The structure of Gould's Belt.
Abstract
Observations of a section of Gould's Belt, extending from 300 to 12 deg galactic longitude, in the 21-cm line of neutral hydrogen are analyzed. It is found that the mean plane of the gas layer is about 3 deg of latitude below the optical equator and that two strong concentrations of neutral hydrogen are associated with the Sco OB2 association and the Lupus section of the Sco-Cen association. A plane self-gravitating model is applied to the data, and a mean total density of 0.23 solar mass per cu pc in the plane of the Belt is obtained. A total mass of 7.3 million solar masses is estimated, of which about 7% is in the form of neutral hydrogen. The hydrogen content in the Lupus gas concentration is estimated to be about 14%, which may indicate that star formation is less advanced in the Lupus section and may still be continuing. The dynamics of the gas layer is examined, and rotation of the Belt is suggested. A scenario for the origin of Gould's Belt is outlined which involves the collapse of a large clump of gas in the Carina spiral arm into a self-gravitating disk as a consequence of the passage of a spiral shock wave about 50 million years ago.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- January 1979
- Bibcode:
- 1979A&A....71..319S
- Keywords:
-
- Cosmic Dust;
- Interstellar Gas;
- Radio Sources (Astronomy);
- Star Clusters;
- Astronomical Maps;
- B Stars;
- Hydrogen Clouds;
- Neutral Gases;
- O Stars;
- Astrophysics;
- Gould's Belt:Gas Dynamics;
- Gould's Belt:Models