J/A+A/655/A72 349 GHz ALMA observations of G023.01-00.41 (Sanna+, 2021)
Physical conditions in the warped accretion disk of a massive star. 349 GHz
ALMA observations of G023.01-00.41.
Sanna A., Giannetti A., Bonfand M., Moscadelli L., Kuiper R., Brand J.,
Cesaroni R., Caratti o Garatti A., Pillai T., Menten K.M.
<Astron. Astrophys. 655, A72 (2021)>
=2021A&A...655A..72S 2021A&A...655A..72S (SIMBAD/NED BibCode)
ADC_Keywords: Radio sources
Keywords: stars: formation - ISM: individual objects: G023.01-00.41 -
ISM: molecules - techniques: high angular resolution
Abstract:
Young massive stars warm up the large amount of gas and dust that
condenses in their vicinity, exciting a forest of lines from different
molecular species. Their line brightness is a diagnostic tool of the
gas's physical conditions locally, which we use to set constraints
on the environment where massive stars form. We made use of the
Atacama Large Millimeter/submillimeter Array at frequencies near
349GHz, with an angular resolution of 0.1", to observe the methyl
cyanide (CH3CN) emission which arises from the accretion disk of a
young massive star. We sample the disk midplane with twelve distinct
beams, where we get an independent measure of the gas's (and
dust's) physical conditions. The accretion disk extends above the
midplane, showing a double-armed spiral morphology projected onto the
plane of the sky, which we sample with ten additional beams: Along
these apparent spiral features, gas undergoes velocity gradients of
about 1km/s per 2000au. The gas temperature (T) rises symmetrically
along each side of the disk, from about 98K at 3000au to 289K at
250au, following a power law with radius R-0.43. The CH3CN column
density (N) increases from 9.2x1015cm-2 to 8.7x1017cm-2 at the
same radii, following a power law with radius R-1.8. In the
framework of a circular gaseous disk observed approximately edge-on,
we infer an H2 volume density in excess of 4.8x109cm-3 at a
distance of 250au from the star. We study the disk stability against
fragmentation following the methodology by Kratter et al.
(2010ApJ...708.1585K 2010ApJ...708.1585K), which is appropriate under rapid accretion, and
we show that the disk is marginally prone to fragmentation along its
whole extent.
Description:
We observed the star-forming region G023.01-00.41 with the 12m-array
of ALMA in band 7 (275-373GHz). Observations were conducted under
program 2016.1.01200.S on 2017 July 10 (Cycle 4) during a 3 hour run,
with precipitable water vapour of 0.35-0.38mm. The 12m-array observed
with 40 antennas covered a baseline range between 16m and 2647m and
achieved an angular resolution and maximum recoverable scale of
approximately 0.08" and 1.4", respectively.
ALMA datacube as described in Section 2 of the paper.
Objects:
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RA (2000) DE Designation(s)
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18 34 42.2 -09 00 41 G023.01-00.41 = MSX5C G023.0126-00.4177
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
349GHz_datacube.gdf 512 4078336 ALMA datacube
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Acknowledgements:
Alberto Sanna, alberto.sanna(at)inaf.it
(End) Alberto Sanna [OAC], Patricia Vannier [CDS] 16-Nov-2021