The Effects of Environment on Mass and Light in Spiral Galaxies : A Study of 17 Nearby Clusters

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Session 106 -- Galaxies: Photometry and Spectrophotometry
Display presentation, Thursday, 12, 1995, 9:20am - 6:30pm

[106.10] The Effects of Environment on Mass and Light in Spiral Galaxies : A Study of 17 Nearby Clusters

Nicole P. Vogt (University of California, Santa Cruz), Martha P. Haynes, Terry Herter (Cornell University)

A survey of 330 nearby galaxies (z $<$ 0.045) has been conducted to resolve the conflicting results of previous studies concerning the distribution of mass and light of galaxies within differing cluster environments. I-band images are deconvolved into disk and bulge luminosity profiles by modelling the major axis profiles as the product of two discrete ellipsoidal components. A series of nine mass models constraining light and dark matter in varied ways are then fit to combined H$\alpha$ and [NII] rotation curves; the ``maximum disk'' models in particular are found to define the stellar mass-to-light ratios in a uniform and representative fashion. HI line profiles provide an equivalent velocity width measurement, and serve as a valuable measure of HI deficiency, particularly for gas-poor objects in cluster cores. The gradient of the velocity profile and terminal velocity point are evaluated relative to the limiting surface brightness of the galaxy image and as a function of disk scale length, and a search is made for variations which correlate with HI deficiencies. A comparison of galaxies within and beyond the Abell radius provides information on the dependence on cluster density. The cluster environment has little effect for the general population upon the stellar mass distributions, and thus significant bias is not introduced by using cluster populations for velocity derivative distance estimations via the Tully-Fisher relation.

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