Cigar-shaped interstellar asteroid may have been a chunk of alien planet

Cast your minds back to 2017 and you may remember a great deal of excitement about a weird shaped asteroid speeding its way through the solar system.

It was christened ‘Oumuamua and astronomers around the world started sharing theories on what it could be. Some even suggested it was an alien probe sent to investigate our corner of the galaxy.

What was pretty clear was that ‘Oumuamua didn’t originate from within our solar system. It had a hyperbolic orbit, meaning it was moving too quickly to be bound by the sun. Therefore, it must have come from some other star.

Now a new idea has surfaced that perhaps the cigar-shaped object was actually a chunk of some alien world that was torn apart by a dying star.

The thinking comes from Yun Zhang of the Chinese Academy of Sciences’ National Astronomical Observatories and UC Santa Cruz’s Douglas N. C. Lin. They took ‘Oumuamua’s oblong size as a starting point and ran computer simulations to try and figure out how something would create that shape.

They found that objects (like comets or asteroids) that get a bit too close to a star can fragment into smaller pieces which then fall either side of the main body. Tidal forces (created by gravity around the star) gradually stretch and elongate these objects into something like ‘Oumuamua.

The pair went further and suggested that if a planet on a highly elliptical orbit got too close to its star, the same thing could happen. Chunks could be shorn off it and compressed by tidal forces as they shoot off into the vacuum of space.

‘It is really a mysterious object, but some signs, like its colors and the absence of radio emission, point to ‘Oumuamua being a natural object,’ Zhang said.

Lin added: ‘Our objective is to come up with a comprehensive scenario, based on well understood physical principles, to piece together all the tantalizing clues.’

If their theory, which has been published in the journal Nature Astronomy is correct, there could be many, many more ‘Oumuamua-shaped objects out there somewhere.

‘The discovery of ‘Oumuamua implies that the population of rocky interstellar objects is much larger than we previously thought,’ Zhang said.

‘On average, each planetary system should eject in total about a hundred trillion objects like ‘Oumuamua. We need to construct a very common scenario to produce this kind of object.’

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