19 new “interstellar travelers” discovered orbiting the Solar System

P. Biosca


Updated:04/29/2020 01:55 h


The end of this decade has been very fruitful for astronomers looking for interstellar objects: at the end of 2017 they found the mysterious Oumuamua, a body that came from beyond our Solar system It was captured just at the end of its journey through our cosmic neighborhood and its origin and composition are still debated. Then it came Borisov, of whom we are certain that it is a comet come from another star to “die” in our space.

But there are other bodies that “take advantage” of the trip to stay with us. This is the case of the 2015 asteroid BZ509, known as «Bee-Zed». Bee-Zed It caught the attention of the scientific community for orbiting in the opposite direction to the rest of the 6,000 bodies that orbit Jupiter. This sort of “suicide asteroid” discovered in 2015 was listed as the first human-captured extrasolar object in the Solar System. The first asteroid that did not form in our cosmic neighborhood, but in another.

When visitors stay to live

However, it would not be the only one: a new study led by the same team that discovered Bee-Zed would have found a total of 19 asteroids that gravitate between Jupiter and Neptune which would also have been created outside our solar limits. Fathi Namouni, a CNRS researcher at the Laboratoire Lagrange (CNRS / Observatoire de la Côte d’Azur / Université Côte d’Azur), and Helena Morais, a researcher at UNESP in Brazil this week published her conclusions in the magazine “Monthly Notices of the Royal Astronomical Society”.

According to their calculations, the current orbits and characteristics of these 19 asteroids can only be explained «if these objects were not in our Solar System at birth, 4.5 billion years ago », they affirm in a release. They all belong to the family of centaurs, asteroids located among gas giants, which sometimes behave like comets, and whose orbits cannot be predicted. So Namouni and Morais developed a simulation back in time, based on secure data, to find past prospects.

Illustration of the orbit of a Centaur asteroid 4.5 billion years ago in the past, compared to the protoplanetary disk. The asteroid orbits the Sun away from the disk in a plane perpendicular to it – NASA

The enigmatic centaurs

Objects in our system already gravitated around the Sun 4.5 billion years ago in the same plane of dust and gas disc in which they were formed. However, the nineteen centaurs weren’t there in the first place. The simulations show not only that these bodies would have to be in a plane perpendicular to the planetary movements at that time, but also that they were found away from the asteroid source disk of our cosmic neighborhood.

That is why the study points out that these 19 asteroids did not originate in the Solar System, but are surely fruit of a nearby star cluster who had great gravitational interactions with ours, who in the end “captured” these bodies for himself. The next step will be to find out if more objects fell into the networks of our borders after this “fight” between the gravity of the stars.


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