Publications of the Astronomical Society of Australia

Research Article

NGC 5128: The Giant Beneath

Gretchen L. H. Harrisa1

a1 Department of Physics and Astronomy, University of Waterloo, Waterloo ON, N2L 3G1, Canada. Email: glharris@astro.uwaterloo.ca

Abstract

This paper reviews what has been learned about the old stellar population of NGC 5128, the only large elliptical galaxy close enough that we can currently observe individual stars as faint as the horizontal branch. Although its galaxy type is still a matter of debate, the uncertainties over distance are now largely resolved; comparison of five stellar distance indicators gives d= 3.8±0.1 Mpc. The globular cluster system, which was once perplexingly invisible, is now known to be predominantly old with a substantial metal-rich component. The globular cluster system (GCS) total population and luminosity function are normal and the clusters follow the same fundamental plane relation as those in the Milky Way and M31. Finally, the halo out to at least ∼7reff is dominated by metal-rich stars which are also predominantly old, with age and metallicity tantalizingly similar to the majority of globular clusters.

(Received September 29 2009)

(Accepted April 12 2010)

Keywords

  • Galaxies: distances;
  • galaxies: stellar content and star clusters;
  • galaxies: individual (NGC 5128)
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