THE TROUBLE WITH HUBBLE TYPES IN THE VIRGO CLUSTER

Quantitative measures of central light concentration and star formatio n activity are derived from R and H alpha surface photometry of 84 bri ght S0-Scd Virgo Cluster and isolated spiral galaxies. For isolated sp irals, there is a good correlation between these two parameters and as signed Hubble types. In the Virgo Cluster, the correlation between cen tral light concentration and star formation activity is significantly weaker. Virgo Cluster spirals have systematically reduced global star formation with respect to isolated spirals, with severe reduction in t he outer disk, but normal or enhanced activity in the inner disk. Assi gned Hubble types are thus inadequate to describe the range in morphol ogies of bright Virgo Cluster spirals. In particular, spirals with red uced global star formation activity are often assigned misleading earl y-type spiral classifications, irrespective of their central light con centrations; 45% +/- 25% of the galaxies classified as Sa in the Virgo Cluster sample have central Light concentrations more characteristic of isolated Sb-Sc galaxies. The misleading classification of low-conce ntration galaxies with low star formation rates as early-type spirals may account for part of the excess of ''early-type'' spiral galaxies i n clusters. Thus, the morphology-density relationship is not all due t o a systematic increase in the bulge-to-disk ratio with environmental density.