Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Young Cluster in IC 1274   IC 1274 is a faintly luminous nebula lying on the near surface of the Lynds
227 (L227) molecular cloud. Four luminous, early-type (B0-B5) stars are located
within a spherical volume ~5' in diameter that appears to be clear of heavy
obscuration. Approximately centered in the cleared region is the B0 V star HD
166033, which is thought to be largely responsible for the cavity's excavation.
Over 80 H-alpha emission sources brighter than V~21 have been identified in the
region. More than half of these are concentrated in IC 1274 and are presumably
members of a faint T Tauri star population. Chandra Advanced CCD Imaging
Spectrometer (ACIS) imaging of a nearby suspected pulsar and time-variable
gamma-ray source (GeV J1809-2327) detected 21 X-ray sources in the cluster
vicinity, some of which are coincident with the early-type stars and H-alpha
emitters in IC 1274. Deep (V~22) optical BVRI photometry has been obtained for
the cluster region. A distance of 1.82 +/- 0.3 kpc and a mean extinction of Av
~1.21 +/- 0.2 mag follow from photometry of the early-type stars. Using
pre-main-sequence evolutionary models, we derive a median age for the H-alpha
emitters and X-ray sources of ~1 Myr; however, a significant dispersion is
present. Our interpretation of the structure of IC 1274 is that the early-type
stars formed recently and are in the process of dispersing the molecular gas on
the near surface of L227. The displaced material was driven against what
remains of the molecular cloud to the east, enabling the formation of the
substantial number of T Tauri stars found there. We identify a V~21.5 star very
near the position of X-ray source 5, the assumed gamma-ray source and young
pulsar candidate. The lack of distinctive characteristics for this source,
however, coupled with the density of faint stars in this region suggest that
this may be a random superposition.

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The categories of this paper are: plasm-ph
0
The categories of this paper are: hep-ph
27
The categories of this paper are: comp-gas
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The categories of this paper are: math-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: nucl-ex
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The categories of this paper are: math
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The categories of this paper are: acc-phys
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The categories of this paper are: gr-qc
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The categories of this paper are: mtrl-th
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The categories of this paper are: q-alg
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The categories of this paper are: funct-an
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The categories of this paper are: cs
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The categories of this paper are: dg-ga
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-ex