A Young Planetary-Mass Object in the rho Oph Cloud Core

TL;DR

This paper reports the discovery of a young planetary-mass object in the rho Oph cloud, characterized by low temperature and mass, indicating the extension of the initial mass function into planetary regimes.

Contribution

The study presents the first identification of a planetary-mass brown dwarf in rho Oph using spectral analysis, suggesting the initial mass function extends into planetary masses.

Findings

Object has a temperature of ~1400 K

Mass estimated at ~2-3 Jupiter masses

Likely the youngest and least massive T dwarf found

Abstract

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 micron 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 (Av ~ 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 ~ 1400 K and suggests a mass of ~ 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 (~ 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.