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J. Farihi, E.E. Becklin, B. Zuckerman (UCLA)
We have completed the most extensive survey to date for low mass stellar and substellar companions to white dwarfs in the solar neighborhood. Over 300 degenerates within roughly 50pc have been examined for infrared excess, infrared companions and for close visual or wide proper motion companions using several instruments spanning the past 15 years. The final phase to be completed was a 1.25 micron wide-field proper motion survey of over 200 nearby degenerates. At least nineteen previously unrecognized companions were discovered in the last two years. Of these recently discovered companions, 72 percent are M dwarfs and the remainder are white dwarfs. Only two of these red dwarfs have a spectral type later than M5.5 and the resulting IMF for companions to white dwarfs drops off quite steeply after this spectral type, which corresponds to around 0.1 solar masses. GD165B, discovered in 1988 as part of our program, is still the only known companion to a white dwarf with spectral type later than M.
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.