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Symposium 241
Symposium 241
Abstract details
The Star Formation History in Andromeda's Diffuse Stellar Halo
T.M. Brown, E. Smith, H.C. Ferguson (STScI), P. Guhathakurta (UCSC),
R.M. Rich (UCLA), J. Kalirai (UCSC), A. Renzini (INAF), & A.V. Sweigart
(NASA/GSFC)Abstract
We present a color-magnitude diagram from deep Hubble Space Telescope
observations of a minor-axis field 21 kpc away from the center of
Andromeda. In both star counts and chemical abundances, this field
represents a transition point between the highly-disturbed inner
spheroid that dominates within 15 kpc and the diffuse population that
dominates beyond 30 kpc. Our observations reach well below the oldest
main sequence turnoff in the population, allowing a complete
reconstruction of the star formation history in this field. We
compare the current observations to our previous observations in the
inner spheroid, outer disk, and tidal stream, and consider
implications for the formation history of these structural components.