Resolved Spectroscopy of a Brown Dwarf Binary at the T Dwarf/Y Dwarf Transition
Abstract
We report resolved near-infrared imaging and spectroscopic observations of the T8.5 binary WISEP J045853.90+643452.6AB obtained with Keck/NIRC2, Keck/OSIRIS, and the Keck Laser Guide Star Adaptive Optics system. These data confirm common proper and radial motion for the two components, and we see the first indications of orbital motion (mostly radial) for this system. H-band spectroscopy identifies both components as very late type brown dwarfs with strong H_2O and CH_4 absorption. The spectrum of WISE J0458+6434B also exhibits a compelling signature of NH_3 absorption over 1.52-1.54 μm when compared to the T9 dwarf UGPS J072227.51–054031.2. Comparison to T8-Y0 spectral standards and H-band spectral indices indicate classifications of T8.5 and T9.5 for these two components, approaching the boundary between the T dwarf and Y dwarf spectral classes.
Additional Information
© 2012 American Astronomical Society. Received 2011 August 27; accepted 2011 October 18; published 2011 December 28. 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, and made possible by the generous financial support of the W. M. Keck Foundation. The authors thank Keck observing assistants Terry Stickel and CynthiaWilburn, and instrument scientists Scott Dahm and Hien Tran, for their assistance in the observations reported here. We also acknowledge guidance on OSIRIS data reduction from Breann Sitarski and Shelley Wright, and Richard Freedman for providing scattering cross-section spectra for various molecules. We thank our referee for her/his helpful and prompt review. This work was supported by a NASA Keck PI Data Award, administered by the NASA Exoplanet Science Institute. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France; the M, L, and T dwarf compendium housed at http://dwarfarchives.org; and the SpeX Prism Spectral Libraries at http://www.browndwarfs.org/spexprism. The authors recognize and acknowledge the very significant cultural role and reverence that the summit ofMauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Facility: Keck:II (NIRC2, OSIRIS, LGSAO)Attached Files
Published - Burgasser2012p17605Astrophys_J.pdf
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- CaltechAUTHORS:20120330-132810208
- NASA
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2012-03-30Created from EPrint's datestamp field
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2021-11-09Created from EPrint's last_modified field
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- Infrared Processing and Analysis Center (IPAC)