Radially Extended Kinematics in the S0 Galaxy NGC 2768 from Planetary
  Nebulae, Globular Clusters and Starlight
  There are only a few tracers available to probe the kinematics of individual
early-type galaxies beyond one effective radius. Here we directly compare a
sample of planetary nebulae (PNe), globular clusters (GCs) and galaxy starlight
velocities out to ~4 effective radii, in the S0 galaxy NGC 2768. Using a
bulge-to-disk decomposition of a K-band image we assign PNe and starlight to
either the disk or the bulge. We show that the bulge PNe and bulge starlight
follow the same radial density distribution as the red subpopulation of GCs,
whereas the disk PNe and disk starlight are distinct components. We find good
kinematic agreement between the three tracers to several effective radii (and
with stellar data in the inner regions). Further support for the distinct
nature of the two galaxy components come from our kinematic analysis. After
separating the tracers into bulge and disk components we find the bulge to be a
slowly rotating pressure-supported system, whereas the disk reveals a rapidly
rising rotation curve with a declining velocity dispersion profile. The
resulting V/sigma ratio for the disk resembles that of a spiral galaxy and
hints at an origin for NGC 2768 as a transformed late-type galaxy. A
two-component kinematic analysis for a sample of S0s will help to elucidate the
nature of this class of galaxy.
