| Title | Studies of nearly face-on spiral galaxies. II. H I synthesis observations and optical surface photometry of NGC 628. |
| Authors | Shostak, G. S.; van der Kruit, P. C. |
| Bibcode | 1984A&A...132...20S Search ADS ↗ |
| Abstract | The authors present H I synthesis and three-colour optical surface photometry observations of the nearly face-on ScI spiral NGC 628 (M74). They deduce: (1) The H I is seen to be much more extended than the light distribution. (2) The H I shows spiral structure out to the edge of the observed extent and correlates in position with the optical spiral structure. (3) The velocity field out to the optical edge can be ascribed to circular rotation. (4) Beyond the optical edge the plane of the H I undergoes a smooth variation in inclination and a rather abrupt change of ≡90° in the line of nodes. (5) The H I velocity dispersion drops from 9 - 10 km s-1 in the inner region to about 7 - 8 km s-1 near the optical edge. It is correlated with surface density. (6) The disk has an exponential optical surface brightness profile in the three colours and a small or non-existent change in colour index. (7) Inside the edge 30 - 50% of the disk mass is in the form of H I. |
| Objects | 1 Objects Search NED ↙ |
