Astron. Astrophys. 360, 702-706 (2000)

Diagnostics of non-thermal processes in chromospheric flares

IV. Limb flare spectra for an atmosphere bombarded by an electron beam

C. Fang ^1,2, J.-C. Hénoux ² and M.D. Ding <sup>1

1</sup> Nanjing University, Department of Astronomy, Nanjing, P.R. China
² Observatoire de Paris, DASOP-UMR8645 (CNRS), 92195 Meudon Cedex, France

Received 8 June 1999 / Accepted 30 May 2000

Abstract

H, Ly, Ly, CaII K and 8542 Å   line profiles have been computed for limb flares with height distributions of temperatures as given by the semi-empirical models F₁ and F₂, by including the non-thermal collisional excitation and ionization of hydrogen and of ionized calcium that results from electron bombardment. In agreement with observations, the computed profiles of the hydrogen lines are very broad, especially at the height where the source function reaches its maximum. Non-thermal effects are less pronounced for CaII lines.

Key words: line: profiles radiation mechanisms: non-thermal Sun: flares

Send offprint requests to: C. Fang

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Contents

• 1. Introduction
• 2. Methodology
• 3. Numerical results
• 4. Discussion and conclusion
• Acknowledgements
• References

© European Southern Observatory (ESO) 2000

Online publication: August 17, 2000
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