Astron. Astrophys. Suppl. Ser.
Volume 144, Number 1, May II 2000
|Page(s)||123 - 140|
|Published online||15 May 2000|
Multiline CO observations of MBM 32 *
Radioastronomisches Institut, Universität Bonn, Auf dem Hügel 71, D-53121 Bonn, Germany
2 I. Physikalisches Institut, Universität zu Köln, Zülpicher Strasse 77, D-50937 Köln, Germany
Send offprint request to: J.G.A. Wouterloot, e-mail: email@example.com
Accepted: 2 February 2000
We present a detailed study of the high latitude cloud MBM 32. Observations were made in the , (2-1), and (3-2) transitions of 12CO and in 13CO(1-0) and (2-1). These data were complemented by 21 cm Hi data and by IRAS 60 and 100 μm 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 (<0.5 ). We study the gas distribution and the CO line ratios within MBM 32, the latter also along a cut through both cloud components. We find that the ratios of different rotational transitions are constant within each cloud part. Only the ratio 12CO(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.
Key words: ISM: clouds / ISM: individual objects: MBM 32 / ISM: molecules / radio lines: ISM
Tables 3 to 6 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (126.96.36.199) or via http://cdsweb.u-strasbg.fr/Abstract.html
© European Southern Observatory (ESO), 2000