Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An X-ray Tour of Massive Star-forming Regions with Chandra   The Chandra X-ray Observatory is providing fascinating new views of massive
star-forming regions, revealing all stages in the life cycles of massive stars
and their effects on their surroundings. I present a Chandra tour of some of
the most famous of these regions: M17, NGC 3576, W3, Tr14 in Carina, and 30
Doradus. Chandra highlights the physical processes that characterize the lives
of these clusters, from the ionizing sources of ultracompact HII regions (W3)
to superbubbles so large that they shape our views of galaxies (30 Dor). X-ray
observations usually reveal hundreds of pre-main sequence (lower-mass) stars
accompanying the OB stars that power these great HII region complexes, although
in one case (W3 North) this population is mysteriously absent. The most massive
stars themselves are often anomalously hard X-ray emitters; this may be a new
indicator of close binarity. These complexes are sometimes suffused by soft
diffuse X-rays (M17, NGC 3576), signatures of multi-million-degree plasmas
created by fast O-star winds. In older regions we see the X-ray remains of the
deaths of massive stars that stayed close to their birthplaces (Tr14, 30 Dor),
exploding as cavity supernovae within the superbubbles that these clusters
created.

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The categories of this paper are: q-fin
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The categories of this paper are: econ
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The categories of this paper are: mtrl-th
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The categories of this paper are: math-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: nlin
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The categories of this paper are: cond-mat
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The categories of this paper are: gr-qc
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The categories of this paper are: cs
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The categories of this paper are: ao-sci
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The categories of this paper are: atom-ph
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The categories of this paper are: stat
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The categories of this paper are: funct-an
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The categories of this paper are: chem-ph