Giant molecular clouds in the galaxy. II. Characteristics of discretefeatures.

The distribution of molecular clouds in the Galactic disk is investigated on the basis of 115.2712-GHz CO observations obtained using the 11-m NRAO and 14-m FCRAO antennas at half-power beamwidths 66 and 50 arcsec, respectively, during 1978-1980. The data, selected from the catalog of Solomon et al. (1984) and including 315 discrete emission features of chord greater than 10 pc, are presented in tables, maps, and graphs and characterized in detail. Findings presented include a correlation between the longitude and velocity of strong CO features and giant H II regions, a wider distribution of cooler clouds, a ringlike concentration of cloud number density at radius 4-8 kpc, and power-law relationships between cloud line width and size and between mean cloud density and size. A total of about 6000 giant molecular clouds of mass greater than 100,000 solar mass and diameter greater than 22 pc is found to contain about 85 percent of the H2 mass of the inner galaxy and to represent the largest interstellar-matter reservoir (about 3 x 10 to the 9th solar mass) in that region.