An L+T Spectral Binary with Possible AB Doradus Kinematics

摘要

We present the identification of WISE?J135501.90?825838.9 as a spectral binary system with a slight possibility of planetary-mass components in the 130–200 Myr AB?Doradus moving group. Peculiarities in the near-infrared spectrum of this source suggest it to be a blended-light binary with L6.0?±?1.0 and T3.0?±?1.8 or L7.0?±?0.6 and T7.5?±?0.4 components. Its proper motion and radial velocity as a combined-light source yield a high membership probability for AB?Doradus. While the?young L6+T3 case is underluminous in a color–magnitude diagram at the AB?Doradus kinematic distance, the?young L7+T7.5 case could be viable. Gravity-sensitive indicators are more consistent with a field-age binary. If confirmed as a young object member of AB?Doradus, we estimate masses of 11?±?1 M Jup and 9?±?1 M Jup with both component masses below the Deuterium-burning mass limit. Otherwise, we find masses of and for the field L6+T3 case and and for the field L7+T7.5 case. Our identification of WISE?J135501.90?825838.9 as a candidate young spectral binary introduces a new technique for detecting and characterizing planetary-mass companions to young brown dwarfs.