Mysterious dimming of star KIC 8462852 likely caused by comet fragments

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Star KIC 8462852 has been making the headlines ever since scientists speculated that its dimming is caused by alien infrastructures. However, that’s likely not the case, a new study has claimed.

According to Massimo Marengo, an Iowa State University associate professor of physics and astronomy, joined hands with two other astronomers to take a closer look at KIC 8462852 to determine what may be causing this mysterious dimming and they have come to a conclusion that the dimming of the star is most probably caused by the destruction of a family of comets.

The star managed to raise the brows of many scientists after a research team led by Tabetha Boyajian of Yale University reported last month about the deep dips in brightness – up to 22 percent – of the the star. The astronomers reported how citizen scientists tagged the star’s deep and irregular dips in brightness as “bizarre” and “interesting.”

Boyajian and the other researchers looked at the data and investigated several possible causes. They wrote the “most promising theory” was a barrage of crumbling comets passing in front of the star.

In a subsequent paper submitted to the Astrophysical Journal, Jason Wright and colleagues at Penn State University speculated about other causes, including alien megastructures built to harvest energy while orbiting the star.

In a bid to check if that was the case, SETI turned its attention towards the mysterious star and suggested that alien megastructure around KIC 8462852 is highly unlikely.

When the Iowa State astronomers studied the star with Spitzer infrared data from January 2015 – two years after the Kepler measurements – Marengo said they didn’t see much. If there had been some kind of catastrophe near the star, he said there would be a lot of dust and debris. And that would show up as extra infrared emissions.

Marengo said the study looked at two different infrared wavelengths: the shorter was consistent with a typical star and the longer showed some infrared emissions, but not enough to reach a detection threshold. The astronomers concluded there were no excess infrared emissions and therefore no sign of an asteroid belt collision, a giant impact on a planet or a dusty cloud of rock and debris.

So Marengo and his colleagues say the destruction of a family of comets near the star is the most likely explanation for the mysterious dimming. The comet fragments coming in rapidly at a steep, elliptical orbit could create a big debris cloud that could dim the star. Then the cloud would move off, restoring the star’s brightness and leaving no trace of excess infrared light.

And what about the alien megastructure theory then?

“We didn’t look for that,” Marengo said. “We can’t really say it is, or is not. But what the star is doing is very strange. 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.”