J/A+A/633/A147 FQS. Galactic Plane CO survey (Benedettini+, 2020)
The Forgotten Quadrant Survey.
12CO and 13CO (1-0) survey of the Galactic Plane in the range
220°<l<240°, -2.5°<b<0°.
Benedettini M., Molinari S., Baldeschi A., Beltran M.T., Brand J.,
Cesaroni R., Elia D., Fontani F., Merello M., Olmi L., Pezzuto S.,
Ryg K.L.J., Schisano E., Testi L., Traficante A.
<Astron. Astrophys. 633, A147 (2020)>
=2020A&A...633A.147B 2020A&A...633A.147B (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Photometry, millimetric/submm
Keywords: ISM: clouds - ISM: structure - ISM: kinematics and dynamics
Abstract:
We present the Forgotten Quadrant Survey (FQS), an ESO large project
that used the 12m antenna of the Arizona Radio Observatory to map the
Galactic Plane in the range 220°<l<240°, and
-2.5°<b<0°, both in 12CO(1-0), and 13CO(1-0), at a
spectral resolution of 0.65km/s and 0.26km/s. We used the (1-0)
transition of carbon monoxide to trace the molecular component of the
interstellar medium. Our data set allows us to easily identify how the
molecular dense gas is organised at different spatial scales: from the
giant clouds with their denser filamentary networks, down to the
clumps and cores that host the new-born stars and to obtain reliable
estimates of their key physical parameters such as size and mass. We
present the first release of the data of the FQS survey and discuss
their quality. Spectra with 0.65km/s velocity channels have noise
ranging from 0.8K to 1.3K for 12CO (1-0) and from 0.3K to 0.6K for
13CO (1-0). In this first paper, we used the 12CO (1-0) spectral
cubes to produce a catalogue of 263 molecular clouds. The clouds are
grouped in three main structures corresponding to the Local, Perseus,
and Outer arms up to a distance of ∼8.6kpc from the Sun. This is the
first self-consistent statistical catalogue of molecular clouds of the
outer Galaxy obtained with a subarcminute spatial resolution and
therefore able to detect not only the classical giant molecular
clouds, but also the small clouds and to resolve the cloud structure
at the sub-parsec scale up to a distance of a few kiloparsec. We found
two classes of objects: structures with sizes above a few parsecs that
are typical molecular clouds and may be self-gravitating, and
subparsec structures that cannot be in gravitational equilibrium and
are likely transient or confined by external pressure. We used the
ratio between the Herschel H2 column density and the integrated
intensity of the CO lines to calculate the CO conversion factor and we
found mean values of (3.3±1.4)x1020cm-2/(K.km/s) and
(1.2±0.4)x1021cm-2/(K.km/s), for 12CO (1-0) and 13CO (1-0),
respectively. FQS contributes to the general effort in producing a new
generation of high-quality spectroscopic data for the Galactic Plane
in the less studied third Galactic Quadrant, toward the outer Galaxy.
FQS has produced a data-set of great legacy value, largely improving
the data quality both in terms of sensitivity and spatial resolution
over previous data sets.
Description:
We used the 12CO (1-0) spectral cube 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 are provided in the file table1.dat
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 145 263 Properties of the molecular cloud catalogue
--------------------------------------------------------------------------------
See also:
http://fqs.iaps.inaf.it : FQS project public web page
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Index [1/263] Molecular cloud index
5- 23 A19 --- Name Name of the molecular cloud:
FQS-MCLLL.lll+B.bbb, with LLL.lll, +B.bbb
the Galactic longitude and latitude of the
cloud centroid
25- 32 F8.4 deg GLON Galactic longitude
34- 40 F7.4 deg GLAT Galactic latitude
42- 48 F7.2 arcsec major Intensity-weighted semi-major axis
50- 55 F6.2 arcsec minor Intensity-weighted semi-minor axis
57- 63 F7.2 deg PA [] Position angle w.r.t. the Galactic
longitude
65- 69 F5.2 km/s Vlsr LSR mean velocity
71- 74 F4.2 km/s sigma Velocity dispersion
76- 81 F6.3 K.km/s ICO 12CO (1-0) integrated intensity across the
area of the cloud
83- 90 F8.2 K.km/s.pc+2 LCO 12CO (1-0) total luminosity
92- 96 F5.3 kpc Dist Kinematic heliocentric distance
98-103 F6.3 pc Rad Equivalent circular radius
105-111 F7.2 pc+2 Area Area
113-121 F9.2 Msun Mass Mass
123-128 F6.2 Msun/pc+2 Sigma Average surface density
130-138 F9.2 --- alphavir Virial parameter
140-141 I2 --- nl Number of dendrogram leaves
143 I1 --- Flag1 [0/1]? Flag (1)
145 I1 --- Flag2 [0/2]? Flag (2)
--------------------------------------------------------------------------------
Note (1): Flag as follows:
0 = the cloud is fully mapped in the Herschel H2 column density map
1 = the area of the cloud as derived from the 12CO (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 surface density are
lower limits and the virial parameter is an upper limit
Note (2): Flag as follows:
0 = the cloud is fully mapped in 12CO (1-0)
2 = the area of the cloud as derived from the 12CO (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
--------------------------------------------------------------------------------
Acknowledgements:
Milena Benedettini, milena.benedettini(at)inaf.it
(End) Patricia Vannier [CDS] 03-Dec-2019