Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Mid-infrared observations of young stellar objects in the vicinity of
  sigma Orionis   We present new mid-infrared observations of objects in the vicinity of the
O-star sigma Orionis, obtained with TIMMI-2 at ESO. By constraining their near-
and mid-infrared spectral energy distributions, we established the nature of
previously known IRAS sources and identified new mid-infrared sources as young
stellar objects with circumstellar disks, likely massive members of the sigma
Ori cluster. For two of these objects we have obtained spectroscopy in the 8-13
micron range in order to investigate the chemistry of the dust grains. TX Ori
exhibits a typical silicate emission feature at 10 micron, with a feature at
about 11.2 micron that we identify as due to crystalline olivine. The IRAS
05358-0238 spectrum is very unusual, with a weak silicate feature and structure
in the range 10-12 micron that may be explained as due to self-absorbed
forsterite. We also provide the first evidence for the presence of
circumstellar disks in the jet sources Haro 5-39/HH 447, V510 Ori/HH 444 and
V603 Ori/HH 445.

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The categories of this paper are: patt-sol
28
The categories of this paper are: alg-geom
16
The categories of this paper are: stat
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci
7
The categories of this paper are: hep-th
15
The categories of this paper are: nucl-ex
2
The categories of this paper are: math
27
The categories of this paper are: comp-gas
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The categories of this paper are: nlin
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The categories of this paper are: solv-int
1
The categories of this paper are: cs
36
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: dg-ga
0
The categories of this paper are: hep-ph