NGC 5128: The Giant Beneath

TL;DR

This review summarizes recent findings on NGC 5128's old stellar populations, globular clusters, and halo characteristics, highlighting its distance, cluster system, and stellar composition as key insights into its structure.

Contribution

The paper consolidates observational data on NGC 5128's stellar populations, globular clusters, and halo, providing updated measurements and analysis of its properties.

Findings

Distance to NGC 5128 is 3.8 ± 0.1 Mpc.

Globular cluster system is predominantly old with a metal-rich component.

Halo is dominated by old, metal-rich stars out to at least 7 effective radii.

Abstract

I review what we have learned about the old stellar population of NGC 5128, the only large E 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 for some, 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 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 ~7r_{eff} is dominated by metal-rich stars which are also predominantly old, with age and metallicity tantalizingly similar to the majority of globular clusters.