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Discovery of a T dwarf binary with the largest known J-band flux reversal

Looper, Dagny L. and Gelino, Christopher R. and Burgasser, Adam J. and Kirkpatrick, J. Davy (2008) Discovery of a T dwarf binary with the largest known J-band flux reversal. Astrophysical Journal, 685 (2). pp. 1183-1192. ISSN 0004-637X. doi:10.1086/590382.

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We present Keck laser guide star observations of two T2.5 dwarfs-2MASS J11061197+2754225 and 2MASS J14044941-3159329-using NIRC2 on Keck II and find 2MASS J14044941-3159329 to be a 0.13" binary. This system has a secondary that is 0.45 mag brighter than the primary in J band, but 0.49 mag fainter in H band and 1.13 mag fainter in K_s band. We use this relative photometry along with near-infrared synthetic modeling performed on the integrated light spectrum to derive component types of T1 ± 1 for the primary and T5 ± 1 for the secondary. Optical spectroscopy of this system obtained with Magellan/LDSS-3 is also presented. This is the fourth L/T transition binary to show a flux reversal in the 1-1.2 µm regime, and this one has the largest flux reversal. Unless the secondary is itself an unresolved binary, the J-band magnitude difference between the secondary and primary shows that the J-band "bump'' is indeed a real feature and not an artifact caused by unresolved binarity.

Item Type:Article
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Burgasser, Adam J.0000-0002-6523-9536
Kirkpatrick, J. Davy0000-0003-4269-260X
Additional Information:© 2008 The American Astronomical Society. Received 2008 February 29; accepted 2008 May 19. We wish to thank our anonymous referee for helpful suggestions that have improved the quality of this paper. We would like to thank our telescope operators on Keck: Jim Lyke, Cynthia Wilburn, Chuck Sorenson, and the rest of the Keck LGS AO team, and our telescope operator on Magellan: Mauricio Martinez. We thank Michael Liu for the LGS AO data on these two sources, and Michael Cushing and Mark Pitts for helpful discussions. D. L. L. thanks Michael Liu and John Rayner for advising her for this project, and David Sanders for financial support. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France. This research has benefitted from the M, L, and T dwarf compendium housed at, and has used data products from the SpeX Prism Spectral Libraries ( This publication also makes use of data products from the Two Micron All Sky Survey (2MASS), which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/ California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. This research has also made use of the NASA/IPAC Infrared Science Archive ( IRSA), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. As all data were obtained from the summit of Mauna Kea, the authors wish to recognize and acknowledge the very significant cultural role and reverence that this mountaintop has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations on the summit. Facilities: Keck:II, Magellan:Clay.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Subject Keywords:binaries: close; binaries: general; stars: individual (2MASS J11061197+2754225, 2MASS J14044941-3159329); stars: low-mass, brown dwarfs; techniques: high angular resolution; techniques: spectroscopic
Issue or Number:2
Record Number:CaltechAUTHORS:LOOapj08
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:13384
Deposited By: Tony Diaz
Deposited On:04 May 2009 15:54
Last Modified:08 Nov 2021 22:37

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