Discovery of the Y1 Dwarf WISE J064723.23-623235.5

Creators: Kirkpatrick, J. Davy; Cushing, Michael C.; Gelino, Christopher R.; Beichman, Charles A.; Tinney, C. G.; Faherty, Jacqueline K.; Schneider, Adam; Mace, Gregory N.

Abstract

We present the discovery of a very cold, very low mass, nearby brown dwarf using data from the NASA Wide-field Infrared Survey Explorer (WISE). The object, WISE J064723.23–623235.5, has a very red WISE color of W1–W2 > 3.77 mag and a very red Spitzer Space Telescope color of ch1–ch2 = 2.82 ± 0.09 mag. In J_(MKO) –ch2 color (7.58 ± 0.27 mag) it is one of the two or three reddest brown dwarfs known. Our grism spectrum from the Hubble Space Telescope (HST) confirms it to be the seventeenth Y dwarf discovered, and its spectral type of Y1 ± 0.5 makes it one of the four latest-type Y dwarfs classified. Astrometric imaging from Spitzer and HST, combined with data from WISE, provides a preliminary parallax of π = 115 ± 12 mas (d = 8.7 ± 0.9 pc) and proper motion of μ = 387 ± 25 mas yr^(–1) based on 2.5 yr of monitoring. The spectrum implies a blue J–H color, for which model atmosphere calculations suggest a relatively low surface gravity. The best fit to these models indicates an effective temperature of 350-400 K and a mass of ~5-30 M_(Jup). Kinematic analysis hints that this object may belong to the Columba moving group, which would support an age of ~30 Myr and thus an even lower mass of <2 M_Jup, but verification would require a radial velocity measurement not currently possible for a J = 22.7 mag brown dwarf.

Additional Information

© 2013 American Astronomical Society. Received 2013 July 5; accepted 2013 August 24; published 2013 October 7. We thank our referee, Sandy Leggett, for a thoughtful and prompt report. We also thank Sergio Fajardo-Acosta for a careful reading of the manuscript. This publication makes use of data products from WISE, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory (JPL)/California Institute of Technology (Caltech), funded by the National Aeronautics and Space Administration (NASA). This work is based in part on observations made with the Spitzer Space Telescope, which is operated by JPL/Caltech under a contract with NASA. Support for this work was provided by NASA through an award issued to programs 70062, 80109, and 90007 by JPL/Caltech. This work is also based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained at STScI, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with programs 12970. Support for these programs was provided by NASA through a grant from STScI. This research has made use of the NASA/IPAC Infrared Science Archive, which is operated by JPL/Caltech, under contract with NASA. This paper includes data gathered with the 6.5m Magellan Telescopes located at Las Campanas Observatory, Chile. C.G.T. acknowledges the support of ARC grants DP0774000 and DP130102695. Australian access to the Magellan Telescopes was supported through the National Collaborative Research Infrastructure Strategy of the Australian Federal Government. Travel support for Magellan observing was provided by the Australian Astronomical Observatory. This paper also includes Magellan data granted by the National Optical Astronomy Observatories (Proposal ID: 2010B-0184, P.I. Mainzer) through the Telescope System Instrumentation Program (TSIP). TSIP is funded by National Science Foundation. We are also indebted to the SIMBAD database, operated at CDS, Strasbourg, France.

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