THE GEMINI NICI PLANET-FINDING CAMPAIGN: DISCOVERY OF A MULTIPLE SYSTEM ORBITING THE YOUNG A STAR HD 1160

Abstract

We report the discovery by the Gemini NICI Planet-Finding Campaign of two\nlow-mass companions to the young A0V star HD 1160 at projected separations of\n81 +/- 5 AU (HD 1160 B) and 533 +/- 25 AU (HD 1160 C). VLT images of the system\ntaken over a decade for the purpose of using HD 1160 A as a photometric\ncalibrator confirm that both companions are physically associated. By comparing\nthe system to members of young moving groups and open clusters with\nwell-established ages, we estimate an age of 50 (+50,-40) Myr for HD 1160 ABC.\nWhile the UVW motion of the system does not match any known moving group, the\nsmall magnitude of the space velocity is consistent with youth. Near-IR\nspectroscopy shows HD 1160 C to be an M3.5 +/- 0.5 star with an estimated mass\nof 0.22 (+0.03,-0.04) M_Sun, while NIR photometry of HD 1160 B suggests a brown\ndwarf with a mass of 33 (+12,-9) M_Jup. The very small mass ratio (0.014)\nbetween the A and B components of the system is rare for A star binaries, and\nwould represent a planetary-mass companion were HD 1160 A to be slightly less\nmassive than the Sun.\n