The distribution of dense H II regions in the inner Galaxy.
Abstract
The distribution of dense radio H II regions in the inner 100 deg of the galaxy is derived using kinematic models based on circular rotation and density-wave theory. A radio nebula is twice as likely to have an optical counterpart in the south as in the north, suggesting a preferential alignment of H II regions with respect to the obscuring matter. Southern nebulae are found to be within 3 kpc of the galactic center; northern nebulae extend inward only to 4 kpc. Kinematic models of the observed longitudes and velocities suggest that the nebulae are completely confined to a narrow pattern, much like a two-armed trailing spiral. The absence of dense nebulae from large areas of the galaxy that are well populated by H I and molecular clouds indicates that the formation of massive stars is not always a consequence of the presence of molecular clouds.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 1979
- DOI:
- 10.1086/157337
- Bibcode:
- 1979ApJ...232..761L
- Keywords:
-
- Dense Plasmas;
- Galactic Structure;
- H Ii Regions;
- Milky Way Galaxy;
- Nebulae;
- Radio Sources (Astronomy);
- Density Wave Model;
- Distribution (Property);
- Galactic Evolution;
- Galactic Nuclei;
- Kinematics;
- Radial Distribution;
- Radiant Flux Density;
- Astrophysics;
- Galactic Structure:H II Regions;
- H II Regions:Distribution;
- H II Regions:Kinematics;
- H II Regions:Radio Radiation