THE ARIZONA RADIO OBSERVATORY CO MAPPING SURVEY OF GALACTIC MOLECULAR CLOUDS. III. THE SERPENS CLOUD IN CO J = 2-1 AND~13CO J = 2-1 EMISSION

摘要

We mapped ~12CO and ~13CO J = 2-1 emission over 1.04 deg2 of the Serpens molecular cloud with 38〃 spatial and 0.3 km s?1 spectral resolution using the Arizona Radio Observatory Heinrich Hertz Submillimeter Telescope. Our maps resolve kinematic properties for the entire Serpens cloud. We also compare our velocity moment maps with known positions of young stellar objects (YSOs) and 1.1 mm continuum emission. We find that 12CO is selfabsorbed and ~13CO is optically thick in the Serpens core. Outside of the Serpens core, gas appears in filamentary structures having LSR velocities which are blueshifted by up to 2 km s?1 relative to the 8 km s?1 systemic velocity of the Serpens cloud. We show that the known Class I, flat, and Class II YSOs in the Serpens core most likely formed at the same spatial location and have since drifted apart. The spatial and velocity structure of the ~12CO line ratios implies that a detailed three-dimensional radiative transfer model of the cloud will be necessary for full interpretation of our spectral data. The "starless cores" region of the cloud is likely to be the next site of star formation in Serpens.