AAS 203rd Meeting, January 2004
Session 32 Spiral Galaxies
Oral, Monday, January 5, 2004, 2:00-3:30pm, Centennial IV

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[32.05] Planetary Nebulae and the Dynamics of Early-Type Galaxies

A. P. N. Sluis, T. B. Williams (Rutgers University)

Efforts to determine the mass distribution of early-type galaxies 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\lambda), making it possible to detect them over extragalactic distances and measure their radial velocities.

We report on observations of four early-type galaxies performed with the Rutgers Fabry-Perot (RFP). Our sample sizes range from 54 PNe (NGC~3384) to 2 PNe (NGC~4636) with a typical limiting magnitude of m5007 = 26.1. We briefly discuss our selection procedure and how the statistical procedure influences the limiting magnitude of our survey. In addition, we constructed simple mass models for the two galaxies with a sufficiently large PN sample, the Leo galaxies NGC~3379 and NGC~3384. Using a Monte Carlo Markov Chain method we explored the space of likely mass models. Our spherical model for the E1 galaxy NGC~3379 shows that mass follows light within five half-light radii with an overall B band mass-to-light ratio ~6 (solar units). Our model for the SB0 galaxy NGC~3384 is not as successful, although it does seem to indicate that mass follows light as well.

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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.