[Previous] | [Session 25] | [Next]
M. Nagasawa (NAOJ), E. Thommes (CITA), D. N. C. Lin (UCO/Lick)
We calculate the collisional evolution of protoplanets after the oligarchic growth during the protoplanetary disk depletion. Previous studies show that the isolated protoplanets grow up to their final sizes through dynamical instability, but the formed terrestrial planets generally emerge with relatively high eccentricities. Although mechanisms which damp the eccentricity have been proposed, these mechanisms tend to prevent orbit crossing and planetary growth.
We consider that the eccentricities are excited through a sweeping secular resonance rather than dynamical instability among the protoplanets. Assuming the uniform depletion of gas disk after the formation of Jupiter, we include the effects of gravity of the disk and gravitational drag from the disk in our simulations. The secular resonance of Jupiter sweeps through the terrestrial region from outside to inside pumping up the eccentricities of protoplanets. When the eccentricities of protoplanets are excited, the tidal drag causes the semi-major axes of them to decay. We find that the migration of protoplanets along with the secular resonance induces isolated protoplanets to grow through collisions and that the tidal drag from the remnant disk effectively damps the eccentricity of the fully grown protoplanets.
M. N. is supported by MEXT (MEXT-16077202) and E. T. is supported by the National Sciences and Engineering Research Council of Canada. This work is partially supported by NASA through its TPF program under the grant NNG04G191G to D. N. C. L.
[Previous] | [Session 25] | [Next]
Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.