J/A+A/654/A144 13CO (1-0) data molecular cloud catalogue (Benedettini+, 2021)
Molecular cloud catalogue from 13CO (1-0) data
of the Forgotten Quadrant Survey.
Benedettini M., Traficante A., Olmi L., Pezzuto S., Baldeschi A.,
Molinari S., Elia D., Schisano E., Merello M., Fontani F., Rygl K.L.J.,
Brand J., Beltran M.T., Cesaroni R., Liu S.J., Testi L.
<Astron. Astrophys. 654, A144 (2021)>
=2021A&A...654A.144B 2021A&A...654A.144B (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Photometry, millimetric/submm
Keywords: ISM: clouds - ISM: structure - ISM: kinematics and dynamics
Abstract:
New-generation spectroscopic surveys of the Milky Way plane have been
revealing the structure of the interstellar medium, allowing the
simultaneous study of dense structures from single star-forming
objects or systems to entire spiral arms.
The good sensitivity of the new surveys and the development of
dedicated algorithms now enable building extensive catalogues of
molecular clouds and deriving good estimates of their physical
properties. This allows studying the behaviour of these properties
across the Galaxy.
We present the catalogue of molecular clouds extracted from the 13CO
(1-0) data cubes of the Forgotten Quadrant Survey, which mapped the
Galactic plane in the range 220°<l<240°, and
-2.5°<b<0° in 12CO (1-0) and 13CO (1-0). We compared the
properties of the clouds of our catalogue with those of other
catalogues.
The catalogue contains 87 molecular clouds for which the main physical
parameters such as area, mass, distance, velocity dispersion, and
virial parameter were derived. These structures are overall less
extended and less massive than the molecular clouds identified in the
12CO (1-0) data-set because they trace the brightest and densest
part of the 12CO (1-0) clouds. Conversely, the distribution of
aspect ratio, equivalent spherical radius, velocity dispersion, and
virial parameter in the two catalogues are similar. The mean value of
the mass surface density of molecular clouds is 87±55M☉/pc2
and is almost constant across the galactocentric radius, indicating
that this parameter, which is a proxy of star formation, is mostly
affected by local conditions.
In data of the Forgotten Quadrant Survey, we find a good agreement
between the total mass and velocity dispersion of the clouds derived
from 12CO (1-0) and 13CO (1-0). This is likely because in the
surveyed portion of the Galactic plane, the H2 column density is not
particularly high, leading to a CO emission with a not very high
optical depth. This mitigates the effects of the different line
opacities between the two tracers on the derived physical parameters.
This is a common feature in the outer Galaxy, but our result cannot be
readily generalised to the entire Milky Way because regions with
higher particle density could show a different behaviour.
Description:
We used the 13CO (1-0) spectral cube of the Forgotten Quadrant
Survey to extract a catalogue of molecular clouds by using the SCIMES
algorithm (Colombo et al., 2015MNRAS.454.2067C 2015MNRAS.454.2067C). A table of the
physical properties of the molecular clouds is provided.
Spectral cubes are available at
https://fqs.iaps.inaf.it/~fqs/RAWDATA/data/cubes_paper_1
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 145 87 Properties of the molecular cloud catalogue
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See also:
http://fqs.iaps.inaf.it : Forgotten Quadrant Survey Home Page
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Index [1/87] Molecular cloud index
3- 22 A20 --- Name Name of the molecular cloud (1)
24- 31 F8.4 deg GLON Galactic longitude
33- 39 F7.4 deg GLAT Galactic latitude
41- 47 F7.2 arcsec maj Intensity-weighted semi-major axis
49- 54 F6.2 arcsec min Intensity-weighted semi-minor axis
56- 62 F7.2 deg PA [] Position angle w.r.t. the
Galactic longitude
64- 68 F5.2 km/s Vlsr Mean velocity
70- 73 F4.2 km/s sigmav Velocity dispersion
75- 78 F4.2 K.km/s ICO 13CO(1-0) integrated intensity across the
area of the cloud
80- 84 F5.3 kpc d Kinematic heliocentric distance
86- 91 F6.3 pc R Equivalent circular radius
93- 98 F6.2 pc+2 A Area
100-107 F8.2 Msun M13CO Mass from 13CO column density
109-116 F8.2 Msun M12CO Mass from X(12CO)
118-125 F8.2 Msun MH2 Mass from Herschel H2 column density
127-132 F6.2 Msun/pc+2 Sigma Average mass surface density
134-138 F5.2 --- alphavir Virial parameter
140-141 I2 --- nl Number of dendrogram leaves
143 I1 --- flag1 [0/1]? Flag (2)
145 I1 --- flag2 [0/2]? Flag (3)
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Note (1): FQS-MC followed by Galactic longitude and latitude of the cloud
centroid, FQS-MCLLL.ll-B.bbb.
Note (2): Flag as follows:
0 = the cloud is fully mapped in the Herschel H2 column density map
1 = area of the cloud as derived from the 13CO(1-0) data is only partially
covered, or not covered at all, by the Herschel H2 column density map;
for those clouds the derived mass and mass surface density are lower
limits and the virial parameter α is an upper limit.
Note (3): Flag as follows:
0 = cloud is fully mapped in 13CO(1-0)
2 = area of the cloud as derived from the 13CO(1-0) touches the border of
the map; those clouds could extend outside the mapped area, therefore
the measured parameters suffer by an uncertainty that depends on how
much CO emission was missed
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Acknowledgements:
Milena Benedettini, milena.benedettini(at)inaf.it
(End) Patricia Vannier [CDS] 06-Sep-2021