J/ApJS/182/131 Molecular clouds and clumps in the GRS (Rathborne+, 2009)
Molecular clouds and clumps in the Boston University-Five College Radio
Astronomy Observatory Galactic Ring Survey.
Rathborne J.M., Johnson A.M., Jackson J.M., Shah R.Y., Simon R.
<Astrophys. J. Suppl. Ser., 182, 131-142 (2009)>
=2009ApJS..182..131R 2009ApJS..182..131R
ADC_Keywords: Molecular clouds ; Surveys ; Carbon monoxide
Keywords: catalogs - Galaxy: kinematics and dynamics - ISM: clouds
ISM: molecules - molecular data
Abstract:
The Boston University-Five College Radio Astronomy Observatory
(BU-FCRAO) Galactic Ring Survey (GRS) of 13CO J=1->0 emission
covers Galactic longitudes 18<l<55.7° and Galactic latitudes
|b|≤1°. Using the SEQUOIA array on the FCRAO 14m telescope, the
GRS fully sampled the 13CO Galactic emission (46" angular resolution
on a 22" grid) and achieved a spectral resolution of 0.21km/s. Because
the GRS uses 13CO, an optically thin tracer, rather than 12CO, an
optically thick tracer, the GRS allows a much better determination of
column density and also a cleaner separation of velocity components
along a line of sight. With this homogeneous, fully sampled survey of
13CO emission, we have identified 829 molecular clouds and 6124
clumps throughout the inner Galaxy using the CLUMPFIND algorithm.
Here we present details of the catalog and a preliminary analysis of
the properties of the molecular clouds and their clumps. Moreover,
we compare clouds inside and outside of the 5kpc ring and find that
clouds within the ring typically have warmer temperatures, higher
column densities, larger areas, and more clumps compared with clouds
located outside the ring. This is expected if these clouds are
actively forming stars. This catalog provides a useful tool for the
study of molecular clouds and their embedded young stellar objects.
Description:
The survey comprises a total of 1993522 spectra. The data are
available to the community at www.bu.edu/galacticring. For more
details of the telescope and instrumental parameters, see Jackson et
al., 2006ApJS..163..145J 2006ApJS..163..145J.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 105 829 Properties of the molecular clouds identified in
the Galactic Ring Survey
table3.dat 100 6124 Properties of the molecular clumps identified in
the Galactic Ring Survey
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See also:
J/ApJ/551/852 : FCRAO CO survey of the outer Galaxy (Heyer+, 2001)
J/ApJS/144/47 : Outer galaxy molecular cloud catalog (Brunt+, 2003)
J/PASJ/56/313 : 13CO survey of Mon + CMa molecular clouds (Kim+, 2004)
J/A+A/474/891 : 13CO observations of YSOs in South Gal. plane (Urquhart+, 2007)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- --- [GRSMC]
7- 19 A13 --- GRSMC Molecular cloud name (GLLL.ll+BB.bb) (1)
21- 25 F5.2 deg GLON Galactic longitude
27- 31 F5.2 deg GLAT Galactic latitude
33- 37 F5.1 km/s Vlsr Velocity of the peak voxel of the emission
39- 42 F4.2 km/s DeltaV Velocity FWHM (2)
44- 47 F4.2 K Tmb Main beam temperature of the peak voxel
49- 53 F5.2 deg GLONc Galactic longitude of centroid (3)
55- 59 F5.2 deg GLATc Galactic latitude of centroid (3)
61- 64 F4.2 deg a Semimajor axis of fitted ellipse (4)
66- 69 F4.2 deg b Semiminor axis of fitted ellipse (4)
71- 73 I3 deg pa [-90/90] Position angle of fitted ellipse (5)
75- 78 F4.2 deg2 Area Projected two-dimensional area
80- 83 F4.2 K Tav Average main beam temperature of the cloud (6)
85- 89 F5.1 K.km/s Ipeak Peak integrated intensity
91- 94 F4.2 K.km/s.deg2 Itot Total 13CO integrated intensity
96-102 E7.2 10+22cm-2 N(H2) Peak H2 column density
104-105 A2 --- Flag [YXV- ] Boundary flag(s) (G1)
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Note (1): Designated as GRSMC (for GRS Molecular Cloud) followed by the
Galactic longitude and latitude (l and b) coordinates of the peak of
the emission in degrees, e.g. GRSMC G053.59+00.04
Note (2): Defined as 2.35 times the velocity dispersion.
Note (3): Galactic coordinates of the centroid of the integrated intensity image
Note (4): Determined from the elliptical Gaussian fit to the integrated
intensity image.
Note (5): measured counter-clockwise from the positive longitude axis.
Note (6): Defined as the average main beam temperature of all the voxels.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- --- [GRSMC]
7- 19 A13 --- GRSMC Molecular cloud name (from the cloud catalog)
21- 24 A4 --- Clump Clump number (cNNN) (1)
26- 30 F5.2 deg GLON Galactic longitude of clump
32- 36 F5.2 deg GLAT Galactic latitude of clump
38- 42 F5.1 km/s Vlsr LSR velocity of the peak voxel of the emission
44- 47 F4.2 deg dLon FWHM extent in galactic longitude
49- 52 F4.2 deg dLat FWHM extent in galactic latitude
54- 57 F4.2 km/s dV FWHM extent in velocity
59- 63 F5.2 K Tmb Main beam temperature of the peak voxel
65- 72 E8.3 deg2 Area Projected two-dimensional area
74- 79 F6.2 K.km/s Ipeak Peak integrated intensity
81- 88 E8.3 K.km/s.deg2 Itot Total 13CO integrated intensity
90- 97 E8.3 cm-2 N(H2) Peak H2 column density
99-100 A2 --- Flag [XVY- ] Boundary flag(s) (G1)
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Note (1): in Simbad.
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Global notes:
Note (G1): Flag denoting if the cloud lies on one of the survey boundaries
as follows:
X = cloud lies on the boundary in Galactic longitude
Y = cloud lies on the boundary in Galactic latitude
V = cloud lies on the boundary in velocity
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History:
Copied at http://www.bu.edu/galacticring/molecular_clouds.html
(End) Emmanuelle Perret [CDS] 12-Jan-2010