POSTER PAPER 2.01
Multiplicity Among Very Low Mass Stars and Brown Dwarfs in the Pleiades
S. E. Dahm, E. L. Mart
Institute: Institute for Astronomy, University of Hawai`i, 2680 Woodlawn Drive, Honolulu, HI 96822
Contact Email: dahm@ifa.hawaii.edu
Abstract:
We present initial results of an HST WFPC-2 photometric
survey of selected very low-mass (VLM) stars and brown dwarf
candidates in the Pleiades. With a sample size
of 23 objects, only one is definitively resolved as a binary with a separation
of less than 12 AU for a given distance
of 125 pc. Three others were found to have elongated
PSFs, but could not be resolved. Of these candidates, CFHT-PL-19
was assessed to be a non-member based upon the proper motion
survey of Moraux, Bouvier and Stauffer (2001).
These results complement those of Martin et al. (2000) in which
an HST NICMOS and CFHT adaptive optics survey of 34 Pleiades
members found no resolved pairs with separations greater
than 27 AU. Combining the new observations with those of
Martin et al. (2000), we find that a dearth of VLM binaries
with separations of greater than 15 AU (P~184 yr) exists within
the Pleiades. These findings provide tentative evidence
that the period distribution of VLM binaries in the Pleiades
is significantly different from that of the cluster
F5-K0 stars and the field solar analogues.
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Manuscript submitted: 2001-Sep-6
"The Future of Cool-Star Astrophysics", 2003, Eds. A. Brown,
G. M. Harper, & T. R. Ayres.
Proceedings of 12th Cambridge Workshop on Cool Stars, Stellar Systems,
& The Sun,
© 2003 University of Colorado.