J/ApJS/257/51 Morphological classif. of MWISP 12CO mol. clouds (Yuan+, 2021)
A morphological classification of 18190 molecular clouds identified in 12CO
data from the MWISP survey.
Yuan L., Yang J., Du F., Liu X., Zhang S., Lin Z., Sun J., Yan Q.-Z.,
Ma Y., Su Y., Sun Y., Zhou X.
<Astrophys. J. Suppl. Ser., 257, 51 (2021)>
=2021ApJS..257...51Y 2021ApJS..257...51Y
ADC_Keywords: Molecular clouds; Carbon monoxide; Morphology;
Interstellar medium; Milky Way; Surveys
Keywords: Interstellar medium ; Interstellar molecules ; Molecular clouds
Abstract:
We attempt to visually classify the morphologies of 18190 molecular
clouds, which are identified in the 12CO(1-0) spectral line data
over ∼450deg2 of the second Galactic quadrant from the Milky Way
Imaging Scroll Painting project. Using the velocity-integrated
intensity maps of the 12CO(1-0) emission, molecular clouds are first
divided into unresolved and resolved ones. The resolved clouds are
further classified as nonfilaments or filaments. Among the 18190
molecular clouds, ∼25% are unresolved, ∼64% are nonfilaments, and ∼11%
are filaments. In the terms of the integrated flux of 12CO(1-0)
spectra of all 18190 molecular clouds, ∼90% are from filaments, ∼9%
are from nonfilaments, and the remaining ∼1% are from unresolved
sources. Although nonfilaments are dominant in the number of the
discrete molecular clouds, filaments are the main contributor of
12CO emission flux. We also present the number distributions of the
physical parameters of the molecular clouds in our catalog, including
their angular sizes, velocity spans, peak intensities of 12CO(1-0)
emission, and 12CO(1-0) total fluxes. We find that there is a
systematic difference between the angular sizes of the nonfilaments
and filaments, with the filaments tending to have larger angular
scales. The H2 column densities of them are not significantly
different. We also discuss the observational effects, such as those
induced by the finite spatial resolution, beam dilution, and
line-of-sight projection, on the morphological classification of
molecular clouds in our sample.
Description:
In this paper, we focus on the unbiased catalog of molecular clouds in
the Galactic plane with 104.75°<l<150.25°,
-5.25°<b<5.25°, and -95km/s<VLSR<25km/s provided by the
Milky Way Imaging Scroll Painting (MWISP; Yan+ 2021A&A...645A.129Y 2021A&A...645A.129Y).
The ongoing unbiased Galactic plane CO survey MWISP is performed using
the 13.7m telescope of Purple Mountain Observatory (PMO) and observes
12CO, 13CO, and C18O (J=1-0) lines simultaneously
(Su+ 2019ApJS..240....9S 2019ApJS..240....9S).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 87 18190 A catalog of molecular clouds
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See also:
J/ApJS/196/18 : CO survey of galactic molecular clouds. II. (Bieging+, 2011)
J/AJ/142/71 : Proper motions and phot. of stars near NGC7380 (Chen+, 2011)
J/MNRAS/418/2121 : CO 3-2 observations of outflows in W5 (Ginsburg+, 2011)
J/A+A/554/A55 : C18O(1-0) and N2H+(1-0) in L1495/B213 (Hacar+, 2013)
J/A+A/550/A83 : NIR observations of CG1 and CG2 (Makela+, 2013)
J/ApJ/828/59 : Molecular clouds in the Milky Way with CO obs. (Su+, 2016)
J/MNRAS/456/2041 : Fragmentation in filamentary mol. clouds (Contreras+ 2016)
J/ApJS/224/7 : CO obs. of the outer arm in the 2nd quadrant (Du+, 2016)
J/ApJS/230/17 : CO obs. of MCs in the Extreme Outer Galaxy (Sun+, 2017)
J/ApJS/248/15 : CO obs. of mol. outflows in Cygnus complex (Zhang+, 2020)
J/ApJS/254/3 : CO obs. of molecular clouds in the MW midplane (Ma+, 2021)
http://www.radioast.nsdc.cn/mwisp.php : MWISP project home page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 22 A22 --- ID Identifier (GLLL.lll+BB.bbb-NNN.NN;
with NNN.NN=VLSR)
24- 30 F7.3 deg GLON [104.7/150.3] Central Galactic longitude (1)
32- 37 F6.3 deg GLAT [-5.3/5.3] Central Galactic latitude (1)
39- 44 F6.2 km/s VLSR [-95/20] Central Local Standard of Rest
velocity (2)
46- 53 F8.2 arcmin2 Area [1/60746] Angluar cloud area, projected
along the line of sight
55- 59 F5.2 km/s Vspan [0.5/43.42] Cloud cube velocity span (3)
61- 64 F4.1 K PInt [1.2/50.8] Peak 12CO(1-0) line intensity
66- 74 F9.2 K.km/s/arcmin2 Flux [0.5/390097] Integrated 12CO(1-0) flux (4)
76- 87 A12 --- Morph Morphology type (5)
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Note (1): Averaged Galactic coordinates in its velocity-integrated 12CO(1-0)
intensity map, weighting by the value of the velocity-integrated
12CO(1-0) intensity.
Note (2): Averaged radial velocity in its radial velocity field, weighting
by the value of the velocity-integrated 12CO(1-0) intensity.
Note (3): In the velocity axis of PPV space, which is calculated using the
number of velocity channels in the cloud cube multiplied by a velocity
resolution of 0.158 km/s.
Note (4): Where
Flux=Integral Tmb(l,b,v)dldbdv=0.167*0.25ΣTmb(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=0.5'*0.5'=0.25arcmin2, the angular size of a pixel is 0.5'.
Note (5): Morphology type as follows:
Filament = 2062 occurrences
Non-Filament = 11680 occurrences
Unresolved = 4448 occurrences
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History:
From electronic version of the journal
References:
Yuan et al. Paper II. 2022ApJS..261...37Y 2022ApJS..261...37Y Cat. J/ApJS/261/37
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 08-Mar-2022