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We propose to observe three Brown Dwarf candidates recently discovered in the
Pleiades - Teide 1 (Rebolo et al 1995), Calar 3 (Zapatero-Osorio et al 1996)
and the likely Brown Dwarf companion to PPl 15.
Teide 1 and Calar 3 are unique objects in being the first free-floating Brown
Dwarfs discovered. This point deserves stressing - they are not companions to
other objects (in fact they are distant from any other objects reducing
confusion) and are certainly Brown Dwarfs. IR observations will provide
important inputs to models of Brown Dwarf atmospheres. As unique objects they
deserve intensive study to more fully characterise this poorly known but
potentially very important class of objects.
PPl 15 is a little more massive than the brown dwarf candidates, but photometry
appears to indicate the presence of a very low mass companion (non-resolved)
about 1 magnitude fainter. Any cooler companion will result in an IR excess,
compared to normal M Dwarfs. ISO data will therefore indicate or refute its
presence with observations in the near-IR. Any confirmed IR excess would
suggest the presence of a very low-mass companion which would be the least
massive BD known in the Pleiades
We intend to image Teide 1 and Calar 3 directly, and search for an IR-excess
in the primary of PPl 15. We will image the Pleiades M6 dwarf HHJ3 to provide
a comparison with PPl 15. PPl 15 and HHJ3 have very similar optical spectral
types.