Ammonia in the galactic halo and the infrared cirrus.
Abstract
The (J,K) = (1,1) transition of NH3 has been detected in the Draco Nebula (l,b = 89°.53, +38°.40; z ⪆ 500 pc) and in one or possibly two molecular clouds which are associated with the high latitude galactic infrared cirrus. The column density ratios for NH3 (10-8) and H2CO (10-7) are low and rather high, respectively, compared to typical ratios for the galactic disk. In spite of the corresponding uncertainties in estimating total hydrogen column densities, it appears likely that at least two of our three clouds are gravitationally bound or collapsing objects. They may therefore be the birth places for those Population I metallicity B-type stars in the galactic halo which cannot possibly have been borne in the galactic disk.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- June 1987
- Bibcode:
- 1987A&A...180..213M
- Keywords:
-
- Ammonia;
- Infrared Spectra;
- Milky Way Galaxy;
- Molecular Clouds;
- Nebulae;
- Star Formation;
- Astronomical Spectroscopy;
- B Stars;
- Gravitational Collapse;
- Line Spectra;
- Astrophysics