Radial Distributions of Massive Star Formation in Virgo Cluster and Isolated Spiral Galaxies
Session 43 -- HII Regions and Star Formation in Spirals
Display presentation, Thursday, January 13, 9:30-6:45, Salons I/II Room (Crystal Gateway)

## [43.03] Radial Distributions of Massive Star Formation in Virgo Cluster and Isolated Spiral Galaxies

R. A. Koopmann (Yale), J. D. P. Kenney (Yale)

Radial distributions of H$\alpha$ and R-band emission and optical rotation curves are presented for a sample of Virgo Cluster and isolated galaxies. These results are part of a study on the influence of dynamics and environment on star formation in cluster and isolated galaxies. We seek to explain why galaxies in the Virgo Cluster have less star formation than do isolated galaxies of the same type and size, and identify specific environmental process which alter galaxy morphology. Our approach is to describe quantitatively the rates and patterns of star formation in both isolated and cluster galaxies and identify the dominant dynamical influences which control them. Environmental signatures will then be sought by comparison of the cluster and isolated samples.

The radial distributions of star formation, as traced by the H$\alpha$ emission, and optical rotation curves are presented for 20 of our sample galaxies. Preliminary results show a good correlation between the predicted location of resonances and peaks and valleys in the radial patterns of star formation in several galaxies. Many HI-deficient galaxies near the cluster core have truncated star-forming disks.