Does the Galaxy have four spiral arms ?
Abstract
The Georgelin and Georgelin (GG) spiral four-arm model for the Galaxy is examined. A two-arm density wave model is shown to predict an H II region in the same direction and with the same radial velocity as observed regions used by GG. Results of the two-arm model indicate that the GG kinematic distances differ from the model by more than a factor of two in 30% of the cases. The galactic rotation curve is also examined, and it is found that the rotation curve does not converge to the curve used in the GG model. Results suggest that the two-arm density wave model can adequately predict the observed locations and velocities of bright galactic H II regions.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 1981
- DOI:
- 10.1086/159401
- Bibcode:
- 1981ApJ...250..551B
- Keywords:
-
- Density Wave Model;
- Galactic Rotation;
- Galactic Structure;
- Milky Way Galaxy;
- Radial Velocity;
- Spiral Galaxies;
- Astronomical Models;
- Galactic Evolution;
- H Ii Regions;
- Hydrodynamics;
- Kinematics;
- Wave Propagation;
- Astrophysics