Discovery of a Young Planetary-Mass Binary

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 ~14 and ~7 times the mass of Jupiter for the primary and the secondary object, respectively, at an age of ~1 million years. A wide (~240-astronomical unit) binary in the ultra-low-mass regime poses a challenge to some popular models of brown dwarf formation.