We present very deep observations of stars in the inner spheroid of the Milky Way. The data have been collected with the Advanced Camera for Surveys aboard HST during Cycle 13. The primary target along the line of sight is the nearby globular star cluster NGC 6397 (see poster at this meeting by Richer et al). By comparing these images with earlier epoch data from 1994 and 1997, we construct a proper-motion diagram and remove virtually every NGC 6397 cluster member. The resulting reduced proper motion diagram is further analyzed to separate foreground disk stars from spheroid stars near the center of the Galaxy. Given the depth of the study, F606W reaches about 30th magnitude, we are able to compare the observed luminosity functions in the disk and spheroid to theoretical luminosity functions down to very low masses (almost 0.1 Msun). We present results on the input mass functions that best describe these populations.
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 2005