AAS 201st Meeting, January, 2003
Session 13. Galaxy - Structure
Poster, Monday, January 6, 2003, 9:20am-6:30pm, Exhibit Hall AB

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[13.08] Tracing the Mass of Early-type Galaxies using Planetary Nebulae

A. P. N. Sluis, T. B. William (Rutgers, The State University of New Jersey)

We report on observations of two ellipticals (NGC~3379 and NGC~1549) and two S0s (NGC~3384 and NGC~4636) performed with the Rutgers Fabry-Perot (RFP). The observations are part of a larger project to study the distribution of mass in the outer regions of early-type galaxies. Efforts to determine this distribution are generally hampered by the scarcity of useful tracers of the potential at large radii. Ellipticals and S0s have steep surface brightness profiles that make absorption line spectroscopy of the stellar population practically impossible beyond a few kpc from the center. Also, their gas content is low and does not extend far beyond the nucleus. Planetary Nebulae (PNe) offer a way around these problems: as remants of intermediate mass stars we expect them to follow the stellar light distribution and be numerous enough to be an effective tracer. PNe radiate hundreds of solar luminosities in a few emission lines (mostly [OIII] 5007 Å), making it possible to detect them over extragalactic distances and at the same time measure their line of sight velocities using the RFP. We present the photometry and the kinematics of the PN systems as well as some simple dynamical mass models for the four galaxies mentioned above.

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