Description
Radial velocities and complete space motions were measured for 116 white dwarf stars with M dwarf companions (WD+M), including thirteen pairs having "halo-like" velocities. These 116 WD+dM binaries were observed on the 3.5 m telescope at the Apache Point Observatory (APO) on nearly 30 half-nights between 2000 September 4 and 2001 October 20. The APO Double Imaging Spectrograph was used with a 15" slit, yielding a resolution of approximately 2arcsrc/pixel. From the near-solar abundance levels of the M dwarf companions, only one potential stellar halo white dwarf (LP 164-52) was found in the sample, 12 of the 13 high-velocity white dwarfs being actually part of the high-velocity tail of the thick disk rather than the dark matter halo of the Galaxy.
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