It is now well known that spiral galaxies are in general embedded in massive dark halos, as evidenced by the flat rotation curves of the cold HI gas disks observed beyond their visible stellar disks. However, early-type galaxies (ellipticals and S0s) lack such easily-observed ubiquitous kinematical tracers, leaving the properties of their outer parts (mass and stellar orbit distributions beyond an effective radius Reff) still woefully unconstrained, except for a relatively small sample of well-studied galaxies. Knowledge of these properties would permit direct comparison with spiral galaxies and with predictions from theories of galaxy formation.

  • References

    last modified by AJR, 3 July 2001