Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Flare activity and photospheric analysis of Proxima Centauri   We present the analysis of emission lines in high-resolution optical spectra
of the planet-host star Proxima Centauri (Proxima) classified as a M5.5V\@. We
carry out the detailed analysis of observed spectra to get a better
understanding of the physical conditions of the atmosphere of this star. We
identify the emission lines in a serie series of 147 high-resolution optical
spectra of the star at different levels of activity and compare them with the
synthetic spectra computed over a wide spectral range. Our synthetic spectra
computed with the PHOENIX 2900/5.0/0.0 model atmosphere fits pretty well the
observed optical-to-near-infrared spectral energy distribution. However,
modelling strong atomic lines in the blue spectrum (3900--4200\AA{}) requires
implementing additional opacity. We show that high temperature layers in
Proxima Centauri consist in at least three emitting parts: a) a stellar
chromosphere where numerous emission lines form. We suggest that some emission
cores of strong absorption lines of metals form there; b) flare regions above
the chromosphere, where hydrogen Balmer lines up to high transition levels
(10--2) form; c) a stellar wind component with V${r}$\,=\,$-$30 \kmps{} seen in
some Balmer lines as blue shifted emission lines. We believe that the observed
He line at 4026\AA{} in emission can be formed in that very hot region. We
show, that real structure of the atmosphere of Proxima is rather complicated.
The photosphere of the star is best fit by a normal M5 dwarf spectrum. On the
other hand emission lines form in the chromosphere, flare regions and extended
hot envelope.

13
The categories of this paper are: quant-ph
3
The categories of this paper are: physics
9
The categories of this paper are: nlin
7
The categories of this paper are: hep-th
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
16
The categories of this paper are: stat
26
The categories of this paper are: bayes-an
14
The categories of this paper are: math-ph
25
The categories of this paper are: patt-sol
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn