Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Chandra and Spitzer Imaging of the Infrared Cluster in NGC 2071   We present results of a sensitive Chandra X-ray observation and Spitzer
mid-IR observations of the infrared cluster lying north of the NGC 2071
reflection nebula in the Orion B molecular cloud. We focus on the dense cluster
core known as NGC 2071-IR which contains at least nine IR sources within a 40 x
40 arcsecond region. This region shows clear signs of active star formation
including powerful molecular outflows, Herbig-Haro objects, and both OH and H2O
masers. We use Spitzer IRAC images to aid in X-ray source identification and to
determine YSO classes using mid-IR colors. Spitzer IRAC colors show that the
luminous source IRS 1 is a class I protostar. IRS 1 is believed to be driving a
powerful bipolar molecular outflow and may be an embedded B-type star or its
progenitor. Its X-ray spectrum reveals a fluorescent Fe emission line at 6.4
keV, arising in cold material near the protostar. The line is present even in
the absence of large flares, raising questions about the nature of the ionizing
mechanism responsible for producing the 6.4 keV fluorescent line. Chandra also
detects X-ray sources at or near the positions of IRS 2, IRS 3, IRS 4, and IRS
6 and a variable X-ray source coincident with the radio source VLA 1, located
just 2 arcsec north of IRS 1. No IR data are yet available to determine a YSO
classification for VLA 1, but its high X-ray absorption shows that it is even
more deeply-embedded than IRS 1, suggesting that it could be an even younger,
less-evolved protostar.

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The categories of this paper are: stat
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The categories of this paper are: cmp-lg
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-th
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The categories of this paper are: q-fin
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The categories of this paper are: nucl-th
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The categories of this paper are: patt-sol
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The categories of this paper are: acc-phys
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The categories of this paper are: physics
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-ex
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The categories of this paper are: atom-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: dg-ga
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The categories of this paper are: alg-geom
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The categories of this paper are: gr-qc