Mysterious dimming of Tabby’s Star not caused by alien megastructure, study shows

Jan. 3 (UPI) — The F-type main-sequence star KIC 8462852, also called Tabby’s Star or Boyajian’s Star, has been described as the “most mysterious star in the universe,” due to its inexplicable brightening and dimming.

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.

Tabby’s Star is 50 percent larger than the sun and roughly 1,000 degrees hotter. It is located 1,275 light years away in the constellation Cygnus.

With the help of funding from a Kickstarter campaign, astronomers used a global network of telescopes to observe the unusual star from March 2016 to December 2017. Astronomers compared possible explanations for the brightening and dimming phenomena with the data collected during the survey.

“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,” Jason Wright, an assistant professor of astronomy and astrophysics at Penn State University, said in a news release. “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.”

The data — published this week online by Astrophysical Journal Letters — showed the star dimmed at certain wavelengths more than others.

“Dust is most likely the reason why the star’s light appears to dim and brighten,” said lead researcher Tabetha Boyajian, an astronomer at Louisiana State University. “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.”

The dimming pattern of Tabby’s Star was so unusual it didn’t get flagged by the algorithms that sift through the data collected by NASA’s planet-hunting Kepler satellite. It wasn’t a strong candidate as a host for exoplanets.

But its peculiarity was spotted by citizen scientists, groups of online volunteers who regularly scan astronomical data for anomalies missed by the computers and the pros.

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

While dust is now the most logical explanation for the dimming pattern, researchers need to investigate further to understand the details of the phenomenon.

“This latest research rules out alien megastructures, but it raises the plausibility of other phenomena being behind the dimming,” Wright said. “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.”

It’s also possible the star is simply getting dimmer and brighter on its own — that nothing is actually blocking the star’s light.