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'Oumuamua: 'space cigar's' tumble hints at violent past

'Oumuamua: 'space cigar's' tumble hints at violent past
From BBC - February 10, 2018

The space interloper 'Oumuamua is spinning chaotically and will carry on doing so for more than a billion years.

That is the conclusion of new Belfast research that has examined in detail the light bouncing off the cigar-shaped asteroid from outside our Solar System.

"At some point or another it's been in a collision," says Dr Wes Fraser from Queen's University.

His team's latest study is featured in Sunday's Sky At Night episode on the BBC and published in Nature Astronomy.

It is yet another intriguing finding about this strange object that has fascinated scientists since its discovery back in October.

'Oumuamua comes from a different star system. Its path across the sky confirms it does not originate in our solar neighbourhood.

Initially, it was thought the object could be a comet, but it displays none of the classic behaviour expected of these cosmic wanderers - such as a dusty, water-ice particle tail.

'Oumuamua is in all likelihood an asteroid, albeit with a highly unusual shape. It has been described as resembling a cigar or cucumber, where the longest dimension is over 200m.

The Queen's team wanted to establish the exact nature and rate of the object's rotation.

To do this, the group studied variations in its brightness over time.

Almost immediately, Dr Fraser and colleagues could see that it was not spinning periodically like many small asteroids, but spinning chaotically - it was tumbling.

In Sunday's Sky At Night programme on BBC Four, the Queen's researcher illustrates this with the aid of a tennis table bat.

Throw it in the air one way and it will turn over evenly about a single axis; throw it up another way and it is possible to make the paddle turn over in an apparently haphazard way.

"It quickly starts to wobble around chaotically, and that's what we call tumbling," he tells presenter Chris Lintott.

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