On the inclinations of the Jupiter Trojans

Abstract

Jupiter Trojans are are characterized by dark photometric colors, high inclinations and an asymmetry in number of bodies between the two swarms. Different models have been proposed to explain the high inclination of the Trojans and to interpret their relation with the TNOs, but none of them can also satisfactorily explain the asymmetry ratio. Recently it has been found that the asymmetry can arise if Jupiter has migrated inwards by at least a few au during its growth. The asymmetry and the dark colors of the Trojans are natural outcomes of this model, but simulations with massless unperturbed disc particles led to a flat distribution of the Trojan inclinations and a final total mass that was 3-4 orders of magnitude larger than the current one. In our work, we investigate the possible origin of the peculiar inclination distribution of the Trojans in the scenario where Jupiter migrates inwards. We analyze different possibilities: (a) the secular evolution of an initially flat Trojan population, (b) the presence of planetary embryos among the Trojans and (c) capture of the Trojans from a pre-stirred planetesimal population. We find that the secular evolution of the Trojans and Saturn do not affect the Trojan inclinations appreciably, nor is there any significant mass depletion. Embryos embedded in the swarms, in contrast, can stir the Trojan inclinations and can also deplete the swarms efficiently, but it turns out that it is very difficult to get rid of all of the massive bodies. We propose that the disc where Jupiter's core was forming was already excited by the presence of other embryos competing in Jupiter's core's feeding zone. We show that the trapped Trojans preserve their high inclination through the gas phase of the disc and that Saturn's perturbations are more effective on highly inclined Trojans, leading to a lower capture efficiency and to a substantial depletion of the swarms.

10 pages, 9 figures. Accepted for publication in A&A

References in corpus (4)

• Solar System evolution from compositional mapping of the asteroid belt
• The timeline of the Lunar bombardment - revisited
• Initial mass function of planetesimals formed by the streaming instability
• The consequences of planetary migration on the minor bodies of the early Solar System

Cited by in corpus (10)

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• Stability of Jovian Trojans and their collisional families
• Origin and Evolution of Jupiter's Trojan Asteroids
• Implications for the collisional strength of Jupiter Trojans from the Eurybates family
• Shape models and spin states of Jupiter Trojans: Testing the streaming instability formation scenario
• How the formation of Neptune shapes the Kuiper belt
• Astrocladistics of the Jovian Trojan Swarms
• The Stability of Uranus Trojans Over the Age of the Solar System