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A. Morbidelli (OCA, Nice, France), H. F. Levison (SWRI/OCA), K. Tsiganis (OCA), R. Gomes (ON/OCA)
The origin of Jupiter Trojans is still an unsolved mystery. Particularly puzzling is the Trojans' inclination distribution, which ranges up to 45 degrees. Here we advocate a new scenario. It is well accepted that Jupiter and Saturn migrated in divergent directions, as a result of their interaction with a disk of left-over planetesimals. Simulations show that it is possible that the ratio between their orbital periods was initially smaller than 2, and that the planets passed through the mutual 1:2 resonance during their migration. When the planets are in/close to the 1:2 resonance, the Trojan region is completely unstable. In this situation the planetesimals that pass through the system, driving planetary migration, can enter the Trojan region and spend there some amount of time before leaving the region again. Thus, a sort of `steady state' Trojan population is created. We have done numerical simulations to characterize the orbital distribution of this population. It matches well the distribution of the currently observed Trojans, in particular in inclination. When the planets depart the 1:2 resonance, the Trojan region becomes stable. Therefore, the transient Trojan population formed during the unstable phase gets frozen in, giving rise to a population of permanently captured, stable Trojans. Full simulations of this process are under the way. A preliminary analysis shows that stable Trojans are indeed produced. An accurate evaluation of the trapping efficiency has not been possible yet, and it will be presented at the meeting.
The author(s) of this abstract have provided an email address for comments about the abstract: morby@obs-nice.fr
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.