lpetrich
Contributor
Astronomers Think They Might Have Figured Out Jupiter's Mysterious Origins noting [1902.04591] The consequences of planetary migration on the minor bodies of the early Solar System
Jupiter seems to be rather big for its position in the Solar System, and among the nearly 4000 exoplanets now known to exist are "hot Jupiters", Jupiter-mass planets orbiting so close to their stars that they are hot enough to glow in visible light. The most successful hypothesis for the origins of these odd planets is that they formed much farther out then where we now observe them, and that they then spiraled in by gravitationally interacting with what remained of the protoplanetary nebula.
So did Jupiter also spiral in after it was formed?
There is a remarkable clue in the form of some asteroids that share Jupiter's orbit. They are the "Trojans", named after heroes of the Trojan War. The L4 or leading ones are named after Greeks and the L5 or trailing ones are named after Trojans, though the leading ones contain a Trojan and the trailing ones a Greek, both named before this convention was followed. Lucy: The First Mission to Jupiter’s Trojans | NASA is a planned mission to them that will involve several flybys of them.
There is a curious asymmetry in them. From
Jupiter trojan, "As of October 2018 there are 4,601 known Jupiter trojans at L4 and 2,439 at L5.[15]" Some astronomers have recently considered how that asymmetry might have formed, and they considered several formation scenarios. Formation in-place gave no asymmetry, while spiraling in from Uranus's present distance gave an asymmetry much like what we observe.
That causes trouble for the "Grand Tack" scenario for the asteroid belt and Mars's low mass, but Jupiter may have overshot its present distance, spiraling in further. It may then have gotten pulled outward to its present position by Saturn.
Jupiter seems to be rather big for its position in the Solar System, and among the nearly 4000 exoplanets now known to exist are "hot Jupiters", Jupiter-mass planets orbiting so close to their stars that they are hot enough to glow in visible light. The most successful hypothesis for the origins of these odd planets is that they formed much farther out then where we now observe them, and that they then spiraled in by gravitationally interacting with what remained of the protoplanetary nebula.
So did Jupiter also spiral in after it was formed?
There is a remarkable clue in the form of some asteroids that share Jupiter's orbit. They are the "Trojans", named after heroes of the Trojan War. The L4 or leading ones are named after Greeks and the L5 or trailing ones are named after Trojans, though the leading ones contain a Trojan and the trailing ones a Greek, both named before this convention was followed. Lucy: The First Mission to Jupiter’s Trojans | NASA is a planned mission to them that will involve several flybys of them.
There is a curious asymmetry in them. From
Jupiter trojan, "As of October 2018 there are 4,601 known Jupiter trojans at L4 and 2,439 at L5.[15]" Some astronomers have recently considered how that asymmetry might have formed, and they considered several formation scenarios. Formation in-place gave no asymmetry, while spiraling in from Uranus's present distance gave an asymmetry much like what we observe.That causes trouble for the "Grand Tack" scenario for the asteroid belt and Mars's low mass, but Jupiter may have overshot its present distance, spiraling in further. It may then have gotten pulled outward to its present position by Saturn.