J/ApJ/883/156 Nobeyama 45m Cygnus-X CO. II. C180 clumps (Takekoshi+, 2019)
Nobeyama 45m Cygnus-X CO survey.
II. Physical properties of C18O clumps.
Takekoshi T., Fujita S., Nishimura A., Taniguchi K., Yamagishi M.,
Matsuo M., Ohashi S., Tokuda K., Minamidani T.
<Astrophys. J., 883, 156 (2019)>
=2019ApJ...883..156T 2019ApJ...883..156T
ADC_Keywords: Carbon monoxide; Interstellar medium; Surveys; Molecular data
Keywords: ISM: clouds ; ISM: individual objects (Cygnus X) ;
stars: luminosity function, mass function
Abstract:
We report the statistical physical properties of the C18O(J=1-0)
clumps present in a prominent cluster-forming region, Cygnus X, using
the data set obtained by the Nobeyama 45m radio telescope. This survey
covers 9deg2 of the northern and southern regions of Cygnus X, and,
in total, 174 C18O clumps are identified using the dendrogram
method. Assuming a distance of 1.4kpc, these clumps have radii of
0.2-1pc, velocity dispersions of <2.2km/s, gas masses of
30-3000M☉, and H2 densities of (0.2-5.5)x104cm-3. We
confirm that the C18O clumps in the northern region have a higher
H2 density than those in the southern region, supporting the
existence of a difference in the evolutionary stages, consistent with
the star-formation activity of these regions. The difference in the
clump properties of the star-forming and starless clumps is also
confirmed by the radius, velocity dispersion, gas mass, and H2
density. The average virial ratio of 0.3 supports that these clumps
are gravitationally bound. The C18O clump mass function shows two
spectral index components, α=-1.4 in 55-140M☉ and
α=-2.1 in >140M☉, which are consistent with the low- and
intermediate-mass parts of the Kroupa's initial mass function. The
spectral index of the star-forming clumps >140M☉ is consistent
with that of the starless clumps ranging from 55-140M☉,
suggesting that the latter will evolve into star-forming clumps while
retaining the gas accretion. Assuming a typical star-formation
efficiency of molecular clumps (10%), about 10 C18O clumps having a
gas mass of >103M☉ will evolve into open clusters containing
one or more OB stars.
Description:
The C18O (J=1-0) data of the Cygnus X region were obtained by the
FOREST receiver mounted on the Nobeyama 45m radio telescope, along
with the 12CO (J=1-0), 13CO (J=1-0), and CN (N=1-0) data. The
observations covered a ∼9deg2 field and the angular resolution of
the telescope was ∼16" FWHM at the C18O band.
The median rms noise level of the final C18O image Trms became
0.35K on the Tmb scale. See Section 2.1.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 98 174 C18O core catalog of the Cygnus-X survey
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See also:
J/ApJ/638/293 : 1.1mm sources in the Perseus Molecular Cloud (Enoch+, 2006)
J/A+A/462/L17 : Dense cores in interstellar molecular clouds (Alves+, 2007)
J/MNRAS/374/1413 : SCUBA survey of Orion (Nutter+, 2007)
J/ApJ/732/101 : C18O cores in the S140 cloud (Ikeda+, 2011)
J/AJ/148/11 : Infrared photometry in Cygnus-X (Kryukova+, 2014)
J/ApJS/217/7 : Orion A dense cores based on 1.1mm & C18O (Shimajiri+, 2015)
J/MNRAS/449/741 : The massive star population of Cygnus OB2 (Wright+, 2015)
J/A+A/592/A54 : Combined ArTeMiS+SPIRE 350um image of NGC6334 (Andre+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [1/174] Sequential object identifier
5- 11 F7.4 deg GLON [77.4/82.3] Peak galactic longitude,
decimal degrees
13- 19 F7.4 deg GLAT [-1.4/1.7] Peak galactic latitude,
decimal degrees
21- 26 F6.2 km/s Vpk [-30.2/16.2] Peak velocity
28- 31 F4.2 K TC18O [1.7/4.5] Peak C18O main beam temperature
33- 36 F4.2 K e_TC18O [0.3/0.7] Uncertainty in TC18O
38- 42 F5.2 K T12CO [5.7/40.7] Peak 12CO main beam
temperature
44- 47 F4.2 K e_T12CO [1.17/6.2] Uncertainty in T12CO
49- 53 F5.3 K.pc2.km/s IC18O [0.12/7.1] C18O integrated intensity,
K.pc2/km/s
55- 59 F5.3 K.pc2.km/s e_IC18O [0.013/0.71] Uncertainty in IC180
61- 64 F4.2 pc Rcl [0.23/1.43] Core radius
66- 70 F5.2 100Msun Mlte [0.3/35.1] LTE mass
72- 75 F4.2 10+4cm-3 nH2 [0.2/5.6] Mean density, hydrogen molecule
77- 80 F4.2 km/s dvcl [0.01/2.2] Intensity-weighted velocity
FWHM
82- 85 F4.2 100Msun Mvir [0.01/7.4] Virial mass
87 A1 --- SF? [Y ] Protostar
89- 96 A8 --- Region Region
98- 98 A1 --- Edge? [Y ] Map edge?
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 08-Mar-2021