Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Infrared Spectroscopy of U Equulei's Warm Circumstellar Gas   Medium and high resolution spectroscopy of U Equulei from 1 to 4 microns
during 1997-2003 has revealed information about its unusual circumstellar
envelope, observed previously at optical and radio wavelengths. Strong
absorption bands of H2O and of CO dominate the 1-4um spectrum. The gas has a
mean temperature of 600 K and 12C/13C =< 10. The CO 2-0 line profiles and
velocities imply no net ejection or infall and indicate either rapid radial gas
motions being seen along a narrow continuum beam, or absorption by orbiting gas
that is nearly coincident with a highly extended continuum source. The gas
could be located in a disk-like structure. The observed high column densities
of warm CO and H2 normally would be associated with sufficient dust to
completely obscure the star at optical wavelengths. The observations thus
indicate either a highly abnormal gas-to-dust ratio, consistent with the
earlier optical observation of abundant refractory metal oxides in the
circumstellar gas, or peculiar geometry and/or illumination.

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The categories of this paper are: physics
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The categories of this paper are: stat
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The categories of this paper are: q-fin
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The categories of this paper are: plasm-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: patt-sol
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The categories of this paper are: gr-qc
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The categories of this paper are: cond-mat
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The categories of this paper are: chem-ph
37
The categories of this paper are: supr-con
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The categories of this paper are: acc-phys
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The categories of this paper are: mtrl-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: q-bio
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The categories of this paper are: chao-dyn
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The categories of this paper are: adap-org