Astronomers Have Identified A Whole Population Of "Alien" Asteroids In The Solar System
Astronomers have identified a list of 19 asteroids that they believe are of interstellar origin. The results are published in the journal Monthly Notices of the Royal Astronomical Society.
Over the past three years, two interstellar objects Omwamwi asteroid and comet Borisov visited the Solar system. But it turns out that astronomers have not noticed for a long time that some asteroids orbiting the Sun, that is, formally part of the Solar system, were born outside of it.
Based on the orbital parameters of some centaur asteroids located between the orbits of Jupiter and Neptune, scientists concluded that these cosmic bodies were captured by the Sun from another star when the Solar system was only a few million years old. At that time, the Sun was part of a star-forming region, a cluster of stars born close together from the same cloud of gas and dust.
"The close location of the stars meant that in those early years they felt each other's gravity much more strongly than today," the first author of the study, Fathi Namouni, from the Cote d'Azur Observatory in France, is quoted as saying in a press release. This allowed asteroids to move from one-star system to another."
The first asteroid with a strange rotation pattern on Mooney and his fellow astronomer, the second author of the article Elena Morais (Helena Morais) from the University of Paulista State in Brazil, found back in 2018.
This asteroid 2015 BZ509 from the centaur group, later named Kaepaokavela, had the same orbit as Jupiter, but rotated in the opposite direction, or, as astronomers say, retrograde.
If it were "native" to the Solar system, it would have to move in the same direction as all the other bodies in the system, so scientists decided to build a model of the origin of the strange asteroid. Simulation results then showed that Kaepaokawela was most likely captured by the Sun from interstellar space about 4.5 billion years ago.
In the new study, scientists studied centaurs and TRANS-Neptunian asteroids with a high inclination of the orbit relative to the plane of the planets' orbits. Some of these asteroids, like Campocavallo, have retrograde rotation.
"At medium and high eccentricities, centaur orbits can be tilted relative to the unchanging plane of the Solar system by almost 180 degrees, which leads to retrograde movement," the authors write.
The list of objects of potentially interstellar origin included 17 centaurs with orbital inclinations exceeding 60 degrees and two TRANS-Neptunian asteroids.
Scientists have created models of the evolution of the orbits of these objects to imagine what happened 4.5 billion years ago. At this time, almost all of the material in the Solar system was on a flat protoplanetary disk leftover from the accretion disk of a young star, and all of its objects were orbiting the Sun in the same plane and the same direction.
But the 19 asteroids identified were not part of this protoplanetary disk. How they ended up inside the Solar system, on their strange elongated, sometimes perpendicular to the orbital plane of the "native" bodies of the Solar system orbits, remains to be seen. But, according to the authors, there is only one explanation for this, which does not contradict the laws of physics: they were captured from interstellar space.