Massive White Dwarfs in Young Star Clusters
  We have carried out a search for massive white dwarfs (WDs) in the direction
of young open star clusters using the Gaia DR2 database. The aim of this survey
was to provide robust data for new and previously known high-mass WDs regarding
cluster membership, to highlight WDs previously included in the Initial Final
Mass Relation (IFMR) that are unlikely members of their respective clusters
according to Gaia astrometry and to select an unequivocal WD sample that could
then be compared with the host clusters' turnoff masses.
  All promising WD candidates in each cluster CMD were followed up with
spectroscopy from Gemini in order to determine whether they were indeed WDs and
derive their masses, temperatures and ages. In order to be considered cluster
members, white dwarfs were required to have proper motions and parallaxes
within 2, 3, or 4-$\sigma$ of that of their potential parent cluster based on
how contaminated the field was in their region of the sky, have a cooling age
that was less than the cluster age and a mass that was broadly consistent with
the IFMR. A number of WDs included in current versions of the IFMR turned out
to be non-members and a number of apparent members, based on Gaia's astrometric
data alone, were rejected as their mass and/or cooling times were incompatible
with cluster membership. In this way, we developed a highly selected IFMR
sample for high mass WDs that, surprisingly, contained no precursor masses
significantly in excess of ${\sim}$6 $M_{\odot}$.
