AAS 204th Meeting, June 2004
Session 80 Nearby Galaxies
Poster, Thursday, June 3, 2004, 9:20am-4:00pm, Ballroom

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[80.11] Dwarf Elliptical Galaxies in the Virgo Cluster: Internal Dynamics

I. M. Hasegan, P. Cote (Rutgers Univ.)

By number, dwarf elliptical galaxies are the most common type in the Local Universe, yet the formation of these objects remains an open question. In particular, very little is known about their dynamical properties. An improved understanding of the internal dynamics of dwarf ellipticals is expected to provide important constraints on the mechanism(s) of their formation. Dynamical studies of giant elliptical galaxies have shown that their fundamental plane, which relates surface brightness, effective radius, velocity dispersion and total luminosity, is one of the most powerful tools for studying the formation and evolution of galaxies of this type.

We present results from a study of fifteen Virgo Cluster dwarf elliptical galaxies having absolute magnitudes in the range -11.6 \leq MB \leq -16.2. This class of objects is poorly represented in existing surveys due to their faintness and low surface brightness (19 \lesssim \muB,0 \lesssim 27 mag/arcsec2).

High-resolution spectra (\sigmains \approx 30 km/s) have been obtained with the Keck II 10-m telescope and the Echelle Spectrograph and Imager (ESI). Radial velocities profiles and internal velocity dispersion profiles have been derived from these spectra. To complement these spectroscopic data, surface brightness profiles have been derived either from archival HST WFPC2 data or from new imaging taken with Advanced Camera for Surveys, as part of the ACS Virgo Cluster Survey (GO-9401). This information is being combined to carry out dynamical modeling of each galaxy, using a standard Jeans equation analysis.

Support for program GO-9401 was provided through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Additional support provided by NASA LTSA grant NAG5-11714.

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