A Targeted Search for Peculiarly Red L and T Dwarfs in SDSS, 2MASS, and WISE: Discovery of a Possible L7 Member of the TW Hydrae Association

Creators: Kellogg, Kendra; Metchev, Stanimir; Geißler, Kerstin; Hicks, Shannon; Kirkpatrick, J. Davy; Kurtev, Radostin

Abstract

We present the first results from a targeted search for brown dwarfs with unusual red colors indicative of peculiar atmospheric characteristics. These include objects with low surface gravities or with unusual dust content or cloud properties. From a positional cross-match of SDSS, 2MASS, and WISE, we have identified 40 candidate peculiar early-L to early-T dwarfs that are either new objects or have not been identified as peculiar through prior spectroscopy. Using low-resolution spectra, we confirm that 10 of the candidates are either peculiar or potential L/T binaries. With a J − K_s color of 2.62 ± 0.15 mag, one of the new objects—the L7 dwarf 2MASS J11193254–1137466—is among the reddest field dwarfs currently known. Its proper motion and photometric parallax indicate that it is a possible member of the TW Hydrae moving group. If confirmed, it would be the lowest-mass (5–6 M_(Jup)) free-floating member. We also report a new T dwarf, 2MASS J22153705+2110554, that was previously overlooked in the SDSS footprint. These new discoveries demonstrate that despite the considerable scrutiny already devoted to the SDSS and 2MASS surveys, our exploration of these data sets is not yet complete.

Additional Information

© 2015 The American Astronomical Society. Received 2014 October 10; accepted 2015 October 22; published 2015 November 24. This work was supported by the NASA Astrophysical Data Analysis Program through award No. NNX11AB18G to S.M. at Stony Brook University and by an NSERC Discovery grant to S.M. at The University of Western Ontario. Part of the data were obtained with the Magellan-Baade 6.5 m telescope under program CN2012A-54. Support for R.K. is provided from Fondecyt Reg. No. 1130140 and by the Ministry of Economy, Development, and Tourisms Millennium Science Initiative through grant IC12009, awarded to The Millennium Institute of Astrophysics (MAS). The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. This publication makes use of data products from the Two Micron All Sky Survey, 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. Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the U.S. Department of Energy Office of Science. The SDSS-III web site is http://www.sdss3.org/. SDSS-III is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS-III Collaboration including the University of Arizona, the Brazilian Participation Group, Brookhaven National Laboratory, Carnegie Mellon University, University of Florida, the French Participation Group, the German Participation Group, Harvard University, the Instituto de Astrofisica de Canarias, the Michigan State/Notre Dame/JINA Participation Group, Johns Hopkins University, Lawrence Berkeley National Laboratory, Max Planck Institute for Astrophysics, Max Planck Institute for Extraterrestrial Physics, New Mexico State University, New York University, Ohio State University, Pennsylvania State University, University of Portsmouth, Princeton University, the Spanish Participation Group, University of Tokyo, University of Utah, Vanderbilt University, University of Virginia, University of Washington, and Yale University. This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. This research has made use of data obtained from or software provided by the US Virtual Astronomical Observatory, which is sponsored by the National Science Foundation and the National Aeronautics and Space Administration. We thank our referee, Jackie Faherty, for her insightful critique. Facilities: IRTF (SpeX spectrograph) - , Magellan:Baade (FIRE spectrograph) - .

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