The most common result from the star formation process is a binary star system. Disks have been observed in many young binary systems, and if planets form at the right places within such disks, they can remain dynamically stable for very long times. The mass and proximity of a stellar companion, however, can influence whether/where planetary accretion can occur around the primary star. We have performed a large number of simulations ( 120) of the late stages of terrestrial planet formation around a solar type star, varying the stellar masses and the binary periastron, in order to make a brief survey of 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, binaries with periastron q > 10 AU, even for the extreme case of equal mass stars, have minimal effect on terrestrial planet formation within 2 AU of the primary star. When the periastron value becomes as small as 5 AU, planets no longer form with a = 1 AU orbits and the mass distribution tilts toward M < 1 Earth-mass, i.e., the formation of Earth-like planets is compromised. Approximately 50% of the observed binaries have q > 7 AU, and given that the galaxy contains nearly 100 billion star systems, a large number of binaries are wide enough to allow both the formation and the long term stability of Earth-like planets.
AAS/Division of Dynamical Astronomy Meeting #37
- Pub Date:
- June 2006