Visitor from another solar system is hiding some real icy mysteries

19 Dec 2017

Image: Roman Mikhailiuk/Shutterstock

A recent interstellar visitor to our solar system could harbour a thick layer of organic material on its surface.

In November, a team of astronomers revealed details of a cosmic traveller dubbed 1I/2017, or ‘Oumuamua (the Hawaiian word for scout), which is somewhat unique because it is believed to have originated in another star system.

For astronomers, it proved a treasure trove of information as measurements showed some peculiar findings. These included its incredibly dark red colour, a possible indication that it could contain organic material, prompting somewhat sensationalist ideas of alien life.

But now, a team of researchers led by Queen’s University Belfast has looked even closer at this mysterious organic material to reveal something that does sound truly fascinating.

Led by Prof Alan Fitzsimmons, the research team measured the way that ‘Oumuamua reflects sunlight and found that it is similar to icy objects with a dry crust. This is because it has been exposed to cosmic rays for possibly billions of years, creating an insulating organic-rich layer on its surface.

When it first appeared, it was presumed to be a comet made from ice and dust, but further inspection led to it being classified as an asteroid.

Now, a few months later, these new findings suggest that it is indeed a comet, despite showing no sign of dust. This indicates that its colour originated from dense rock and metal, which had been reddened by radiation over millennia.

Like a tiny world

“We have discovered that the surface of ‘Oumuamua is similar to small solar system bodies that are covered in carbon-rich ices, whose structure is modified by exposure to cosmic rays,” Fitzsimmons said.

“We have also found that a half-metre-thick coating of organic-rich material could have protected a water-ice-rich, comet-like interior from vaporising when the object was heated by the sun, even though it was heated to over 300C.”

Publishing its findings in Nature Astronomy, the researchers identified that the object is the same colour as some of the icy minor planets studied in the outskirts of our solar system.

This, they said, indicated that planetary systems in our galaxy also contain minor planets.

The study’s co-lead, Dr Michele Bannister, said of these findings: “It’s fascinating that the first interstellar object discovered looks so much like a tiny world from our own home system.

“This suggests that the way our planets and asteroids formed has a lot of kinship to the systems around other stars.”

Colm Gorey was a senior journalist with Silicon Republic