A study conducted by scientists at the Institute of Earth Sciences and Precise Sciences at the São Paulo State University (IGCE-UNESP) in Rio Claro, Brazil, identified 19 asteroids of interstellar origin that are classified as centaurs, objects of the outer solar system, that revolve around the sun in the region between the orbits of Jupiter and Neptune.
An article about the study entitled “An interstellar origin for centaurs with a high tendency”; is published in the Monthly communications from the Royal Astronomical Society. The study was supported by FAPESP.
“The solar system was created 4.5 billion years ago in a star kindergarten with its systems of planets and asteroids. The stars were close enough to each other to promote strong gravitational interactions that led to material exchange between the systems. Some objects that are now in the solar system must have formed around other stars. Until recently, however, we could not distinguish between interstellar objects and objects that formed around the sun. We did the first identification in 2018, ”Maria Helena Moreira Morais, one of the two co-authors, told Agência FAPESP.
The discovery by Brazilian researchers, published in the Royal Astronomical Society’s Monthly Notices, provides clues to understanding the star kindergarten from which the sun came. Credit: NASA
Morais studied physics and applied mathematics at the University of Porto (Portugal) and received his doctorate in dynamics of the solar system at the University of London (Great Britain). She is currently a professor at IGCE-UNESP. The other co-author is Fathi Namouni, a researcher at the Côte d’Azur Observatory in Nice, France.
The first identification Morais referred to was asteroid 514107 Ka’epaoka’awela, as reported by Agência FAPESP in 2018.
The name Ka’epaoka’awela is Hawaiian and can be roughly translated as “impish, moving companion of Jupiter”. It has occupied the path corresponding to Jupiter’s orbit for at least 4.5 billion years, but rotates in the opposite direction from the planets, that is, it is a retrograde co-orbital asteroid of Jupiter.
“When we identified it as an object that came from outside the solar system, we didn’t know if it was an isolated case or part of a large population of migrant asteroids,” Morais said. “In this latest study, we identified 19 centaurs of interstellar origin.”
The researcher’s composition of an artistic image from NASA showed what the original solar system would look like, with the addition of a centaur in the polar orbit outside. Photo credit: Maria Helena Moreira Morais
Similar to Ka’epaoka’awela, the centaurs identified in the study have highly inclined orbits in relation to the orbital plane of the planets. “In order to investigate the origin of these objects, we created a computer simulation that works like a time machine and whose trajectories run back 4.5 billion years. Using the simulation, we were able to find out where these objects were at the time, ”said Morais.
The planets and asteroids that came from the solar system emerged from a thin disk of gas and dust that once orbited the sun. For this reason, they were all in the disk plane 4.5 billion years ago. If the centaurs are from the solar system, they should have moved in the plane of the disk at this point. “However, our simulation showed that these objects rotated in orbits perpendicular to the plane of the disk around the sun 4.5 billion years ago. In addition, they did this in a region away from the gravitational effects of the original disc, ”said Morais.
These two results showed that the centaurs were not originally part of the solar system and must have been caught by nearby stars during the period of planet formation.
The discovery of a population of asteroids of interstellar origin in the solar system is an important step in understanding the differences and similarities between objects that have formed in the solar system and objects in the solar system that were originally extrasolar. Future astronomical observations and possibly space missions will deepen this understanding. “Studies of this population will reveal information about the star nursery that gave birth to the sun, the detection of interstellar objects in the original solar system, and the importance of interstellar matter for the chemical enrichment of the solar system,” said Morais.
Regarding chemical enrichment, it should be remembered that the primordial universe consists mainly of hydrogen and helium. The lightest natural elements in the periodic table were created by nuclear fusion within stars and then distributed in space. The region in which the solar system is located was chemically enriched by these elements, which contributed to the composition of the human body.
Reference: “An interstellar origin for centaurs with a high inclination” by F. Namouni and MHM Morais, April 23, 2020, Monthly communications from the Royal Astronomical Society.
DOI: 10.1093 / mnras / staa712