Multiline CO observations of MBM 32

Abstract

We present a detailed study of the high latitude cloud MBM 32. Observations were made in the , (2-1), and (3-2) transitions of 12 CO and in 13 CO(1-0) and (2-1). These data were complemented by 21 cm Hi data and by IRAS 60 and 100 μ m data. Our data show that MBM 32 consists of a main cloud component at km s-1 (mass about 16.9 ), and a smaller component at km s-1 (4.1 ), in addition to some emission in between those two velocities ( CO(CO(1-0) is lower in the cloud center. This suggests equal excitation conditions through MBM32 and line temperatures determined through clump filling factors. All CO components show associated Hi emission, but small velocity differences of typically 1 km s-1 exist between the Hi and CO gas. The mass of associated Hi gas is similar to the molecular mass for all components. There is a good correlation between FIR, CO, and Hi emission. The dust mass is about 0.073 , and the ratio of gas and dust mass (280) is lower than found from similar (IRAS) data for denser clouds, suggesting that the amount of dust colder than 20 K is relatively small. We subdivide the CO data cubes in Gaussian shaped clumps; 40-50% of the CO emission can be assigned to the larger clumps. The remaining emission comes from either more extended clumps or from overlapping unresolved clumps.