[Previous] | [Session 52] | [Next]
L. M. Raschke, P. Jonsson, S. Severson, S. M. Faber (University of California - Santa Cruz), B. A. Macintosh (Lawrence Livermore National Laboratory)
We have observed the centers of 10 nearby early-type galaxies using the Lick Adaptive Optics (AO) system in the H-band. The Lick AO system gives us near diffraction-limited performance in the H-band with a resolution of 0.\arcsec15. This resolution allows us to study the central surface brightness profiles of these galaxies.
Observations made with Hubble Space Telescope have shown that the central surface brightness profiles of early-type galaxies come in two distinct types: cores which show a central flattening in surface brightness and power laws whose surface brightness continues to increase at small radii. Furthermore, it has been shown that the profile type is correlated with global properties of the galaxy. By studying the correlations between global and central properties of these galaxies we can gain some insight into their formation and evolution. Until recently, this work was confined to the realm of space telescope observations because of the need for high resolution at the centers of these galaxies. Adaptive Optics has opened up this field for ground-based observations.
We present results from our observations made in the falls of 1999 and 2000. We have fit five-parameter Nuker laws to our galaxies and compared the central parameters from the fits to the global properties of the galaxies. One galaxy, UGC 11975, is a particularly interesting case. This galaxy has a ``core'' profile type yet is much less luminous than galaxies with similar central parameters. For this galaxy, we obtained BVRJHK photometry as well as Keck ESI spectra in order to further study the global properties of the galaxy.