Author name code: kucera-therese ADS astronomy entries on 2022-09-14 author:"Kucera, Therese A." ------------------------------------------------------------------------ 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 Bibcode: 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. 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 Bibcode: 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. 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 Bibcode: 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. 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. Bibcode: 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. Title: Observations and 3D MHD Modeling of Small-scale Solar Prominence Oscillations Authors: Ofman, L.; Kucera, T.; DeVore, C. R. Bibcode: 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 & 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. 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. Bibcode: 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. 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. Bibcode: 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. 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. Bibcode: 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. 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. Bibcode: 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. 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. Bibcode: 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. 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. Bibcode: 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. 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. Bibcode: 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. 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. Bibcode: 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<logT<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. Title: Using SDO/AIA to Understand the Thermal Evolution of Solar Prominence Formation Authors: Viall, Nicholeen M.; Kucera, Therese A.; Karpen, Judith T. Bibcode: 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. 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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}})< 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 Bibcode: 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<logT<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 Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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 <10 {km} {{{s}}}-1, and 90 large-amplitude oscillations (LAOs), with velocities >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. Bibcode: 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. Bibcode: 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. Bibcode: 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 & 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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 <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. Bibcode: 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. Bibcode: 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. Bibcode: 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 http://www.aanda.org Title: Mass Flows in a Prominence Spine as Observed in EUV Authors: Kucera, T. A.; Gilbert, H. R.; Karpen, J. T. Bibcode: 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 Bibcode: 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. Bibcode: 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&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 Bibcode: 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. Bibcode: 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" (2013, ApJ, 777, 108) Authors: Schmieder, B.; Kucera, T. A.; Knizhnik, K.; Luna, M.; Lopez-Ariste, A.; Toot, D. Bibcode: 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 Bibcode: 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 Bibcode: 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 Bibcode: 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 Bibcode: 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 Bibcode: 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 Bibcode: 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 ~<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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 & Gibson 2011). Title: Comparing Spatial Distributions of Solar Prominence Mass Derived from Coronal Absorption Authors: Gilbert, Holly; Kilper, Gary; Alexander, David; Kucera, Therese Bibcode: 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 < λ < 911 Å), a second where both H0 and He0 are ionized (228 Å < λ < 504 Å), and finally at wavelengths where H0, He0, and He+ are all ionized (λ < 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 < 504 Å), and a line that ionizes only H (504 Å < λ < 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 < 50.4 nm), and a line that ionizes only H (50.4 nm < lambda < 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 < 504 Å), and a line that ionizes only H (504 Å < λ < 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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&T RTOP 432-03-52-17 Title: Thermal Properties of Prominence Motions as Observed in the UV Authors: Kucera, T. A.; Landi, E. Bibcode: 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 Bibcode: 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 Bibcode: 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 (<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. Bibcode: 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. Bibcode: 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. Bibcode: 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 >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 Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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&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. Bibcode: 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. Bibcode: 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&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 Bibcode: 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. Bibcode: 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. Bibcode: 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 & 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 (< 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 (>~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 >~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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 >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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 1993BAAS...25.1214K Altcode: No abstract at ADS Title: Observations and analysis of solar flares at radio and other wavelengths Authors: Kucera, Therese Ann Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 1991BAAS...23R1065K Altcode: No abstract at ADS 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. Bibcode: 1991BAAS...23.1043W 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. 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. Bibcode: 1988BAAS...20..976J Altcode: No abstract at ADS