Interstellar asteroid likely came from 2-star system

The first asteroid from outside our solar system ever spotted passing Earth likely came from a star system with two 'suns,' a Canadian team of astronomers says.

Oumuamua was likely kicked out as planets formed, University of Toronto astronomers report

'Oumuamua — the interstellar asteroid spotted passing through our solar system last year, and pictured in this artist's impression — was going too fast to be captured by the gravity of the planets. But an object with a slower velocity could conceivably be pulled into the orbit of a giant planet like Jupiter. (M. Kornmesser/ESO)

​Our first known interstellar visitor likely came from a two-star system.

That's the latest from astronomers who were amazed by the mysterious cigar-shaped object, detected as it passed through our inner solar system last fall.

The University of Toronto's Alan Jackson reported Monday that the asteroid — the first confirmed object in our solar system originating elsewhere — is probably from a binary star system. That's where two stars orbit a common centre. According to Jackson and his team, the asteroid was likely ejected from its system as planets formed.

"It has been wandering interstellar space for a long time since," the scientists wrote in the Royal Astronomical Society's journal, Monthly Notices.

This illustration shows a hypothetical planet covered in water around the binary star system of Kepler-35A and B. Binary star systems are where two stars orbit a common centre. (NASA/JPL-Caltech)

Discovered millions of kilometres away from Earth in October using a telescope in Hawaii, the asteroid is called Oumuamua, Hawaiian for messenger from afar arriving first, or scout. The red-tinged rock is estimated to be possibly 400 metres (1,300 feet) long and zooming away from the Earth and sun at more than 26 kilometres (16 miles) per second.

Last month, a science team led by Wesley Fraser of Queen's University Belfast reported that Oumuamua is actually tumbling through space, likely the result of a collision with another asteroid or other object that kicked it out of its home solar system. He expects it to continue tumbling for billions of more years.

Scientists originally thought it might be an icy comet, but now agree it is an asteroid.

'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,' University of Toronto researcher Alan Jackson said in a statement. (University of Toronto Scarborough)

"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.

Close binary star systems may be the source of the majority of interstellar objects out there, both icy comets and rocky asteroids, according to the researchers.


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