Consequences of planetary migration on the minor bodies of the early solar system
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Pebble accretion is an efficient mechanism that is able to build up the
core of the giant planets within the lifetime of the protoplanetary disc
gas-phase. The core grows via this process until the protoplanet reaches
its pebble isolation mass and starts to accrete gas. During the growth,
the protoplanet undergoes a rapid, large-scale, inward migration due to
the interactions with the gaseous protoplanetary disc. In this work, we
have investigated how this early migration would have affected the minor
body populations in our solar system. In particular, we focus on the
Jupiter Trojan asteroids (bodies in the coorbital resonance 1:1 with
Jupiter, librating around the L4 and L5 Lagrangian
points called, respectively, the leading and the trailing swarm) and the
Hilda asteroids. We characterised their orbital parameter distributions
after the disc dispersal and their formation location and compare them
to the same populations produced in a classical in situ growth model. We
find that a massive and eccentric Hilda group is captured during the
migration from a region between 5 and 8 au and subsequently depleted
during the late instability of the giant planets. Our simulations also
show that inward migration of the giant planets always produces a
Jupiter Trojans' leading swarm more populated than the trailing one,
with a ratio comparable to the current observed Trojan asymmetry ratio.
The in situ formation of Jupiter, on the other hand, produces symmetric
swarms. The reason for the asymmetry is the relative drift between the
migrating planet and the particles in the coorbital resonance. The
capture happens during the growth of Jupiter's core and Trojan asteroids
are afterwards carried along during the giant planet's migration to
their final orbits. The asymmetry and eccentricity of the captured
Trojans correspond well to observations, but their inclinations are near
zero and their total mass is three to four orders of magnitude higher
than the current population. Future modelling will be needed to
understand whether the dynamical evolution of the Trojans over billions
of years will raise the inclinations and deplete the masses to observed
values.
Original language | English |
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Article number | A169 |
Journal | Astronomy & Astrophysics |
Volume | 623 |
Number of pages | 18 |
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: 279328417