Other
Scientific paper
Dec 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011agufm.p21c1689d&link_type=abstract
American Geophysical Union, Fall Meeting 2011, abstract #P21C-1689
Other
[5749] Planetary Sciences: Fluid Planets / Origin And Evolution, [5799] Planetary Sciences: Fluid Planets / General Or Miscellaneous, [6220] Planetary Sciences: Solar System Objects / Jupiter, [6275] Planetary Sciences: Solar System Objects / Saturn
Scientific paper
It has been proposed that the outward orbital migration of Jupiter and Saturn, driven by a gas-dominated protosolar disk, may help explain why they did not move much closer to the Sun. It has also been suggested that some properties of the inner Solar System may be interpreted by invoking an inward migration of Jupiter and Saturn followed by outward migration, once they get caught in the 2:3 mean motion resonance. Hydrodynamical calculations indicate that outward migration of a compact Jupiter-Saturn system may arise from an imbalance between positive and negative Lindblad torques exerted on Jupiter by the disk. The torque density distribution acting on Jupiter extends over ~3 Hill radii on either side of the planet's orbit. The negative part of the distribution samples outer disk portions, partially depleted by the tidal perturbations of both planets. The positive part of the distribution samples inner disk portions, depleted only by the action of Jupiter. The net result may be a positive torque exerted on Jupiter. Saturn, trapped in resonance with Jupiter, migrates outward as well. This mechanism requires the exterior planet's mass not to exceed the interior planet's mass. Thus, it is assumed that neither planet accretes gas from the disk. Yet, models of giant planet formation indicate that these planets would accrete gas at whatever rate the disk provides (Lissauer et al., 2009, Icarus, 199, 338). We performed 2D and 3D hydrodynamical calculations of a Jupiter-Saturn system tidally interacting with a protoplanetary disk and investigated how gas accretion affects their migration history. We assumed initial conditions shown to result in the outward migration of non-accreting planets and recovered such scenario. We then allowed the planets to accrete gas at a disk-limited rate. In agreement with estimates derived for single planets, the assumed disk conditions lead to a mass-doubling time scale of the exterior planet that is 6-9 times as short as that of interior planet. Under these circumstances, the exterior planet's mass would quickly approach the interior planet's mass, halting outward migration. Planetary accretion is responsible for another effect that conspires against outward migration. A stationary disk, in which the accretion rate is nearly constant over its radius, would have a reduced surface density S within the orbit of an accreting planet. The reduction factor depends on the planet's accretion efficiency E, i.e., the ratio of the accretion rate onto the planet to the accretion rate through the disk interpolated at the planet's position. One can show that dMe/dt~(1+E)dMi/dt, where dMe/dt and dMi/dt are the disk accretion rates exterior and interior of the planet's orbit (Lubow & D'Angelo, 2006, Astrophys. J., 641, 526). In a stationary disk, S is proportional to the accretion rate and therefore Si~Se/(1+E), reducing the positive Lindblad torques acting on the planet. We estimated the accretion efficiency allowing for accretion onto Jupiter, but not onto Saturn, and found that E~5-6. Including accretion onto Saturn would likely yield a smaller Si/Se ratio. We simulated the migration of the two planets in such a stationary disk and found that it is directed toward the star and occurs on a time scale of order the viscous diffusion time scale.
D'Angelo Gennaro
Marzari Francesco
No associations
LandOfFree
Considerations on the Outward Migration of Jupiter and Saturn does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Considerations on the Outward Migration of Jupiter and Saturn, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Considerations on the Outward Migration of Jupiter and Saturn will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-869353