Determination of the 3D structure of an EUV-filament observed by SoHO/CDS, SoHO/SUMER and VTT/MSDP

P. Schwartz (1) , Petr Heinzel (1) , U. Anzer (2) , Brigitte Schmieder (3, 4, 5)

1 Astronomical Institute, Academy of Sciences
2 MPA - Max-Planck-Institut für Astrophysik
3 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique
4 Physique solaire
5 UiO - University of Oslo

Heinzel et al. (\cite{hein1}) found that filaments seem to be much more extended in EUV spectral lines than in Halpha. In this paper we reconstruct the 3D structure of the extensions of the EUV-filament observed on 15 October 1999 by SoHO/CDS and SoHO/SUMER. Small Halpha structures were observed by VTT/MSDP. We computed the bottom and top heights of the EUV-filament extensions for several values of the hydrogen Lyman-continuum optical thickness tau₉₁₂ using the spectroscopic model of Heinzel et al. (\cite{hein2}). For this we used CDS observations of the two coronal lines Mg X 624.94 Å and Si XII 520.60 Å. Further, we develop a new method for estimating tau₉₁₂ using the O V line measured by CDS and the O VI measured by SUMER onboard SoHO. The latter line is used as a proxy to deduce the intensity variations of O V underneath the filament. This method also takes into account the presence of prominence-corona transition regions.

Domaines: Astrophysique [astro-ph]

P. Schwartz, Petr Heinzel, U. Anzer, Brigitte Schmieder. Determination of the 3D structure of an EUV-filament observed by SoHO/CDS, SoHO/SUMER and VTT/MSDP. Astronomy and Astrophysics - A&A, 2004, 421, pp.323-338. ⟨10.1051/0004-6361:20034199⟩. ⟨hal-03785320⟩