Brown dwarf companions to white dwarfs
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Author
Burleigh, Matt R.
Steele, Paul R.
Dobbie, Paul D.
Farihi, Jay
Napiwotzki, Ralf
Maxted, Pierre F. L.
Barstow, Martin A.
Jameson, Richard F.
Casewell, Sarah L.
Gaensicke, Boris T.
Marsh, Tom R.
Attention
2299/7091
Abstract
Brown dwarf companions to white dwarfs are rare, but recent infra-red surveys are slowly revealing examples. We present new observations of the post-common envelope binary WD0137-349, which reveals the effects of irradiation on the approximate to 0.05M(circle dot) secondary, and new observations of GD 1400 which show that it too is a close, post-common envelope system. We also present the latest results in a near-infrared photometric search for unresolved ultra-cool companions and to white dwarfs with UKIDSS. Twenty five DA white dwarfs were identified as having photometric excesses indicative of a low mass companion, with 8-10 of these having a predicted mass in the range associated with brown dwarfs. The results of this survey show that the unresolved (< 2 '') brown dwarf companion fraction to DA white dwarfs is 0.3 <= f(WD+BD) <= 1.3%.