A density-wave map of the galactic spiral structure.
Abstract
Summary. The large-scale spiral structure is mapped by constructing a model based on density-wave kinematics that reproduces the main features of the 21-cm H I observations. The map shows a basically two-armed spiral pattern with a pitch angle of 6 80 between the 4-kpc dispersion ring and the solar circle. Near the solar circle, two additional major arms originate, and the pattern outside is multiple-armed, with pitch angles of 160. Comparison of the gas flow in both a linear and a shock solution shows that the shock model gives a better representation of the tangential directions of spiral arms. Comparison with two more open models favors the tightly-wound pattern found here. A synthetic photograph of the Galaxy is produced from the model. Key words: galactic structure - 21-cm radiation spiral density waves
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- January 1976
- Bibcode:
- 1976A&A....46..261S
- Keywords:
-
- Density Wave Model;
- Galactic Structure;
- H Lines;
- Spiral Galaxies;
- Astronomical Maps;
- Computer Graphics;
- Flow Velocity;
- Optical Thickness;
- Shock Waves;
- Astrophysics