2MASS J09393548-2448279: The coldest and least luminous brown dwarf binary known?

Adam J. Burgasser, C. G. Tinney, Michael C. Cushing, Didier Saumon, Mark S. Marley, Clara S. Bennett, J. Davy Kirkpatrick

Research output: Contribution to journalArticlepeer-review

49 Scopus citations


Determinations of the luminosity and atmospheric properties of the T8 brown dwarf 2MASS J09393548-2448279 are presented, based on Spitzer IRAC and IRS observations and ground-based astrometry. We find log10 (L bol/L)=-5.69 ± 0.03 for this source, comparable to the current low-luminosity record holder 2MASS J04151954-0935066. However, modeling of near-and mid-infrared spectral data indicates an effective temperature of 600 ± 35 K., roughly 100 K cooler than 2M0415. These parameters require a highly inflated radius for 2M0939 (R ≈ 0.13 R ) which cannot be reconciled with brown dwarf structure models. However, if this source is an unresolved, equal-mass binary, then the reduced luminosity of each component (Lbol ≈ 10-6 L ) can be brought into agreement with the inferred atmospheric parameters for an age of 0.4-12 Gyr and component masses of 0.01-0.05 M . This hypothesis can be tested through future high-resolution imaging and/or spectroscopic observations.

Original languageEnglish (US)
Pages (from-to)L53-L56
JournalAstrophysical Journal
Issue number1 PART 2
StatePublished - 2008
Externally publishedYes


  • Binaries: Close-stars: Fundamental parameters
  • Brown dwarfs
  • Stars: Individual (2MASS J04151954-0935066, 2MASS J09393548-2448279)
  • Stars: Low-mass

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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