Yanna Lee

Invisible to the naked eye, light peculiarities emanating from a distant star — KIC 8462852 — grabbed the attention of amateur and professional astronomers alike when they viewed the abnormalities through NASA telescopes four years ago. The abnormal phenomenon and its possible causes have recently been thrust into the spotlight once again due to a new Yale study determining that the phenomenon was most likely caused by a swarm of comet fragments.

Over 1,400 light years away from the Earth, KIC 8462852 has exhibited extreme fluctuation in its light output over the past four years. Amateur astronomers from a citizen science project called Planet Hunters first spotted this anomaly while combing through public data collected by the NASA Kepler spacecraft. Planet Hunters was established in 2010 with the help of Debra Fischer, an extrasolar planet hunter and astronomy professor at Yale. KIC 8462852’s light curve -— a graph showing light intensity over time from a celestial object — first became a subject of interest in the planet hunter community four years ago when the group noticed the star had dimmed by almost 15 percent. Two years ago, the star took its biggest dip in light emanation by more than 20 percent. Changes in a star’s light output can indicate that another planet or object is passing in front of it. Tabetha Boyajian, a Yale postdoctoral fellow, along with a team of scientists from several institutions that included Fischer analyzed the bizarre decrease in light output from KIC 8462852.

Titled “Where’s the Flux”, or “WTF” for short, the research paper closely scrutinized the possibility of instrumental or data error on NASA’s part, intrinsic variability — an internal cause for the star’s dimming —  or extrinsic variability and interference of “dust clumps” with the star. Boyajian’s team discredited all these theories except the one hypothesizing that dust clumps blocked the star’s light. The paper concluded that the anomalous light curve was most likely caused by “the break-up of a exocomet.” The theory of comet fragments bypasses many constraints on the type of objects, including size and orbital distance, that might have caused the light curve.

“The comet scenario was our best [explanation],” Boyajian said. “But it was our best guess. We definitely need more data to be able to say what it is exactly.”

But Fischer said this answer was not satisfying, arguing that a swarm of comets would not have led to the steep dip observed.

Researchers said they initially encountered hardship when they were not able to come up with a ready explanation for the anomaly.

Fischer said the team sat on the result for two years. She added that even after reaching out to other experts in the field, they all “came up empty-handed.”

“Unlike any of the other 155,000 stars in the Kepler field, there is nothing like [KIC 8462852]. So that means we had to think outside the box a bit,” Fischer said.

One expert the team contacted was Saul Rappaport, physics professor emeritus at the Massachusetts Institute of Technology. There was “considerable head-scratching,” but Rappaport said he considers solving mysteries like these the impetus for scientific development.

Boyajian and her team also called for future observations to specify the nature of the planet.

“I think that ground-based monitoring with optical telescopes is a good method for finding the next major dipping event in this star,” Rappaport said. “Once such an event is found, various other larger telescopes covering a wider range of wavelengths, and possibly spectroscopy, can be brought to bear on the object.”

A few months ago, the team also submitted a proposal to monitor the star with the Allen Telescope owned by the Search for Extraterrestrial Intelligence Institute, according to Boyajian. Now all the team needs now to complete further research is for KIC 8462852 to dip again, she added.

The paper received national media attention when outside researchers interpreted the data as possible evidence for alien megastructures, but Rappaport said in a paper that this theory is “akin to the ancients invoking a deity to explain each part of nature that they couldn’t fathom.”

KIC 8462852 is located between the Cygnus and Lyra constellations above the Milky Way.