On the structure of interstellar matter III. Density wave kinematics and spiral structure in neutral hydrogen gas.
Abstract
An operational definition for interstellar clouds is given which permits a separation of the 21-cm cloud radiation from that of the intercloud medium, called stratum here, to be made even for galactic plane regions. The cloud radiation includes the emission from the fluctuating part of the interstellar gas density field and variations of the line profiles produced by small scale velocity field fluctuations, while the stratum radiation contains the large scale density variation and all large scale velocity field effects. The velocity field therefore can be determined by investigating stratum line profiles. An explicit discussion of such an analysis is given.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- October 1974
- Bibcode:
- 1974A&A....35..177R
- Keywords:
-
- Density Distribution;
- Galactic Structure;
- Hydrogen Clouds;
- Interstellar Matter;
- Microwave Emission;
- Emission Spectra;
- Gas Density;
- Interstellar Gas;
- Spiral Galaxies;
- Velocity Distribution;
- Wave Propagation;
- Astrophysics