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K.A. Williams (UCSC), M. Bolte (UCO/Lick Obs.), M.T. Ruiz (Univ. de Chile), M.A. Wood (FIT)
We present early results of two observational programs: one to constrain models of white dwarf physics and a second to better determine the maximum progenitor mass for white dwarfs along with a redetermination of the initial mass/final mass relation. Deep VLT photometry of the globular cluster NGC 6397 is used in conjunction with deep HST photometry of several globular clusters to create a single white dwarf luminosity function extending to MV > 16. The effects of convective coupling, crystallization, and chemical fractionation are constrained by the observed features in the WDLF. These features can be used to constrain the cooling model physics, and thereby reduce uncertainty in the ages derived for old stellar systems. In addition, we present Keck spectroscopy of white dwarf candidates from four young open clusters. These spectra are used to constrain the initial-final mass relation for white dwarfs as well as to constrain the maximum mass for white dwarf progenitors. These spectra are part of a larger imaging and spectroscopic program to locate white dwarfs in young open clusters and study their physical properties.
The author(s) of this abstract have provided an email address for comments about the abstract: williams@ucolick.org