THE MOLECULAR GAS TOWARD CASSIOPEIA-A

Fully sampled 20'' resolution maps of Cassiopeia A in the J = 1 - 0 li ne of (CO)-C-13, and additional observations of the J = 1 - 0 and J = 2 - 1 lines of (CO)-C-12 and (CO)-C-13 are presented. From the peak (C O)-C-12 line intensity, the kinetic temperature of the molecular gas r eaches 20K. The warmest clouds are in the SE part of the region mapped . From the (CO)-C-13 data, there are at least eleven molecular clouds. Ten clouds are in the Perseus spiral arm, approximately 3. kpc from t he sun; one is in the solar neighborhood. For the Perseus arm clouds, a Large Velocity Gradient analysis of J = 2 - 1 and J = 1 - 0 lines of (CO)-C-13 gives H-2 densities less-than-or-equal-to 4000 cm-3. For th ese clouds, masses from CO data are significantly smaller than obtaine d from the virial theorem if only gravity is important; the clouds tow ard the SE of Cas A are closest to being bound. A comparison with OH, H2CO and NH3 absorption line maps shows a reasonable agreement of the positions of maxima; most interestingly a few OH clouds have only weak CO counterparts. From these data, relative abundances are obtained. T he atomic and CO content of the Perseus and Orion arm clouds is compar ed.