J: Filaments and Prominences,
Tom Berger (12)

Last Updated Fri Dec 5 16:24:42 2008

1: Thomas Berger (berger@lmsal.com), Lockheed Martin Solar and Astophysics Lab [H]
[soi] I will chair the filament/prominence working group.
[poster]
2: Roberto Casini (casini@ucar.edu), HAO-NCAR [H]
[soi] magnetic-field diagnostics of chromospheric and prominence plasmas (theory/modeling/instrumentation)
[none]
3: Paulett Liewer (paulett.liewer@jpl.nasa.gov), JPL [F]
[soi] I am interested in filaments and CMEs and stereoscopy, epsecially with STEREO
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4: Yong Lin (yong.lin@astro.uio.no), Institute of Theoretical Astrophysics, University of Oslo [H]
[soi] I am interested in the magnetic structure of solar prominences/filaments. I have investigated this by using the high-resolution data obtained from the Swedish 1-m Solar Telescope (SST).
[poster] Swaying threads of solar filaments Yong Lin (1), Roberto Soler (2) and Oddbjorn Engvold (1)Abstract:Thin threads of solar filaments seen in high resolution with the Swedish 1-m Solar Telescope in La Palma are subject to swaying motions with periods of 2-4 minutes and amplitudes of 40-70 km, which are damped on time scale up ~3 periods. The nature of these oscillations is investigated via modeling of MHD waves in thread-like magnetic flux tubes. The model threads are uniformly filled with filament plasma, embedded in hot corona-like plasma and covered with a transversely changing, thin transition sheet. (1) Institute of Theoretical Astrophysics, University of Oslo, Norway(2) Departament de Fisica, Universitat de les Illes Balears, Palma de Mallorca, Spain
5: Duncan H Mackay (duncan@mcs.st-and.ac.uk), University of St Andrews [C]
[soi] Working Group J: Review Talk. Solar filaments are found over a wide range of latitudes and magnetic environments on the Sun. The talk will first review the magnetic environments in which filaments form and then discuss recent case studies of filament formation. The observations will then be compared to theoretical models of filament formation to determine which models are the most revelant.
[posternone] Where do Solar Filaments Form ? This paper examines the locations where large, stable solar filaments form relative to magnetic bipoles lying underneath them. The study extends the earlier work of F. Tang to include two additional classification categories for stable filaments and to consider their population during four distinct phases of the solar cycle. With this new classification scheme, results show that over 92% of filaments form in flux distributions that are non-bipolar in nature where the filament lies either fully (79%) or partially (13%) above a PIL external to any single bipole. Filaments which form within a single bipole (traditionally called Type-A) are not so common as previously thought. These results are a significant departure from those of F. Tang. We also demonstrate that only filaments which form along the external PIL lying between two bipoles (62% of the full sample, traditionally called Type-B) show any form of solar cycle dependence, where their number significantly increases with magnetic activity over the solar cycle.
6: Tetsuya Magara (t.magara@nao.ac.jp), Hinode Science Center, NAOJ [J]
[soi] I am interested in the magnetic structure of a prominence, especially for its formation and dynamic nature. I investigate these topics using MHD simulation.
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7: Sara F. Martin (sara@helioresearch.org), Helio Research [C]
[soi] My interest is in all stages of the build-up to CMEs, especially the long-term build-up including the development and evolution of filament channels, cancelling magnetic fields in the channels, and the formation, helicity and evolution of filaments, filament cavities, and their overlying coronal loops. My second interest is in the origin, observations and studies of the whole solar cycle.
[poster] We present a broad concept for the build-up to CMEs which will be tested in future observational and theoretical research. In this concept CME build-up consists of four linked stages of magnetic field evolution that ultimately lead to the triggering of a CME. These four stages are: (1) cancelling of magnetic fields along a polarity reversal boundary, (2) formation of a filament channel concurrent with the ascent of horizontal magnetic field into the chromosphere from cancellation sites, (3) thread-by-thread formation of a filament magnetic field and visible filament when the filament channel attains maximum development, (4) thread-by-thread building of the filament cavity magnetic field as mass drains from the visible threads thereby incrementally releasing filament magnetic field into the cavity magnetic field until the phase of rapid acceleration or until one of many possible triggering mechanisms initiates the phase of rapid acceleration of the CME. We acknowledge NSF grant ATM-0519249 which enabled the development of this concept.
8: Karin Muglach (kmuglach@gmx.de), NRL [F]
[soi] I can give a presentation on filament formation
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9: Olga Panasenco (OlgaPanasenco@aol.com), Helio Research [F]
[soi] (Statement of Interest for Working Group J)Build-up and maintenance of the filament enviro nment. Discuss how filament channels and filaments are essential to setting the stage of eruptive solar events.
[poster] (Poster Abstract For Working Group F: CMEs)Using SOHO/MDI, STEREO/SECCHI/EUVI, and various ground-based solar data, we study the history of the rapid development of a filament channel, filament and CME together with photospheric magnetic field changes in an active region AR 10956, with eruption on 2007 May 19. This example allows us to trace the cancelling of magnetic fields in association with changes in filament structures one day before the eruption. The evolution of a filament channel and filament with implied concurrent magnetic reconnection at the photosphere and chromosphere is a very important part of a concept for build-up to CMEs. (See also poster by Martin et al. 'A New Concept for the Long-Term Build-up to CMEs'.)
10: Susanna Parenti (s.parenti@oma.be), Royal Observatory of Belgium [G]
[soi] WG J: UV prominences observations: A review of some recent results for the properties of solar prominences obtained using UV data will be presented. These results were obtained from the first SOHO/SUMER spectral atlas, built for a prominence observed in October 8, 1999.The properties derived include density, Differential Emission Measure, non-thermal velocities. Such results will be compared to other recent results from literature to highlight similarities and disagreements.
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11: Pavol Schwartz (schwartz@asu.cas.cz), Astronomical Institute, Academy of Sciences of the Czech Republic [H]
[soi] We continue with the work presented in Heinzel et al. (2008), where we were estimating optical thickness in EUV and H_alpha using multi-wavelength observations of the prominence made on 2007 April 25. In our recent work presented in the poster we are analyzing multi-wavelength observations of prominences made from April 2007 till beginning of 2008. These observations were not planned as an observing campaign therefore it was hard for us to find simultaneous observations in different spectral ranges (optical, EUV and X-rays), suitable for estimation of values of the optical thickness of the prominence in EUV and the H_alpha. Observations in different spectral ranges are important also for estimation of density and ionization degree of prominence plasma (consisting mainly of hydrogen and helium) and finally for calculations of the mass loading of the prominence. Therefore we would like to propose multi-wavelength observing campaigns of prominences, filaments and surrounding coronal cavities using following space missions and ground-based instruments: SoHO, STEREO, TRACE, Hinode and HSFA2, MSDP spectrographs (Meudon, Themis, Bialkow - Poland). Our requirements for observations are as follows: For Hinode/EIS, SoHO/EIT and TRACE - we need observations in the 195 A bandpass but observations of EIT in 304 A bandpass would be also useful. The advantage of EIT is that it is observing in the full-disk so the pointing of the instrument is not necessary. Disadvantage - its spatial resolution is low (around 5 arcsec). TRACE has better spatial resolution (1 arcsec) but its FOV however is limited. STEREO/EUVI observations could be used for estimation of the 3D structure of the prominence/filament/cavity. XRT could take partial frame images or at least the full disk observations. The images should be taken with suitable exposure times and suitable focal plane analysis filter (mainly thinner) should be chosen for observations of the rather faint cavity around the prominence. SoHO/CDS would be observing in the EUV coronal line MgX 624 A. Wavelength of this line is below the head of the hydrogen Lyman continuum (912 A) but it is not far below so MgX radiation is efficiently absorbed by hydrogen plasma of the prominence/filament. Spatial resolution of the CDS is low (6 arcsec X 4 arcsec) so emission from areas of the prominence with different opacities could be mixed together in one pixel (see Appendix in Heinzel et al 2008). The SDO/EVE MEGS-B normal-incidence spectrograph is observing the MgX line as well. Can it make similar rasters as CDS but with better spatial resolution? HSFA2 spectrograph can make scans of the prominence in several diagnostically important lines simultaneously (including the H_alpha and CaII H and K lines) obtaining high-dispersion profiles. The MSDP can make 2D intensity maps at different wavelength positions of the H_alpha profile.
[poster] Title: XUV Prominences and Surrounding Cavities. In our recently published paper (Heinzel at al 2008) we presented a new method for estimation of the optical thickness at hydrogen Lyman continuum of the quiescent prominence from simultaneous multi-wavelength observations from space and ground: in EUV spectral range made by TRACE, Hinode/EIS and SoHO/CDS, in soft X-ray continuum by Hinode/XRT and in H alpha by Hinode/SOT and ground-based spectrographs MSDP in Meudon and HSFA2 in Ondrejov. Observations of the prominence and its cavity were made on 2007 April 25. The method takes into account two mechanisms responsible for an intensity depression of the coronal EUV line radiation at the prominence location (Anzer & Heinzel 2005): First one is the absorption by EUV continua of HI, HeI and HeII (for EUV lines below 912 A). Second one is the so-called coronal emissivity blocking by a cool prominence and its low-density cavity. In the EUV observations of TRACE and Hinode/EIS, both a very dark absorption feature of the prominence and the cavity surrounding it were visible. In the X-ray continuum only the cavity was visible because of no absorption by the prominence plasma in this spectral region. The novel approach of the method is that the amount of intensity depression in the cavity is almost the same (except for a constant factor) for both the EUV coronal lines and the X-ray continuum. Then additional depression of the intensities of EUV coronal lines at the prominence is due to the absorption only. From values of the optical thickness at the head of hydrogen Lyman continuum the column density of hydrogen was computed. It represents an important quantity for estimation of the mass loading of the prominence. In recent work we continue with the application of the method for other prominences observed simultaneously by SoHO/EIT, STEREO/EUVI, Hinode/XRT and HSFA2 from April 2007 till beginning of 2008. We included in the method also the asymmetrical distribution of the coronal emission and non-linear spatial averaging of the optical thickness estimated from EUV observations (both suggested in Heinzel et al. 2008). The results of presented work are crucial for answering questions of the nature and presence of the cavity and the mass loading of prominences.
12: Lawrence Sparks (sparks@jpl.nasa.gov), Jet Propulsion Laboratory [F]
[soi] I have been invited to give a presentation to the Filaments and Prominences working group
[none]

Second Choice

Stuart Bale, Rebecca Centeno, Tetsuya Magara, Susanna Parenti, Alexei Pevtsov, Nour-Eddine Raouafi, Kimberley Steed, Yingna Su, Adriaan Van Ballegooijen, Marco Velli, Yuming Wang, David Webb, Anthony Yeates,