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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



  history
ID: 225906.0, MPI für Astronomie / Publikationen_mpia
First determination of the dynamical mass of a binary L dwarf
Authors:Bouy, H.; Duchêne, G.; Köhler, R.; Brandner, W.; Bouvier, J.; Martín, E. L.; Ghez, A.; Delfosse, X.; Forveille, T.; Allard, F.; Baraffe, I.; Basri, G.; Close, L.; McCabe, C. E.
Date of Publication (YYYY-MM-DD):2004
Title of Journal:Astronomy and Astrophysics
Volume:423
Start Page:341
End Page:352
Review Status:not specified
Audience:Not Specified
Abstract / Description:We present here the results of astrometric,
photometric and spectroscopic observations
leading to the determination of the orbit and
dynamical masses of the binary L dwarf 2MASSW
J0746425+2000321. High angular resolution
observations spread over almost 4 years and
obtained with the Hubble Space Telescope (HST),
the ESO Very Large Telescope (VLT), and a the W.
M. Keck Observatory (Keck) allow us to cover
‚‚sim;36% of the period, corresponding to 60% of
the orbit, and, for the first time, to derive a
precise estimate of the total and individual
masses of such a late-type object. We find an
orbital period of
3850.9+904-767 days. The
corresponding total mass is
0.146+0.016-0.006
M‚‚odot; with uncertainties depending
on the distance. Spatially resolved low
resolution optical (550-1025 nm) spectra have
been obtained with HST/STIS, allowing us to
measure the spectral types of the two components
(L0‚‚plusmn; 0.5 for the primary and L1.5
‚‚plusmn;0.5 for the secondary). We also present
precise photometry of the individual components
measured on the high angular resolution images
obtained with HST/ACS and WFPC2 (visible),
VLT/NACO (J, H and KS bands) and Keck
I (KS band). These spectral and
photometric measurements enable us to estimate
their effective temperatures and mass ratio, and
to place the object accurately in a H-R diagram.
The binary system is most likely formed by a
primary with a mass of 0.085‚‚plusmn;0.010
M‚‚odot; and a secondary with a mass
of 0.066‚‚plusmn;0.006 M‚‚odot;, thus
clearly substellar, for an age of approximately
300‚‚plusmn;150 Myr. H‚‚alpha; variability
indicates chromospheric and/or magnetic activity.
Free Keywords:stars: low-mass; brown dwarfs; star: individual: 2MASSW J0746425+2000321
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
External Affiliations:Physik, Giessenbachstra‚‚szlig;e, 85748 Garching
bei M‚‚uuml;nchen, Germany
<EMAIL>hbouy@mpe.mpg.de</EMAIL>; European
Southern Observatory, Karl
Schwarzschildstra‚‚szlig;e 2, 85748 Garching bei
M‚‚uuml;nchen, Germany; Laboratoire
d'Astrophysique de l'Observatoire de Grenoble,
414 rue de la piscine, 38400 Saint Martin
d'H‚‚egrave;re, France), AB(Laboratoire
d'Astrophysique de l'Observatoire de Grenoble,
414 rue de la piscine, 38400 Saint Martin
d'H‚‚egrave;re, France
<EMAIL>Gaspard.Duchene@obs.ujf-grenoble.fr</EMAIL>;
Division of Astronomy & Astrophysics, University
of California in Los Angeles, Los Angeles,
CA90095-1562, USA), AC(Max-Planck Institut
f‚‚uuml;r Astronomie, K‚‚ouml;nigstuhl 17, 69117
Heidelberg, Germany
<EMAIL>koehler@mpia.de</EMAIL>), AD(Max-Planck
Institut f‚‚uuml;r Astronomie, K‚‚ouml;nigstuhl
17, 69117 Heidelberg, Germany
<EMAIL>brandner@mpia.de</EMAIL>), AE(Laboratoire
d'Astrophysique de l'Observatoire de Grenoble,
414 rue de la piscine, 38400 Saint Martin
d'H‚‚egrave;re, France
<EMAIL>Jerome.Bouvier@obs.ujf-grenoble.fr</EMAIL>),
AF(Instituto de Astrofisica de Canarias, 38200 La
Laguna, Spain <EMAIL>ege@ll.iac.es</EMAIL>),
AG(Division of Astronomy & Astrophysics,
University of California in Los Angeles, Los
Angeles, CA90095-1562, USA
<EMAIL>ghez@astro.ucla.edu</EMAIL>),
AH(Laboratoire d'Astrophysique de l'Observatoire
de Grenoble, 414 rue de la piscine, 38400 Saint
Martin d'H‚‚egrave;re, France
<EMAIL>Xavier.Delfosse@obs.ujf-grenoble.fr</EMAIL>),
AI(Laboratoire d'Astrophysique de l'Observatoire
de Grenoble, 414 rue de la piscine, 38400 Saint
Martin d'H‚‚egrave;re, France;
Canada-France-Hawaii Telescope Corporation, PO
Box 1597, Kamuela Hi-96743, USA
<EMAIL>forveille@cfht.hawaii.edu</EMAIL>),
AJ(Centre de Recherche Astronomique de Lyon (UML
5574), Ecole Normale Sup‚‚eacute;rieure, 69364
Lyon Cedex 07, France
<EMAIL>fallard@ens-lyon.fr</EMAIL>), AK(Centre de
Recherche Astronomique de Lyon (UML 5574), Ecole
Normale Sup‚‚eacute;rieure, 69364 Lyon Cedex 07,
France <EMAIL>ibaraffe@ens-lyon.fr</EMAIL>),
AL(University of California at Berkeley,
Astronomy Department, MC 3411 Berkeley, CA 94720,
USA <EMAIL>basri@astro.berkeley.edu</EMAIL>),
AM(Steward Observatory, University of Arizona,
933 N. Cherry Ave., Tucson, AZ 85721-0065, USA
<EMAIL>lclose@as.arizona.edu</EMAIL>),
AN(Division of Astronomy & Astrophysics,
University of California in Los Angeles, Los
Angeles, CA90095-1562, USA
<EMAIL>mccabe@astro.ucla.edu</EMAIL>)
Identifiers:URL:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bi... [ID No:1]
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