Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Class I methanol masers in the outflow of IRAS 16547-4247   The Australia Telescope Compact Array (ATCA) has been used to image class I
methanol masers at 9.9, 25 (a series from J=2 to J=9), 84, 95 and 104 GHz
located in the vicinity of IRAS 16547-4247 (G343.12-0.06), a luminous young
stellar object known to harbour a radio jet. The detected maser emission
consists of a cluster of 6 spots spread over an area of 30 arcsec. Five spots
were detected in only the 84- and 95-GHz transitions (for two spots the 84-GHz
detection is marginal), while the sixth spot shows activity in all 12 observed
transitions. We report the first interferometric observations of the rare 9.9-
and 104-GHz masers. It is shown that the spectra contain a very narrow spike
(<0.03 km/s) and the brightness temperature in these two transitions exceeds
5.3x10^7 and 2.0x10^4 K, respectively. The three most southern maser spots show
a clear association with the shocked gas traced by the H_2 2.12 micron emission
associated with the radio jet and their velocities are close to that of the
molecular core within which the jet is embedded. This fact supports the idea
that the class I masers reside in the interface regions of outflows. Comparison
with OH masers and infrared data reveals a potential discrepancy in the
expected evolutionary state. The presence of the OH masers usually means that
the source is evolved, but the infrared data suggest otherwise. The lack of any
class II methanol maser emission at 6.7 GHz in the source raises an additional
question, is this source too young or too old to have a 6.7 GHz maser? We argue
that both cases are possible and suggest that the evolutionary stage where the
class I masers are active, may last longer and start earlier than when the
class II masers are active. However, it is currently not possible to reveal the
exact evolutionary status of IRAS 16547-4247.

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The categories of this paper are: nucl-ex
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The categories of this paper are: q-bio
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-th
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The categories of this paper are: hep-lat
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The categories of this paper are: cmp-lg
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The categories of this paper are: econ
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The categories of this paper are: hep-ex
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The categories of this paper are: hep-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: solv-int
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The categories of this paper are: nucl-th
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The categories of this paper are: alg-geom
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The categories of this paper are: ao-sci
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The categories of this paper are: cond-mat
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The categories of this paper are: patt-sol