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Astron. Astrophys. 330, 351-358 (1998)

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Non-thermal hydrogen line emission caused
by an oblique incident proton beam through charge exchange

X. Zhao 1, C. Fang 1, 2 and J.-C. Hénoux 2

1 Department of Astronomy, Nanjing University, Nanjing, P.R. China
2 Observatoire de Paris, DASOP, CNRS-URA 2080, Meudon, France

Received 4 August 1997 / Accepted 18 September 1997


In this paper, formulae are given for computing the non-thermal emission of superthermal hydrogen atoms generated through charge exchange by the bombardment of the solar atmosphere by an oblique incident proton beam with a given pitch angle. Specifically, we discuss the non-thermal emission of hydrogen in Ly [FORMULA], Ly [FORMULA], and H [FORMULA] lines and find that the profiles of these lines are quite different from the ones caused by bombardment by a proton beam moving vertically. The intensity and the asymmetry of the non-thermal emission profiles strongly depend on the beam pitch angle [FORMULA] and on the angle [FORMULA] between the direction of magnetic field and the line of sight. By computing the thermal emission under the semi-empirical flare atmospheric models F1, F2, and the quiet-Sun atmospheric model C, we compare the relative importance of thermal and non-thermal emission. For the H [FORMULA] line, the non-thermal emission, with the proton flux used, is too small to be detectable; for the Ly [FORMULA] line, the contribution of non-thermal emission to the line wings is smaller than the one of a vertical beam; while for the Ly [FORMULA] line, line wing enhancement and broadening are significant. Thus, Ly [FORMULA] line is a good diagnostic tool for non-thermal proton beam bombardment.

Key words: line: profiles – atomic processes – Sun: flares

Send offprint requests to: J.-C. Hénoux

© European Southern Observatory (ESO) 1998

Online publication: January 8, 1998