On the inclinations of the Jupiter Trojans
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Jupiter Trojans are a resonant asteroidal population characterised by
photometric colours that are compatible with trans-Neptunian objects,
high inclinations, and an asymmetric distribution of the number of
asteroids between the two swarms. Different models have been proposed to
explain the high inclination of the Trojans and to interpret their
relation with the Trans-Neptunian objects, but none of these models can
also satisfactorily explain the asymmetry ratio between the number of
asteroids in the two swarms. It has recently been found that the
asymmetry ratio can arise if Jupiter has migrated inwards through the
protoplanetary disc by at least a few astronomical units during its
growth. The more numerous population of the leading swarm and the dark
photometric colours of the Trojans are natural outcomes of this new
model, but simulations with massless unperturbed disc particles led to a
flat distribution of the Trojan inclinations and a final total mass of
the Trojans that was 3-4 orders of magnitude larger than the current
mass. We here investigate the possible origin of the peculiar
inclination distribution of the Trojans in the scenario where Jupiter
migrates inwards. We analyse 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 in which Jupiter grows and
migrates. We find that the secular evolution of the Trojans and secular
perturbations from Saturn do not affect the inclination distribution of
the Trojans appreciably, nor is there any significant mass depletion
over the age of the Solar System. Embryos embedded in the Trojan swarms,
in contrast, can stir the Trojans to their current degree of excitation
and can also deplete the swarms efficiently, but it is very difficult to
remove all of the massive bodies in 4.5 Gyr of evolution. We propose
that the disc where Jupiter's core was forming was already stirred to
high inclination values by other planetary embryos competing in the
feeding zone of Jupiter's core. We show that the trapped Trojans
preserve their high inclination through the gas phase of the
protoplanetary 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 during 4.5 Gyr of evolution.
Original language | English |
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Article number | A89 |
Journal | Astronomy & Astrophysics |
Volume | 631 |
Number of pages | 10 |
ISSN | 0004-6361 |
DOIs | |
Publication status | Published - 2019 |
Externally published | Yes |
- minor planets, asteroids: general, planets and satellites: dynamical evolution and stability
Research areas
ID: 279328331