‘Alien megastructure’ star theory gets much needed dose of reality

5 Oct 2017

Image: Dotted Yeti/Shutterstock

The theory of an ‘alien megastructure’ surrounding a distant star has been dealt a further blow with new scientific evidence.

Despite very few people in the astronomical community still believing that KIC 8462852 is the first sign of a possible alien megastructure, some new findings suggest the strange original readings might be the work of uneven dust.

The star – otherwise known as either Boyajian’s Star or Tabby’s Star – first came to astronomers’ attention when they noticed it had unusual dips in brightness, by as much as 20pc over a matter of days.

Not only that but, unlike most stars, this star has had much subtler but longer-term enigmatic dimming trends.

The peculiar nature of the star spurred the theory that an alien megastructure surrounding the star to harness its energy was responsible for the dips in readings.

Now, however, a paper published to The Astrophysical Journal identified what researchers described as a ‘smoking gun’ for the uneven dust cloud theory, as they found less dimming in the infrared light from the star than in its ultraviolet light.

Science tells us that any object larger than dust particles would dim all wavelengths of light equally when passing in front of Tabby’s Star.

Tabby's Star

This illustration depicts a hypothetical uneven ring of dust orbiting KIC 8462852, also known as Tabby’s Star. Image: NASA/JPL-Caltech

Some mysteries remain

“This pretty much rules out the alien megastructure theory, as that could not explain the wavelength-dependent dimming,” said lead author of the study Huan Meng from the University of Arizona.

“We suspect, instead, there is a cloud of dust orbiting the star with a roughly 700-day orbital period.”

However, there is still much to understand about the phenomenon. While this latest theory offers an explanation for long-term dims, it doesn’t account for the shorter ones seen in three-day spurts so far this year.

There also remains the mystery of the massive 20pc dips seen during previous observations, once seen as being the result of a comet swarm.

Siegfried Vanaverbeke, a volunteer at the citizen science research group AstroLAB, is also investingating Tabby’s Star. He said further research is needed to answer these questions.

“Tabby’s Star could have something like a solar activity cycle,” he said. “This is something that needs further investigation and will continue to interest scientists for many years to come.”

Previous theories into the interstellar oddity suggested it could be a ‘planet killer’ with the dimming attributed to enormous amounts of debris created by a destroyed planet as its mantles were gradually ripped apart by the sheer power of the star.

Colm Gorey was a senior journalist with Silicon Republic