The gemini NICI planet-finding campaign: Discovery of a multiple system orbiting the young A star HD1160

We report the discovery of two low-mass companions to the young A0V star HD1160 at projected separations of 81 ± 5AU (HD1160B) and 533 ± 25AU (HD1160C) by the Gemini NICI Planet-Finding Campaign. Very Large Telescope images of the system taken over a decade for the purpose of using HD1160A as a photometric calibrator confirm that both companions are physically associated. By comparing the system to members of young moving groups and open clusters with well-established ages, we estimate an age of 50⁺⁵⁰ _-40Myr for HD1160 ABC. While the UVW motion of the system does not match any known moving group, the small magnitude of the space velocity is consistent with youth. Near-IR spectroscopy shows HD1160C to be an M3.5 ± 0.5 star with an estimated mass of 0.22^+0.03 _-0.04 M_⊙, while NIR photometry of HD1160B suggests a brown dwarf with a mass of 33 ⁺¹² _-9 M _Jup. The very small mass ratio (0.014) between the A and B components of the system is rare for A star binaries, and would represent a planetary-mass companion were HD1160A to be slightly less massive than the Sun.