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

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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 1

1 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


H[FORMULA], Ly[FORMULA], Ly[FORMULA], CaII K and [FORMULA]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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© European Southern Observatory (ESO) 2000

Online publication: August 17, 2000