Volume 525, January 2011
|Number of page(s)||5|
|Section||Stellar structure and evolution|
|Published online||07 December 2010|
Resolving the L/T transition binary SDSS J2052-1609 AB⋆
Max-Planck-Institut für Astronomie,
2 Department of Physics and Astronomy, State University of New York, Stony Brook, NY 11794-3800, USA
3 Centro de Astrobiología, INTA-CSIC, PO Box 78, 28691, Villanueva de la Cañada, Madrid, Spain
Accepted: 25 September 2010
Context. Binaries provide empirically derived key constraints for star formation theories, including the overall binary fraction, mass ratio distribution, and the separation distribution. They play crucial roles in calibrating the output of theoretical models, such as absolute magnitudes, colors, and effective temperature depending on mass, metallicity, and age.
Aims. We present first results of our ongoing high-resolution imaging survey of late type brown dwarfs. The survey aims at resolving tight brown dwarf binary systems to better constrain the T dwarf binary fraction. We intend to follow up on the individual binaries to determine orbital parameters.
Methods. Using NACO at the VLT, we performed AO-assisted near-infrared observations of SDSS J2052-1609. High-spatial resolution images of the T1 dwarf were obtained in H and KS filters.
Results. We resolved SDSS J2052-1609 into a binary system with a separation of 0.1009 ± 0.001″. Archival data from HST/NICMOS taken one year before our observations proves the components are co-moving. Using the flux ratio between the components we infer J, H, and KS magnitudes for the resolved system. From the near-IR colors, we estimate spectral types of T1 for component A and T2.5 ± 1 for component B. A first estimate of the total system mass yields Mtot ≥ 78 MJup, when assuming a circular orbit.
Key words: stars: low-mass / brown dwarfs / stars: individual: SDSS J2052-1609 AB
Based on observations collected at the European Southern Observatory, Paranal, Chile, under program 083.C-0305(A). This work is partly based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute (STScI) and is associated with program GO-11136. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.
© ESO, 2010
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