(Star’s Mysterious Dimming Likely Caused by Comets)

About one month ago, a group of scientists floated the idea that the dimming of star KIC 8462852 could be caused by an orbiting megastructure of alien origin. However, there were more promising, natural theories.

 Now, a new study using data from NASA’s Spitzer Space Telescope reinforces the theory the dimming is caused by a swarm of comets.

According to Iowa State Univ., the star undergoes deep dips in brightness, up to 22%, sometimes for days, even months, at a time. None of the other 150,000 plus stars in Kepler’s database exhibit similar characteristics. The original Yale Univ. study was based on Kepler observations from 2011 and 2013.

But the Spitzer Space Telescope recently observed KIC 8462852 in 2015. The new study was led by Massimo Marengo, of Iowa State Univ. It is slated for publication in the Astrophysical Journal Letters.  

“Spitzer has observed all of the hundreds of thousands of stars where Kepler hunted for planets, in the hope of finding infrared emission from circumstellar dust,” said Michael Werner, the Spitzer project scientist at NASA”s Jet Propulsion Laboratory.   

According to NASA, if the dimming was caused by planetary impact, or a collision of asteroids, an excess presence of infrared light would surround the star. But Spitzer found no such evidence. This bolsters the theory cold comets are responsible for the dimming. “It’s possible that a family of comets is traveling on a very long, eccentric orbit around the star,” said NASA. “At the head of the pack would be a very large comet, which would have blocked the star’s light in 2011, as noted by Kepler. Later, in 2013, the rest of the comet family, a band of varied fragments lagging behind, would have passed in front of the star and again blocked its light.”

The comet family would leave behind no detectable infrared signal.

According to Marengo, the star’s observed behavior is reminiscent of the odd behaviors that led to the discovery of pulsars. “They were emitting odd signals nobody had ever seen before, and the first one discovered was named LGM-1 after ‘Little Green Men,’” Marengo said.

Further observations are needed to solve the mystery of KIC 8462852.