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M. J. Pierce (University of Wyoming), R. C. Berrington (ASEE/NRL)
We present new redshifts and velocity dispersions for over 200 elliptical galaxies in the Coma, Perseus, and Abell 2199 clusters acquired with the multi-object spectrograph (Hydra) on the WIYN 3.5-m telescope. The spectra were obtained at a dispersion of 0.48 Å/pixel enabling high-precision velocity dispersion measurements. We also present new I-band photometric data acquired with WIYN. These data are combined in order to examine the sources of scatter in the Fundamental Plane of elliptical galaxies. We find that the rms scatter is 12% in distance and that this is considerably higher than can be explained by observational errors alone. We examine various sources for the observed scatter including anisotropy and variations in the mix of stellar populations but fail to identify the source. Although some of the observed scatter could be due to line-of-sight depth of the cluster populations we conclude that most of the scatter arises from the failure of ellipticals to form a homologous faimily. We briefly discuss the prospects for obtaining high-precision, redshift-independent distances within z < 0.05 in order to characterize the velocity field within this volume.