[Previous] | [Session 21] | [Next]
R. F. Green, G. A. Bower (NOAO/KPNO), K. Gebhardt (UC-Santa Cruz), STIS Team
NGC 4486B is a dwarf companion to M 87. Its projected separation is 7.3\arcmin, or 34 kpc. The radial velocity difference is only some 200 km/s, suggesting that NGC 4486B may be bound to M 87. Lauer et al.~showed from their WFPC2 images that NGC 4486B has a double nucleus reminiscent of that in M 31, and a disk-like central distribution of stars. The two peaks are separated by 10-13 pc, are closely matched in central surface brightness, lie at comparable distances from the photocenter, but do not comprise a distinct nuclear component. NGC 4486B is unique among dwarf galaxies with MB = -17 mag in containing a resolved core. The superior angular resolution of STIS allows a more detailed look at the kinematics of the nuclear region. STIS spectra show a peak in the velocity dispersion just outboard of the fainter nuclear component, with a relatively flat dispersion profile through the rest of the nuclear region. We examine the degree of anisotropy allowed in solutions for groups of orbital families and consistency with the eccentric disk solutions developed for M 31.
This work was supported by NASA Guaranteed Time Observer funding to the STIS Science Team and is based upon observations obtained with the NASA/ESA Hubble Space Telescope, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.