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Dust, Not Aliens, Is Likely Cause of Star's Weird Dimming

12 January 2018

Though astronomers aren't yet sure what explains the star's unusual light patterns, new research has ruled out the possibility of an alien megastructure.

The star, named KIC 8462852, and known as Tabby's Star, has been brightening and dimming in an odd way, which has prompted alien life enthusiasts to suggest that it is circled by a massive construction built by an advanced alien civilization.

Boyajian "absolutely" intends to pursue follow-up observations of KIC 8462852, but she isn't sure whether numerous same contributors to the first Kickstarter campaign would come back in light of the fact that aliens have been ruled out.

But early analysis, detailed today in Astrophysical Journal Letters, found that whatever is blocking the star's light is definitely not opaque and most likely filtering the light as dust does. The mystery of Tabby's Star is so compelling that more than 1,700 people donated over $100,000 through a crowdfunding campaign in support of dedicated ground-based telescope time to observe and gather more data on the star through a network of telescopes around the world.

Between March 2016 and December 2017, scientists watched the star closely, observing four distinct episodes when the star's light dipped. "But most of all, they're mysterious", wrote the authors.

The goal of the study was to analyse the dips at all wavelengths because if they were all of near-equal measure, they would be caused by a physical structure, which includes the possibility of an alien megastructure.

Tabby's Star, a mysterious dimming star that has puzzled astronomers so completely that the wildest of explanations for its behavior have been proposed, turns out to be a natural astronomical phenomenon after all.

But Boyajian's new research says different colours of light are being blocked at various intensities. "Instead, [we find] that the blue dips are much deeper - about twice as deep - as they are when we look at infrared wavelengths. the dips are not caused by opaque macroscopic objects (like megastructures or planets or stars) but by clouds of very small particles of dust (less than 1 micron in typical size)". Earlier this year the star - which has been nicknamed "Tabby's Star" after Tabetha Boyajian who first documented its freakish behavior - began dipping in brightness with no obvious explanation.

The team indeed found four episodes when the star's light dipped, beginning in May 2017.

Artist's concept of Tabby's Star. During the telescope's heyday, between 2009 and 2013, it stared at 150,000 stars, trying to spot these tiny changes, in the process identifying 2,341 exoplanets. This strongly suggests that it's some kind of huge dust cloud that keeps passing in front of the star, and not a planet or alien structure. "It's going to take us a long time to get through it all".

"It's exciting. I am so appreciative of all of the people who have contributed to this in the past year - the citizen scientists and professional astronomers", Dr. Boyajian said.

The initial findings about KIC 8462852 were made through Planet Hunters, but the follow-up observations were conducted through a Kickstarter campaign in which more than 1,700 people raised more than $100,000.

Not only that, but many observations were also conducted by amateur astronomers.

"We don't really have a working model quite yet, so things are still up in the air in terms of how everything is put together", Boyajian said.

Dust, Not Aliens, Is Likely Cause of Star's Weird Dimming