Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The role of non-thermal electrons in the hydrogen and calcium lines of
  stellar flares   There is observational evidence showing that stellar and solar flares occur
in a similar circumstance, although the former are usually much more energetic.
It is expected that the bombardment by high energy electrons is one of the
chief heating processes of the flaring atmosphere. In this paper we study how a
precipitating electron beam can influence the line profiles of Ly_alpha,
H_alpha, Ca II K and Ca II 8542. We use a model atmosphere of a dMe star and
make non-LTE computations taking into account the non-thermal collisional rates
due to the electron beam. The results show that the four lines can be enhanced
to different extents. The relative enhancement increases with increasing
formation height of the lines. Varying the energy flux of the electron beam has
different effects on the four lines. The wings of Ly_alpha and H_alpha become
increasingly broad with the beam flux; change of the Ca II K and Ca II 8542
lines, however, is most significant in the line centre. Varying the electron
energy (i.e., the low-energy cut-off for a power law beam) has a great
influence on the Ly_alpha line, but little on the H_alpha and Ca II lines. An
electron beam of higher energy precipitates deeper, thus producing less
enhancement of the Ly_alpha line. The Ly_alpha/H_alpha flux ratio is thus
sensitive to the electron energy.

2
The categories of this paper are: math
28
The categories of this paper are: alg-geom
23
The categories of this paper are: solv-int
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
0
The categories of this paper are: hep-ph
24
The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
26
The categories of this paper are: bayes-an
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn