Star counts and carbon monoxide observations of Maddalena's cloud

The inner region of Maddalena's cloud, a massive, cold object in the outer Galaxy has been mapped, in both (C-12)O and (C-13)O (J = 1-0) using the FCRAO 14 m telescope. The visual extinction has been determined by star counts and is used to investigate the gas and dust properties of the cloud. The results indicate that the (C-13)O column density to visual extinction ratio is similar to that found in local molecular clouds. This suggests that if the gas to dust ratio is normal, the CO abundance is similar to that of the clouds near the sun. The masses derived from the LTE and virial analyses differ by a factor of five; the virial analysis gives a mass five times larger than the LTE value. The structure and kinematics of the cloud inferred from the CO maps suggest that the inner region of the cloud may be expanding. Thus, both the kinematics of the cloud and the mass discrepancy suggest that this object may not be gravitationally bound. If it is assumed that the LTE mass to be correct, the ratio of molecular hydrogen column density to CO integrated intensity is much lower than that found for most GMCs in the inner Galaxy.