  Many open clusters have a deficit of observed white dwarfs (WDs) compared
with predictions of the number of stars to have evolved into WDs. We evaluate
the number of WDs produced in open clusters and the number of those WDS
detectable using photometric selection techniques. This calculation includes
the effects of varying the initial-mass function (IMF), the maximum progenitor
masses of WDs, and the binary fraction. Differences between the calculated
number of observable WDs and the actual number of WDs observed in a specific
cluster then indicate the true deficit of WDs that must be explained through
effects such as dynamical evolution of the cluster or close binary evolution.
Observations of WDs in three open clusters, the Hyades, Pleiades, and Praesepe,
are compared to the calculated observable populations in those clusters. The
results suggest that a large portion of the white dwarf deficit may be
explained by the presence of WDs in unresolved binary systems. However, the
calculated WD populations still over-predict the number of observable WDs in
each cluster. While these calculations cannot determine the cause of this
residual white dwarf deficit, potential explanations include a steep high-mass
IMF, dynamical evolution of the cluster, or an increased likelihood of
equal-mass components in a binary system. Observations of complete WD samples
in open clusters covering a range of ages and mass can help to distinguish
between these possibilities.
