Asteroid experts at São Paulo State University’s Institute of Geosciences and Exact Sciences (IGCE-UNESP) have discovered 19 space rocks of interstellar origin classified as Centaurs are roaming the outer Solar System. Professor Maria Helena Moreira Morais, one of the two co-authors, said: “The Solar System formed 4.5 billion years ago in a stellar nursery, with its systems of planets and asteroids.
“The stars were close enough to each other to foster strong gravitational interactions that led to an exchange of material among the systems.
“Some objects now in the Solar System must therefore have formed around other stars.
“Until recently, however, we couldn’t distinguish between captured interstellar objects and objects that formed around the Sun.
“The first identification was made by us in 2018.”
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The first identification to which Professor Morais referred was the asteroid 514107 Ka’epaoka’awela, as reported by the São Paulo Research Foundation (FAPESP) in 2018.
The name Ka’epaoka’awela is Hawaiian and can be translated to “mischievous opposite-moving companion of Jupiter”.
This asteroid has occupied the path corresponding to gas giant Jupiter’s orbit for at least 4.5 billion years, but it revolves around the Sun in the direction opposite to that of the planets.
Because of this has a Ka’epaoka’awela is a retrograde co-orbital asteroid of Jupiter.
Professor Morais said: “However, our simulation showed that 4.5 billion years ago, these objects revolved around the Sun in orbits perpendicular to the disk’s plane.
“In addition, they did so in a region distant from the gravitational effects of the original disk.”
These two findings showed that the Centaurs did not originally belong to the Solar System and must have originated from nearby stars during the planetary formation period.
The discovery in the Solar System of a population of asteroids of interstellar origin is a major step in the understanding of the differences and similarities between objects that formed in the Solar System and objects in the Solar System that were originally extrasolar.