Praesepe and the seven white dwarfs

We report the discovery, from our preliminary survey of the Praesepe open cluster, of two new spectroscopically confirmed white dwarf candidate members. We derive the effective temperatures and surface gravities of WD0837 + 218 and WD0837 + 185 (LB5959) to be 17845(-565)(+555) K and log g = 8.48(-0.08)(+0.07) and 14170(-1590)(+1380) K and log g = 8.46(-0.16)(+0.15), respectively. Using theoretical evolutionary tracks we estimate the masses and cooling ages of these white dwarfs to be 0.92 +/- 0.05 M(circle dot) and 280(-30)(+40) Myr and 0.90 +/- 0.10 M(circle dot) and 500(-100)(+170) Myr, respectively. Adopting reasonable values for the cluster age we infer the progenitors of WD0837 + 218 and WD0837 + 185 had masses of 2.6 less than or equal to M less than or equal to M(crit) M(circle dot) and 2.4 less than or equal to M less than or equal to 3.5 M(circle dot), respectively, where M(crit) is the maximum mass of a white dwarf progenitor. We briefly discuss these findings in the context of the observed deficit of white dwarfs in open clusters and the initial mass-final mass relationship.