J/ApJS/261/37 13CO emission in the MWISP 12CO molecular clouds (Yuan+, 2022)
Molecular gas structures traced by 13CO emission in the 18190 12CO molecular
clouds from the MWISP survey.
Yuan L., Yang J., Du F., Su Y., Liu X., Zhang S., Sun Y., Zhou X.,
Yan Q.-Z., Ma Y.
<Astrophys. J. Suppl. Ser., 261, 37 (2022)>
=2022ApJS..261...37Y 2022ApJS..261...37Y
ADC_Keywords: Molecular clouds; Carbon monoxide; Interstellar medium; Surveys
Keywords: Interstellar medium ; Interstellar molecules ; Molecular clouds
Abstract:
After morphological classification of 18190 12CO molecular clouds,
we further investigate the properties of their internal molecular gas
structures traced by the 13CO (J=1-0) line emissions. Using three
different methods to extract the 13CO gas structures within each
12CO cloud, we find that ∼15% of the 12CO clouds (2851) have
13CO gas structures and these 12CO clouds contribute about 93% of
the total integrated flux of 12CO emission. In each of the
2851 12CO clouds with 13CO gas structures, the 13CO emission
area generally does not exceed 70% of the 12CO emission area, and
the 13CO integrated flux does not exceed 20% of the 12CO
integrated flux. We reveal a strong correlation between the
velocity-integrated intensities of 12CO lines and those of 13CO
lines in both 12CO and 13CO emission regions. This indicates the
H2 column densities of molecular clouds are crucial for the 13CO
line emission. After linking the 13CO structure detection rates of
the 18190 12CO molecular clouds to their morphologies, i.e.,
nonfilaments and filaments, we find that the 13CO gas structures are
primarily detected in 12CO clouds with filamentary morphologies.
Moreover, these filaments tend to harbor more than one 13CO
structure. That demonstrates filaments not only have larger spatial
scales, but also have more molecular gas structures traced by 13CO
lines, i.e., local gas density enhancements. Our results favor the
turbulent compression scenario for filament formation, in which
dynamical compression of turbulent flows induces local density
enhancements. The nonfilaments tend to be in the low-pressure and
quiescent turbulent environments of the diffuse interstellar medium.
Description:
The 13CO data is from the MWISP survey, which is an ongoing northern
Galactic plane CO survey. This survey is conducted by the 13.7m
telescope at Delingha, China.
As described in Yan+ (2021, J/ApJS/257/51), a total of 18190 available
molecular clouds have been identified from the 12CO data cube. In
Paper I, we completed the morphological classification for these
12CO molecular clouds, which are mainly classified into filaments
and nonfilaments. In this work, we aim to analyze the properties of
high column density gas traced by the 13CO line emission in these
molecular cloud samples.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 112 2851 A catalog of 12CO/13CO line emission parameters
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See also:
J/A+A/592/A54 : Combined ArTeMiS+SPIRE 350um image of NGC6334 (Andre+, 2016)
J/A+A/600/A141 : Orion A integral shaped filament image (Kainulainen+, 2017)
J/ApJ/858/90 : Radial profiles of 5 nearby galaxies (Gallagher+, 2018)
J/A+A/631/A72 : SABOCA 350um view of ATLASGAL massive clumps (Lin+, 2019)
J/A+A/638/A44 : Infrared dark cloud G28.3 HI and CI maps (Beuther+, 2020)
J/A+A/646/A170 : Serpens filament 13CO, C18O and C17O datacubes (Gong+, 2021)
J/A+A/645/A27 : Orion B in 18 molecular tracers maps (Gratier+, 2021)
J/ApJS/257/51 : Morphologies of MWISP 12CO mol. clouds (Yuan+, 2021)
J/A+A/660/A56 : NGC 6334 maps and CO velocity cubes (Arzoumanian+, 2022)
J/A+A/663/A56 : SEDIGISM: Molecular Cloud morphology I. (Neralwar+, 2022)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- ID [674/627890] Identifier number
8- 29 A22 --- Name Name (GLLL.lll+BB.bbb-VLSR)
31- 37 F7.3 deg GLON [104.79/150.2] Galactic longitude,
12CO intensity-weighted average
center (1)
39- 44 F6.3 deg GLAT [-5.11/5.3] Galactic latitude,
12CO intensity-weighted average
center (1)
46- 51 F6.2 km/s VLSR [-93.6/9] 12CO intensity-weighted
average central (LSR) velocity (2)
53- 60 F8.2 arcmin2 Area12CO [2/60746] Angular area, 12CO (1-0)
62- 66 F5.2 km/s Vspan12CO [0.8/43.5] Velocity span of
12CO(1-0) (3)
68- 72 F5.2 K Tpk12CO [2.4/51] Peak value of 12CO (1-0)
74- 82 F9.2 K.km/s/arcmin2 Flux12CO [3/390097] Integrated flux of
12CO(1-0) line emission (4)
84- 91 F8.2 arcmin2 Area13CO [1.2/13881] Angular area,
13CO(1-0)
93- 97 F5.2 km/s Vspan13CO [0.5/37.4] Velocity span
of 13CO(1-0) (3)
99- 103 F5.2 K Tpk13CO [0.6/16] Peak value of 13CO (1-0)
105- 112 F8.2 K.km/s/arcmin2 Flux13CO [0.3/39385] Integrated flux of
13CO(1-0) line emission (4)
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Note (1): The central Galactic coordinates for each 12CO cloud are the
averaged Galactic coordinates in its velocity-integrated intensity 12CO
map, weighting by the value of the velocity-integrated 12CO intensity.
Note (2): The central velocity (VLSR) for each cloud is the averaged radial
velocity in its radial velocity field, weighting by the value of the
velocity-integrated 12CO intensity.
Note (3): Vspan represents the velocity span of each cloud cube in the
velocity axis of PPV space, which is calculated using the number of
velocity channels in the 12CO cloud cube multiplied by a velocity
resolution of 0.167km/s. The Vspan,13CO is the velocity range between
the maximal and minimal velocity for all the extracted 13CO gas
structures within each 12CO molecular cloud.
Note (4): The Flux12CO is the integrated flux of 12CO(1-0) line emission for
each cloud, F12CO=
integral(Tmb(l,b,v)dldbdv)=0.167*0.25Σ(Tmb)(l,b,v)K.km/s.arcmin2,
where Tmb(l,b,v) is the 12CO line intensity at the coordinate of
(l,b,v) in PPV space, dv=0.167km/s is the velocity resolution,
dldb=0.5arcmin*0.5arcmin=0.25arcmin2, the angular size of a pixel is
0.5 arcmin. The F13CO is calculated using the 13CO(1-0) line
emission within each cloud through the same formula, but Tmb(l,b,v) is
the 13CO line intensity.
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History:
From electronic version of the journal
References:
Yuan et al. Paper I. 2021ApJS..257...51Y 2021ApJS..257...51Y Cat. J/ApJS/257/51
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 30-Sep-2022