2007ApJ...654L..81M

A robust unconstrained orbital solution is obtained for the G2 V star HIP 16853 = HD 22705 at 42 pc, which is a probable member of the 28-30 Myr old Tucana-Horologium stream of post-T Tauri stars. The solution yields an apparent semimajor axis of 5.1±0.7 mas, a period of 201±2 days, and an inclination of 80°±7°. Assuming a mass of 1 M_☉for the primary, the close companion is only 0.4 M_☉, which implies a spectral type M0.5 at this age. The expected maximum separation (a) between the companions is 18 mas, which makes this system amenable for high-resolution observations. The wide companion HIP 16853 B at 14" is investigated as a possible tertiary component but rejected on account of the near-infrared photometric data inconsistent with the well-defined H-R diagram of the Tucana-Horologium group.