Multiplicity of Young Brown Dwarfs in Cha I

Viki Joergens, Eike Guenther, Ralph Neuhäuser, Fernando Comerón, Nuria Huélamo, João Alves, Wolfgang Brandner

How frequent are brown dwarf binaries? Do brown dwarfs have planets? Are

current theoretical pre-main-sequence evolutionary tracks valid down to

the substellar regime? - Any detection of a companion to a brown dwarf

takes us one step forward towards answering these basic questions of

star formation. We report here on a search for spectroscopic and visual

companions to young brown dwarfs in the Cha I star forming cloud. Based

on spectra taken with UVES at the VLT, we found significant radial

velocity (RV) variations for five bona-fide and candidate brown dwarfs

in Cha I. They can be caused by either a (substellar or planetary)

companion or stellar activity. A companion causing the detected RV

variations would have about a few Jupiter masses. We are planning

further UVES observations in order to explore the nature of the detected

RV variations. We also found that the RV dispersion is only ˜2

km/s indicating that there is probably no run-away brown dwarf among

them. Additionally a search for companions by direct imaging with the

HST and SOFI (NTT) has yielded to the detection of a few companion

candidates in larger orbits.

Department of Astrophysics
External organisation(s)
European Southern Observatory (Germany), Max-Planck-Institut für extraterrestrische Physik, Thüringer Landessternwarte Tautenburg
Publication date
Austrian Fields of Science 2012
103004 Astrophysics
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