Adaptive Optics Observations of the Binary Star HD 435871

Abstract

We present adaptive optics observations of HD 43587, one of the primary targets of the COROT (Convection, Rotation, and Planetary Transits) asteroseismology and planet-finding space mission and a star that was previously detected as a spectroscopic binary by Vogt and coworkers. We resolve a close companion, which is responsible for the radial velocity variations of the primary. Our observations over a 3 year interval measure the orbital displacement of the companion. Combining these measurements with the radial velocity data of Vogt and coworkers, we solve for the three-dimensional orbit of the system and derive individual masses for HD 43587 and its companion. This is particularly interesting in the perspective of the upcoming COROT mission. These observations were part of a preparatory program for COROT, in which we observed all COROT potential primary targets and some of its secondary targets with adaptive optics. The majority of these stars have potential companions in a 30'' field. Most of these are probably background objects, but some are found within a few arcseconds of the COROT targets and are likely to be true physical companions.