Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: ALMA reveals a candidate hot and compact disk around the O-type
  protostar IRAS 16547$-$4247   We present high angular resolution ($\sim$ 0.3$"$) submillimeter continuum
(0.85 mm) and line observations of the O-type protostar IRAS 16547$-$4247
carried out with the Atacama Large Millimeter/Submillimeter Array (ALMA). In
the 0.85 mm continuum band, the observations revealed two compact sources (with
a separation of 2$"$), one of them associated with IRAS 16547$-$4247, and the
other one to the west. Both sources are well resolved angularly, revealing a
clumpy structure. On the other hand, the line observations revealed a rich
variety of molecular species related to both continuum sources. In particular,
we found a large number of S-bearing molecules, such as the rare molecule
methyl mercaptan (CH$_3$SH). At scales larger than 10,000 AU, molecules (e.g.,
SO$_2$ or OCS) mostly with low excitation temperatures in the upper states
(E$_k$ $\lesssim$ 300 K) are present in both millimeter continuum sources, and
show a southeast-northwest velocity gradient of 7 km s$^{-1}$ over 3$"$ (165 km
s$^{-1}$ pc$^{-1}$). We suggest that this gradient probably is produced by the
thermal (free-free) jet emerging from this object with a similar orientation at
the base. At much smaller scales (about 1000 AU), molecules with high
excitation temperatures (E$_k$ $\gtrsim$ 500 K) are tracing a rotating
structure elongated perpendicular to the orientation of the thermal jet, which
we interpret as a candidate disk surrounding IRAS 16547$-$4247. The dynamical
mass corresponding to the velocity gradient of the candidate to disk is about
20 M$_\odot$, which is consistent with the bolometric luminosity of IRAS
16547$-$4247.

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The categories of this paper are: stat
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The categories of this paper are: nlin
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The categories of this paper are: supr-con
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-lat
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The categories of this paper are: hep-ex
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The categories of this paper are: nucl-th
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The categories of this paper are: mtrl-th
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The categories of this paper are: cond-mat
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The categories of this paper are: alg-geom
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The categories of this paper are: atom-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: eess
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The categories of this paper are: solv-int
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The categories of this paper are: q-alg
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The categories of this paper are: hep-ph