Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Predicting Lyman-alpha and Mg II Fluxes from K and M Dwarfs Using GALEX
  Ultraviolet Photometry   A star's UV emission can greatly affect the atmospheric chemistry and
physical properties of closely orbiting planets with the potential for severe
mass loss. In particular, the Lyman-alpha emission line at 1216 Angstroms,
which dominates the far-ultraviolet spectrum, is a major source of
photodissociation of important atmospheric molecules such as water and methane.
The intrinsic flux of Lyman-alpha, however, cannot be directly measured due to
the absorption of neutral hydrogen in the interstellar medium and contamination
by geocoronal emission. To date, reconstruction of the intrinsic Lyman-alpha
line based on Hubble Space Telescope spectra has been accomplished for 46 FGKM
nearby stars, 28 of which have also been observed by the Galaxy Evolution
Explorer (GALEX). Our investigation provides a correlation between published
intrinsic Lyman-alpha and GALEX far- and near-ultraviolet chromospheric fluxes
for K and M stars. The negative correlations between the ratio of the
Lyman-alpha to the GALEX fluxes reveal how the relative strength of Lyman-alpha
compared to the broadband fluxes weakens as the FUV and NUV excess flux
increase. We also correlate GALEX fluxes with the strong near-ultraviolet Mg II
h+k spectral emission lines formed at lower chromospheric temperatures than
Lyman-alpha. The reported correlations provide estimates of intrinsic
Lyman-alpha and Mg II fluxes for the thousands of K and M stars in the archived
GALEX all-sky surveys. These will constrain new stellar upper-atmosphere models
for cool stars and provide realistic inputs to models describing exoplanetary
photochemistry and atmospheric evolution in the absence of ultraviolet
spectroscopy.

1
The categories of this paper are: cs
27
The categories of this paper are: comp-gas
11
The categories of this paper are: hep-lat
19
The categories of this paper are: eess
24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
7
The categories of this paper are: hep-th
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
23
The categories of this paper are: solv-int
20
The categories of this paper are: acc-phys
36
The categories of this paper are: cmp-lg
29
The categories of this paper are: funct-an
9
The categories of this paper are: nlin
16
The categories of this paper are: stat
0
The categories of this paper are: hep-ph