2007ApJS..171..478L

Forty molecular cloud cores in the southern hemisphere from the initial Spitzer Space Telescope Cores-to-Disks (c2d) Legacy program source list have been surveyed in ¹³CO(2⟶1), ¹²CO(4⟶3), and ¹²CO(7⟶6) with the Antarctic Submillimeter Telescope and Remote Observatory (AST/RO). The cores, 10 of which contain embedded sources, are located mostly in the Vela, Ophiuchus, Lupus, Chamaeleon, Musca, and Scorpius complexes. ¹²CO(7⟶6) emission was undetected in all 40 clouds. We present data of 40 sources in ¹³CO(2⟶1) and ¹²CO(4⟶3), significant upper limits of ¹²CO(7⟶6), as well as a statistical analysis of the observed properties of the clouds. We find the typical ¹³CO(2⟶1) line width to be 2.0 km/s for cores with embedded stars and 1.8 km/s for all others. The typical ¹²CO(4⟶3) line width is 2.6-3.7 km/s for cores with known embedded sources, and 1.6-2.3 km/s for all others. The average ¹³CO column density derived from the line intensities was found to be 1.9x10¹⁵/cm2 for cores with embedded stars and 1.5x10¹⁵/cm2 for all others. The average kinetic temperature in the molecular cores, determined through a large velocity gradient analysis of a set of nine cores, has an average lower limit of 16 K and an average upper limit of 26 K. The average molecular hydrogen density has an average lower limit of 10^2.9/cm3 and an average upper limit of 10^3.3/cm3 for all cores. For a different subset of nine cores, we have derived masses. They range from 4 to 255 M_☉. Overall, our c2d sample of southern molecular cores has a range of properties (line width, column density, size, mass, embedded stars) similar to those of past studies.