A T8.5 brown dwarf member of the ξ ursae majoris system

Edward L. Wright, M. F. Skrutskie, J. Davy Kirkpatrick, Christopher R. Gelino, Roger L. Griffith, Kenneth A. Marsh, Tom Jarrett, M. J. Nelson, H. J. Borish, Gregory MacE, Amanda K. Mainzer, Peter R. Eisenhardt, Ian S. McLean, John J. Tobin, Michael C. Cushing

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24 Scopus citations


The Wide-field Infrared Survey Explorer has revealed a T8.5 brown dwarf (WISE J111838.70+312537.9) that exhibits common proper motion with a solar-neighborhood (8 pc) quadruple star system - ξ Ursae Majoris. The angular separation is 8.′5, and the projected physical separation is ≈4000 AU. The sub-solar metallicity and low chromospheric activity of ξ UMa A argue that the system has an age of at least 2 Gyr. The infrared luminosity and color of the brown dwarf suggests the mass of this companion ranges between 14 and 38 MJ for system ages of 2 and 8 Gyr, respectively.

Original languageEnglish (US)
Article number84
JournalAstronomical Journal
Issue number3
StatePublished - Mar 2013
Externally publishedYes


  • brown dwarfs
  • infrared: stars
  • solar neighborhood
  • stars: late-type
  • stars: low-mass

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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