Ophiuchus 1622−2405: Not a Planetary‐Mass Binary

We present an analysis of the mass and age of the young low-mass binary Oph1622-2405. Using resolved optical spectroscopy of the binary, we measurespectral types of M7.25+/-0.25 and M8.75+/-0.25 for the A and B components,respectively. We show that our spectra are inconsistent with the spectral typesof M9 and M9.5-L0 from Jayawardhana & Ivanov and M9+/-0.5 and M9.5+/-0.5 fromClose and coworkers. Based on our spectral types and the theoreticalevolutionary models of Chabrier and Baraffe, we estimate masses of 0.055 and0.019 Msun for Oph 1622-2405A and B, which are significantly higher than thevalues of 0.013 and 0.007 Msun derived by Jayawardhana & Ivanov and above therange of masses observed for extrasolar planets (M<=0.015 Msun). Planet-likemass estimates are further contradicted by our demonstration that Oph1622-2405A is only slightly later (by 0.5 subclass) than the composite of theyoung eclipsing binary brown dwarf 2M 0535-0546, whose components havedynamical masses of 0.034 and 0.054 Msun. To constrain the age of Oph1622-2405, we compare the strengths of gravity-sensitive absorption lines inoptical and near-infrared spectra of the primary to lines in field dwarfs (>1Gyr) and members of Taurus (~1 Myr) and Upper Scorpius (~5 Myr). The linestrengths for Oph 1622-2405A are inconsistent with membership in Ophiuchus (<1Myr) and instead indicate an age similar to that of Upper Sco, which isagreement with a similar analysis performed by Close and coworkers. We concludethat Oph 1622-2405 is part of an older population in Sco-Cen, perhaps Upper Scoitself.Comment: The Astrophysical Journal, in pres