Disk Contamination in a sample of proper motion selected halo stars: A Comment on "Direct Detection of Galactic Halo Dark Matter", B.A. Oppenheimer et al., Science

Based on a proper motion survey, Oppenheimer et al. claim the detection of a white dwarf component of the dark matter of the halo. I show that most of the white dwarfs in their sample are likely disk white dwarfs which have been previously detected, and represent no new population.