A Study of Environmental Influences on the Structure of Spiral Galaxy Disks.

Detailed photographic surface photometry has been performed on late-type spiral galaxies in the clusters Abell 426, Abell 1367, and Abell 2151. Surface brightness profiles obtained from the photometry are analyzed in terms of environmental parameters such as the projected distance from cluster center, projected distance to the nearest neighbor, and local projected galaxy density. Evidence for the modification of the structure of spiral galaxy disks is presented, with some qualitative discussion of the specific causes of the changes. Specifically, the galaxy parameters appear to be influenced by the distance to the nearest neighbor and the local projected galaxy density. Also, there appears to exist a systematic difference in surface brightness at a specific galactocentric distance between the spirals in Abell 1367 and Abell 2151. The elliptical and SO galaxies in these two clusters also exhibit a surface brightness difference, but the trend is in the opposite sense than the trend in the spirals.