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Comet fragments likely to blame for dimming of star KIC 8462852, not aliens

What exactly caused star KIC 8462852 to dim by as much as a quarter in 2011 and 2013? Some researchers believe the mysterious dimming of the distant star may be due to the simultaneous destruction of a group of comets, instead of the far fetched theories that briefly grabbed headlines last month.

Iowa State University physics and astronomy associate professor Massimo Marengo and two colleagues took a renewed look at infrared data on the star from NASA’s Sptizer Space Telescope. Their findings have been published in the journal Astrophysical Journal Letters, and conclude that the most likely reason for the drop in the star’s brightness is comet fragments.

“The scenario invoking the fragmentation of a family of comets on a highly elliptical orbit is instead consistent with the lack of strong infrared excess found by our analysis,” the researchers wrote. Other researchers have come to the same conclusion, including Yale University’s Tabetha Boyajian, who also argued comet fragments were to blame for the dimming.

Related: SETI looking for alien signals around the mysteriously dim star KIC 8462852

Marengo’s findings will come as somewhat disappointing to supporters of a theory first postulated by Penn State researcher Jason Wright. In his own paper, he argued that the dimming is consistent with what would be expected of an alien megastructure — similar to the theorized Dyson Sphere — orbiting the star.

Wright’s paper set the physics and astronomy world afire, and even triggered SETI to start looking closer for alien signals emanating from KIC 8462852. But Marengo still believes his theory is the most likely.

His research shows that there was not enough excess infrared to suggest some type of asteroid or planetary collision, or any debris field. The comets likely came in from a steep orbit that briefly dimmed the star. As the cloud moved away, the brightness of the star was restored.

Will Marengo completely reject the megastructure theory? No, he told phys.org in an interview, and his research could not confirm or deny Wright’s theories. “What the star is doing is very strange,” he adds. “It’s interesting when you have phenomena like that – typically it means there’s some new physical explanation or a new concept to be discovered.”