Evolution and spiral structure of spiral galaxies.
Abstract
A density wave theory for slowly evolving galaxies is proposed in which the axisymmetric unsteady basic state is substituted for the usual axisymmetric steady basic state. The dispersion relationship, the conservation equation, and the energy equation are derived. It is shown that density waves can obtain energy through energy interchange with galactic differential motion. A distinction is made between trailing and leading waves which suggests a way to determine the trend of galactic evolution. For the Milky Way the expanding velocity in the solar vicinity is found to be less than or equal to 12 km/sec and the time-scale of the evolution is found to be approximately equal to or more than a billion years.
- Publication:
-
Scientia Sinica
- Pub Date:
- October 1979
- Bibcode:
- 1979SciSn..22.1185L
- Keywords:
-
- Density Wave Model;
- Galactic Evolution;
- Galactic Structure;
- Spiral Galaxies;
- Conservation Equations;
- Milky Way Galaxy;
- Astrophysics;
- Density Waves:Galaxies;
- Density Waves:Galaxy