title: Discovery of a young planetary-mass binary.
abstract: We have identified a companion to the young planetary-mass brown dwarf Oph 162225-240515. This pair forms a resolved binary consisting of two objects with masses comparable to those of extrasolar giant planets. Several lines of evidence confirm the coevality and youth of the two objects, suggesting that they form a physical binary. Models yield masses of approximately 14 and approximately 7 times the mass of Jupiter for the primary and the secondary object, respectively, at an age of approximately 1 million years. A wide ( approximately 240-astronomical unit) binary in the ultra-low-mass regime poses a challenge to some popular models of brown dwarf formation.
authors.affiliation: Department of Astronomy and Astrophysics, University of Toronto, Toronto, ON M5S 3H8, Canada. rayjay@astro.utoronto.ca
authors.forename: Ray
authors.initials: R
authors.lastname: Jayawardhana
authors.forename: Valentin D
authors.initials: VD
authors.lastname: Ivanov