On the Value of High Precision Radial Velocity Observations and Astrometric Orbits for Binary Stars Hosting Exoplanets

Abstract Observations have concluded that exoplanet hosting binary stars appear to have wider mean separations than a definitive sample of “field binaries” as well as an apparent deficit of very close pairs. Many exoplanets orbit near their host stars equatorial plane, especially for close-in, small planets. Precision radial velocities of exoplanets in close binary stars are sparse but badly needed in order to provide statistical samples revealing the host stars spin axis and determinations of the masses and orbital planes of their planets. Astrometric orbits of the stars can provide precise binary orbital elements. In the quest for occurrence rates, the detection of planets is biased against transit recognition of small planets in binary systems. Together the measurements of binary host stars and their planets are required to yield robust tests of planet formation, stability, and evolution mechanisms as well as provide correct small planet occurrence rates.