A YOUNG PLANETARY-MASS OBJECT IN THE rho OPH CLOUD CORE

作者：Marsh Kenneth A^*; Kirkpatrick J Davy; Plavchan Peter

来源：Astrophysical Journal Letters, 2010, 709(2): L158-L162.

DOI：10.1088/2041-8205/709/2/L158

• brown dwarfs
• infrared: stars
• stars: low-mass
• stars: pre-main sequence

We report the discovery of a young planetary-mass brown dwarf in the rho Oph cloud core. The object was identified as such with the aid of a 1.5-2.4 mu m low-resolution spectrum obtained using the NIRC instrument on the Keck I telescope. Based on the COND model, the observed spectrum is consistent with a reddened (A(V) similar to 15-16) brown dwarf whose effective temperature is in the range 1200-1800 K. For an assumed age of 1 Myr, comparison with isochrones further constrains the temperature to similar to 1400 K and suggests a mass of similar to 2-3 Jupiter masses. The inferred temperature is suggestive of an early T spectral type, which is supported by spectral morphology consistent with weak methane absorption. Based on its inferred distance (similar to 100 pc) and the presence of overlying visual absorption, it is very likely to be a rho Oph cluster member. In addition, given the estimated spectral type, it may be the youngest and least massive T dwarf found so far. Its existence suggests that the initial mass function for the rho Oph star-forming region extends well into the planetary-mass regime.

• 出版日期2010-2-1