Planet formation in slightly inclined binary systems

One of the major problems of planet formation in close binary systems, such as alpha Centauri AB, is the formation of planetary embryos or cores by mutual accretion of km-sized planetesimals. In this contribution, we test the planetesimal accretion in such close binary systems but with small inclinations i(B) = 0.1-10 degrees between the binary orbital plane and the gas disk plane. Compared to previous studies (coplanar case with i(B) = 0), we find that (1) planetesimal disk is stratified in the vertical direction and planetesimals are redistributed on different orbit groups with respect to their sizes, thus (2) collisions between similar-sized bodies dominate, leading to low dV and favoring planetesimal accretion (3) the planetesimal collision timescale at 1-2 AU is estimated as: T-col(B) similar to (1 + 100i(B)) x 10(3) yrs, where 0 <= i(B) <= 10 degrees. As a conclusion, although planetesimal accretion are much more favored in slightly inclined binary systems, it is significantly less efficient and slowed-down as compared to the single-star case.