THE NEAREST ISOLATED MEMBER OF THE TW HYDRAE ASSOCIATION IS A GIANT PLANET ANALOG

Abstract

In a recent search for unusually red L and T dwarfs, we identified 2MASS J11193254–1137466 as a likely young L7 dwarf and potential member of the TW Hydrae association. We present spectra that confirm the youth of this object. We also measure a radial velocity of 8.5 ± 3.3 km s −1 that, together with the sky position, proper motion, and photometric distance, results in a 92% probability of membership in the TW Hydrae association, with a calibrated field contamination probability of 0.0005% using the BANYAN II tool. Using the age of TW Hydrae and the luminosity of 2MASS J11193254–1137466, we estimate its mass to be 4.3–7.6 M Jup . It is the lowest-mass and nearest isolated member of TW Hydrae at a kinematic distance of 28.9 ± 3.6 pc, and the second-brightest isolated <10 M Jup object discovered to date.