Asteroid Oumuamua Likely Came From A Binary Star System

Asteroid Oumuamua
Image credit: European Southern Observatory / M. Kornmesser – NASA

Asteroid Oumuamua caught the attention of many scientists and astronomers when it appeared in our solar system last year, particularly because of its cigar shape, and rather odd movement. A new study suggests that the asteroid likely came from a binary star system.

A team led by Alan Jackson of the University of Toronto at Scarborough conducted a study that sheds light on the origin of the cigar-shaped asteroid, suggesting that it came from a binary star system that is much different than our own.

The researchers referred to computer modeling for more accurate results. They discovered that rocky objects similar to asteroid Oumuamua, which is also the first known interstellar object to enter our solar system, are likely to have been ejected from a binary system. Binary systems, unlike our solar system, consist of two stars that orbit the center of the system.

Jackson and his team discovered one interesting property of binary systems. Two close-orbiting stars are better at ejecting asteroids compared to the systems consisting of one star. On the other hand, systems with only one star are more commonly found ejecting icy comets, as comets are located much farther away from the solar system’s star. That makes comets less bound by gravity, which is not the case for asteroids, which are nearer.

As there are two stars, those systems have more powerful gravitational fields, given both of the stars orbit each other. This property allows them to eject a lot of asteroids and comets and send them into interstellar space.

“It’s really odd that the first object we would see from outside our system would be an asteroid, because a comet would be a lot easier to spot and the solar system ejects many more comets than asteroids,” Jackson said in a statement.

According to Jackson, it’s most likely that the asteroid Oumuamua was ejected from its home binary star system at the time when planets were forming. NASA wrote on its website about how comets and asteroids get ejected into interstellar space. According to NASA, a lot of the celestial objects were ejected into interstellar space through encounters with Jupiter. Many asteroids and comets interacted with the young Jupiter that then ejected them either into interstellar space, or towards the sun.

NASA believes that planetary systems that came from other stars likely grew in the same way ours did with Jupiter.

“Galactic budget of interstellar objects like 1I/’Oumuamua should be dominated by planetesimal material ejected during planet formation in circumbinary systems, rather than in single star systems or widely separated binaries,” the researchers wrote in their study. “The rocky population, of which 1I/’Oumuamua seems to be a member, should be predominantly sourced from A-type and late B-star binaries.”

“The same way we use comets to better understand planet formation in our own Solar System, maybe this curious object can tell us more about how planets form in other systems,” Jackson said in a statement.

The study was published in the journal Monthly Notices of the Royal Astronomical society.