2mass-planck-allsky

2MASS J09393548-2448279: The Coldest and Least Luminous Brown Dwarf Binary Known?

December 2008 • 2008ApJ...689L..53B

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

Abstract • 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(Lbol/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.

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Davy Kirkpatrick

Senior Scientist