HR: 0830h
AN: P51D-0468    [PDF]
TI: A Planetesimal Accretion Zone in a Circumbinary Disk.
AU: * Nakagawa, Y
EM: yoshi@kobe-u.ac.jp
AF: Kobe University, Dept. of Earth and Planetary Sciences, Faculty of Science, Kobe, 657-8501 Japan
AU: Moriwaki, K
EM: kmori@kobe-u.ac.jp
AF: Kobe University, Dept. of Earth and Planetary Sciences, Faculty of Science, Kobe, 657-8501 Japan
AB: Until recently, it had been believed that only single solar-type stars might harbor planetary systems. On the other hand, circumbinary disks have been detected by mm/sub-mm wavelength observation. Planets may be formed also in such disks. We investigate the conditions for planetesimal accretion in a circumbinary disk. The binary system gives stronger gravitational perturbation against planetesimals orbiting nearer to the binary. Therefore, the relative velocities between planetesimals will be larger, and when they exceed the escape velocity, it is impossible for the planetesimals to accumulate into a planet. We perform long-term numerical integrations of binary and planetesimal orbital motions, and find the upper limit of planetesimal semimajor axes where the velocity dispersion of the planetesimals exceeds the escape velocity. That is, when the binary semimajor axis is set to 1 AU, the eccentricity to 0.1 and the total mass to 1 $M_\odot$, the planetesimals are prevented from accreting when they orbit in a zone within 13 AU from the barycenter of the binary system. In regions outer than 13 AU, planetesimals can accrete. We also derive an analytic expression of the eccentricity of a planetesimal excited by the gravitational perturbation of the binary.
DE: 5455 Origin and evolution
DE: 6040 Origin and evolution
SC: Planetary Sciences [P]
MN: 2003 Fall Meeting