Cool Stars 14 - Submitted Abstract # 74
This version created on 05 October 2006

On the search for benchmark brown dwarfs in binaries


Avril Day-Jones, University of Hertfordshire
David Pinfield, University of Hertfordshire
Hugh Jones, University of Hertfordshire
Tim Kendall, University of Hertfordshire

For the vast majority of known brown dwarfs, properties such as
gravity and metallicity are uncertain;  This is due to our inability
to fit these properties spectroscopically because ultra-cool brown
dwarf atmospheric physics is very complex and models are incomplete.
Benchmark brown dwarfs are those for which these properties can be
determined independently, and finding a large enough benchmark
population will aid our understanding of how brown dwarf spectra vary
as their physical characteristics change.  Thus, benchmark brown
dwarfs could provide the fiducial calibrators to facilitate our
spectroscopic interpretation of all brown dwarf observations.  We are
undertaking a search for brown dwarfs as binary companions to white
dwarfs and subgiants.  Both high mass white dwarfs and subgiants can
provide accurate age constraints which can be inferred (by
association) for brown dwarf companions.  Subgiant companions can also
have well constrained metalicity.  We have searched 2MASS and
superCOSMOS in the south for white dwarf / brown dwarf binaries and
find 1 potential common proper motion wide white dwarf/ L-dwarf binary
candidate.  We also present preliminary findings from our AAT survey
around southern subgiant stars.

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