Milky Way Molecular Clouds from CO Measurements

Milky Way Molecular Clouds from CO Measurements MWMC ivo://nasa.heasarc/mwmc NASA/GSFC HEASARC Miville-Deschenes et al. 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source This study presents a catalog of 8107 molecular clouds that covers the entire Galactic plane and includes 98% of the 12CO emission observed within b +/- 5 deg. The catalog was produced using a hierarchical cluster identification method applied to the result of a Gaussian decomposition of the Dame+ (2001ApJ...547..792D) data. The total H2 mass in the catalog is 1.2 x 109 Msun, in agreement with previous estimates. The authors find that 30% of the sight lines intersect only a single cloud, with another 25% intersecting only two clouds. The most probable cloud size is R~30pc. In contrast with the general idea, the authors find a rather large range of values of surface densities, Sigma = 2 to 300 Msun/pc2, and a systematic decrease with increasing Galactic radius, Rgal. The cloud velocity dispersion and the normalization sigma0 = sigmav / R1/2 both decrease systematically with Rgal. When studied over the whole Galactic disk, there is a large dispersion in the line width-size relation and a significantly better correlation between sigmav and SigmaR. The normalization of this correlation is constant to better than a factor of two for Rgal < 20kpc. This relation is used to disentangle the ambiguity between near and far kinematic distances. The authors report a strong variation of the turbulent energy injection rate. In the outer Galaxy it may be maintained by accretion through the disk and/or onto the clouds, but neither source can drive the 100 times higher cloud-averaged injection rate in the inner Galaxy. The data set used in this catalog come from that of Dame+ (2001ApJ...547..792D). Those authors combined observations obtained over a period of 20 yr with two telescopes, one in the north (first located in New York City and then moved to Cambridge, Massachusetts) and one in the south (Cerro Tololo, Chile). These 1.2m telescopes have an angular resolution of ~8.5' at 115GHz, the frequency of the 12CO 1-0 line. For the current study the authors used the data set covering the whole Galactic plane with +/- 5 deg in Galactic latitude. This table was created by the HEASARC in March 2019 based upon the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/834/57">CDS Catalog J/ApJ/834/57</a> file table1.dat. This is a service provided by NASA HEASARC . 2017ApJ...834...57M https://heasarc.gsfc.nasa.gov/W3Browse/all/mwmc.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=mwmc& GET text/xml 180 99999 true 195.04490461 -67.90146559 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=mwmc GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_mwmc&Action=More+Options&Action=Parameter+Search&ConeAdd=1 RADIO CATALOG 0.0166666666666667 Radio public mwmc Milky Way Molecular Clouds from CO Measurements name Source Designation meta.id;meta.main char nullable ra Right Ascension degree pos.eq.ra;meta.main double nullable dec Declination degree pos.eq.dec;meta.main double nullable "area" Angular Area degree^2 phys.angArea double nullable int_intensity Integrated CO Emission K.km/s spect.line.intensity;arith.sum double nullable nh2 Average Column Density cm^-2 phys.columnDensity double nullable surface_density Surface Density Solar_Mass/pc^2 phys.density double nullable radial_velocity Centroid Velocity km/s spect.dopplerVeloc double nullable velocity_dispersion Velocity Standard Deviation (Sigma_V_) km/s phys.veloc.dispersion double nullable "__x_ra_dec" System unit vector column double nullable "__y_ra_dec" System unit vector column double nullable "__z_ra_dec" System unit vector column double nullable "__row" System index column char nullable size_far Far-Derived Physical Size pc phys.size double nullable mass_near Near-Derived Mass Solar_Mass phys.mass double nullable bii Galactic Latitude degree pos.galactic.lat double nullable extent_upper Largest Eigenvalue of the Inertia Matrix degree phys.angSize;stat.max double nullable num_pixels Number of Pixels on the Sky meta.number short nullable distance_far Far Kinematic Distance kpc pos.distance double nullable galactic_plane_angle Angle with Respect to b=0 degree pos.posAng;pos.galactocentric double nullable mass_far Far-Derived Mass Solar_Mass phys.mass double nullable lii_error Uncertainty in Galactic Longitude degree stat.error;pos.galactic.lon double nullable surface_area_near Near-Derived Physical Area pc^2 phys.area double nullable size_near Near-Derived Physical Size pc phys.size double nullable distance_near Near Kinematic Distance kpc pos.distance double nullable bii_error Uncertainty in Galactic Latitude degree stat.error;pos.galactic.lat double nullable z_distance_near Near Distance to Galactic Mid-Plane kpc pos.cartesian.z;pos.galactocentric double nullable extent Angular Size degree phys.angSize double nullable lii Galactic Longitude degree pos.galactic.lon double nullable source_number Sequential Identification Number for Each Molecular Cloud in the Catalog meta.id;src short nullable extent_lower Smallest Eigenvalue of the Inertia Matrix degree phys.angSize;stat.min double nullable z_distance_far Far Distance to Galactic Mid-Plane kpc pos.cartesian.z;pos.galactocentric double nullable radial_distance Galactocentric Radius kpc pos.distance;pos.galactocentric double nullable surface_area_far Far-Derived Physical Area pc^2 phys.area double nullable num_components Number of Gaussian Components meta.number short nullable distance_flag Flag [01] Indicates Distance: 0=Near, 1=Far meta.code;pos.distance short nullable