Oumuamua is the first interstellar asteroid we’ve seen pass through the inner solar system. While this curious object came and went in late 2017, a new study suggests that there may be a permanent population of interstellar asteroids among other minor planets in the solar system. They may have been hidden in front of our eyes for billions of years, according to a recent study published in the Monthly Notices of the Royal Astronomical Society.
According to this research focused on a handful of strange space rocks known as Centaurs , which orbit the sun in the vicinity of Jupiter and Saturn and which can be both asteroids and comets (hence their name is centaur, from the mythological half-human being half horse).
Astronomers have long been puzzled by centaurs because their orbits are so unpredictable; simulations suggest that they should collide with objects or fly out of the solar system. The new research suggests it’s because our solar system stole them when it was very young. With much less expansion under the belt of the universe, the stars were closer together.
“The proximity of the stars meant that they felt gravity much stronger in those early days than today,” says Fathi Namouni, an astronomer at the Observatoire de la Cote d’Azur in France and lead author of the study. “This allowed asteroids to be pulled from one star system to another.”
The infiltrators
There are 19 interstellar objects; 17 of them are Centaurs and the other two are beyond the orbit of Neptune . The 19 objects have a high inclination with respect to the orbital plane of the solar system where the planets more or less reside. When the experts carried out a computer simulation, they discovered that asteroids did not reach their orbits by rising above the orbital plane, but orbited much further than the planets and in a polar orbit, about 90 degrees from other objects. in the solar system. These two facts suggest that they did not form with the other planets, comets, and asteroids; Rather, they may have been snatched from another star when the Sun and the solar system were still within the stellar nursery from which they formed.
Scientists have hypothesized that objects move between solar systems, with the first confirmed intruders in our neighborhood in recent years being ‘Oumuamua and Comet Borisov. Both objects just passed through our solar system and weren’t caught by the Sun’s gravity. But the authors believe that these other asteroids were more likely to roam other star systems and get stuck here, because in the early days of the solar system , with more than 4,000 million years less of expansion, everything was much more united, more together. And identifying the original interstellar asteroids in our cosmic neighborhood is important because they are much easier to study than objects in distant solar systems.
“The discovery of a complete population of asteroids of interstellar origin is an important step to understand the similarities and physical and chemical differences between interstellar and asteroids born in the sola r system”, explains Maria Helena Morais, astronomer at the Universidade Estadual Paulista in Brazil and co-author of the study. “This population will give us clues about the cluster of early sun births, how the capture of interstellar asteroids occurred and the role that interstellar matter had in the chemical enrichment of the solar system and in shaping its evolution.”
Referencia: An interstellar origin for high-inclination Centaurs. F Namouni, M H M Morais. Monthly Notices of the Royal Astronomical Society, Volume 494, Issue 2, May 2020, Pages 2191–2199. DOI:https://doi.org/10.1093/mnras/staa712
