Alien megastructure star’s strange behaviour can’t be understood with traditional explanations, scientists say

The star is gradually getting darker – and nobody knows why

An illustration of what those comet swarms that some have said explain the strange behaviour might look like (JPL-Caltech/NASA)

The star that some say has a huge alien megastructure built around it just got even more mysterious.

Scientists said last year that the star, named KIC 8462852, appeared to be getting darker with no obvious explanation. Some suggested that the flickering and dimming was the result of an alien megastructure being built around it, to harvest energy.

But others said that the behaviour might just be happening as comets or other debris passed around the front of the star and obscured it from our view.

But a new paper looks at those explanations, and concludes that all previous models can’t account for the way that the light coming from the star is behaving. “No known or proposed stellar phenomena can fully explain all aspects of the observed light curve,” the authors, Caltech’s Ben Montet and the Carnegie Institute’s Joshua Simon, write.

“We spent a long time trying to convince ourselves this wasn’t real,” Montet told Gizmodo. “We just weren’t able to.”

The study used Nasa’s Kepler Space Telescope to look at how brightly the star shone. It found that it dipped by about 0.34 per cent per year during the fist 1,000 days it was observed, and then dipped by more than 2 per cent in the next 200 days.

That rate of dimming can’t easily be explained by any of the leading hypothesis, which said that the star could be explained by comet swarms passing over the front of it or the effects of a warped star.

The paper doesn’t provide any evidence for the primary competing explanation: that a megastructure like a Dyson sphere is being erected around the star by an alien race. But it does mean that scientists will have to work harder to find out whether that is or isn’t the case.

And even if they are able to prove that the star’s behaviour isn’t evidence of alien megastructures, it does appear to suggest that something is happening that hasn’t been seen before. It’s likely that it is a combination of different things – potentially previous explanations – that have added together to create the unusual behaviour.

The researchers compared their data with 193 nearby stars and 355 stars that are similar to KIC 8462852, and found nothing similar to the odd behaviour.

The paper has at the moment only been published on pre-print site arXiv. That means that it hasn’t yet been peer-reviewed but that the findings can now be scrutinised by experts in the astronomical community.

The alien megastructures explanation was advanced last year, when scientists spotted the strange behaviour and found no easy understanding of what is going on. Some suggested that an easy way of explaining the odd behaviour might be that an alien megastructure was being built.

At the time, astronomer Jason Wright told The Independent: "I can’t figure this thing out and that’s why it’s so interesting, so cool – it just doesn’t seem to make sense."

He told The Atlantic that while aliens should always be the “very last hypothesis you consider”, what he had spotted “looked like something you would expect an alien civilisation to build”.