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Now astronomers have identified a more permanent external presence in our solar system. It is a group of interstellar asteroids that were recorded long ago and never left. And they’ve been hidden from view for billions of years, according to a new study published this week in the Royal Astronomical Society’s Monthly Notices.
These asteroids probably existed when our solar system was forming 4.5 billion years ago. They originated from a different star system. And when our solar system was forming, it was probably also closer to other baby star systems.
“The proximity of the stars meant they felt each other’s gravity much stronger in those early days than they do today,” said Fathi Namouni, a researcher at the Côte d’Azur Observatoire and lead author of the study, in a statement. . “This allowed the asteroids to be dragged from one star system to another.”
Namouni and her fellow researcher Maria Helena Moreira Morais at the Universidade Estadual Paulista in Brazil used numerical models to simulate the infancy of our solar system and determine the location of asteroids billions of years ago.
The simulation placed the moving asteroids in an orbit perpendicular to the plane where planets and asteroids in the solar system orbit around the sun. The asteroids were also very distant from the original disk where the planets formed around the sun.
This suggested that asteroids were captured from another star system as planets formed in our solar system.
The 19 asteroids have been in plain sight since then, orbiting the sun along with asteroids called Centaurs that can be found between Jupiter and Neptune.
Centaurs are unusual in that they look and act like asteroids and comets. This dual nature is why they are called centaurs, after half-horse and half-human creatures in mythology. According to NASA estimates, two-thirds of the centaurs came from the frozen outskirts of the solar system.
Centaurs also have orbits that are difficult to understand or predict.
“Discovering an entire population of asteroids of interstellar origin is an important step in understanding the physical and chemical similarities and differences between interstellar and solar-born asteroids,” Morais said in a statement. “This population will give us clues to the Sun’s early-birth cluster, how the capture of interstellar asteroids occurred, and the role interstellar matter played in the chemical enrichment of the solar system and in shaping its evolution.”
Foreign residents
Morais also identified an interstellar “immigrant” who lived in our solar system in 2018.
For billions of years, it lived in our solar system without us knowing it was there. But this object could not remain hidden around Jupiter forever. It was peculiar enough to be noticed by investigators.
Researchers call this exo-asteroid 2015 BZ509. It is known as an exo-asteroid because it originated outside of our solar system.
At first glance, 2015 BZ509 is just one of many objects that orbit the gas giant Jupiter in a stable configuration called resonance. Although all the planets and most objects in our solar system orbit around the sun moving in the same direction, the exo-asteroid follows its own path. With its retrograde orbit, 2015 BZ509 is moving in the opposite direction.
“It takes the same amount of time for the asteroid and Jupiter to complete an orbit around the Sun, but one moves clockwise and the other moves counterclockwise so that they intersect twice for each full orbit,” he wrote. Morais in 2018. “This pattern repeats forever, it is a stable configuration, in a simplified model with only the Sun, Jupiter and the asteroid. We saw that when we include the other planets it is still very stable, over the age of the solar system” .
That orbit is the same path that the object has always followed, which means it could not have formed in our solar system. If it were native to our solar system, it would have inherited the direction of the gas and dust that formed all the other planets and objects. Morais believed that, like the newly discovered alien asteroids, this one was also captured during the early stages of our solar system.
The exo-asteroid serves as a warning for objects that may enter our solar system.
“If they pass, they can also be captured in a stable orbit, as is the case in 2015 BZ509,” said Morais.
