Radial velocity simulations for the Space Interferometry Mission reference grid

Our work involves radial velocity simulations for the SIM (Space Interferometry Mission) positional reference grid. The decision was made to use distant (D ∼ 1kpc) cool red-giant stars (so-called K-giants, based on their spectral type of K) as the grid stars. The currently planned strategy is to conduct two radial velocity measurements of each candidate star, with the measurements taken one year apart. With our radial-velocity accuracy of 50m/s, if the two radial velocity determinations differ by more than 50m/s, the star is rejected from the grid star list. Our goal in this study is to simulate this observing strategy by generating a set of binary systems, incline them at random angles with respect to viewing from the Earth, and then calculating the radial velocity of the primary star as measured from the Earth at two separate time intervals one year apart. We can then determine how many binary systems would have escaped our detection, and what magnitude of reflex motion would the primary stars exhibit in these missed binary systems. It is then possible to decide if these missed binary systems would add unacceptable positional noise into the grid