An L+T Spectral Binary with Possible AB Doradus Kinematics [SSA]

http://arxiv.org/abs/1801.06134


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$\pm$1.0 and T3.0$\pm$1.8 or L7.0$\pm$0.6 and T7.5$\pm$0.4 components. Its proper motion and radial velocity as a combined-light source yield a high membership probability for AB~Doradus. While the young L6+T3 case is underluminous in a color-magnitude diagram at the AB~Doradus kinematic distance, the young L7+T7.5 case could be viable. Gravity-sensitive indicators are more consistent with a field-age binary. If confirmed as a young object, member of AB~Doradus, we estimate masses of 11$\pm$1\,\mjup\ and 9$\pm$1\,\mjup\ with both component masses below the Deuterium burning mass limit. Otherwise, we find masses of $72^{+4}{-5}$ and $61^{+6}{-8}$ for the field L6+T3 case and $70^{+2}{-4}$ and $42^{+5}{-6}$ 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.

Read this paper on arXiv…

D. Gagliuffi, J. Gagne, J. Faherty, et. al.
Fri, 19 Jan 18
23/68

Comments: 12 pages, 2 figures, 7 subfigures