Observations of Tabby's Star confirm there is no alien megastructure

Global studies funded by Kickstarter effort indicate dust causes the star's unpredictable dimming and brightening.
By Laurel Kornfeld | Jan 06, 2018
Followup observations of KIC8462852, also known as "Tabby's Star" for researcher Tabetha Boyajian, who first studied it, have confirmed its strange periods of dimming and brightening are not caused by the presence of an alien megastructure, as some people initially suggested.

Led by Boyajian of Louisiana State University (LSU), more than 100 scientists took part in observations of the star, located about 1,000 light years away, using a global network of telescopes.

An average star approximately 50 percent bigger and 1,000 degrees hotter than the Sun, "Tabby's Star" was first discovered by citizen scientists in Zooniverse's Planet Hunters program, a project in which volunteers sift through data collected by NASA's Kepler mission to search for exoplanets that computers may have missed.

It was nicknamed for Boyajian after she published a paper on its unusual light curve in September 2015.

The global followup observations were funded by a Kickstarter campaign in which more than 1,700 people donated a total of $100,000 for the project.

Between March 2016 and December 2017, researchers led by Boyajian studied the star and collected data on it using the Las Cumbres Observatory in Goleta, California.

Four separate dimming incidents were detected by the observers beginning in May 2017. Donors from the Kickstarter campaign nicknamed the incidents Elsie, Celeste, Scara Brae, and Angkor. The latter are names of lost cities in Scotland and Cambodia respectively.

"Dust is most likely the reason why the star's light appears to dim and brighten," said Boyajian, lead author of a paper on the findings published in The Astrophysical Journal Letters.

"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."

She noted the dimmings observed actually occurred more than 1,000 years ago.

"They're almost certainly caused by something ordinary, at least on a cosmic scale. And yet that makes them more interesting, not less," the study's authors wrote in the paper.

Having so many people worldwide gather such a large amount of data about a single target reflects a new era in astronomy, one in which citizen scientists are playing a key role, noted LSU doctoral student Tyler Ellis, who worked on the study.

"If it wasn't for people with an unbiased look on our universe, this unusual star would have been overlooked. Again, without the public support for this dedicated observing run, we would not have this large amount of data," Boyajian emphasized.



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