Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Time-resolved Ultraviolet Spectroscopy of the M-dwarf GJ 876
  Exoplanetary System   Extrasolar planets orbiting M-stars may represent our best chance to discover
habitable worlds in the coming decade. The ultraviolet spectrum incident upon
both Earth-like and Jovian planets is critically important for proper modeling
of their atmospheric heating and chemistry. In order to provide more realistic
inputs for atmospheric models of planets orbiting low-mass stars, we present
new near- and far-ultraviolet (NUV and FUV) spectroscopy of the M-dwarf
exoplanet host GJ 876 (M4V). Using the COS and STIS spectrographs aboard the
Hubble Space Telescope, we have measured the 1150-3140A spectrum of GJ 876. We
have reconstructed the stellar HI LyA emission line profile, and find that the
integrated LyA flux is roughly equal to the rest of the integrated flux
(1150-1210A + 1220-3140A) in the entire ultraviolet bandpass (F(LyA)/F(FUV+NUV)
~0.7). This ratio is ~ 2500x greater than the solar value. We describe the
ultraviolet line spectrum and report surprisingly strong fluorescent emission
from hot H2 (T(H2) > 2000 K). We show the light-curve of a chromospheric +
transition region flare observed in several far-UV emission lines, with
flare/quiescent flux ratios >= 10. The strong FUV radiation field of an M-star
(and specifically LyA) is important for determining the abundance of O2 -- and
the formation of biomarkers -- in the lower atmospheres of Earth-like planets
in the habitable zones of low-mass stars.

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The categories of this paper are: adap-org
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The categories of this paper are: dg-ga
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The categories of this paper are: cs
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The categories of this paper are: alg-geom
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The categories of this paper are: bayes-an
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The categories of this paper are: gr-qc
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The categories of this paper are: math
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The categories of this paper are: acc-phys
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-ex
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The categories of this paper are: atom-ph
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The categories of this paper are: q-fin
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The categories of this paper are: nucl-th
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The categories of this paper are: math-ph
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The categories of this paper are: q-alg
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The categories of this paper are: plasm-ph