Tabby’s Star and the Alien Megastructure Theory Debunked

KIC 8462852
Image Credit: NASA

There’s a star located 1,280 light-years away in the constellation Cygnus that has been confusing astronomers ever since it was discovered in 2015 during the Kepler mission. The star, officially called KIC 8462852, is 50% bigger than our own sun, burns over a thousand degrees hotter, and with an apparent magnitude of +11.7 is visible using a 5-inch (130 mm) telescope or larger on a dark sky.

These days, however, it is mostly referred to as Tabby’s Star, after Tabetha Boyaijan, an assistant professor with the Louisiana State Department of Physics and Astronomy, who has researched the star and written papers about it. Of particular interest is the star’s dimming and brightening unpredictably for reasons completely unknown, sometimes for up to a week at a time. There’s also the fact that it has been growing fainter over the past century, in contrast to other F type stars which should exhibit a consistent brightness.

Various Theories

The logical conclusion is that there is something blocking it, with scientists theorizing that it could be a group of planets. However, data from Kepler shows that the star has dimmed by up to 22%, and if this dip was caused by a mass of planets then there would have to be at least 50 of them in perfect alignment in front of the star in order to account for the luminosity drop. Nonetheless, the Kepler missions, which started in 2009, has not provided enough data evidence to help astronomers debunk such a theory, with the same going for an even more imaginative explanation suggested by some astronomers that it may be caused by a megastructure of alien origin, such as a Dyson swarm, which could theoretically be built around a star to capture light for energy purposes.

Kickstarter Campaign

A recent Kickstarter campaign in which more than 1,700 people raised over $100,000 has helped fund observation time with Las Cumbres University in California, with observations of the star taking place between March 2016 and December 2017. Making Las Cumbres Observatory ideal for the project is the fact that it is the only global robotic telescope network on earth that is able to provide continuous observations, and as explained on its website, consists of a “21 telescopes at eight sites around the world working together as a single instrument.”

Data from the observatory also allows astronomers to confirm the quality of Kepler’s information and observe the star in real-time rather than using data that was several years old. As a result, a “family” of dips has been observed over the past six months, leading to the theory of an alien megastructure causing the phenomenon to be disproved. As Boyijan subsequently explains:

“Dust is most likely the reason why the star’s light appears to dim and brighten. The new data shows that different colors of light are being blocked at different intensities. Therefore, whatever is passing between us and the star is not opaque, as would be expected from a planet or alien megastructure.”

Caused by Dust

The universe is filled with dust, with astronomers familiar with its unique signature, but while its presence provides the best explanation for the star’s random periods of dimming, Boyaijin says astronomers still have to identify what kind of dust would produce this effect. Other pertinent questions include how was it produced, why is it in front of the star, and are there multiple factors behind the phenomenon?

While there are already a number of theories on the origin of the dust, including comets and stars consuming planets and expelling moons, only time, and additional observation, will ultimately provide the answer. In the meantime, the star currently remains a unique phenomenon but as Boyajian points out:

“It’s unique to anything we’ve ever observed, but space is still very much unexplored.”

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