Abstract

We calculate herein the late stages of terrestrial planet accumulation around a solar-type star that has a binary companion with semimajor axis larger than the terrestrial planet region. We perform more than 100 simulations to survey binary parameter space and to account for sensitive dependence on initial conditions in these dynamical systems. As expected, sufficiently wide binaries leave the planet formation process largely unaffected. As a rough approximation, binary stars with periastron q_B>10 AU have a minimal effect on terrestrial planet formation within ~2 AU of the primary, whereas binary stars with q_B<~5 AU restrict terrestrial planet formation to within ~1 AU of the primary star. Given the observed distribution of binary orbital elements for solar-type primaries, we estimate that about 40%-50% of the binary population is wide enough to allow terrestrial planet formation to take place unimpeded. The large number of simulations allows us to determine the distribution of results-the distribution of plausible terrestrial planet systems-for effectively equivalent starting conditions. We present (rough) distributions for the number of planets, their masses, and their orbital elements.