Astron. Astrophys. 355, 1146-1151 (2000)

Solar arch filaments observed with THEMIS ^*

P. Mein ¹, C. Briand ^2,1, P. Heinzel ³ and N. Mein <sup>1

1</sup> Observatoire de Paris, Section de Meudon, DASOP-LPSH, UMR 8645, 92195 Meudon Cedex, France
² Themis, IAC, Via Lactea, 38205 La Laguna, Tenerife, Spain
³ Astronomical Institute, Academy of Sciences of the Czech Republic, 25165 Ondejov, Czech Republic

Received 28 September 1999 / Accepted 22 December 1999

Abstract

Arch Filaments (AF) have been observed in the CaII 8542 Å line with the THEMIS telescope in September 1998. We present a preliminary analysis of MSDP spectro-imaging data. A cloud-model fit provides line-of-sight velocities and a set of plausible values for the model parameters. The high sensitivity of the filament opacity to temperature, coupled with the rough linearity versus electronic density, shows that this CaII line should be very efficient to complement usual H data for a more rigorous diagnostics.

Key words: Sun: chromosphere Sun: filaments line: profiles

* Based on observations made with the THEMIS telescope operated on the island of Tenerife by CNRS-CNR in the spanish Observatorio del Teide of the Instituto de Astrofisica de Canarias

Send offprint requests to: P. Mein (meinp@obspm.fr)

This article contains no SIMBAD objects.

Contents

• 1. Introduction
• 2. Spectro-imaging data: THEMIS and the MSDP spectrographs
• 3. CaII line profiles of arch filaments
• 4. CaII 8542 Å line formation in a dynamical cloud model
  • 4.1. Calcium atomic model
  • 4.2. Cloud geometry and incident radiation
• 5. Model of a typical arch filament
• 6. Sensitivity of line profiles to model parameters
• 7. Conclusions
• Acknowledgements
• References

© European Southern Observatory (ESO) 2000

Online publication: March 21, 2000
helpdesk.link@springer.de