A Young Brown Dwarf Companion to DH Tauri

We present the detection of a young brown dwarf companion, DH Tau B, associated with the classical T Tauri star DH Tau. Near-infrared coronagraphic observations with CIAO on the Subaru Telescope have revealed DH Tau B with H=15 mag located 2.3" (330 AU) away from the primary, DH Tau A. Comparing its position with a Hubble Space Telescope archive image, we confirmed that DH Tau A and B share a common proper motion, suggesting that they are physically associated with each other. The near-infrared color of DH Tau B is consistent with those of young stellar objects. The near-infrared spectra of DH Tau B show deep water absorption bands, a strong K I absorption line, and a moderate Na I absorption line. We derived its effective temperature and surface gravity of T_eff=2700-2800 K and logg=4.0-4.5, respectively, by comparing the observed spectra with synthesized spectra of low-mass objects. The location of DH Tau B on the H-R diagram gives its mass of 30MJ-50MJ.

Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.