No Alien Megastructure Around Tabby’s Star, Mysterious Dimming Has Some Other Reason

Perhaps the most intriguing possible solution to an as-yet explicable cosmic phenomenon has been ruled out by a large team of researchers. Tabby’s star (formally called KIC 8462852), which was dubbed the “most mysterious star in the universe” because of the inexplicable sporadic dimming and brightening of its light, does not display that strange behavior due to the presence of an alien megastructure orbiting it.

In a paper published Wednesday in the Astrophysical Journal Letters, Tabetha Boyajin from Lousiana State University (KIC 8462852 is nicknamed Tabby’s star in her honor) and over 200 other researchers used data collected by a network of ground-based telescopes and determined that the strange changes in the star’s light were cause by something that had nothing to do with an advanced alien civilization.

“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,” Boyajin said in a statement.

Explaining the methodology, study coauthor Jason Wright from Penn State University said in the statement: “We were hoping that once we finally caught a dip happening in real time we could see if the dips were the same depth at all wavelengths. If they were nearly the same, this would suggest that the cause was something opaque, like an orbiting disk, planet, or star, or even large structures in space.”

Instead, the star, which is about 50 percent larger than the sun, 1,000 degrees hotter and 1,000 light-years away, was seen dimming a lot more at some wavelengths than at others, leading the researchers to conclude light from the star was being obscured by dust, which is not opaque.

The paper is titled “The First Post-Kepler Brightness Dips of KIC 8462852” because it was NASA’s Kepler space observatory that confirmed the dimming of Tabby’s star. Between March 2016 and December 2017, the star was observed using Las Cumbres Observatory, and the funding for telescope viewing time, about $100,000, was collected using a Kickstarter campaign.

Previously, the star’s unusual behavior was identified by citizen scientists who poured over the vast troves of data collected by Kepler in its mission to hunt for exoplanets. The planets were identified when they passed in front of their parent stars, causing a dip in their brightness.

Since May 2017, four incidents of Tabby’s star dimming were noted by researchers.

Referring to those, the researchers wrote: “They’re ancient; we are watching things that happened 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. But most of all, they’re mysterious.”

As to what the cause behind the dimming could be, Wright offered some ideas.

“There are models involving circumstellar material — like exocomets, which were Boyajian’s team’s original hypothesis — which seem to be consistent with the data we have. Some astronomers favor the idea that nothing is blocking the star — that it just gets dimmer on its own — and this also is consistent with this summer's data,” he said.