J/A+A/684/A142 NH3 Observations of Cygnus X (Zhang+, 2024)
Surveys of clumps, cores, and condensations in Cygnus X.
Temperature and non-thermal velocity dispersion revealed by VLA NH3
observations.
Zhang X., Qiu K., Zhang Q., Cao Y., Cheng Y., Liu J., Wang Y., Lu X., Pan X.
<Astron. Astrophys. 684, A142 (2024)>
=2024A&A...684A.142Z 2024A&A...684A.142Z (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Velocity dispersion ; Radio lines
Keywords: stars: formation - stars: massive - ISM: kinematics and dynamics -
ISM: molecules
Abstract:
The physical properties, evolution, and fragmentation of
massive dense cores (MDCs, ∼0.1pc) are fundamental to the
understanding of high-mass star formation.
We aim at characterizing the temperature, velocity dispersion, and
fragmentation of the MDCs in the Cygnus X giant molecular cloud and to
investigate their stability and dynamics.
We present the Karl G. Jansky Very Large Array (VLA) observations of
the NH3 (J, K) = (1,1) and (2,2) inversion lines towards 35 MDCs in
Cygnus X, from which the temperature and velocity dispersion are
calculated. We extract 202 fragments (∼0.02pc) from the NH3 (1,1)
moment-0 maps with the GAUSSCLUMPS algorithm. The stability of the
MDCs and their NH3 fragments is analyzed through evaluating the
corresponding kinetic, gravitational potential, and magnetic energies
and the virial parameters.
The MDCs in Cygnus X have a typical mean kinetic temperature TK of
∼20K. Virial analysis shows that many MDCs are at sub-virialized
states, indicating that the kinetic energy is insufficient to support
these MDCs against their gravity. The calculated non-thermal velocity
dispersions of most MDCs are at transonic to mildly supersonic levels,
and the bulk motions only have a minor contribution to the velocity
dispersion. As for the NH3 fragments, with TK∼19K, their non-thermal
velocity dispersions are mostly trans- to sub-sonic. Unless there is a
strong magnetic field, most NH3 fragments are probably not at
virialized states. We also find that most of the NH3 fragments are
dynamically quiescent while only a few are active due to star
formation activity.
Description:
Physical parameters of the ammonia fragments.
Objects:
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RA (2000) DE Designation(s)
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20 30 04.79 +40 51 36.0 Cygnus X = 4FGL J2028.6+4110e
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablef1.dat 80 202 Physical parameters of the ammonia fragments
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See also:
J/A+A/241/551 : Radio continuum in Cygnus X region (Wendker+ 1991)
J/A+A/375/539 : JHK photometry of compact HII regions in Cyg X
(Comeron+, 2001)
J/A+A/407/1039 : X-ray power spectra of Cygnus X-1 (Pottschmidt+, 2003)
J/A+A/452/975 : Temporal variability of Cygnus X-1 (Axelsson+, 2006)
J/A+A/476/1243 : Millimeter continuum mapping of Cygnus X (Motte+, 2007)
J/A+A/527/A135 : Gas dynamics in Massive Dense Cores in Cygnus-X
J/ApJ/720/679 : Optical spectroscopy in Cygnus X region (Beerer+, 2010)
(Csengeri+, 2011)
J/ApJ/727/114 : BLAST 2005: a 10deg2 survey in Cygnus X (Roy+, 2011)
J/A+A/570/A1 : Cygnus-X CO and SiO outflows datacubes
(Duarte-Cabral+, 2014)
J/AJ/148/11 : Infrared photometry in Cygnus-X (Kryukova+, 2014)
J/MNRAS/458/3027 : Young and embedded clusters in Cygnus-X (Maia+, 2016)
J/ApJ/883/156 : Nobeyama 45m Cygnus-X CO. II. C180 clumps (Takekoshi+, 2019)
J/A+A/653/A108 : Globules and pillars in Cygnus X (Schneider+, 2021)
J/A+A/664/A88 : LOFAR 148MHz Cygnus X region image (Emig+, 2022)
Byte-by-byte Description of file: tablef1.dat
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Bytes Format Units Label Explanations
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1- 8 F8.4 deg RAdeg Right Ascension (J2000)
10- 16 F7.4 deg DEdeg Declination (J2000)
18- 21 F4.1 arcsec Maj Major axis
23- 26 F4.1 arcsec Min Minor axis
28- 33 F6.1 deg theta Position angle
35- 39 F5.3 pc Reff Effective radius
41- 45 F5.3 pc Rdec Deconvolved radius
47- 50 F4.1 K Tk Kinetic temperature
52- 55 F4.2 km/s sigmav Velocity dispersion
57- 60 F4.2 km/s vnt Nonthermal velocity dispersion
62- 65 F4.2 km/s vng Nonthermal velocity dispersion excluding
fitted bulk motions
67- 70 F4.2 --- MNT Mach number of vnt
72- 75 F4.2 --- Mng Mach number of vng
77- 80 F4.1 10+15cm-2 N(NH3) NH3 column density
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Acknowledgements:
Xu Zhang, xu.zhang.nju(at)gmail.com
(End) Patricia Vannier [CDS] 23-Feb-2024