HI rotation curves of spiral galaxies. I. NGC 3198.
Abstract
Observations of the spiral galaxy NGC 3198 in the 21 cm line using the Westerbork Synthesis Radio Telescope with an angular resolution of 25" x 35" are presented. The H I distribution extends to about two Holmberg radii and the radial velocity field is symmetric and regular over the entire area. A new method for the derivation of rotation curves is described. Results obtained show that the rotation curve of NGC 3198 is flat to within 5 km s^-1^ out to the last measured point at 11 disk lengths. This implies a large discrepancy between the observed rotation curve and that predicted from the light distribution.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- October 1989
- Bibcode:
- 1989A&A...223...47B
- Keywords:
-
- Galactic Rotation;
- H I Regions;
- Spiral Galaxies;
- Density Distribution;
- Hydrogen;
- Line Spectra;
- Optical Properties;
- Radio Telescopes;
- Velocity Distribution;
- Astrophysics