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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



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ID: 225823.0, MPI für Astronomie / Publikationen_mpia
ε Indi Ba, Bb: The nearest binary brown dwarf
Authors:McCaughrean, M. J.; Close, L. M.; Scholz, R.-D.; Lenzen, R.; Biller, B.; Brandner, W.; Hartung, M.; Lodieu, N.
Date of Publication (YYYY-MM-DD):2004
Title of Journal:Astronomy and Astrophysics
Volume:413
Start Page:1029
End Page:1036
Review Status:not specified
Audience:Not Specified
Abstract / Description:We have carried out high angular resolution
near-infrared imaging and low-resolution
(R‚‚sim;1000) spectroscopy of the nearest known
brown dwarf, \varepsilon Indi B, using the ESO
VLT NAOS/CONICA adaptive optics system. We find
it to be a close binary (as also noted by Volk et
al. 2003), with an angular separation of 0.732
arcsec, corresponding to 2.65 AU at the 3.626 pc
distance of the \varrepsilon Indi system. In our
discovery paper (Scholz et al. 2003), we
concluded that \varepsilon Indi B was a ‚‚sim;50
MJup T2.5 dwarf: our revised finding
is that the two system components (\varepsilon
Indi Ba and \varrepsilon Indi Bb) have spectral
types of T1 and T6, respectively, and estimated
masses of 47 and 28 MJup,
respectively, assuming an age of 1.3 Gyr. Errors
in the masses are ‚‚plusmn;10 and ‚‚plusmn;7
MJup, respectively, dominated by the
uncertainty in the age determination (0.8-2 Gyr
range). This uniquely well-characterised T dwarf
binary system should prove important in the
study of low-mass, cool brown dwarfs. The two
components are bright and relatively
well-resolved: \varepsilon Indi B is the only T
dwarf binary in which spectra have been obtained
for both components. The system has a
well-established distance and age. Finally,
their orbital motion can be measured on a fairly
short timescale (nominal orbital period ‚‚sim;15
yrs), permitting an accurate determination of
the true total system mass, helping to calibrate
brown dwarf evolutionary models.
Free Keywords:astrometry; surveys; stars: late-type;
; stars: low mass; Brown dwarfs; stars: binaries:
; general
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
External Affiliations:der Sternwarte 16, 14482 Potsdam, Germany),
AB(Steward Observatory, University of Arizona,
933 N. Cherry Ave., Tucson, AZ 85721-0065, USA),
AC(Astrophysikalisches Institut Potsdam, An der
Sternwarte 16, 14482 Potsdam, Germany),
AD(Max-Planck-Institut f‚‚uuml;r Astronomie,
K‚‚ouml;nigstuhl 17, 69117 Heidelberg, Germany),
AE(Steward Observatory, University of Arizona,
933 N. Cherry Ave., Tucson, AZ 85721-0065, USA),
AF(Max-Planck-Institut f‚‚uuml;r Astronomie,
K‚‚ouml;nigstuhl 17, 69117 Heidelberg, Germany),
AG(European Southern Observatory, Alonso de
Cordova 3107, Vitacura, Santiago, Chile),
AH(Astrophysikalisches Institut Potsdam, An der
Sternwarte 16, 14482 Potsdam, Germany)
Identifiers:URL:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bi... [ID No:1]
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