Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Mid-Infrared Imaging of Young Stellar Objects   We present arcsecond resolution mid-infrared (8--13 $\mu$m) images and
photometry of four young stellar objects (YSOs)~--- L1551-IRS5, HL~Tau, AS~205,
and AS~209 (V1121~Oph)~--- taken with the Berkeley Mid-Infrared Camera. For
AS~205, a known T Tauri binary, we also present near-infrared JHK images and
HKL$^{\prime}$ speckle imaging data. All three single stars are unresolved in
our mid-IR images. Our data is the first to resolve in the mid-IR both
components of the close binary AS~205 (projected separation $\sim$1.3$^{\prime
\prime}$ (210~A.U.)). AS~205~North is the IR brighter star in our data while
published observations find it to be the optically fainter star. Pre-main
sequence evolutionary models suggest the AS~205 system is non-coeval; we
discuss possible explanations for this result and comment on the circumstellar
material and evolutionary status of this young binary. Nearly all of our
objects exhibit changes in their mid-IR flux in measurements separated by
intervals of days up to many years; the variations range from 30--300\%. We
speculate that the cause of the variability lies in the accretion disks of
these objects; the data suggest disk accretion rate fluctuations of nearly an
order of magnitude. The existence of large mid-IR variability argues that
simultaneous multiwavelength observations are needed for a proper analysis of
YSO spectral energy distributions.

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The categories of this paper are: dg-ga
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The categories of this paper are: gr-qc
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The categories of this paper are: nlin
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The categories of this paper are: nucl-ex
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The categories of this paper are: cmp-lg
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The categories of this paper are: math
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The categories of this paper are: stat
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The categories of this paper are: cond-mat
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The categories of this paper are: econ
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The categories of this paper are: chem-ph
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The categories of this paper are: q-fin
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The categories of this paper are: acc-phys
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The categories of this paper are: hep-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: atom-ph
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The categories of this paper are: supr-con