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UK research suggests interstellar visitors had a violent past

12 February 2018

‘Oumuamua

Artist’s impression of ‘Oumuamua
(Credit: ESO/M. Kornmesser)

The first-ever observed interstellar visitor to our solar system has had a violent past – causing it to tumble around chaotically as it travels through space – an STFC-funded scientist has discovered.

`Oumuamua is the first interstellar asteroid ever to be seen entering our Solar System from a different planetary system, and it fascinated astronomers all over the world when it was first spotted in October last year. The strange rock was originally thought to be a comet, then it was later revealed as a cucumber-shaped asteroid.

Since October, Dr Wes Fraser, from Queen’s University Belfast (QUB) has been analysing the brightness measurements of the object. Very quickly he discovered that ‘Oumuamua wasn’t spinning periodically like most of the small asteroids and bodies that we see in our solar system. Instead, it is tumbling, or spinning chaotically, and has been for many billions of years.

While it is difficult to pinpoint the exact reason for this, it is thought that `Oumuamua impacted with another object before it was fiercely thrown out of its origin system and into interstellar space.

Dr Fraser explains: “Our modelling of this body suggests the tumbling will last for many billions of years to hundreds of billions of years before internal stresses cause it to rotate normally again.

“While we don’t know the cause of the tumbling, we predict that it was most likely sent tumbling when there was impact with another planetesimal in its system, before it was ejected into interstellar space.”

The research findings, which have been published in Nature Astronomy, have helped to build a more accurate profile of `Oumuamua. 

Since `Oumuamua was spotted in October, a team of researchers at Queen’s University Belfast have been analysing the object in detail. This is the third paper to be published by their team, all of whom have been supported by funding from STFC.

For more information visit the QUB news page.

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