21-cm line studies of spiral galaxies. I. Observations of the galaxies NGC 5033, 3198, 5055, 2841, and 7331.
Abstract
We have mapped the galaxies NGC 5033, 3198, 5055, 2841, and 7331 in the 21-cm line with angular resolutions such that the ratio radius/beam size is of order 5-10. For four of the five galaxies we find that both the H I distribution and the velocity field cannot be described by the simple picture of a spiral having an axisymmetric disk in differential rotation. For those four galaxies we show that the main deviations from circular motion can be described by a warping of the plane at large radii. The determination of the mass distributions for these galaxies is severely compromised by this. For all galaxies we find asymmetries in the H I distribution, and for most of them there are H I clouds in the outer parts which do not coincide with optical features. NGC 5055 and NGC 2841 have H I disks extending 2 and 2.5 times as far as the Holmberg radius. NGC 3198, NGC 2841, and NGC 7331 have a depression in the H I distribution in the central parts.
- Publication:
-
The Astronomical Journal
- Pub Date:
- December 1981
- DOI:
- 10.1086/113062
- Bibcode:
- 1981AJ.....86.1791B
- Keywords:
-
- Astronomical Maps;
- Hydrogen;
- Kinematics;
- Line Spectra;
- Neutral Gases;
- Radio Galaxies;
- Spiral Galaxies;
- Angular Resolution;
- Astronomical Models;
- Contours;
- Data Processing;
- Mass Distribution;
- Radial Velocity;
- Radio Telescopes;
- Astronomy;
- Neutral Hydrogen:Spiral Galaxies;
- Rotation:Spiral Galaxies;
- Spiral Galaxies:Mass Distribution