DDA 36th Meeting, 10-14 April 2005
Session 7 Planets: Orbits and Tides
Oral, Tuesday, April 12, 2005, 9:35am-12:15pm

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[7.04] Dynamical Evolution of Short Period Planets in the Multiple Systems during the Host-Stars Contraction to the Main Sequence

M. Nagasawa, D. N. C. Lin (UCO/Lick Observatory)

We study the dynamical evolution of short-period extrasolar planets orbiting young host stars with other eccentric planets. During the fast stages of planet formation, the host-stars are in pre-main sequence stage and are surrounded by protoplanetary disks. As the host-stars evolve onto to the main sequence, the disks are depleted and the stellar radii and the speed of rotation change. All these effects influence the evolution of the orbits of short-period planets. In addition, when the short period planets whose period is less than 6 days have large eccentricities, the tidal dissipation of energy during the circularization would induce interior heating, inflation, Roche lobe overflow, and ultimately mass losses.

We study the necessary conditions for the survival of hot Jupiters including the potential of the evolving disk, the potential due to the flattening of the star produced by the increasing stellar rotation, and the post-Newtonian potential of the host star. We find that the short-period planets orbiting around young stellar objects whose spin periods are longer than a few days may be highly vulnerable to the dissipation of the disk and evolution of the stars. Based on these results, we suggest that fast rotators have more short-period planets in multiple systems than slow rotating stars.

This work was partly performed while MN held a JSPS Postdoctoral Fellowship for Research Abroad (Heisei 14). This work is supported in part by NASA through grant NAG5-11779 to D. N. C. Lin.

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Bulletin of the American Astronomical Society, 37 #2
© 2005. The American Astronomical Soceity.