  We report the results of a CCD imaging survey, complimented by astrometric
and spectroscopic follow-up studies, that aims to probe the fate of
heavy-weight intermediate mass stars by unearthing new, faint, white dwarf
members of the rich, nearby, intermediate age open clusters NGC3532 and
NGC2287. We identify a total of four white dwarfs with distances, proper
motions and cooling times which can be reconciled with membership of these
populations. We find that WDJ0643-203 in NGC2287, with an estimated mass of
M=1.02-1.16Msun, is potentially the most massive white dwarf so far identified
within an open cluster. Guided by the predictions of modern theoretical models
of the late-stage evolution of heavy-weight intermediate mass stars, we
conclude that there is a distinct possibility it has a core composed of O and
Ne. We also determine that despite the cooling times of the three new white
dwarfs in NGC3532 and the previously known degenerate member NGC3532-10
spanning ~90Myr, they all have remarkably similar masses (M~0.9-1Msun). This is
fully consistent with the results from our prior work on a heterogeneous sample
of ~50 white dwarfs from 12 stellar populations, on the basis of which we
argued that the stellar initial mass-final mass relation is less steep at
Minit>4Msun than in the adjacent lower initial mass regime. This change in the
gradient of the relation could account for the secondary peak observed in the
mass distribution of the field white dwarf population and mitigate the need to
invoke close binary evolution to explain its existence. Spectroscopic
investigation of numerous additional candidate white dwarf members of NGC3532
unearthed by a recent independent study would be useful to confirm (or
otherwise) these conclusions.
