Keck Observations in the INfrared of Taurus and ρ Oph Exoplanets And Ultracool Dwarfs (KOINTREAU). II. Two Young Bound Companions to Ophiuchus Stars

Abstract We present the second set of discoveries from Keck Observations in the INfrared of Taurus and ρ Oph Exoplanets And Ultracool dwarfs (KOINTREAU), an adaptive optics survey of young stars in the Taurus and ρ Oph star-forming regions using Keck/NIRC2 in conjunction with the Keck infrared pyramid wavefront sensor. We have discovered two faint comoving companions to young stars ISO-Oph 96 and 2MASS J16262785−2625152. The companion to ISO-Oph 96, KOINTREAU-3b, is at a projected separation of 340 au (2 . ″ 49). Using our NIRC2 photometry and evolutionary models, and assuming that the companion has the same extinction as its host star, we infer that KOINTREAU-3b has a mass of 3.4 ± 0.7 M Jup . The companion to 2MASS J16262785−2625152, KOINTREAU-4b, has a projected separation of 180 au (1 . ″ 25) and could have a mass of either 11 . 5 − 1.6 + 1.2 M Jup or 15 . 3 − 0.8 + 0.7 M Jup , depending on whether the host star is a member of ρ Oph or Upper Sco.