Gliese 569B: A young multiple brown dwarf system?

Matthew Kenworthy, Karl Heinz Hofmann, Laird Close, Phil Hinz, Eric Mamajek, Dieter Schertl, Gerd Weigelt, Roger Angel, Yuri Y. Balega, Joannah Hinz, George Rieke

Research output: Contribution to journalArticlepeer-review

33 Scopus citations


The nearby late M star Gliese 569B was recently found by adaptive optics imaging to be a double with separation ∼1 AU. To explore the orbital motion and masses, we have undertaken a high-resolution (∼0″.05) astrometric study. Images were obtained over 1.5 yr with bispectrum speckle interferometry at the 6.5 m Multiple Mirror Telescope (MMT) and 6 m Special Astrophysical Observatory telescope. Our data show motion corresponding to more than half the orbital period and constrain the total mass to be greater than 0.115 M, with a most probable value of 0.145 M. Higher masses cannot be excluded without more extended observations, but from statistical analysis we find an 80% probability that the total mass is less than 0.21 M. An infrared spectrum of the blended B double obtained with the MMT has been modeled as a blend of two different spectral types, chosen to be consistent with the measured J-and K-band brightness difference of a factor of ∼2. The blended fit is not nearly as good as that to a pure M8.5+ template. Therefore, we hypothesize that the brighter component likely has two unresolved components with near equal masses, each the same as the fainter component. If G1 569B is a triple, our dynamical limits suggest each component has a mass of 50+23-4 MJup. We infer an age for the system of 300 Myr from its kinematic motion, which places it as a member of the Ursa Major moving group. All the above parameters are consistent with the latest DUSTY evolution models for brown dwarfs.

Original languageEnglish (US)
Pages (from-to)L67-L70
JournalAstrophysical Journal
Issue number1 PART 2
StatePublished - Jun 10 2001


  • Binaries: general
  • Stars: evolution
  • Stars: formation
  • Stars: individual (G1 569)
  • Stars: low-mass, brown dwarfs

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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