Jupiter is notorious for capturing objects that go too close to the gas giant and its enormous gravity. Asteroids known as Jupiter Trojans are a large group of space rocks trapped by the planet, which usually stay in a stable orbit near one of Jupiter’s Lagrangian points.
But now the Hubble Space Telescope has spotted a comet near Jupiter’s Trojan asteroid population. This is the first time a comet has been found in this region, and the team of scientists studying the object – called P / 2019 LD2 (LD2) – thinks the unexpected comet is only a temporary visitor.
Scientists believe that the gravitational pull of the monster planet will eventually kick the comet back to its original orbit to the Sun.
“The visitor must have come on the right orbit in the orbit of Jupiter to have this form of configuration that gives it the appearance of sharing its orbit with the planet,” said Hubble researcher Bryce Bolin of Caltech. ‘We’re investigating how it was captured by Jupiter and ended up under the Trojans. But we think it may be related to the fact that it had a somewhat close encounter with Jupiter. ‘
P / 2019 LD2 (LD2) belongs to a class of icy bodies that usually occur in the space between Jupiter and Neptune, called Centaurs. Centaurs become active as they approach the sun and warm up. Then they dynamically change into more comet-like.
The observations of the team with Hubble show that the object shows signs of becoming an active comet, shooting out a long tail, protruding radiation material and enveloping itself in a coma of dust and gas.
“Only Hubble could detect active comet-like features in such great detail, and the images clearly show these features, such as a broad tail of about 400,000 miles and high resolution near the core due to a coma and rays,” said Bolin. said.
The object was first seen in early June 2019 by the ATLAS telescopes of the University of Hawaii’s Asteroid Terrestrial-Impact Last Alert System. Several other telescopes, including the Spitzer Space Telescope (just before it retired), made follow-up observations and provided clues as to the composition of the comet-like object and the gases that drove its activity. Visible light images by Hubble provided more details.
The research team performed computer simulations of the projected path of P / 2019 LD2 (LD2), which showed that the object probably swung near Jupiter about two years ago. The planet then gravely launched the wandering visitor of the Trojan asteroid group’s co-orbital location, leading Jupiter about 437 million miles.
“The coolest thing is that you actually catch Jupiter to throw this object around and to change its orbit and bring it into the inner system,” said team member Carey Lisse of the Johns Hopkins University Applied Physics Laboratory (APL). “Jupiter controls what goes on with comets as soon as they end up in the inner system by changing their orbits.”
Currently, no spacecraft has ever visited the Trojan asteroids. But later this year, a mission named Lucy will fly through seven Trojan asteroids, plus a main-belt steroid, to investigate the diversity of this population in a single 12-year record mission. The launch window Lucy spacecraft opens October 16, 2021.
Further reading:
Paper published in The Astronomical Journal
Hubble Space Telescope Press Release
Article: Jupiter’s Trojan asteroids offer surprises even before NASA’s Lucy mission gets a chance to visit them.