Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Frequency of Mid-Infrared Excess Sources in Galactic Surveys   We have identified 230 Tycho-2 Spectral Catalog stars that exhibit 8 micron
mid-infrared extraphotospheric excesses in the MidCourse Space Experiment (MSX)
and Spitzer Space Telescope Galactic Legacy MidPlane Survey Extraordinaire
(GLIMPSE) surveys. Of these, 183 are either OB stars earlier than B8 in which
the excess plausibly arises from a thermal bremsstrahlung component or evolved
stars in which the excess may be explained by an atmospheric dust component.
The remaining 47 stars have spectral classifications B8 or later and appear to
be main sequence or late pre-main-sequence objects harboring circumstellar
disks. Six of the 47 stars exhibit multiple signatures characteristic of
pre-main-sequence circumstellar disks, including emission lines, near-infrared
K-band excesses, and X-ray emission. Approximately one-third of the remaining
41 sources have emission lines suggesting relative youth. Of the 25 GLIMPSE
stars with SST data at >24 microns, 20 also show an excess at 24 microns. Three
additional objects have 24 micron upper limits consistent with possible
excesses, and two objects have photospheric measurements at 24 microns. Six MSX
sources had a measurement at wavelengths >8 microns. We modeled the excesses in
26 stars having two or more measurements in excess of the expected photospheres
as single-component blackbodies. We determine probable disk temperatures and
fractional infrared luminosities in the range 191 < T < 787 and 3.9x10^-4 <
L_IR/L_* < 2.7x10^-1. We estimate a lower limit on the fraction of Tycho-2
Spectral Catalog main-sequence stars having mid-IR, but not near-IR, excesses
to be 1.0+-0.3%.

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The categories of this paper are: adap-org
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The categories of this paper are: atom-ph
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The categories of this paper are: math
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The categories of this paper are: eess
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The categories of this paper are: mtrl-th
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The categories of this paper are: comp-gas
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The categories of this paper are: nucl-th
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The categories of this paper are: dg-ga
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The categories of this paper are: plasm-ph
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The categories of this paper are: q-fin
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The categories of this paper are: chem-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: hep-lat
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The categories of this paper are: solv-int
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The categories of this paper are: math-ph
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The categories of this paper are: patt-sol