J/ApJ/723/492 Physical properties of GRS molecular clouds (Roman-Duval+, 2010)
Physical properties and Galactic distribution of molecular clouds identified in the Galactic Ring Survey. Roman-Duval J., Jackson J.M., Heyer M., Rathborne J., Simon R. <Astrophys. J., 723, 492-507 (2010)> =2010ApJ...723..492R
ADC_Keywords: Molecular clouds ; Milky Way ; Radio lines ; Surveys Keywords: Galaxy: structure - ISM: clouds - molecular data Abstract: We derive the physical properties of 580 molecular clouds based on their 12CO and 13CO line emission detected in the University of Massachusetts-Stony Brook (UMSB) and Galactic Ring surveys (GRS). We provide a range of values of the physical properties of molecular clouds, and find a power-law correlation between their radii and masses, suggesting that the fractal dimension of the interstellar medium is around 2.36. This relation, M=(228±18)R2.36±0.04, allows us to derive masses for an additional 170 Galactic Ring Survey (GRS) molecular clouds not covered by the UMSB survey. We derive the Galactic surface mass density of molecular gas and examine its spatial variations throughout the Galaxy. We find that the azimuthally averaged Galactic surface density of molecular gas peaks between Galactocentric radii of 4 and 5kpc. Although the Perseus arm is not detected in molecular gas, the Galactic surface density of molecular gas is enhanced along the positions of the Scutum-Crux and Sagittarius arms. Description: In this paper, we derive the physical properties (mass, radius, surface density, etc.) and the Galactic mass distribution of a sample of 750 molecular clouds identified in the GRS (Rathborne et al. 2009, Cat. J/ApJS/182/131), for which kinematic distances are available from Roman-Duval et al. (2009, Cat. J/ApJ/699/1153). The sample of molecular clouds used in this analysis was identified by their 13CO J=1->0 emission in the BU-FCRAO GRS (Jackson et al. 2006ApJS..163..145J). The GRS was conducted using the FCRAO 14m telescope in New Salem, Massachusetts between 1998 and 2005. We also make use of the 12CO University of Massachusetts-Stony Brook (UMSB) survey (Sanders et al. 1986ApJS...60....1S; Clemens et al. 1986ApJS...60..297C), a joint program between FCRAO and the State University of New York at Stony Brook performed between 1981 November and 1984 March. All of the observations were obtained using the FCRAO 14m telescope. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 94 749 Catalog of Molecular Cloud's Masses and Physical Properties
See also: J/ApJS/196/18 : CO survey of galactic molecular clouds. II. (Bieging+, 2011) J/MNRAS/410/1237 : Red MSX survey (RMS) massive young stars (Urquhart+, 2011) J/PASJ/62/557 : CO clouds in the GC from NANTEN (Takeuchi+, 2010) J/ApJ/699/1153 : Kinematic distances to GRS molecular clouds (Roman-Duval+, 2009) J/ApJS/182/131 : Molecular clouds and clumps in the GRS (Rathborne+, 2009) J/ApJ/672/930 : CO clouds in third Galactic quadrant (Vazquez+, 2008) J/PASJ/57/917 : CO molecular clouds in southern Galactic Warp (Nakagawa+, 2005) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 5 A5 --- --- [GRSMC] 7- 19 A13 --- GRSMC GRS [Galactic Ring Survey] molecular cloud name (G0LL.ll+0B.bb) 21- 25 F5.2 deg GLON Galactic longitude 27- 31 F5.2 deg GLAT Galactic latitude 33- 38 F6.2 km/s VLSR Local Standard of Rest velocity 40- 43 F4.2 km/s DelV Full-Width at Half-Maximum velocity dispersion 45- 48 F4.1 pc Rad Physical radius 50- 55 E6.2 Msun Mass Molecular cloud mass 57- 62 E6.2 Msun e_Mass Uncertainty in Mass 64- 69 F6.1 cm-3 nH2 Mean number density of H2 71- 74 F4.2 K Tex Mean excitation temperature 76- 79 F4.2 --- tau Mean 13CO center-of-line optical depth τ 81- 85 F5.1 Msun/pc2 Sigma Mean surface mass density of the cloud Σ 87- 92 F6.2 --- alpha Virial α parameter (1) 94 A1 --- Note [io] Cloud inside (i) or outside (o) the University of Massachusetts-Stony Brook (UMSB) Survey.
Note (1): α is defined as the ratio of the virial mass to the mass α=Mvir/M. This means that clouds having α>1 are not gravitionally bound.
Nomenclature note: Molecular clouds are <GRSMC LL.ll+B.bb> in the dictionary of nomenclature. History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 16-Jul-2012
|The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line|