Wide Cool and Ultracool Companions to Nearby Stars from Pan-STARRS 1

Creators: Deacon, Niall R.; Liu, Michael C.; Magnier, Eugene A.; Aller, Kimberly M.; Best, William M. J.; Dupuy, Trent; Bowler, Brendan P.; Mann, Andrew W.; Redstone, Joshua A.; Burgett, William S.; Chambers, Kenneth C.; Draper, Peter W.; Flewelling, H.; Hodapp, Klaus W.; Kaiser, Nick; Kudritzki, Rolf-Peter; Morgan, Jeff S.; Metcalfe, Nigel; Price, Paul A.; Tonry, John L.; Wainscoat, Richard J.

Abstract

We present the discovery of 57 wide (>5") separation, low-mass (stellar and substellar) companions to stars in the solar neighborhood identified from Pan-STARRS 1 (PS1) data and the spectral classification of 31 previously known companions. Our companions represent a selective subsample of promising candidates and span a range in spectral type of K7-L9 with the addition of one DA white dwarf. These were identified primarily from a dedicated common proper motion search around nearby stars, along with a few as serendipitous discoveries from our Pan-STARRS 1 brown dwarf search. Our discoveries include 23 new L dwarf companions and one known L dwarf not previously identified as a companion. The primary stars around which we searched for companions come from a list of bright stars with well-measured parallaxes and large proper motions from the Hipparcos catalog (8583 stars, mostly A-K dwarfs) and fainter stars from other proper motion catalogs (79170 stars, mostly M dwarfs). We examine the likelihood that our companions are chance alignments between unrelated stars and conclude that this is unlikely for the majority of the objects that we have followed-up spectroscopically. We also examine the entire population of ultracool (>M7) dwarf companions and conclude that while some are loosely bound, most are unlikely to be disrupted over the course of ~10 Gyr. Our search increases the number of ultracool M dwarf companions wider than 300 AU by 88% and increases the number of L dwarf companions in the same separation range by 82%. Finally, we resolve our new L dwarf companion to HIP 6407 into a tight (0."13, 7.4 AU) L1+T3 binary, making the system a hierarchical triple. Our search for these key benchmarks against which brown dwarf and exoplanet atmosphere models are tested has yielded the largest number of discoveries to date.

Additional Information

© 2014 The American Astronomical Society. Received 2013 November 8; accepted 2014 July 8; published 2014 August 22. The Pan-STARRS1 Surveys (PS1) have been made possible through contributions of the Institute for Astronomy, the University of Hawaii, the Pan-STARRS Project Office, the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, Queen's University Belfast, the Harvard–Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, the National Aeronautics and Space Administration under grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation under grant No. AST-1238877, the University of Maryland, and Eotvos Lorand University (ELTE). The authors thank Bill Golisch, Dave Griep, and Eric Volqardsen for assisting with the IRTF observations. This research has benefited from the SpeX Prism Spectral Libraries, maintained by Adam Burgasser, at http://www.browndwarfs.org/spexprism. 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. This research has benefited from the M, L, and T dwarf compendium housed at DwarfArchives.org and maintained by Chris Gelino, Davy Kirkpatrick, and Adam Burgasser. M.C.L. and E.A.M. were supported by NSF grants AST09-09222 (awarded to M.C.L.) and AST-0709460 (awarded to E.A.M.). E.A.M. was also supported by AFRL Cooperative Agreement FA9451-06-2-0338. 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. The United Kingdom Infrared Telescope is operated by the Joint Astronomy Centre on behalf of the Science and Technology Facilities Council of the U.K. This paper makes use of observations processed by the Cambridge Astronomy Survey Unit (CASU) at the Institute of Astronomy, University of Cambridge. The authors thank Mike Irwin and the team at CASU for making the reduced WFCAM data available promptly and Tim Carroll, Thor Wold, Jack Ehle and Watson Varricatt for assisting with UKIRT observations. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France. The VISTA Data Flow System pipeline processing and science archive are described in Irwin et al. (2004) and Hambly et al. (2008). We have used data from the first data release. This paper makes use of the Topcat software package (Taylor 2005). This research has made use of the Washington Double Star Catalog maintained at the U.S. Naval Observatory. We thank Luca Casagrande, Jackie Faherty, Adam Kraus, Eddie Schlafly, and Josh Schlieder for helpful discussions and our referee Sébastien Lépine for many helpful comments which improved the manuscript. Finally, 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. Facilities: IRTF (SpeX), PS1, UKIRT (WFCAM), UH:2.2m (SNIFS)

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