There
is now agreement, within a few % as to the distance
to NGC 5128, making it possible to interpret observed
properties with new confidence.
Although there is
still debate as to whether this is an S0p or Ep galaxy, the properties
of its halo and individual stars are consistent with classifying
NGC 5128 as an Ep.
We have a sample of ~
600 globular clusters
confirmed by radial velocity and/or angular resolution, approximately
50% of the estimated total population. Roughly half of these are
metal-rich and the majority are old.
In spite of these
numbers, global properties of the system are not well known because of
major biases in the spatial coverage.
Observations of the
spatial structure
of > 200 GCs shows that they follow the same fundamental plane
relation as do GCs in the Milky Way and M31. The NGC 5128 system allows
us to trace this relation to higher GC luminosity and mass than
we can in the Milky Way or M31.
Over a wide range in
galactocentric distance, the halo stars are remarkably similar and
predominantly metal-rich; and it appears that these metal-rich stars
are old, possibly with ages similar to those of the metal-rich GCs.
We may need to observe the halo to galactocentric
distances twice that of current
datasets in order to uncover its metal-poor component.
Acknowledgments
GLHH acknowledges financial support through a research grant from the Natural Sciences and Engineering Research Council of Canada. The beginnings of this paper were developed during a visit to ESO Garching, sponsored through the ESO visitor programme.