Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spitzer-MIPS Observations of the eta Cha Young Association   We have mapped the eta Chamaeleontis young stellar association in the
far-infrared with the Multiband Imaging Photometer for Spitzer (MIPS) on the
Spitzer Space Telescope. All sixteen members within the map region were
detected at 24 um, along with five members at 70 um and two at 160 um. Ten
stars show far-infrared excess emission indicating the presence of
circumstellar disks; six of these have central clearings as evidenced by the
onset of excess emission at >5 um. No new infrared excess sources are
identified among the 113 2MASS field stars with 24 um photometry but not seen
as X-ray sources, indicating that membership lists derived from X-ray surveys
are reasonably complete. Circumstellar disks in the eta Cha association span
the range from 1e-1 to 1e-4 in their fractional infrared luminosity, with a
median Ldust /Lstar of 0.04. The presence of optically thick, optically thin,
and intermediate optical depth disks within the same stellar group, in
combination with the large fraction of disks with inner holes, indicates that
the Cha association represents a crucial stage in circumstellar disk evolution.

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The categories of this paper are: math
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The categories of this paper are: plasm-ph
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The categories of this paper are: hep-th
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The categories of this paper are: dg-ga
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The categories of this paper are: cmp-lg
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The categories of this paper are: bayes-an
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The categories of this paper are: supr-con
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The categories of this paper are: nucl-th
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The categories of this paper are: alg-geom
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The categories of this paper are: cond-mat
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The categories of this paper are: nlin
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The categories of this paper are: gr-qc
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The categories of this paper are: math-ph
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The categories of this paper are: adap-org
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The categories of this paper are: hep-ph
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The categories of this paper are: nucl-ex