Bibcode
Beuzit, J.-L.; Ségransan, D.; Forveille, T.; Udry, S.; Delfosse, X.; Mayor, M.; Perrier, C.; Hainaut, M.-C.; Roddier, C.; Roddier, F.; Martín, E. L.
Bibliographical reference
Astronomy and Astrophysics, v.425, p.997-1008 (2004)
Advertised on:
10
2004
Journal
Citations
92
Refereed citations
84
Description
We present some results of a CFHT adaptive optics search for companions
to nearby dwarfs. We identify 21 new components in solar neighbourhood
systems, of which 13 were found while surveying a volume-limited sample
of M dwarfs within 12 pc. We are obtaining complete observations for
this subsample, to derive unbiased multiplicity statistics for the
very-low-mass disk population. Additionally, we resolve for the first
time 6 known spectroscopic or astrometric binaries, for a total of 27
newly resolved companions. A significant fraction of the new binaries
has favourable parameters for accurate mass determinations. The newly
resolved companion of Gl 120.1C was thought to have a spectroscopic
minimum mass in the brown-dwarf range (Duquennoy & Mayor
cite{duquennoy91}), and it contributed to the statistical evidence that
a few percent of solar-type stars might have close-in brown-dwarf
companions. We find that Gl 120.1C actually is an unrecognised
double-lined spectroscopic pair. Its radial-velocity amplitude had
therefore been strongly underestimated by Duquennoy & Mayor
(cite{duquennoy91}), and it does not truly belong to their sample of
single-lined systems with minimum spectroscopic mass below the
substellar limit. We also present the first direct detection of Gl
494B, an astrometric brown-dwarf candidate. Its luminosity straddles the
substellar limit, and it is a brown dwarf if its age is less than
˜300 Myr. A few more years of observations will ascertain its mass
and status from first principles.
Based on observations made at Canada-France-Hawaii Telescope, operated
by the National Research Council of Canada, the Centre National de la
Recherche Scientifique de France and the University of Hawaii. Some of
the data presented herein were obtained at the W. M. Keck Observatory,
which is operated as a scientific partnership among the California
Institute of Technology, the University of California and the National
Aeronautics and Space Administration. The Observatory was made possible
by the generous financial support of the W. M. Keck Foundation.