London, July 23 (ANI): A new computer simulation has suggested that millions of objects in the solar system's main asteroid belt may be icy interlopers from beyond Neptune that were flung into their present orbits after a violent migration of the giant planets.
The solar system's main asteroid belt is a diverse mix of objects that orbit between Mars and Jupiter.
These asteroids are generally thought to have formed close to their present locations, so their compositions should reflect the original distribution of gas and dust that surrounded the sun there and eventually condensed into solid bodies.
"People have just been assuming that what we see there, formed there," said Hal Levison of the Southwest Research Institute in Boulder, Colorado.
But, according to Levison, some 20 per cent of the asteroids in the belt may be comet-like objects that were born in colder climes, beyond the orbit of Neptune.
The results come from new simulations using a theory called the Nice model, which suggests the solar system's giant planets were born closer together and were surrounded by a vast disc of leftovers from the planets' formation called planetesimals.
According to the model, Jupiter and Saturn entered a tight orbital dance about 700 million years after the solar system formed.
Their gravity then flung Uranus and Neptune out into the planetesimal disc like bowling balls, causing the objects there to scatter like pins.
Past simulations have tracked the trajectories of these planetesimals and showed they wind up forming the Kuiper belt of icy debris where Pluto sits, some of the distant satellites of Jupiter and Saturn, and Trojan asteroids, bodies that share Jupiter's orbit but are centred at two points ahead of and behind the planet.
The new simulation fed planetesimals into the region surrounding Jupiter and Saturn as the planets moved to see how many would be captured as so-called Hilda asteroids, a group outside the main asteroid belt that orbits the sun three times for each two orbits of Jupiter.
While some of the objects became Hildas and Trojans, most of the captured objects wound up in the outer portion of the solar system's main asteroid belt.
Indeed, the outer asteroid belt boasts objects that are thought to have ice, while the inner asteroid belt is dominated by rocky bodies.
If these icy outer objects are newcomers, it would mean that objects in the asteroid belt did not all form close to their present locations. (ANI)