Wide cool and ultracool companions to nearby stars from pan-STARRS 1

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

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    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.

    Original languageEnglish
    Article number119
    Number of pages40
    JournalThe Astrophysical Journal
    Volume792
    Issue number2
    DOIs
    Publication statusPublished - 22 Aug 2014

    Keywords

    • binaries: general
    • brown dwarfs
    • stars: low-mass
    • surveys

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