucera, T. A.
2010AGUFMSH51A1668S Altcode:
The highly ionized corona emits strongly in EUV atomic emission
lines. Comparison of relative emission in various lines provides the
temperature and density of the coronal plasma. We use an Fe XII line
ratio to probe the density of a prominence cavity at heights generally
only accessible to spectroscopic instruments. We take a novel approach
in this diagnostic by fully accounting for the 3D structure of the
corona so as to compensate for the projection effects in optical thin
emission. The density inside the cavity and the streamer are constrained
using a forward model where in emission is synthesized with CHIANTI. The
synthetic emission and scattering is compared to Hinode/EIS and MLSO
MKIV data. A least squares minimization is conducted using a genetic
algorithm. In particular, this work addresses the degree to which we
can answer the question, “Is there a density jump at all heights?”.

---------------------------------------------------------
Title: Creating synthetic coronal observational data from MHD models:
the forward technique
Authors: Rachmeler, L. A.; Gibson, S. E.; Dove, J.; Kucera, T. A.
2010AGUFMSH31A1786R Altcode:
We present a generalized forward code for creating simulated
coronal observables off the limb from numerical and analytical MHD
models. This generalized forward model is capable of creating emission
maps in various wavelengths for instruments such as Hinode/XRT,
STEREO/SECCHI/EUVI, and coronagraphs, as well as spectropolarimetric
images and line profiles. The inputs to our code can be analytic MHD or
morphological models (of which four come with the code) or 2.5D and 3D
numerical datacubes. We present some examples of the observable data
created with our code as well as its functional capabilities. This
code is currently available for beta-testing (contact authors), with
the ultimate goal of release as a SolarSoft package.

---------------------------------------------------------
Title: Automated Detection of Oscillating Regions in the Solar
Atmosphere
Authors: Ireland, J.; Marsh, M. S.; Kucera, T. A.; Young, C. A.
2010SoPh..264..403I Altcode: 2010SoPh..tmp..127I; 2010SoPh..tmp..115I; 2010arXiv1007.0975I
Recently observed oscillations in the solar atmosphere have been
interpreted and modeled as magnetohydrodynamic wave modes. This has
allowed for the estimation of parameters that are otherwise hard
to derive, such as the coronal magnetic-field strength. This work
crucially relies on the initial detection of the oscillations, which
is commonly done manually. The volume of Solar Dynamics Observatory
(SDO) data will make manual detection inefficient for detecting all
of the oscillating regions. An algorithm is presented that automates
the detection of areas of the solar atmosphere that support spatially
extended oscillations. The algorithm identifies areas in the solar
atmosphere whose oscillation content is described by a single, dominant
oscillation within a user-defined frequency range. The method is based
on Bayesian spectral analysis of time series and image filtering. A
Bayesian approach sidesteps the need for an a-priori noise estimate
to calculate rejection criteria for the observed signal, and it also
provides estimates of oscillation frequency, amplitude, and noise,
and the error in all of these quantities, in a self-consistent
way. The algorithm also introduces the notion of quality measures to
those regions for which a positive detection is claimed, allowing for
simple post-detection discrimination by the user. The algorithm is
demonstrated on two Transition Region and Coronal Explorer (TRACE)
datasets, and comments regarding its suitability for oscillation
detection in SDO are made.

---------------------------------------------------------
Title: Thermal Properties of Coronal Cavities as Observed by the
X-Ray Telescope on Hinode
Authors: Reeves, Kathy; Gibson, S. E.; Kucera, T. A.; Hudson, H. S.;
Tripathi, D.
2010AAS...21640511R Altcode: 2010BAAS...41..891R
Coronal cavities are voids in coronal emission often observed above
high latitude filament channels. Sometimes, these cavities have
areas of bright X-ray emission in their centers (i.e. Hudson et al
1999). In this study, we use data from the X-ray Telescope (XRT)
on Hinode to examine the thermal emission properties of two kinds of
coronal cavities, those with and without enhanced emission at their
centers. For cavities with bright X-ray emission in their centers,
we find evidence for elevated temperatures in the cavity center. We
find no obvious correlation between the presence of bright cavity
cores and filament presence or eruption. This work is part of the
effort of the International Space Science Institute International Team
on Prominence Cavities

---------------------------------------------------------
Title: Geometric Model of a Coronal Cavity
Authors: Kucera, Therese A.; Gibson, S. E.; Rastawicki, D.; Dove, J.;
de Toma, G.; Hao, J.; Hudson, H. S.; Marque, C.; McIntosh, P. S.;
Reeves, K. K.; Schmidt, D. J.; Sterling, A. C.; Tripathi, D. K.;
Williams, D. R.; Zhang, M.
2010AAS...21640510K Altcode: 2010BAAS...41..890K
We observed a coronal cavity from August 8-18 2007 during a
multi-instrument observing campaign organized under the auspices of
the International Heliophysical Year (IHY). Here we present initial
efforts to model the cavity with a geometrical streamer-cavity
model. The model is based the white-light streamer model of Gibson et
al. (2003), which has been enhanced by the addition of a cavity and
the capability to model EUV and X-ray emission. The cavity is modeled
with an elliptical cross-section and Gaussian fall-off in length and
width inside the streamer. Density and temperature can be varied in the
streamer and cavity and constrained via comparison with data. Although
this model is purely morphological, it allows for three-dimensional,
multi-temperature analysis and characterization of the data, which
can then provide constraints for future physical modeling. Initial
comparisons to STEREO/EUVI images of the cavity and streamer show that
the model can provide a good fit to the data. This work is part of the
effort of the International Space Science Institute International Team
on Prominence Cavities.

---------------------------------------------------------
Title: Physics of Solar Prominences: I—Spectral Diagnostics and
Non-LTE Modelling
Authors: Labrosse, N.; Heinzel, P.; Vial, J. -C.; Kucera, T.; Parenti,
S.; Gunár, S.; Schmieder, B.; Kilper, G.
2010SSRv..151..243L Altcode: 2010SSRv..tmp...34L; 2010arXiv1001.1620L
This review paper outlines background information and covers recent
advances made via the analysis of spectra and images of prominence
plasma and the increased sophistication of non-LTE ( i.e. when there is
a departure from Local Thermodynamic Equilibrium) radiative transfer
models. We first describe the spectral inversion techniques that have
been used to infer the plasma parameters important for the general
properties of the prominence plasma in both its cool core and the
hotter prominence-corona transition region. We also review studies
devoted to the observation of bulk motions of the prominence plasma and
to the determination of prominence mass. However, a simple inversion
of spectroscopic data usually fails when the lines become optically
thick at certain wavelengths. Therefore, complex non-LTE models become
necessary. We thus present the basics of non-LTE radiative transfer
theory and the associated multi-level radiative transfer problems. The
main results of one- and two-dimensional models of the prominences and
their fine-structures are presented. We then discuss the energy balance
in various prominence models. Finally, we outline the outstanding
observational and theoretical questions, and the directions for future
progress in our understanding of solar prominences.

---------------------------------------------------------
Title: Preface
Authors: Christian, Eric R.; Kaiser, Michael L.; Kucera, Therese A.;
St. Cyr, O. C.; van Driel-Gesztelyi, Lidia; Mandrini, Cristina H.
2009SoPh..256....1C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Using Prominence Mass Inferences in Different Coronal Lines
to Obtain the He/H Abundance
Authors: Gilbert, Holly; Kilper, G.; Alexander, D.; Kucera, T.
2009SPD....40.1011G Altcode:
In a previous study we developed a new technique for deriving prominence
mass by observing how much coronal radiation in the Fe XII (λ195)
spectral line is absorbed by prominence material. In the present work
we apply this method, which allows us to consider the effects of both
foreground and background radiation in our calculations, to a sample
of prominences absorbing in a coronal line that ionizes both H and He
(λ &lt; 504 Å), and a line that ionizes only H (504 Å &lt; λ &lt;
911 Å). This approach, first suggested by Kucera et al. (1998),
permits the determination of the abundance ratio of neutral helium
and hydrogen in the prominence. This ratio should depend on how the
prominence is formed, on its current thermodynamic state, and on its
dynamical evolution. Thus, it may provide useful insights into the
formation and evolution of prominences.

---------------------------------------------------------
Title: Automated Detection of Oscillating Areas in the Solar
Atmosphere
Authors: Ireland, Jack; Marsh, M. S.; Kucera, T. A.; Young, A.
2009SPD....40.1517I Altcode:
Recently observed oscillations in the solar atmosphere have been
interpreted and modeled as magnetohydrodynamic wave modes. This
has allowed the estimation of parameters that are otherwise hard
to derive, such as the coronal magnetic field strength. This work
crucially relies on the initial detection of the waves, which is
commonly done manually. The volume of Solar Dynamics Observatory
(SDO) data will make manual detection inefficient for detecting all
the oscillating regions. An algorithm is presented which automates the
detection of areas of the solar surface that support spatially extended
oscillations. The method is based on Bayesian spectral analysis of
time series and image filtering. A Bayesian approach sidesteps the
need for an a priori noise estimate to calculate rejection criteria
for the observed signal, and also provides estimates of oscillation
frequency, amplitude and noise, and the error in all these quantities,
in a self-consistent way. The algorithm also introduces the notion
of quality measures to those regions for which a positive detection
is claimed, allowing simple post-detection discrimination by the
user. The algorithm is demonstrated on Transition Region and Coronal
Explorer (TRACE) datasets, and comments regarding its suitability for
oscillation detection in SDO are made.

---------------------------------------------------------
Title: Automated detection of oscillations in extreme ultraviolet
imaging data
Authors: Ireland, J.; Marsh, M. S.; Kucera, T. A.; Young, C. A.
2008AGUFMSH13A1507I Altcode:
The corona is now known to support many different types of
oscillation. Initial detection of these oscillations currently
relied on manual labor. With the advent of much higher cadence EUV
(extreme ultraviolet) data at better spatial resolution, sifting
through the data manually to look for oscillatory material becomes
an onerous task. Further, different observers tend to see different
behavior in the data. To overcome these problems, we introduce a
Bayesian probability-based automated method to detect areas in EUV
images that support oscillations. The method is fast and can handle
time series data with even or uneven cadences. Interestingly, the
Bayesian approach allows us to generate a probability that a given
frequency is present without the need for an estimate of the noise in
the data. We also generate simple and intuitive "quality measures" for
each detected oscillation. This will allow users to select the "best"
examples in a given dataset automatically. The method is demonstrated
on existing datasets (EIT, TRACE, STEREO). Its application to Solar
Dynamics Observatory data is also discussed. We also discuss some of
the problems in detecting oscillations in the presence of a significant
background trend which can pollute the frequency spectrum.

---------------------------------------------------------
Title: Using Prominence Mass Inferences in Different Coronal Lines
to Obtain the He/H Abundance
Authors: Gilbert, H.; Kilper, G.; Alexander, D.; Kucera, T.
2008AGUFMSH13A1509G Altcode:
In a previous study we developed a new technique for deriving prominence
mass by observing how much coronal radiation in the Fe XII (19.5 nm)
spectral line is absorbed by prominence material. In the present work
we apply this method, which allows us to consider the effects of both
foreground and background radiation in our calculations, to a sample
of prominences absorbing in a coronal line that ionizes both H and He
(lambda &lt; 50.4 nm), and a line that ionizes only H (50.4 nm &lt;
lambda &lt; 91.1 nm). This approach, first suggested by Kucera et
al. (1998), permits the determination of the abundance ratio of neutral
helium and hydrogen in the prominence. This ratio should depend on
how the prominence is formed, on its current thermodynamic state,
and on its dynamical evolution. Thus, it may provide useful insights
into the formation and evolution of prominences.

---------------------------------------------------------
Title: Bayesian Analysis of Solar Oscillations
Authors: Marsh, M. S.; Ireland, J.; Kucera, T.
2008ApJ...681..672M Altcode: 2008arXiv0804.1447M
A Bayesian probability-based approach is applied to the problem
of detecting and parameterizing oscillations in the upper solar
atmosphere for the first time. Due to its statistical origin, this
method provides a mechanism for determining the number of oscillations
present, gives precise estimates of the oscillation parameters
with a self-consistent statistical error analysis, and allows the
oscillatory model signals to be reconstructed within these errors. A
highly desirable feature of the Bayesian approach is the ability to
resolve oscillations with extremely small frequency separations. The
code is applied to SOHO CDS O V λ629 observations and resolves four
distinct P4,P5,P6, and P7
p-modes within the same sunspot transition region. This suggests that
a spectrum of photospheric p-modes is able to propagate into the
upper atmosphere of the Sun and Sun-like stars, and places precise
observational constraints on models of umbral eigenmodes.

---------------------------------------------------------
Title: A Bayesian Analysis of MHD Waves in the Lower Atmosphere
Authors: Marsh, M. S.; Ireland, J.; Kucera, T.
2008IAUS..247...48M Altcode: 2007IAUS..247...48M
Magneto-hydrodynamic wave modes propagating from the solar
photosphere into the corona have the potential to be exploited as an
observational tool in an analogous way to the use of acoustic waves
in helio/terrestrial seismology. In regions of strong magnetic field
photospheric p-modes are thought to undergo mode conversion to slow
magneto-acoustic waves, and that these slow magnetoacoustic p-modes
may be waveguided from the photosphere into the solar corona along
the magnetic field. A Bayesian analysis technique is applied to
observations which suggests four distinct p-modes may be resolved in
the transition region.

---------------------------------------------------------
Title: Analysis of EUV, UV, and H-alpha Emission from Two Very
Different Prominences
Authors: Kucera, T. A.; Landi, E.
2008AGUSMSP43B..03K Altcode:
Analysis of EUV, UV, and H-alpha Emission from Two Very Different
Prominences T. Kucera (NASA/GSFC), E. Landi (Artep Inc.) We analyze the
properties of a pair of prominences observed the UV and EUV in April
2004. One was a generally quiet prominence which exhibited a period of
activation. Another was a large "coronal cloud" type prominence. Both
were observed in by SOHO/SUMER, TRACE, and in Hα by BBSO and MLSO. The
quiet promince was also observed by the SOHO/CDS instrument. TRACE
and Hα data provide 2D images on with time cadences on the order of 1
minute. The SUMER data was taken from a single slit location with a 90
second cadence and included a number of lines spanning the temperature
range 80,000 to 1.6 million K. This observing program was designed
to allow us to study prominence dynamics. CDS raster data was taken
with a slower cadence, in lines formed at temperatures from 20,000
- 1 million K. We combine these different data sets to analyze the
thermal properties, including differential emission measures (DEMs),
of these very different prominences, and compare the results to those
of prominences previously analyzed by ourselves and others. This
work was partly funded through a NASA Heliophysics GI RTOP and NASA
award NNH04AA12

---------------------------------------------------------
Title: Using Prominence Mass Inferences in Different Coronal Lines
to Obtain the He/H Abundance
Authors: Gilbert, H. R.; Kilper, G.; Kucera, T.; Alexander, D.
2008AGUSMSP43B..05G Altcode:
In a previous study we developed a new technique for deriving prominence
mass by observing how much coronal radiation in the Fe XII (λ195)
spectral line is absorbed by prominence material. In the present work
we apply this method, which allows us to consider the effects of both
foreground and background radiation in our calculations, to a sample
of prominences absorbing in a coronal line that ionizes both H and He
(λ &lt; 504 Å), and a line that ionizes only H (504 Å &lt; λ &lt;
911 Å). This approach, first suggested by Kucera et al. (1998),
permits the determination of the abundance ratio of neutral helium
and hydrogen in the prominence. This ratio should depend on how the
prominence is formed, on its current thermodynamic state, and on its
dynamical evolution. Thus, it may provide useful insights into the
formation and evolution of prominences.

---------------------------------------------------------
Title: Overview of STEREO/EUVI and SOHO/EIT data during the WHI
Campaign
Authors: Kucera, T. A.
2008AGUSMSH51A..05K Altcode:
The poster will present an overview of the data from the March-April,
2008 Whole Heliospheric Interval Campaign. These instruments will show
the targets during the campaign from three points of view at a range
of temperatures. Targets are expected to include coronal cavities,
coronal holes, active regions and prominences.

---------------------------------------------------------
Title: Multi-wavelength Comparison of Prominence Cavities
Authors: Schmit, D. J.; Gibson, S.; de Toma, G.; Reeves, K.; Tripathi,
D.; Kucera, T.; Marque, C.; Tomczyk, S.
2008AGUSMSP43B..04S Altcode:
Recent observational campaigns have brought together a wealth of
data specifically designed to explore the physical properties and
dynamics of prominence cavities. In particular, STEREO and Hinode
data have provided new perspectives on these structures. In order to
effectively analyze the data in a cohesive manner, we produce overlays
of several distinct and complimentary datasets including SOHO UVCS,
CDS, and EIT, Hinode SOT and EIS, STEREO SECCHI, TRACE, and Nancay
Radioheliograph data as well as new observations of coronal magnetic
fields in cavities from the Coronal Multichannel Polarimeter. We are
thus able to investigate how sensitive morphology is to the wavelength
observed which details the nature of the plasma in the cavity.

---------------------------------------------------------
Title: The Solar Terrestrial Relations Observatory (STEREO) Education
and Outreach (E/PO) Program
Authors: Peticolas, L. M.; Craig, N.; Kucera, T.; Michels, D. J.;
Gerulskis, J.; MacDowall, R. J.; Beisser, K.; Chrissotimos, C.;
Luhmann, J. G.; Galvin, A. B.; Ratta, L.; Drobnes, E.; Méndez, B. J.;
Hill, S.; Marren, K.; Howard, R.
2008SSRv..136..627P Altcode: 2007SSRv..tmp..211P
The STEREO mission’s Education and Outreach (E/PO) program began early
enough its team benefited from many lessons learned as NASA’s E/PO
profession matured. Originally made up of discrete programs, by launch
the STEREO E/PO program had developed into a quality suite containing
all the program elements now considered standard: education workshops,
teacher/student guides, national and international collaboration,
etc. The benefit of bringing so many unique programs together is the
resulting diverse portfolio, with scientists, E/PO professionals, and
their education partners all of whom can focus on excellent smaller
programs. The drawback is a less cohesive program nearly impossible
to evaluate in its entirety with the given funding. When individual
components were evaluated, we found our programs mostly made positive
impact. In this paper, we elaborate on the programs, hoping that others
will effectively use or improve upon them. When possible, we indicate
the programs’ effects on their target audiences.

---------------------------------------------------------
Title: The STEREO Mission: An Introduction
Authors: Kaiser, M. L.; Kucera, T. A.; Davila, J. M.; St. Cyr, O. C.;
Guhathakurta, M.; Christian, E.
2008SSRv..136....5K Altcode: 2007SSRv..tmp..198K
The twin STEREO spacecraft were launched on October 26, 2006, at 00:52
UT from Kennedy Space Center aboard a Delta 7925 launch vehicle. After
a series of highly eccentric Earth orbits with apogees beyond the moon,
each spacecraft used close flybys of the moon to escape into orbits
about the Sun near 1 AU. Once in heliospheric orbit, one spacecraft
trails Earth while the other leads. As viewed from the Sun, the two
spacecraft separate at approximately 44 to 45 degrees per year. The
purposes of the STEREO Mission are to understand the causes and
mechanisms of coronal mass ejection (CME) initiation and to follow the
propagation of CMEs through the inner heliosphere to Earth. Researchers
will use STEREO measurements to study the mechanisms and sites of
energetic particle acceleration and to develop three-dimensional
(3-D) time-dependent models of the magnetic topology, temperature,
density and velocity of the solar wind between the Sun and Earth. To
accomplish these goals, each STEREO spacecraft is equipped with an
almost identical set of optical, radio and in situ particles and
fields instruments provided by U.S. and European investigators. The
SECCHI suite of instruments includes two white light coronagraphs,
an extreme ultraviolet imager and two heliospheric white light imagers
which track CMEs out to 1 AU. The IMPACT suite of instruments measures
in situ solar wind electrons, energetic electrons, protons and heavier
ions. IMPACT also includes a magnetometer to measure the in situ
magnetic field strength and direction. The PLASTIC instrument measures
the composition of heavy ions in the ambient plasma as well as protons
and alpha particles. The S/WAVES instrument uses radio waves to track
the location of CME-driven shocks and the 3-D topology of open field
lines along which flow particles produced by solar flares. Each of the
four instrument packages produce a small real-time stream of selected
data for purposes of predicting space weather events at Earth. NOAA
forecasters at the Space Environment Center and others will use these
data in their space weather forecasting and their resultant products
will be widely used throughout the world. In addition to the four
instrument teams, there is substantial participation by modeling and
theory oriented teams. All STEREO data are freely available through
individual Web sites at the four Principal Investigator institutions
as well as at the STEREO Science Center located at NASA Goddard Space
Flight Center.

---------------------------------------------------------
Title: An Observation of Low-Level Heating in an Erupting Prominence
Authors: Kucera, T. A.; Landi, E.
2008ApJ...673..611K Altcode:
Here we present multiwavelength observations of low-level heating in
an erupting prominence observed in the UV and EUV over a wide range of
temperatures and wavelengths by the Solar and Heliospheric Observatory
(SOHO) Solar Ultraviolet Measurements of Emitted Radiation (SUMER)
instrument and the Transition Region and Coronal Explorer (TRACE),
and also in Hα by the Yunnan Astronomical Observatory. The eruption
occurred on 2004 April 30. The heating is relatively mild, leading
only to the ionization of hydrogen and helium. It is also localized,
occurring along the bottom edge of the erupting prominence and in
a kinklike feature in the prominence. The heating is revealed as
a decrease in the Lyman absorption relative to other parts of the
prominence. This decrease results in an apparent increase in emission in
all the lines observed by SUMER, especially those formed at temperatures
of ~105 K. However, this is due to the disappearance of
cooler absorbing material in the prominence rather than to an increase
in these higher temperature species. These observations suggest that
there may be low-level heating occurring in other erupting prominences
that do not show heating to coronal temperatures. They also indicate
that the prominence-corona transition region is best modeled with two
or more structures along the line of sight. We discuss the results in
terms of models of heating in erupting prominences and observations
of Lyman absorption in prominences.

---------------------------------------------------------
Title: The STEREO Science Center
Authors: Kaiser, M. L.; Thompson, W. T.; Kucera, T. A.
2007AGUSMSH41A..01K Altcode:
The STEREO Science Center (SSC), at the NASA Goddard Space Flight
Center, is the "one-stop shopping" location for STEREO data, observation
plans, analysis software, and links to other mission resources. Along
with the other data products, a special "Space Weather Beacon" telemetry
stream, relayed through an array of antenna partners coordinated by
NOAA, provides near-real-time images, and will soon also provide
near-real- time radio and in-situ data. Through interaction with
the Solar Software library, the SSC also acts as a focal point for
software coordination. The SSC is closely integrated with the Virtual
Solar Observatory, making data easily accessible to users. Details on
access to the SSC will be given and examples of the various types of
data available at the SSC will be shown.

---------------------------------------------------------
Title: Observation of Low Level Heating in an Erupting Prominence
Authors: Kucera, Therese A.; Landi, E.
2007AAS...210.2905K Altcode: 2007BAAS...39..138K
We present multi-wavelength observations of low level heating in an
erupting prominence observed in the UV and EUV over a wide range of
temperatures and wavelengths by SOHO's SUMER instrument, TRACE and
also in H-alpha by the Yunnan Astronomical Observatory. The eruption
occurred on 2004 April 30. The heating is relatively mild, leading only
to the ionization of neutral hydrogen and probably helium. It is also
localized, occurring along the bottom edge of the erupting prominence
and in a kink-like feature in the prominence. The heating is revealed
as a decrease in the Lyman absorption. This decrease results in an
apparent increase in emission in all the lines observed by SUMER,
especially those formed at temperatures ∼10^5 K. However, this is
due to the disappearance of cooler absorbing material in the prominence
rather than an increase in these higher temperature species. This
project was funded by the NASA SEC GI RTOP 955518.02.01.01.15 and NASA
awards NNG06EA14I and NNH06CD24C.

---------------------------------------------------------
Title: Ultraviolet Observations of Prominence Activation and Cool
Loop Dynamics
Authors: Kucera, T. A.; Landi, E.
2006ApJ...645.1525K Altcode:
In this paper we investigate the thermal and dynamic properties of
dynamic structures in and around a prominence channel observed on
the limb on 2003 April 17. Observations were taken with the Solar and
Heliospheric Observatory's Solar Ultraviolet Measurements of Emitted
Radiation (SOHO SUMER) in lines formed at temperatures from 80,000 K
to 1.6 MK. The instrument was pointed to a single location and took
a series of 90 s exposures. Two-dimensional context was provided by
the Transition Region and Coronal Explorer (TRACE) in the UV and EUV
and the Kanzelhöhe Solar Observatory in Hα. Two dynamic features
were studied in depth: an activated prominence and repeated motions
in a loop near the prominence. We calculated three-dimensional
geometries and trajectories, differential emission measures, and
limits on the mass, pressure, average density, and kinetic and thermal
energies. These observations provide important tests for models of
dynamics in prominences and cool (~105 K) loops, which
will ultimately lead to a better understanding of the mechanism(s)
leading to energy and mass flow in these solar features.

---------------------------------------------------------
Title: Thermal Analysis of Post-eruption Loops From 80,000 to 1.6
Million K
Authors: Kucera, Therese A.; Landi, E.
2006SPD....37.0802K Altcode: 2006BAAS...38..230K
We analyze the thermal properties of a set of post eruptive loops
which appeared after a prominence eruption on April 30, 2004. The event
was observed by TRACE and SOHO/SUMER. The SUMER data was taken from a
single slit location with a 90 second cadence and included a number
of lines spanning the temperature range 80,000 to 1.6 million K. We
perform a differential emission measure analysis of the loops in order
to study their thermal evolution.This work was partly funded through
a NASA SEC GI RTOP andNASA grants NNH04AA12I, W10,232 and NNG04ED07P

---------------------------------------------------------
Title: Thermal and Kinetic Properties of Motions in a Prominence
Activation and Nearby Loop
Authors: Kucera, T. A.; Landi, E. E.
2005AGUSMSP21B..01K Altcode:
We perform a quantitative analysis of the thermal properties of
a prominence activation and motions in a nearby loop. In order to
make measurements of the quickly moving features seen in loops and
prominences in the UV we use the SOHO/SUMER spectrograph to take a
time series of exposures from a single pointing position, providing
a measurement of spectral line properties as a function of time and
position along the slit. The lines observed cover a broad range
of temperatures from 80,000 - 1.6 million K. These measurements
are combined with TRACE movies in transition region and coronal
temperature bands to obtain more complete information concerning
prominence structure and motions. The resulting observations allow
us to analyze the thermal and kinetic energy of the moving sources as
functions of time. The loop and prominence are most apparent in lines
formed at temperatures below 250,000 K. We find that in most cases
the temperature distribution of plasma in a moving feature changes
relatively little over time periods of about 20 minutes.

---------------------------------------------------------
Title: STEREO's Interactions With the Virtual Solar and Heliospheric
Observatories
Authors: Thompson, W. T.; Kaiser, M. L.; Kucera, T. A.; Davila, J. M.;
Hourcle, J.; Schroeder, P.
2005AGUSMSH43B..06T Altcode:
STEREO (Solar TErrestrial RElations Observatory) will observe
the Sun and solar storms with two nearly identical spacecraft in
heliocentric orbits, one ahead of Earth, the other trailing behind. This
multi-spacecraft approach provides both stereoscopic views of the solar
corona with the imaging telescopes, and multipoint observations of the
heliosphere with the in-situ and radio experiments. Combined analysis
with other viewpoints will be essential to STEREO science. Data archived
at the NASA/GSFC STEREO Science Center will be completely integrated
into the Virtual Solar Observatory (VSO), with shared resources and
personnel. The in-situ and radio data will also be directly available
through the Virtual Heliospheric Observatory (VHO). This dual system
will ensure the maximum visibility of STEREO data to both the imaging
and particle/field communities. Linkages between the VSO and VHO will
allow all the STEREO data to be available through either system. Event
lists will enhance the data set, and ease the data selection process.

---------------------------------------------------------
Title: STEREO Science Center
Authors: Kucera, T. A.; Thompson, W. T.; Kaiser, M. L.
2004AGUFMSH21B0411K Altcode:
STEREO (Solar TErrestrial RElations Observatory) will employ two nearly
identical spacecraft in heliocentric orbits, one ahead of Earth,
the other trailing behind, to provide the first-ever stereoscopic
measurements to study the Sun and the nature of its coronal mass
ejections. Scheduled for launch in early 2006, STEREO will complement
the Living With a Star program by providing a unique new viewpoint. The
STEREO Science Center at the NASA Goddard Space Flight Center will be
the “one-stop shopping” location for STEREO data, observation plans,
analysis software, and links to other mission resources. Along with
the other data products, a special “Space Weather Beacon” telemetry
stream, relayed through an array of antenna partners coordinated by
NOAA, will provide near-real-time images, radio, and in-situ data.

---------------------------------------------------------
Title: The STEREO Science Center
Authors: Thompson, W. T.; Kaiser, M.; Kucera, T.
2004AAS...204.7206T Altcode: 2004BAAS...36..799T
STEREO (Solar TErrestrial RElations Observatory) will employ two nearly
identical spacecraft in heliocentric orbits, one ahead of Earth,
the other trailing behind, to provide the first-ever stereoscopic
measurements to study the Sun and the nature of its coronal mass
ejections. Scheduled for launch in early 2006, STEREO will provide a
unique new viewpoint of the heliosphere. The STEREO Science Center at
the NASA Goddard Space Flight Center will be the "one-stop shopping"
location for STEREO data, observation plans, analysis software, and
links to other mission resources. Along with the other data products,
a special "Space Weather Beacon" telemetry stream, relayed through
an array of antenna partners coordinated by NOAA, will provide
near-real-time images, radio, and in-situ data.

---------------------------------------------------------
Title: Challenges in modeling the Sun-Earth System
Authors: Spann, J.; Wu, S.; Adrian, M.; Suess, S.; Giles, B.;
Gosling, J.; Heelis, R.; Zanetti, L.; Kozyra, J.; Kucera, T.; Lin,
B.; Russell, C.
2004AGUSMSM21A..01S Altcode:
The transfer of mass, energy and momentum through the coupled Sun-Earth
system spans a wide range of scales in time and space. While profound
advances have been made in modeling isolated regions of the Sun-Earth
system, minimal progress has been achieved in modeling the end-to-end
system. Currently, end-to-end modeling of the Sun-Earth system is a
major goal of the National Space Weather and NASA Living With a Star
(LWS) programs. The uncertainty in the underlying physics responsible
for coupling contiguous regions of the Sun-Earth system is recognized
as a significant barrier to progress. Overarching questions remain
such as: what are the primary problems that need to be resolved to
enable significant progress in comprehensive modeling of the Sun-Earth
system? and which model/technique improvements are required and what
new data coverage is needed to enable full model advances? This poster
highlights topics germane to modeling the Sun-Earth system and provides
a top overview of barriers to making progress in those areas. The result
of addressing these issues ultimately attends to fundamental space
plasma processes; knowledge of which can be applied to space weather
problems at Earth, to life sustaining activities elsewhere, and to
understanding and predicting the environments of Earth-like planets and
moons. Topics to be addressed include: corotating interaction regions,
coronal mass ejections, energetic particles, system preconditioning,
extreme events and super storms, and end-to-end modeling efforts. These
topics will be addressed at length at the upcoming modeling workshop
entitled "Challenges in modeling the Sun-Earth System" to be held in
Huntsville, AL, October 18-22, 2004.

---------------------------------------------------------
Title: Prominence energetics measured with SOHO/SUMER and TRACE
Authors: Kucera, T. A.; Landi, E.
2004AAS...204.5501K Altcode: 2004BAAS...36Q.760K
The mechanisms by which solar prominences are filled with plasma are
still undetermined. In this study we perform a quantitative analysis
of the thermal properties of moving features in prominences in order
to put constraints on models of prominence formation and dynamics. In
order to make such measurements of the quickly moving features seen
in prominences in the UV we use the SOHO/SUMER spectrograph to
take a time series of exposures from a single pointing position,
providing a measurement of spectral line properties as a function
of time and position along the slit. The line observed cover a broad
range of temperatures from 80,000 - 1.6 million K. These measurements
are combined with TRACE movies in transition region and coronal
temperature bands to obtain more complete information concerning
prominence structure and motions. The resulting observations allow
us to analyze the thermal and kinetic energy of the moving prominence
sources as functions of time. This work was partly funded through
NASA SR&amp;T RTOP 432-03-52-17

---------------------------------------------------------
Title: Thermal Properties of Prominence Motions as Observed in the UV
Authors: Kucera, T. A.; Landi, E.
2003AGUFMSH42B0538K Altcode:
The mechanisms by which solar prominences are filled with plasma are
still undetermined. In this study we perform a quantitative analysis of
the thermal properties of moving features in prominences in order to put
constraints on models of prominence formation and dynamics. In order to
make such measurements of moving features seen in prominences in the
UV we use the SOHO spectrometers SUMER and CDS to take a time series
of exposures at a single pointing position, providing a measurement
of spectral line properties as a function of time and position along
the slit. The resulting observations in spectral lines in a range of
"transition region" temperatures allow us to analyze the evolution of
thermal properties of quickly moving prominence features as a function
of time.

---------------------------------------------------------
Title: Correction to “Are CME `interactions' really important for
accelerating major solar energetic particle events?”
Authors: Richardson, Ian G.; Lawrence, Gareth R.; Haggerty, Dennis K.;
Kucera, Therese A.; Szabo, Adam
2003GeoRL..30.1763R Altcode: 2003GeoRL..30nSSC5R
No abstract at ADS

---------------------------------------------------------
Title: Are CME “interactions” really important for accelerating
major solar energetic particle events?
Authors: Richardson, Ian G.; Lawrence, Gareth R.; Haggerty, Dennis K.;
Kucera, Therese A.; Szabo, Adam
2003GeoRL..30.8014R Altcode: 2003GeoRL..30lSEP2R
Recent studies have proposed that the presence or absence of an
“interaction” with a preceding coronal mass ejection (CME) or other
coronal structure within ~50 Rs of the Sun discriminates
large, fast CMEs associated with major solar energetic particle (SEP)
events from those that are not. We conclude that there is no compelling
evidence that, if such interactions take place, they play an important
role in SEP acceleration. Reasons include: The reported statistical
results are consistent with a chance association between interacting
CMEs and SEP events; Energetic SEPs are detected at Earth typically
before or around the time when the “primary” CME enters the LASCO
C2 field of view - interactions higher in the corona cannot play a
role in acceleration of these particles; For ~60% of major SEP events
in 1997-2001, the preceding CME fades into the background corona or
is relatively narrow (&lt;40°), suggesting any interaction will be
weak; Radio signatures attributed to CME interaction occur after SEP
acceleration has commenced.

---------------------------------------------------------
Title: DEM measurements of moving UV features in prominences
Authors: Kucera, T. A.; Landi, E.
2003SPD....34.0412K Altcode: 2003BAAS...35Q.812K
Multi-thermal features with speeds of 5-70 km/s perpendicular to the
line of sight are common in the prominences which showed traceable
motions. These speeds are noticeably higher than the typical speeds of
5-20 km/s observed in H-alpha data from “quiet" prominences and are
more typical of “activated" prominences in which H-alpha blob speeds of
up to 40 km/s have been reported. In order to make a more quantitative
determination of the thermal properties of the moving features seen
in the UV, we use the SOHO Coronal Diagnostic Spectrometer to take a
time series of exposures from a single pointing position, providing
a measurement of spectral line properties as a function of time and
position along the slit. The resulting observations in lines of O III,
O IV, O V, Ne IV, Ne V, Ne VI, and Ne VII allow us to calculate the
differential emission measure of moving features and provide a test
of models of flows in prominences. Support for this work was partially
provided by NASA RTOP 432-03-52-17.

---------------------------------------------------------
Title: Behaviour of Hydrogen Lyman lines in a prominence region from
SUMER and CDS
Authors: Aznar Cuadrado, R.; Andretta, V.; Teriaca, L.; Kucera, T. A.
2003MmSAI..74..611A Altcode:
We present observations of a prominence, taken on 1998 February 20 in
the framework of SOHO Joint Observing Program no. 63. The instruments
involved were SUMER and the NIS Spectrograph of CDS. The SUMER spectral
range includes the hydrogen Lyman series - starting from Ly-epsilon -
down to the head of the Lyman continuum, while CDS observed a number of
lines from T ~ 104 K to T ~ 2x 106 K. For these
observations, we were able to obtain a satisfactory determination of
the pointing of the SUMER slit relative to CDS. We thus examined - and
compared with information from CDS spectra - the main characteristics of
the hydrogen Lyman series lines and of other strong lines in the SUMER
spectral interval. We also studied the properties (depth, asymmetry)
of the central reversal present in several or all of the Lyman lines
in some regions of the prominence.

---------------------------------------------------------
Title: Prominence Motions Observed at High Cadences in Temperatures
from 10 000 to 250 000 K
Authors: Kucera, T. A.; Tovar, M.; De Pontieu, B.
2003SoPh..212...81K Altcode:
We report here for the first time observations of prominence velocities
over a wide range of temperatures and with a high time cadence. Our
study of ultraviolet movies of prominences reveals that multi-thermal
features with speeds of 5-70 km s−1 perpendicular to the
line of sight are common in the prominences which showed traceable
motions. These speeds are noticeably higher than the typical speeds of
5-20 km s−1 observed in Hα data from `quiet' prominences
and are more typical of `activated' prominences in which speeds of
up to 40 km s−1 have been reported. The observations
were performed using five separate datasets taken by the Solar and
Heliospheric Observatory's Coronal Diagnostic Spectrometer (SOHO/CDS)
in its wide slit overlappogram mode in lines from He i, O v, and Mg ix
and a separate prominence observation taken with both the Transition
Region and Coronal Explorer (TRACE) in its 1216 and 1600 Å bands and
in Hα by the Swedish Vacuum Solar Telescope (SVST) at La Palma. The
movies were taken with cadences &gt;1 image per minute and were made
simultaneously or near-simultaneously in spectral lines formed at two
or more temperatures. We traced motion that lasted for 3 to 20 min and
went distances up to 105 km. Most, but not all, of these
were chiefly horizontal. In many cases we were able to observe the
same motions over temperature ranges from 20 000 to 250 000 K or 10
000 to 100 000 K. Observations are compared with model predictions.

---------------------------------------------------------
Title: SUMER observations of hydrogen Lyman series and continuum in
a prominence
Authors: Andretta, Vincenzo; Aznar Cuadrado, Regina; Kucera, Therese
A.; Teriaca, Luca
2002ESASP.506..419A Altcode: 2002svco.conf..419A; 2002ESPM...10..419A
We present observations of a prominence, taken on February 20, 1998 in
the framework of SOHO Joint Observing Program no. 63. The instruments
involved were SUMER and the Normal Incidence Spectrograph (NIS) of
CDS. The SUMER spectral range includes the hydrogen Lyman series
- starting from Ly-ɛ - down to the head of the Lyman continuum,
while CDS observed a number of lines from T ~ 104K to T ~
2×106K. For these observations, we were able to obtain a
satisfactory determination of the pointing of the SUMER slit relative to
CDS. We thus examined - and compared with information from CDS spectra
- the main characteristics of the hydrogen Lyman series lines and of
other strong lines in the SUMER spectral interval. We also studied
the properties (depth, asymmetry) of the central reversal present in
several or all of the Lyman lines in some regions of the prominence.

---------------------------------------------------------
Title: Multi-wavelength Structure of an Active Region Filament
Authors: Balasubramaniam, K. S.; Kucera, T. A.; McAllister, A. H.
2002AGUFMSH52A0469B Altcode:
In this work we will compare the structure of active region filaments
near a sunspot, in a number of wavelengths. The data were obtained
from three sources on June 20, 2001 between 14:00 and 16:00 NSO/SP,
photospheric and chromospheric observations of intensities (G-Band),
and spectroscopy (Hα, MgI 5172 Å, and CaI 6122 Å) to determine
velocities, and magnetic fields; TRACE observations at 1600Å continuum,
and coronal measurements in 171 Å; SOHO/EIT coronal observations in
Fe XII 195A, SOHO/CDS spectroscopic observations in spectral lines --
SiXII 520.66 Å, OIV 554.52 Å, NeVI 562.80 Å, HeI 584.33 Å, OIII
599.59 Å, HeII 303.78 Å, MgIX 368.07 Å, MgX 624.94 Å, OV 629.73
Å, SiXII 520.66 Å, OIV 554.52 Å, NeVI 562.80 Å, HeI 584.33 Å,
OIII 599.59 Å, HeII 303.78 Å, MgIX 368.07 Å, MgX 624.94 Å, OV
629.73 Å; and SOHO/MDI magnetic and intensity images. The common FOV
covers about 100 arcseconds. We will present the evolutionary nature of
the photospheric magnetic field, the the corresponding chromospheric
velocities and the coronal variations of this filament region. During
the initial period of the observations, this active region filament
system is disrupted by an adjoining solar flare. The structure and
dynamics of the filament system during this eruption will be traced.

---------------------------------------------------------
Title: The Living with a Star Data Environment
Authors: Kucera, T. A.
2002AGUFMSH52C..05K Altcode:
Living with a Star (LWS) is a program of applied scientific research
geared towards understanding and predicting the effects of the Sun
on human society. The LWS data environment is key to the success of
the program. We will have to combine diverse data sets from a wide
array of sources, including ones beyond the formal LWS missions. Data
must be integrated with models and across disciplines. The size of
some of the data sets will be unprecedented in our field, requiring
innovations in data searching and selection techniques. We will have
to work together as a community to develop easy data access, metadata
standards, community software trees, and other essentials to the free
sharing of data needed to attain LWS goals.

---------------------------------------------------------
Title: Transverse prominence motions from 10,000 - 250,000K
Authors: Kucera, T. A.; Tovar, M.; de Pontieu, B.
2002ESASP.508..307K Altcode: 2002soho...11..307K
We address the origin of prominence material by comparing high cadence
(30-60 s) He I and O V EUV observations from SOHO/CDS wide slit movies,
and also, for another prominence observation, observations from TRACE
at 1216 Å and 1600 Å and SVST in Hα. The EUV and UV observations
regularly show small scale structures with plane-of-the sky velocities
of 20-80 km/s. Many, although not all, of these motions are seen in
multiple wavelength bands, representing temperatures ranging from 10,000
- 100,000K or 20,000 - 250,000K, depending on the data set. The Hα
observations contain line shift information showing clearly that the
associated UV prominence intensity motions do actually represnt real
mass motions, as opposed to temperature or density waves. The results
also indicate that the "prominence-corona transition region" is not an
outside layer to the prominence as a whole, but is rather associated
with smaller scale structures all through the prominence. More
work is needed to determine what mechanism can explain these fast,
multi-temperature prominence motions.

---------------------------------------------------------
Title: Transverse Prominence Motions from 10,000-250,000 K
Authors: Kucera, T. A.; Tovar, M.; De Pontieu, B.
2002AAS...200.3718K Altcode: 2002BAAS...34..697K
We address the origin of prominence material by comparing high cadence
(30-60 s) He I and O V EUV observations from SOHO/CDS wide slit movies,
and also, for another prominence observation, observations from TRACE
at 1216 Å and 1600 Å and SVST in Hα . The EUV and UV observations
regularly show small scale structures with plane-of-the-sky velocities
of 20-80 km/s. Many, although not all, of these motions are seen in
multiple wavelength bands, representing temperatures ranging from 10,000
-- 100,000 K or 20,000 -- 250,000 K, depending on the data set. The Hα
observations contain line shift information showing clearly that the
associated UV prominence intensity motions do actually represent real
mass motions, as opposed to temperature or density waves. The results
indicate that the “prominence-corona transition region” is not an
outside layer to the prominence as a whole, but is rather associated
with smaller scale structures all through the prominence. Support for
this work was provided by NASA SR&amp;T Grant NASW-00034. SOHO is a
joint project of ESA and NASA.

---------------------------------------------------------
Title: White Light Intercalibrations of UVCS, LASCO-C2 and Spartan
201/WLC
Authors: Frazin, R. A.; Romoli, M.; Kohl, J. L.; Gardner, L. D.;
Wang, D.; Howard, R. A.; Kucera, T. A.
2002ISSIR...2..249F Altcode: 2002ESASR...2..249F; 2002rcs..conf..249F
This paper describes comparisons among white light polarized radiances
(pB) as measured by the Ultraviolet Coronagraph Spectrometer White
Light Channel (UVCS/WLC), the Large Angle and Spectrometric Coronagraph
Experiment C2 instrument (LASCOC2) and the Spartan 201 White Light
Coronagraph (Spartan 201/WLC). UVCS/WLC and LASCO-C2 are generally in
agreement, although there are some systematic trends and discrepancies
that still require explanation. UVCS/WLC and Spartan 201/WLC agree
to within the measurement uncertainties. Spartan 201/WLC and LASCO-C2
are not directly compared to each other in this paper.

---------------------------------------------------------
Title: Prominence Plasma Motions Measured in the Ultraviolet
Authors: Kucera, T. A.; De Pontieu, B.
2001AGUSM..SH41B10K Altcode:
We present a study of velocities and trajectories of blobs visible
in UV emission in SOHO/CDS and TRACE prominence movies. It has long
been known that prominences are highly dynamic structures exhibiting
flowing material. In particular, recent observations in H-alpha indicate
that material is counter-streaming at velocities of 5-10 km/s along
the prominence spine and in the barbs.* These observations are highly
relevant to fundamental questions concerning the source of prominence
plasma. Many models of prominence flows involve heating of chromospheric
material. By investigating the properties of moving prominence plasma in
the 20,000 to 200,000 K range we will be able to provide parameters for
comparison with such models. The CDS data were taken in He I (584.33
A) and O V (629.7 A) with the wide (90 arcsec) slit which allows 30
sec cadence movies to be taken simultaneously in a few well isolated
lines. We also consider separate TRACE prominence data with Lyman-alpha
(1216 A) and C IV (1600 A) observations. Preliminary results indicate
motions in the 20-70 km/s range, with most of the observed motion
horizontal to the solar surface. Support for this work is provided by
NASA SR&amp;T Grant NASW-00034 *Zirker et al., 1998, Nature, 396, 40

---------------------------------------------------------
Title: Source Region of High and Low Speed Wind during the Spartan
201-05 Flight
Authors: Guhathakurta, Madhullika; Sittler, Ed, Jr.; Fisher, Richard;
Kucera, Therese; Gibson, Sarah; McComas, Dave; Skoug, Ruth
2001SSRv...97...45G Altcode:
The large-scale coronal magnetic fields of the Sun are believed to play
an important role in organizing the coronal plasma and channeling the
high and low speed solar wind along the open magnetic field lines of the
polar coronal holes and the rapidly diverging field lines close to the
current sheet regions, as has been observed by the instruments aboard
the Ulysses spacecraft from March 1992 to March 1997. We have performed
a study of this phenomena within the framework of a semi-empirical
model of the coronal expansion and solar wind using Spartan, SOHO,
and Ulysses observations during the quiescent phase of the solar
cycle. Key to this understanding is the demonstration that the white
light coronagraph data can be used to trace out the topology of the
coronal magnetic field and then using the Ulysses data to fix the
strength of the surface magnetic field of the Sun. As a consequence,
it is possible to utilize this semi-empirical model with remote sensing
observation of the shape and density of the solar corona and in situ
data of magnetic field and mass flux to predict values of the solar
wind at all latitudes through out the solar system. We have applied
this technique to the observations of Spartan 201-05 on 1 2 November,
1998, SOHO and Ulysses during the rising phase of this solar cycle and
speculate on what solar wind velocities Ulysses will observe during
its polar passes over the south and the north poles during September
of 2000 and 2001. In order to do this the model has been generalized
to include multiple streamer belts and co-located current sheets. The
model shows some interesting new results.

---------------------------------------------------------
Title: Wavelengths of Forbidden Transitions Arising from Levels Within
the Fe+19 2S22P3 Ground Configuration
Authors: Kucera, T. A.; Feldman, U.; Widing, K. G.; Curdt, W.
2000ApJ...538..424K Altcode:
In this paper we report the identification of all remaining unidentified
forbidden lines arising from transitions within levels of the
Fe+19 ground configuration. These lines were identified using
data from the SOHO/SUMER spectrograph and Skylab. Adjusted wavelength
values are also given for some previously observed lines. Forbidden
lines that are the result of transitions within levels of the ground
configuration of a highly ionized astrophysically abundant element
generally have longer wavelengths than resonance lines emitted by
the same ion. Many of these forbidden lines are fairly prominent in
low-density plasmas and traditionally have been used in determining
properties of high-temperature astrophysical plasmas. The identified
Fe+19 forbidden lines span the 300-2665 Å wavelength
range. Since spontaneous decay rates of forbidden transitions arising
from the same upper level are known quite accurately, these lines can
be used for calibrating spectrometers over wide wavelength ranges.

---------------------------------------------------------
Title: Source Region of High and Low Speed Wind During the Flight
of Spartan 201-05
Authors: Guhathakurta, M.; Sittler, E.; Fisher, R.; Gibson, S.;
Kucera, T.
2000SPD....31.0903G Altcode: 2000BAAS...32..841G
The large scale coronal magnetic fields of the Sun are believed to play
an important role in organizing the coronal plasma and channeling the
high and low speed solar wind along the open magnetic field lines of
the polar coronal holes and the rapidly diverging field lines close
to the current sheet regions, as has been observed by the instruments
aboard the Ulysses spacecraft from 3/92-3/97. We have performed a study
of this phenomena within the framework of a semi-empirical model of the
coronal expansion and solar wind using Spartan201-03, September, 1995,
SOHO and Ulysses observations during the quiescent phase of the past
solar cycle. Key to this understanding is the demonstration that the
white light coronagraph data can be used to trace out the topology of
the coronal magnetic field and then using the Ulysses data to fix the
strength of the surface magnetic field of the Sun. As a consequence,
it is possible to utilize this semi-empirical model with remote
sensing observation of the shape and density of the solar corona and
in situ data of magnetic field and mass flux to predict values of the
solar wind at all latitudes throuhtout the solar system. We will apply
this technique to the observations of Spartan 201-05 on 1-2 November,
1998, SOHO and Ulysses during the rising phase of this solar cycle and
speculate on what solar wind velocities Ulysses will observe during
its polar passes over the south and the north poles during September
of 2000 and 2001. This work has been funded by NASA SR &amp; T.

---------------------------------------------------------
Title: Newly Discovered Fe XX lines in Flares Observed by SOHO/SUMER
and Skylab.
Authors: Kucera, T. A.; Feldman, U.; Widing, K. G.; Curdt, W.; Khan,
J. I.
2000SPD....31.0264K Altcode: 2000BAAS...32..822K
We have used UV spectra from solar flares observed with SOHO/SUMER and
Skylab to identify all of the all remaining unidentified forbidden
lines arising from transitions within levels of the Fe XX ground
configuration. We have also obtained more accurate wavelengths for
previously observed lines. Forbidden lines resulting from transitions
within levels of the ground configuration of highly ionized elements
generally have longer wavelengths than resonance lines emitted by
the same ions. Many of these forbidden lines are fairly prominent in
low-density plasmas, and have traditionally been used in determining
properties of high temperature astrophysical plasmas. The identified Fe
XX forbidden lines span the 300-2665 Angstroms wavelength range. Since
spontaneous decay rates of forbidden transitions arising from the same
upper level are known quite accurately, these lines can be used for
calibrating spectrometers over wide wavelength ranges.

---------------------------------------------------------
Title: Solar Irradiances of Ultraviolet Emission Lines Measured
During the Minimum of Sunspot Activity in 1996 and 1997
Authors: Wilhelm, K.; Lemaire, P.; Dammasch, I. E.; Hollandt, J.;
Schuhle, U.; Curdt, W.; Kucera, T.; Hassler, D. M.; Humbler, M. C. E.
2000PCEC...25..389W Altcode:
No abstract at ADS

---------------------------------------------------------
Title: 3-D Magnetic Configurations for Filaments and Flares: The
Role of “Magnetic Dips” and “Bald Patches”
Authors: Aulanier, G.; Schmieder, B.; van Driel-Gesztelyi, L.; Kucera,
T.; Démoulin, P.; Fang, C.; Mein, N.; Vial, J. -C.; Mein, P.; Tang,
Y. H.; Deforest, C.
2000AdSpR..26..485A Altcode:
The 3-D magnetic configuration of a filament and of a low energy
flare is reconstructed, using linear mag- netohydrostatic (lmhs)
extrapolations. In both cases, we find observational signatures
of energy release at the locations of computed “bald patches”
separatrices, characterised by field lines which are tangent to
the photosphere.The filament was observed on Sept. 25, 1996, in Hα
with the MSDP on the German VTT, Tenerife, as well as in Si IV with
SOHO/SUMER. It is modeled as a twisted flux-tube deformed by the
magnetic polarities observed with SOHO/MDI. The shape and location of
the computed dipped field lines are in good agreement with the shape of
the filament and its feet observed in Hα. Some “bald patches” (BPs)
are present where the distribution of dips reaches the photosphere. We
show that some of the large scale field lines rooted in BPs can be
related to bright fine structures in Si IV. We propose that the plasma
there is heated by ohmic dissipation from the currents expected to be
present along the BP separatrices.The flare was observed on May 18,
1994, in soft X-rays with Yohkoh/SXT, and in Hα at Mitaka (Japan). The
magnetic field is directly extrapolated from a photospheric magnetogram
from Kitt Peak Observatory. The intersections with the photosphere of
the computed separatrices match well the bright Hα ribbons. The later
are associated to three BPs, with overlaying dipped field lines. We
show that enhanced densities are present in these dips, which can be
correlated with dark Hα fibrils.Both cases show the importance of
dipped field lines and BPs in the solar atmosphere. Energy release
via ohmic dissipation as well as reconnection along BP separatrices
is proposed to provide heating observed as UV brightenings in filament
channels and even as small flares

---------------------------------------------------------
Title: Diagnostics Constraints on Prominence Parameters from SOHO
and Ground-based Observations
Authors: Schmieder, B.; Kotrč, P.; Heinzel, P.; Kucera, T.;
Andretta, V.
1999ESASP.448..439S Altcode: 1999ESPM....9..439S; 1999mfsp.conf..439S
No abstract at ADS

---------------------------------------------------------
Title: Hydrogen Lyman Lines and Continuum Emission in a Polar-Crown
Prominence Observed with SUMER/SOHO
Authors: Schmieder, B.; Kucera, T.; Heinzel, P.; Vial, J. -C.
1999ESASP.446..605S Altcode: 1999soho....8..605S
We present, for the first time, a quasi-simultaneous spectroscopic
observation of the whole Lyman series of HI and continuum in a
quiescent prominence. Namely we have extended our previous study of
higher Lyman lines to lower members of the series, particularly
L-alpha and L-beta. For the latter two lines, we compare our
calibrated profiles (free of geocoronal absorption) with previous
data from OSO-8 LPSP spectrometer and (for L-alpha) from UVSP/SMM. We
demonstrate the importance of Lyman lines for studies of the base of
the prominence-corona transition region.

---------------------------------------------------------
Title: Working Group 5: Prominences and Coronal Mass Ejections
Authors: Kucera, T.; Antiochos, S. K.
1999ESASP.446...97K Altcode: 1999soho....8...97K
No abstract at ADS

---------------------------------------------------------
Title: The Role of "Magnetic Dips" and "Bald Patches" for a Filament
Observed by SOHO and GBO
Authors: Aulanier, G.; Schmieder, B.; Kucera, T.; van Driel-Gesztelyi,
L.; Démoulin, P.; Mein, N.; Vial, J. -C.; Mein, P.
1999ASPC..184..291A Altcode:
The studied filament was observed on Sept. 25, 1996, in Hα with
the MSDP on the German VTT, Tenerife, as well as in Si IV with
SOHO/SUMER. The 3-D magnetic configuration of the filament channel is
reconstructed, using linear magnetohydrostatic (lmhs) extrapolations
from a SOHO/MDI magnetogram, which is modified by a background magnetic
component constraining a twisted flux-tube. This flux-tube is deformed
by the magnetic polarities observed with SOHO/MDI. The shape and
location of the computed "dipped field lines" are in good agreement
with the shape of the filament and its feet observed in Hα. Some "bald
patches" (BPs) are present where the distribution of dips reaches the
photosphere. We find observational signatures in Si IV brightenings of
energy release at the locations of computed "bald patch separatrices",
defined by field lines which are tangent to the photosphere. We propose
that the plasma is there heated by ohmic dissipation from the expected
currents in the BP separatrices. The results show the importance of
"dipped field lines" and "bald patches" in filament channels.

---------------------------------------------------------
Title: Filament channel structures in a SI IV line related to a 3d
magnetic model
Authors: Kucera, T. A.; Aulanier, G.; Schmieder, B.; Mein, N.; Vial,
J. -C.
1999SoPh..186..259K Altcode:
A recent 3D magnetic model of filament support (Aulanier and Démoulin,
1998) has shown that specific morphologies derived from the model, based
on SOHO/MDI magnetograms, match quite well with the observations of a
filament observed in Hα and Ca ii lines with the German telescope VTT
in Tenerife on 25 September 1996 (Aulanier et al., 1998, 1999a). Some
predictions of this model concern the filament channel. To continue the
comparison of model and data, we have investigated the same filament
region observed in ultraviolet by the SOHO spectrometers SUMER and
CDS. The elongated EUV fine structures in the filament channel observed
in the Si iv 1393.76 Å line by SUMER have similar orientations
and locations to features predicted by the model of Aulanier et
al. (1999a). These regions are near the bases of field lines which
tangentially join to the photosphere in so called 'bald patches' and
are parts of large arcades above the filament channel. In addition,
we consider the Si iv Doppler shifts in these structures and compare
them to what might be expected from the model field structure. Our
study also suggests that the filament has a very low opacity in Si iv,
lower than that of the O v line observed by CDS.

---------------------------------------------------------
Title: Properties of Coronal White-Light Transients in the SPARTAN
201/WLC and SOHO/LASCO Coronagraphs
Authors: Biesecker, D. A.; Kucera, T. A.; Fisher, R. R.; Gibson,
S. E.; Guhathakurta, M.; Wang, D.
1999AAS...194.1610B Altcode: 1999BAAS...31..851B
The SPARTAN 201/WLC was used to observe the solar corona from about
20:30 UT on 98/11/01 to about 13:30 UT on 98/11/03. The SOHO/LASCO
coronagraphs were operating continuously throughout this period. The
range of heights in the corona covered by the SPARTAN and LASCO
coronagraphs and the temporal cadence of the data allow the properties
of coronal transients to be examined in greater detail than previously
possible with white light data. The SPARTAN coronagraph observes in
white light brightness and polarized brightness at heights of 1.3
to 5.5 solar radii. The LASCO coronagraphs observe in white light
brightness and polarized brightness at heights of 2.5 to 30 solar
radii. We will measure the velocity and mass of the observed coronal
transients with time. There were at least 4 coronal mass ejections
observed with SOHO/LASCO during the time of the SPARTAN flight. Using
solar disk images as a proxy, we will correct the data for plane of
the sky projection. We will explore the height at which the CME's are
initiated and the heights at which they are accelerated. In addition,
we will determine what fraction of the mass is in a CME when it is
initiated and how much is added throughout the event.

---------------------------------------------------------
Title: The SPARTAN 201 White Light Coronagraph Experiment on STS-95
Authors: Fisher, R. R.; Guhathakurta, M.; Kucera, T.; Gibson, S.;
Johnson, J.; Card, G.; Spartan201 Team
1999AAS...194.1612F Altcode: 1999BAAS...31..851F
The White Light Coronagraph Experiment included in the SPARTAN
201 payload was flown on the STS-95 Space Shuttle mission which was
launched on 29 October 1998. The flight systems and payload instruments
were operated for a total duration of 41 hours from low earth orbit
from 31 October to 2 November. The white light coronagraph experiment
was designed to investigate the physical properties and the physical
processes of the solar corona, and the instrument and spacecraft systems
were configured for flight operations at a time of enhanced solar
activity. The operational performance of the experiment and SPARTAN 201
carrier system are described, and the preliminary scientific topics of
investigations are identified. Comparisons with other types of coronal
data, ground-based K-coronameter and other space coronagraphs, are
briefly reviewed. The data reduction plans and the scientifc goals for
this mission are described. A summary of scientific insights gathered
from this new data set is included in this presentation.

---------------------------------------------------------
Title: Temporal Evolution and Physical Properties of North Polar
Coronal Hole from SPARTAN 201-05, SOHO, TRACE and Mk3
Authors: Guhathakurta, M.; Deforest, C.; Fisher, R. R.; Ofman, L.;
Kucera, T.; Gibson, S.; Spartan201 Team
1999AAS...194.3203G Altcode: 1999BAAS...31..870G
Polar coronal rays/plumes as long lived structures that extend out
to 6 R_sun were first observed during the first flight of SPARTAN 201
spacecraft during April 11-12 of 1993. In this paper we will present
detail observations from the WLC aboard Spartan 201 spacecraft (31
Oct.- 2 Nov.,1998) of the north polar coronal hole and comapre its
physical properties to the past three Spartan missions. We will present
comparisons of the Spartan WL observations with the Mk3 pB observations,
SOHO LASCO and EIT observations, and finally the high resolution TRACE
171 Angstroms observations, to characterize the north polar coronal
hole all the way from the base of the corona out to 30 R_sun. We will
also look for signatures of waves (quasi-period variations) in the
coronal hole plumes and interplume regions in the high cadence Spartan
pB observations obtained during this mission.

---------------------------------------------------------
Title: Comparison of Coronal Data between the SPARTAN 201/WLC,
SOHO/LASCO, and the MARK 3 Coronagraph
Authors: Kucera, T. A.; Wang, D.; Lecinski, A.; Biesecker, D. A.;
Fisher, R. R.; Gibson, S. E.; Guhathakurta, M.
1999AAS...194.1611K Altcode: 1999BAAS...31..851K
We compare coronal data from three different coronagraphs operating
during the flight of SPARTAN 201-5 on Nov 1-3, 1998. The SPARTAN
201/White Light Coronagraph provides reliable data from 1.5--4.0
solar radii, bridging a gap in the radial coverage between the Mark
3 Coronagraph (which has reliable data from 1.16--1.8 solar radii)
and the SOHO/LASCO C2 (2.5--6 solar radii). We will compare the
radial brightness profiles of different coronal features as seen by
the three different instruments, comparing the apparent structures in
total white-light and polarized brightness.

---------------------------------------------------------
Title: Observations of Hydrogen and Helium Continua in Solar
Prominences
Authors: Andretta, V.; Kucera, T. A.; Poland, A. I.
1999ASPC..158..162A Altcode: 1999ssa..conf..162A
No abstract at ADS

---------------------------------------------------------
Title: Solar irradiances of UV and EUV lines during the minimum of
the sunspot activity in 1996
Authors: Wilhelm, K.; Lemaire, P.; Dammasch, I. E.; Hollandt, J.;
Schühle, U.; Curdt, W.; Kucera, T.; Hassler, D. M.; Huber, M. C. E.
1999AdSpR..24..229W Altcode:
Full Sun observations in UV and EUV emission lines were performed
by SUMER (Solar Ultraviolet Measurements of Emitted Radiation) on
SOHO (Solar and Heliospheric Observatory) in 1996. The radiometric
preflight calibration of SUMER is traceable to a primary radiometric
source standard - the electron storage ring BESSY. Based on this
calibration and on its inflight refinements, the irradiance values at
SOHO have been obtained for the lines He i (λ584.33), O v (λ629.74),
Ne viii (λ770.41), S v (λ786.47), O iv (λ787.72), S vi (λλ933.39,
944.52), H i Ly ɛ (λ937.80), C iii (λ977.04), N v (λ1238.81),
Si i (λ1256.52), and C iv (λ1548.20), and the continuum near 1549
Å. In this contribution, we compare our measurements with other recent
irradiance determinations and discuss, in particular, the observations
in the C iv line.

---------------------------------------------------------
Title: Comparison of Prominences in Hα and He II 304 Å
Authors: Wang, Haimin; Chae, Jongchul; Gurman, Joseph B.; Kucera,
Therese A.
1998SoPh..183...91W Altcode:
In this letter, we bring attention to prominences which show different
morphology in Hα and He ii 304 Å, as observed simultaneously by
BBSO and EIT on board SOHO. Those two lines have been thought to
represent similar chromospheric structures although they are formed at
significantly different temperatures. We give two examples representing
two kinds of anomaly: (1) prominences showing strong Hα emissions in
the lower part and strong He ii emissions in the upper part, and (2)
erupting prominences showing extensive He ii emission, but nothing in
Hα. Our results indicate that a part or the whole of a prominence may
be too hot to emit Hα radiation, possibly due to heating or thermal
instability. Please note that these are not just two isolated cases,
many other prominences show the similar differences in Hα and He ii
304 Å.

---------------------------------------------------------
Title: Neutral Hydrogen Column Depths in Prominences Using EUV
Absorption Features
Authors: Kucera, T. A.; Andretta, V.; Poland, A. I.
1998SoPh..183..107K Altcode:
Observations of prominence regions in hot coronal lines (≳106 K)
at wavelengths below the hydrogen Lyman absorption limit show what
appear to be absorption features. Other authors have suggested that
these observed features may be due to H and He continuum absorption. But
there has, as yet, been no conclusive evidence that this is indeed the
case. In this paper we present new Solar and Heliospheric Observatory
(SOHO) observations that allow us to address this problem in a
quantitative manner. We find that continuum absorption is the best
explanation for the absorption observed in imaging data from the Coronal
Diagnostic Spectrometer (CDS) on board SOHO. Furthermore, we discuss
a new technique to measure the column depth of neutral hydrogen in a
prominence, and use it to obtain estimates of the prominence filling
factors as well. We calculate the column depth of neutral hydrogen,
ξH∼1018 cm−2, and the filling factor, f≳0.3.

---------------------------------------------------------
Title: SUMER Observations of the Evolution and the Disappearance of
a Solar Prominence
Authors: Ofman, L.; Kucera, T. A.; Mouradian, Z.; Poland, A. I.
1998SoPh..183...97O Altcode:
The mechanisms that lead to the formation and the disappearance of
prominences are poorly understood, at present. An arch-shaped prominence
was observed with the Solar Ultraviolet Measurements of Emitted
Radiation (SUMER) spectrometer on board the Solar and Heliospheric
Observatory (SOHO) on 31 March-1 April 1996. The observations were
performed at three wave-bands in the Lyman continuum. Ten successive
images were obtained at 41-minute time intervals. Based on computed
models of Gouttebroze, Heinzel, and Vial (1993), we have determined the
temperature distribution of the prominence using the intensity ratio of
876 Å and 907 Å. The observed time sequence shows that parts of the
prominence disappear possibly by heating, while other parts exhibit
heating and cooling with apparent outward motion. We model the heat
input with the linearized MHD equations using a prescribed initial
density and a broad-band spectrum of Alfvén waves. We find a good
qualitative agreement with observations. In the model the prominence
is heated by the resonant absorption of Alfvén waves with frequencies
that match the resonant condition for a particular flux tube structure
that is determined by the magnetic field topology and plasma density.

---------------------------------------------------------
Title: SOHO: Atomic physics and the solar atmosphere
Authors: Kucera, T. A.
1998AIPC..443..173K Altcode:
Many aspects of the Sun's corona and wind are studied using data
from the ultraviolet spectrum. Accurate atomic parameters are needed
to interpret these data correctly, and a good understanding of the
behaviors of atoms and ions in plasmas is essential to modeling
the Sun's atmosphere. Here I present two examples of studies being
carried out using the Solar and Heliospheric Observatory (SOHO) extreme
ultraviolet spectrographs. The first of these is the study of flows in
the Sun's chromosphere and corona. SOHO has provided new information
concerning previous observations of the predominant down-flows in the
Sun's lower atmosphere. Accurate measurements of Doppler line shifts
have been extended to the corona. It has also been found that the
Doppler shifts vary over different parts of the Sun. The second study
discussed involves the use of SOHO data to measure elemental abundances
in coronal structures know as streamers, giving more information on
the “FIP” effect-the observation that there is a relative deficit
of elements with high first ionization potentials (FIPs) in the corona
and solar wind.

---------------------------------------------------------
Title: Filament Observations with SOHO Sumer/cds: The Behaviour of
Hydrogen Lyman Lines
Authors: Schmieder, B.; Heinzel, P.; Kucera, T.; Vial, J. -C.
1998SoPh..181..309S Altcode:
On 21 September 1996, a filament close to an area of enhanced network
was observed with the Solar Ultraviolet Measurements of Emitted
Radiation (SUMER) spectrometer and Coronal Diagnostic Spectrometer
(CDS). CDS provided intensity, Doppler shift and linewidth maps of the
region in six lines whose temperature range covers 104 to
106 K. SUMER observations consisted of maps of the region
in four hydrogen Lyman lines (Lδ, L∈, L-6, L-7) and a Svi line
(944 Å). In all the Lyman lines we detect a central absorption
and an asymmetry in the intensity of the two peaks. First NLTE
computations indicate that such reversed Lyman profiles and their
absolute intensities can be reproduced with the existing filament models
provided that we take into account a prominence-corona transition region
(PCTR). We discuss the Lyman lines' asymmetry in terms of macroscopic
flows by comparison with the Hei line Doppler shifts observed with CDS.

---------------------------------------------------------
Title: Solar irradiances and radiances of UV and EUV lines during
the minimum of sunspot activity in 1996
Authors: Wilhelm, K.; Lemaire, P.; Dammasch, I. E.; Hollandt, J.;
Schuehle, U.; Curdt, W.; Kucera, T.; Hassler, D. M.; Huber, M. C. E.
1998A&A...334..685W Altcode:
Full Sun observations in UV and EUV emission lines were performed
by SUMER (Solar Ultraviolet Measurements of Emitted Radiation) on
SOHO (Solar and Heliospheric Observatory) in 1996. The radiometric
pre-flight calibration of SUMER is traceable to a primary radiometric
source standard - the electron storage ring BESSY. Based on this
calibration, the irradiance values at SOHO and at 1 AU have been
obtained for the lines He i (lambda 584.33 { Angstroms}), O v (lambda
629.74 { Angstroms}), Ne viii (lambda 770.41 { Angstroms}), S v (lambda
786.47 { Angstroms}), O iv (lambda 787.72 { Angstroms}), S vi (lambda
lambda 933.39, 944.52 { Angstroms}), H i Ly epsilon (lambda 937.80 {
Angstroms}), C iii (lambda 977.04 { Angstroms}), N v (lambda 1238.81
{ Angstroms}), Si i (lambda 1256.52 { Angstroms}), and C iv (lambda
1548.20 { Angstroms}). The spatially resolved measurements allowed
good estimates to be made of the active region contributions to the
irradiance of the quiet Sun. The centre-to-limb radiance variations of
these lines have also been obtained from these measurements. For quiet
solar conditions, a radiance spectrum was determined for wavelengths
from 800 { Angstroms} to 1500 { Angstroms} near the centre of the
solar disk.

---------------------------------------------------------
Title: SUMER/SOHO Filament Observations in Selected Lyman Lines
Authors: Schmieder, B.; Kucera, T.; Heinzel, P.; Vial, J. -C.
1998ASPC..150..205S Altcode: 1998IAUCo.167..205S; 1998npsp.conf..205S
No abstract at ADS

---------------------------------------------------------
Title: Filament Disparition Brusque and CME - September 25-26,
1996 Event
Authors: van Driel-Gesztelyi, L.; Schmieder, B.; Aulanier, G.;
Demoulin, P.; Martens, P. C. H.; Zarro, D.; Deforest, C.; Thompson,
B.; St. Cyr, C.; Kucera, T.; Burkepile, J. T.; White, O. R.; Hanaoka,
Y.; Nitta, N.
1998ASPC..150..366V Altcode: 1998IAUCo.167..366V; 1998npsp.conf..366V
No abstract at ADS

---------------------------------------------------------
Title: Helical Structure in an Eruptive Prominence Related to a CME
(SUMER, CDS, LASCO)
Authors: Kucera, T. A.; Poland, A. I.; Wiik, J. E.; Schmieder, B.;
Simnett, G.
1998ASPC..150..318K Altcode: 1998IAUCo.167..318K; 1998npsp.conf..318K
SOHO (SUMER/CDS) observed an eruptive prominence on May 1,1996,
associated with a CME observed by LASCO. We investigate the
physical conditions of this prominence in order to quantify velocity,
temperature, and density. SUMER spectra in Si IV and O IV lines are used
to obtain Doppler-shift images of the prominence. The prominence shows
large-scale red and blueshifted regions, revealing a large helical
structure with a global twist. In addition, fine structure analysis
shows multiple components in the line profile, suggesting integration
of many threads along the line-of-sight with a large dispersion of
velocities (∼150 km s-1).

---------------------------------------------------------
Title: Dynamics and Fine Structures in Quiescent Prominences (MSDP/Pic
du Midi, SOHO/SUMER and CDS)
Authors: Li, K.; Malherbe, J. -M.; Wiik, J. E.; Schmieder, B.; Roudier,
Th.; Kucera, T.; Poland, A.
1998ASPC..150...32L Altcode: 1998IAUCo.167...32L; 1998npsp.conf...32L
No abstract at ADS

---------------------------------------------------------
Title: Observation of Prominence Heating and the Heating Mechanism
Authors: Ofman, L.; Mouradian, Z.; Kucera, T. A.; Poland, A. I.
1998ASPC..150..159O Altcode: 1998IAUCo.167..159O; 1998npsp.conf..159O
No abstract at ADS

---------------------------------------------------------
Title: Eruptive prominence and associated CME observed with SUMER,
CDS and LASCO (SOHO)
Authors: Wiik, J. E.; Schmieder, B.; Kucera, T.; Poland, A.; Brekke,
P.; Simnett, G.
1997SoPh..175..411W Altcode:
Observations of an eruptive prominence were obtained on 1 May 1996,
with the SUMER and CDS instruments aboard SOHO during the preparatory
phase of the Joint Observing Programme JOP12. A coronal mass ejection
observed with LASCO is associated temporally and spatially with this
prominence. The main objective of JOP12 is to study the dynamics of
prominences and the prominence-corona interface. By analysing the
spectra of Oiv and Siiv lines observed with SUMER and the spectra of
15 lines with CDS, Doppler shifts, temperatures and electron densities
(ratio of Oiv 1401 to 1399Å) were derived in different structures of
the prominence. The eruptive part of the prominence consists of a bubble
(plasmoid) of material already at transition region temperatures with
red shifts up to 100 km s-1 and an electron density of the
order of 1010cm-3. The whole prominence was very
active. It developed both a large helical loop and several smaller loops
consisting of twisted threads or multiple ropes. These may be studied
in the SUMER movie (movie 2). The profiles of the SUMER lines show a
large dispersion of velocities (±50 km s-1) and the ratio
of the Oiv lines indicates a large dispersion in electron density (3 x
109cm-3 to 3x 1011cm-3). The
CME observed by LASCO left the corona some tens of minutes before the
prominence erupted. This is evidence that the prominence eruptions are
probably the result of the removal of the restraining coronal magnetic
fields which are in part responsible for the original stability of
the prominence.

---------------------------------------------------------
Title: Coordinated SOHO, Yohkoh, and Magnetogram Observations Of
Transient Loop Brightenings
Authors: Zarro, D. M.; Metcalf, T. R.; Fisher, G. H.; Siegmund, O.;
Longcope, D. W.; Kucera, T.; Griffiths, N. W.
1997SPD....28.0503Z Altcode: 1997BAAS...29..909Z
Transient soft X-ray brightenings occur frequently in solar active
regions, with typical durations of 2-10 minutes. They have been
observed with the Yohkoh Soft X-ray Telescope (SXT) and appear to be
associated primarily with interactions of multiple loops that brighten
initially near their footpoints (Shimuzu et al. 1994, Ap.J., 422,
906). Suggested mechanisms for the production of soft X-ray emission
include: conduction-driven chromospheric evaporation; Alfvenic outflows
from reconnection of colliding field lines; and expulsion of untwisting
loop material in emerging flux tubes (Uchida and Shibata 1988, Solar
Phys., 116, 291). To further study the dynamics of transient soft X-ray
brightenings and their relationship to the lower atmospheric magnetic
field, we have conducted a coordinated SOHO/Yohkoh campaign to observe
soft X-ray brightenings in a small active region at disk center on
1996 June 6. The region was observed simultaneously by Yohkoh SXT, the
Coronal Diagnostic Spectrometer (CDS) on SOHO, and the Imaging Vector
Magnetograph (IVM) at Mees Observatory, Hawaii. In particular, the CDS
instrument obtained Mg X (609 Angstroms) line spectra with 2-3 arcsec
spatial resolution in a 2x2 arcmin field with approximately 8 minute
cadence. The Mg X line is formed in the low corona at approximately
10(6) K. Individual Mg X spectra were obtained with 5 second exposures
per slit position. The SXT and CDS observations show evidence of soft
X-ray brightness variations on timescales of 5-10 minutes. The CDS Mg
X spectra show a mixture of red and blue Doppler shifts (&lt; 100 km
s(-1) ) that are spatially associated with loop footpoints indicated
by the IVM. Based on the observed temporal and spatial variations of
the implied plasma upflows and downflows, we investigate the validity
of different proposed models of transient soft X-ray brightenings.

---------------------------------------------------------
Title: A Reconnection Model for Observed Transient Loop Brightenings
Authors: Longcope, D. W.; Fisher, G. H.; Metcalf, T. R.; Lemen, J.;
Zarro, D. M.; Kucera, T.; Griffiths, N.; Siegmund, O. H. W.
1997SPD....28.0128L Altcode: 1997BAAS...29..884L
Several recent theoretical models explain coronal activity in terms of
magnetic reconnection at “separator” field lines. These are field
lines lying at the boundary between domains of coronal flux with
distinct photospheric origin. Transient brightenings of X-ray loops
(Shimizu et al. 1992) may be the manifestations of such localized events
(Longcope 1996). Their relative simplicity, compared to large events
such as flares, makes them ideal objects for exploring reconnection
models. Toward this end, a campaign of coordinated observations of
loop brightenings in a small active region was undertaken on June 6,
1996. High time cadence observations were made of the transition region
and low corona in EUV (SUMER and CDS) and of the high corona in soft
X-rays (Yohkoh), while high cadence, high resolution vector magnetograms
were obtained with the Imaging Vector Magnetograph at the University of
Hawaii. This series of magnetograms is used to calculate the magnetic
topology of the coronal field, and to locate the separator field
lines. The high time cadence of the magnetograms allows the estimation
of reconnection rates: the rate at which flux must be exchanged between
domains. The "minimum current corona" model (Longcope 1996) is then
used to provide quantitative predictions of energy released on each
separator due to this reconnection. The observational results of the
campaign are described in a companion paper by Zarro et al at this
meeting; we discuss our predictions in the context of their results.

---------------------------------------------------------
Title: Measuring the He I/H ratio in a prominence using Lyman
absorption
Authors: Kucera, T. A.; Andretta, V.; Poland, A. I.
1997SPD....28.0112K Altcode: 1997BAAS...29Q.881K
We investigate a method for measuring the ratio of neutral helium to
hydrogen in solar prominences. The upper limit to the Lyman continuum
occurs at 911 Angstroms for H, 504 Angstroms for He I, and 228 Angstroms
for He II. Lyman absorption by prominences and other structures is
clearly visible in emission of hot coronal lines observed by the Coronal
Diagnostic Spectrometer (CDS) and Extreme Ultraviolet Imaging Telescope
(EIT) aboard the Solar and Heliospheric Observatory (SOHO). By comparing
the absorption in lines absorbed by H only and by H and He I, the ratio
of He I to H in prominences can be determined. We attempt to do this
by comparing the absorption by a prominence in the Mg X line at 624.9
Angstroms and the Mg IX line at 368.1 Angstroms, both observed by CDS.

---------------------------------------------------------
Title: Determination of the Formation Temperature of Si IV in the
Solar Transition Region
Authors: Doschek, G. A.; Mariska, J. T.; Warren, H. P.; Wilhelm, K.;
Lemaire, P.; Kucera, T.; Schühle, U.
1997ApJ...477L.119D Altcode:
Using spectra obtained with the Solar Ultraviolet Measurements
of Emitted Radiation (SUMER) spectrometer flown on the Solar and
Heliospheric Observatory spacecraft, we deduce the temperature
of formation of the Si IV ion in the solar transition region
from the Si IV ultraviolet spectral line intensity ratio, 3p
2P3/2-3d 2D3/2,5/2/3s
2S1/2-3p 2P1/2,
and compare the result to the temperature predicted under the
assumption of ionization equilibrium. The wavelengths are as
follows: 2D3/2,5/2, 1128.325, 1128.340 Å
2P1/2, 1402.770 Å. Ratios are derived for
typical features of the quiet Sun, such as cell center and network,
and are systematically higher than those predicted at the 6.3 ×
104 K ionization equilibrium temperature of formation
of Si IV. For most solar features the ratios imply a temperature
of formation of about 8.5 × 104 K. The ratios for the
faintest features imply a temperature of formation of up to 1.6 ×
105 K. It is not clear, however, that all the discrepancies
between the measured and theoretical ratios are due to a temperature
effect. Accurate temperature measurements are important since a large
discrepancy from ionization equilibrium has significant implications
for the physics of the transition region, such as the possible presence
of nonthermal electrons.

---------------------------------------------------------
Title: Prominence Activity Related to CME Observed by SOHO, YOHKOH
and Ground-Based Observatories
Authors: Schmieder, B.; van Driel-Gesztelyi, L.; Wiik, J. E.; Kucera,
T.; Thompson, B.; de Forest, C.; Saint Cyr, C.; Simnett, G. M.
1997ESASP.404..663S Altcode: 1997cswn.conf..663S
No abstract at ADS

---------------------------------------------------------
Title: Evidence for a Cutoff in the Frequency Distribution of Solar
Flares from Small Active Regions
Authors: Kucera, T. A.; Dennis, B. R.; Schwartz, R. A.; Shaw, D.
1997ApJ...475..338K Altcode:
In this paper, we present evidence that active regions with small
sunspot areas have an upper limit to the energy of the flares they
produce. This result is consistent with predictions of the avalanche
model of Lu et al. We used data from the Hard X-Ray Burst
Spectrometer on the Solar Maximum Mission to study differences in
the frequency distributions of solar flares as grouped by active
region characteristics. The active region parameters considered
were the total sunspot area, the longitudinal extent, the Mount
Wilson class, and the McIntosh class. We find that there are
significantly fewer high count rate flares (&gt;~104
counts s-1 above 60 keV) from regions with small sunspot
areas (0-500 microhemispheres) than would be expected from a power-law
extrapolation from the frequency distribution of flares with peak rates
greater than 50 counts s-1 above 60 keV. This is not found
in the distribution of flares produced by regions with large sunspot
areas (600-3600 microhemispheres). Using our analysis of the data and
the predictions of the avalanche model, we calculated a limit to the
energy of a flare that can be produced by an active region with given
sunspot area. There are no statistically significant differences
between the frequency distributions of flares with peak count rates
&gt;~103 counts s-1 grouped according to the
other region characteristics studied. We also find that, in all
cases, large complex regions appear to produce a lower percentage of
low-energy events than do smaller, simpler regions. It is possible
that this effect is the result of biases against observations of low
count rate flares and the determination of their locations.

---------------------------------------------------------
Title: Coordinated Observations of Prominences with SUMER/CDS and
Ground Observatories
Authors: Wiik, J. E.; Schmieder, B.; Kucera, T.; Poland, A.
1997ASPC..118..278W Altcode: 1997fasp.conf..278W
An international campaign for the observation of prominences
and filaments was successfully accomplished between June 3 and
9 1996. Several ground observatories took part in the campaign
which included the space observatories SOHO and Yohkoh. The main
objective of this campaign was to study the dynamics of prominences
and the prominence-corona interface, the formation of filaments and
the fine structures at different temperatures. We will reported on
two Joint Observing Programmes of SUMER and CDS aboard SOHO (JOP 12
and JOP 17), which have been achieved. Finally we will present as an
exemple a prominence observed on May 1, 1996 during the tests of the
programme JOP 12. This prominence was associated with a CME (observed
with LASCO). Very active parts with Dopplershifs up to +/- 36kms(-1)
were measured in the SUMER spectra of the prominence, indicating the
presence of twisted ropes during the eruption. Mean electron densities
have spatial and temporal dispersion of one order of magnitude (10(9)
- 10(10) cm(-3) ).

---------------------------------------------------------
Title: "Prominences, filaments and chromospheric activity" June 1996
campaign with SOHO, YOHKOH and Wrocław.
Authors: Wiik, J. E.; Rudawy, P.; Schmieder, B.; Kucera, T.; Rompolt,
B.; Poland, A.
1997joso.proc...93W Altcode:
No abstract at ADS

---------------------------------------------------------
Title: A Study of the Thermal/Nonthermal Electric Field Model in
Solar Flares Using Spectral and Spatial X-Ray Data from Compton
Gamma Ray Observatory and YOHKOH
Authors: Kucera, T. A.; Love, P. J.; Dennis, B. R.; Holman, G. D.;
Schwartz, R. A.; Zarro, D. M.
1996ApJ...466.1067K Altcode:
We have analyzed a solar flare in terms of a model in which electric
fields produce both thermal emission from Joule-heated electrons
and nonthermal emission from runaway electrons. The flare was
observed by the Compton Gamma Ray Observatory Burst and Transient
Source Experiment (BAT SE), the Yohkoh satellite, and GOES. The
measured BATSE hard X-ray spectra were fitted with functions
derived from the electric field model, thus allowing values for the
temperature [(4-5) x 107 K] and emission measure [(1 x
1046)-(2 x 1047)cm-3] of the thermal
source to be determined. These are qualitatively consistent with the
characteristics of the loop-top emission observed with the Yohkoh
Hard X-ray Telescope. Furthermore, the hard X-ray footpoint emission
observed by Yohkoh had flatter spectra than the loop-top emission,
as predicted by the model We found that the effects of changes in
the nonthermal parameters on the model spectra are not unique; it is
possible to establish two of the three nonthermal parameters only
if the third is determined by other means. Using Yohkoh images in
conjunction with the fits to BATSE spectra, we calculated upper limits
on the length of the region in which the electric field causes runaway
electron acceleration. We find that this distance must be shorter than
the length of the flaring loop (i.e., less than 3 x 109 cm).

---------------------------------------------------------
Title: Evidence for a Cutoff in the Frequency Distribution of Solar
Flares from Small Active Regions
Authors: Kucera, T. A.; Dennis, B. R.; Schwartz, R. A.; Shaw, D.
1996AAS...188.7014K Altcode: 1996BAAS...28..940K
We present evidence that active regions with small-sunspot areas
have an upper limit to the energy of the flares they produce. This
result is consistent with predictions of the avalanche model of Lu et
al. (1993). The results were obtained using data from the Hard X-ray
Burst Spectrometer on the Solar Maximum Mission to study differences in
the frequency distributions of solar flares as grouped by active region
characteristics. Active region parameters considered were longitudinal
extent, total sunspot area, Mt. Wilson Class, and McIntosh Class. We
find that there are fewer high count-rate flares (ga 10(4) counts s(-1)
) from regions with small sunspot areas (0-500 micro-hemispheres) than
would be expected from a power-law extrapolation from the frequency
distribution of flares with peak-rates &gt;50 counts s(-1) . This is
not found in the distribution of flares produced by regions with large
sunspot areas (600-3600 micro-hemispheres). Using our analysis of the
data and the predictions of the avalanche model, we calculated a limit
to the energy of a flare which can be produced by an active region with
given sunspot area. There are no statistically significant differences
between the frequency distributions of flares with peak count rates ga
10(3) counts s(-1) grouped according to the other region characteristics
studied. We also find that in all cases, large, complex regions appear
to produce a lower percentage of low-energy events than do smaller,
simpler regions. It is possible that this effect is the result of
biases against observations of low count-rate flares and determination
of their locations.

---------------------------------------------------------
Title: A Solar EUV Spectral Atlas Observed with SUMER
Authors: Brekke, P.; Wilhelm, K.; Lemaire, P.; Curdt, W.; Schuhle,
U.; Poland, A.; Kucera, T.; Hassler, D. M.; Siegmund, O. H. W.
1996AAS...188.3713B Altcode: 1996BAAS...28..879B
We present the first solar EUV spectral atlas in the wavelength range
500 -- 1600 { Angstroms}. The spectra were recorded with the Solar
Ultraviolet Measurements of Emitted Radiation (SUMER) which is part
of the ESA/NASA Solar and Heliospheric Observatory (SOHO). The solar
spectrum below 1200 { Angstroms} is not very well known. Thus, the
present spectral atlas, and SUMER observations in general, represents
a new important diagnostic tool to study essential physical parameters
of the solar atmosphere. It includes emission from atoms and ions in
the temperature range 10(4) to 2 x 10(6) K. Thus, emission lines and
continua emitted from the lower chromosphere to the lower corona
can be studied. The atlas is also useful as a planning tool for
SUMER studies to determine useful dwell times, possible blends, and
to select proper data extraction windows. The angular resolution of
SUMER is close to 1 arcsec, but the atlas presented here represents an
average along part of the 1-arcsec wide slit, typically 30 arcsec. The
spectral resolving power of the instrument is lambda /Delta lambda =
17770-38300. For more details about the SUMER instrument we refer to
Wilhelm et al. (Solar Physics, 162, 189, 1995). The spectral data in
this atlas were obtained with the spectrometer slit positioned at the
center of the solar disk with a dwell time of 300 s to bring up weak
lines and continua. The full spectral range was put together from
a number of exposures each covering approximately 20 { Angstroms}
in 1st order on the coated, and therefore most sensitive, part (KrB)
of the detector. 1st and 2nd order spectra are superimposed. The
spectral atlas is available in a computer readable format together
with a IDL program to read and display the data using a widget
interface. The atlas and the programs can be obtained via the World
Wide Web (http://hydra.mpae.gwdg.de/mpae_projects/SUMER/sumer.html)
or by contacting one of the authors.

---------------------------------------------------------
Title: A Study of the Thermal/Nonthermal Electric Field Model Using
Spectral and Spatial X-ray Data from CGRO and YOHKOH
Authors: Kucera, T. A.
1996mpsa.conf..563K Altcode: 1996IAUCo.153..563K
No abstract at ADS

---------------------------------------------------------
Title: A Study of the Thermal/Nonthermal Electric Field Model Using
Spectral and Spatial X-Ray Data from CGRO and Yohkoh
Authors: Kucera, T. A.; Love, P. J.; Dennis, B. R.; Holman, G. D.;
Schwartz, R. A.; Zarro, D. M.
1995SPD....26.1305K Altcode: 1995BAAS...27..987K
No abstract at ADS

---------------------------------------------------------
Title: A Multisource Limb Flare Observed at Multiple Radio Wavelengths
Authors: Kucera, T. A.; Dulk, G. A.; Gary, D. E.; Bastian, T. S.
1994ApJ...433..875K Altcode:
A flare with several radio sources occurred on the solar limb at 2155
UT on 1989 June 20. It was observed by the Very Large Array (VLA) and
the Owens Valley Radio Observatory (OVRO). The VLA data consisted of
images at 1.4 GHz, while OVRO provided spectral and spatial information
over the range 1-15 GHz. We develop a new gyrosynchrotron model to
analyze the sources observed at flare peak. This model differs from
many previous ones in that it contains spatial variations of both
the magnetic field and accelerated particle density. It uses a new
gyrosynchrotron approximation which is valid at very low harmonics of
the gyrofrequency. For the first time we find that the cause of the
change of microwave source size with frequency in the event studied
was due primarily to the spatial variation of the accelerated electron
density. This is contrary to the common assumption that the variation
in size is due to a nonuniform magnetic field. We also investigate a
polarized source which brightened later in the flare, finding that it
could have been due to plasma radiation or gyrosynchrotron emission.

---------------------------------------------------------
Title: Multiple Wavelength Observations of an Off-Limb Eruptive
Solar Flare
Authors: Kucera, T. A.; Dulk, G. A.; Kiplinger, A. L.; Winglee, R. M.;
Bastian, T. S.; Graeter, M.
1993ApJ...412..853K Altcode:
The eruptive prominence and limb flare which occurred at 1454 UT on
June 20, 1989 is described and analyzed. This event was observed by
many different instruments providing an unusual amount and variety of
data: images at 1.4 GHz, 37 GHz, and H-alpha, and spectra in hard X-ray,
soft X-ray, and radio frequencies. This array of data makes it possible
to explore the relationships between flare and eruptive prominence
emissions at different wavelengths. VLA images at 1.4 GHz show changing
sources in a set of high (about 10 exp 10 cm) coronal loops associated
with the erupting prominence. We use a full gyrosynchrotron code to
model a 1.4 GHz source early in the flare as a large coronal loop. The
model results lead us to conclude that the initial acceleration occurs
in smaller, denser loops which also produce the flare's hard X-ray
emission. We also present evidence that a source at 1.4 GHz later in
the event is due to second-harmonic plasma emission. This source is
adjacent to a leg of the prominence and comes from a dense column of
material in the magnetic structure supporting the prominence.

---------------------------------------------------------
Title: Model of Gyrosynchrotron Emission Sources Observed in the
Microwaves
Authors: Kucera, T. A.; Dulk, G. A.; Gary, D. E.
1993BAAS...25.1214K Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Observations and analysis of solar flares at radio and other
wavelengths
Authors: Kucera, Therese Ann
1993PhDT.........4K Altcode:
This thesis concerns observations and modeling of two flares observed by
the Very Large Array (VLA) and other instruments on 20 June 1989. We
investigate the events to determine the emission mechanism of the
observed radiation, the structure of the magnetic fields, and the
spectra and locations of the accelerated electron populations. The
event of 1454 UT consisted of an eruptive prominence accompanied by a
flare. The event was observed with an unusual number of instruments in
radio, H(alpha), and X-ray wavelengths. These data are used to construct
a new, advanced model of a source observed at 1.4 GHz as gyrosynchrotron
radiation emitted from a high coronal loop. Our results indicate that
the initial acceleration occurred in smaller, denser loops which also
produced the flare's hard X-ray emission. We also present evidence
that other sources observed at 1.4 GHz later in the event were due to
second harmonic plasma radiation emitted from the prominence. Microwave
observations of erupting prominences are very rare, and we are the first
to observe and analyze plasma emission from such an event. Finally,
we investigate a source of microwaves and soft X-rays occurring
later in the flare and calculate a lower limit to the density of
the source. The flare of 2155 UT was observed by the VLA and Owens
Valley Radio Observatory. We develop a second gyrosynchrotron model
to analyze the sources observed at flare peak. This model differs from
the previous one in that it has a different radio source structure. It
uses a new gyrosynchrotron approximation which is valid at very low
harmonics of the gyrofrequency. For the first time we find that the
cause of the change of microwave source size with frequency in the
event studied was variation in the accelerated electron density. This
is contrary to the common assumptions that the variation in size is
due to a nonuniform magnetic field.

---------------------------------------------------------
Title: VLA and Trieste Observations of Type-I Storms - Type-Iv
and Pulsations
Authors: Zlobec, P.; Messerotti, M.; Dulk, G. A.; Kucera, T.
1992SoPh..141..165Z Altcode:
A prime objective of this experiment was to determine whether type
I or IV sources at 333 MHz contain features of small (arc sec)
scale. With the VLA, our resolution was better than 4″. However,
we never observed any structure of size smaller than about 30″,
with the typical source sizes being between about 40″ and 90″.

---------------------------------------------------------
Title: The impulsive phase of a large solar limb flare of June
20, 1989
Authors: Graeter, Martin; Kucera, Therese A.
1992SoPh..141...91G Altcode:
On 1989 June 20, we observed in Hα the impulsive phase of a 3B/X1.6
limb flare with high temporal resolution. Line profiles have been
acquired every 2.3 s with an imaging spectrograph. During the eruption
of a filament we observed in Hα a moving plasma blob from what we
believe to be a second loop which correlated spatially and temporally
with a microwave source at 1.4 GHz observed by VLA. A magnetodynamic
model is used to understand the development of the moving plasma blob.

---------------------------------------------------------
Title: Model of Gyrosynchrotron Emission from a High Coronal Loop
Authors: Kucera, T. A.; Dulk, G. A.; Bastian, T. S.
1992AAS...180.4205K Altcode: 1992BAAS...24..796K
Gyrosynchrotron emission is a main source of microwave emission from
solar flares. We have developed a model of a high, face-on, coronal
flare loop with a dipole magnetic field. The loop is divided into
homogeneous segments to which are applied a general gyrosynchrotron
code. We compare the model with observations made of an off-limb
flare taken in June of 1989 during the first Max '91 campaign. These
observations force a strong set of constraints upon the model. VLA
imaging data at 1.4 GHz dictate the source position, shape and
brightness at that frequency. Radiometer data from RSTN and Bern
provide microwave spectra to compare to model-produced spectra, and
there are constraints from SMM/HXRBS hard X-ray spectra and derived
emission measures. The model is also compared with general results
from previous measurements of source parameters at other frequencies.

---------------------------------------------------------
Title: Simultaneous Hα and Microwave Observations of a Limb Flare
on 1989JUN20
Authors: Graeter, M.; Kucera, T. A.
1992LNP...399..372G Altcode: 1992esf..coll..372G; 1992IAUCo.133..372G
On June 20, 1989 during the Max '91 campaign a large limb flare
occurred in active region 5528. It was observed at radio, X-ray, and
H wavelengths. From the temporal, spectral, and spatial information
we get insight into the first seven minutes of flare development
since the start of the hard X-ray flare at 14:54 UT. Images in H show
a blueshifted eruption of a filament which appears later outside the
limb as a giant growing prominence. While the filament is erupting large
blobs of plasma are seen to move out with speeds of several hundred km/s
in the plane of the sky. One of them coincides spatially and temporally
with a moving source seen in VLA images (see Fig. 1. at 14:57:36 UT). It
is speculated that the moving plasma blob is at the top of a second
loop which evolves magnetodynamically. Between the footpoints of the
loop system a large H kernel develops. Two more eastern subkernels
probably form the second ribbon. Later the main kernel develops two
links with the off limb loop. Microwave emission sources are seen near
both footpoints of the H loop at 15:00:01 UT in Fig. 1.

---------------------------------------------------------
Title: Multifrequency Observations of a Remarkable Solar Radio Burst
Authors: White, S. M.; Kundu, M. R.; Bastian, T. S.; Gary, D. E.;
Hurford, G. J.; Kucera, T.; Bieging, J. H.
1992ApJ...384..656W Altcode:
Observations of an impulsive solar-radio burst from three observatories
are presented. The striking observational aspects of this flare are
that the time profile was identical throughout at 8.6, 15, and 86
GHz, that the spectrum was apparently flat from 15 to 86 GHz, and
that there was a sharp cutoff in the spectrum between 5.0 and 8.6
GHz. The simplest interpretation of the cutoff, namely as a plasma
frequency effect, leads to the conclusion that there was exceptionally
high-density material in the solar corona (of about 5 x 10 exp 11/cu
cm). Very Large Array images at 15 GHz show a single-loop structure
which brightened uniformly and showed little change in size during the
whole impulsive phase. The flat spectrum is consistent with optically
thin thermal bremsstrahlung emission, but the lack of observed soft
X-ray emission and other properties of the flare cannot easily be
accommodated by this mechanism. The possibility is explored that the
emission is optically thick due to thermal absorption of nonthermal
gyrosynchrotron emission, or optically thin gyrosynchrotron emission
absorbed by high-density material intervening along the line of
sight. Both of these explanations also face difficulties.

---------------------------------------------------------
Title: Observations of Two Large Off Limb Solar Flares in the Radio,
X-Rays, and Hα
Authors: Kucera, T. A.; Dulk, G. A.; Winglee, R. M.; Kiplinger, A. L.;
Bastian, T. S.; Gary, D. E.
1991BAAS...23R1065K Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Observations of Two Large Limb Flares on 20 June 1989
Authors: Kucera, T. A.; Winglee, R. M.; Dulk, G. A.; Bastian, T. S.;
Gary, D. E.
1991max..conf..172K Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Multiwavelength Investigations of the 1989 June 30 Solar
Flares Including Interferometric Observations of Their Microwave
Emitting Sources
Authors: Crannell, C. J.; Gary, D. E.; Hurford, G. J.; Starr, R.;
Kucera, T.
1991max..conf..192C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Coronal Metal Abundances from Radio/Soft X-ray Observations
Authors: Kucera, T. A.; Dulk, G. A.; Belkora, L. A.; Rottman, G. J.;
Guhathakurta, M.; Orrall, F. Q.
1990BAAS...22..852K Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Pulsations during a type IV burst observed at Trieste and
the VLA
Authors: Zlobec, P.; Messerotti, M.; Dulk, G. A.; Kucera, T.
1990PDHO....7..200Z Altcode: 1990ESPM....6..200Z; 1990dysu.conf..200Z
On November 14, 1988 we made simultaneous, 327/330 MHz observations of
a type IV burst at the VLA and the Trieste Astronomical Observatory,
obtaining high spatial resolution with the VLA and high time resolution
at Trieste.

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Title: Cotemporal XUV and Radio Observations of the Solar Corona
Authors: Jones, M. D.; Rottman, G. J.; Dulk, G. A.; Kucera, T. A.;
Orrall, F. Q.; Large, M. I.; Gray, A.
1988BAAS...20..976J Altcode:
No abstract at ADS