Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: High Resolution HST-STIS Spectra of CI and CO in the Beta Pictoris
  Circumstellar Disk   High resolution FUV echelle spectra showing absorption features arising from
CI and CO gas in the Beta Pictoris circumstellar (CS) disk were obtained on
1997 December 6 and 19 using the Space Telescope Imaging Spectrograph (STIS).
An unsaturated spin-forbidden line of CI at 1613.376 A not previously seen in
spectra of Beta Pictoris was detected, allowing for an improved determination
of the column density of CI at zero velocity relative to the star (the stable
component), N = (2-4) x 10^{16} cm^{-2}. Variable components with multiple
velocities, which are the signatures of infalling bodies in the Beta Pictoris
CS disk, are observed in the CI 1561 A and 1657 A multiplets. Also seen for the
first time were two lines arising from the metastable singlet D level of
carbon, at 1931 A and 1463 A The results of analysis of the CO A-X (0-0),
(1-0), and (2-0) bands are presented, including the bands arising from {13}^CO,
with much better precision than has previously been possible, due to the very
high resolution provided by the STIS echelle gratings. Only stable CO gas is
observed, with a column density N(CO) = (6.3 +/- 0.3) x 10^{14} cm{-2}. An
unusual ratio of the column densities of {12}^CO to {13}^CO is found (R = 15
+/- 2). The large difference between the column densities of CI and CO
indicates that photodissociation of CO is not the primary source of CI gas in
the disk, contrary to previous suggestion.

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The categories of this paper are: cond-mat
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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: math-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: supr-con
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The categories of this paper are: quant-ph
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The categories of this paper are: funct-an
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The categories of this paper are: math
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The categories of this paper are: ao-sci
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-fin
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The categories of this paper are: cs
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The categories of this paper are: econ
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The categories of this paper are: adap-org
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The categories of this paper are: atom-ph