The Mysterious “Megastructure Star” originally discovered by citizen scientists reviewing images from the Kepler space telescope and previously reported on Science Rocks My World has gotten additional focus from NASA.
The new study, based on data from the Spitzer Space Telescope, still doesn’t completely solve the mystery, but it does a good job of ruling out one more possible explanation:
The source of the still-mysterious dimming is very likely not the result of an asteroid-planet collision or asteroids colliding with each other.
An article from NASA provides the fascinating details of the new study:
A new study using data from NASA’s Spitzer Space Telescope addresses the mystery, finding more evidence for the scenario involving a swarm of comets. The study, led by Massimo Marengo of Iowa State University, Ames, is accepted for publication in the Astrophysical Journal Letters.
One way to learn more about the star is to study it in infrared light. Kepler had observed it in visible light. If a planetary impact, or a collision amongst asteroids, were behind the mystery of KIC 8462852, then there should be an excess of infrared light around the star. Dusty, ground-up bits of rock would be at the right temperature to glow at infrared wavelengths.
At first, researchers tried to look for infrared light using NASA’s Wide-Field Infrared Survey Explorer, or WISE, and found none. But those observations were taken in 2010, before the strange events seen by Kepler — and before any collisions would have kicked up dust.
To search for infrared light that might have been generated after the oddball events, researchers turned to Spitzer, which, like WISE, also detects infrared light. Spitzer just happened to observe KIC 8462852 more recently in 2015.
“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 in Pasadena, California, and the lead investigator of that particular Spitzer/Kepler observing program.
But, like WISE, Spitzer did not find any significant excess of infrared light from warm dust. That makes theories of rocky smashups very unlikely, and favors the idea that cold comets are responsible. It’s possible that a family of comets is traveling on a very long, eccentric orbit around the star. 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.
By the time Spitzer observed the star in 2015, those comets would be farther away, having continued on their long journey around the star. They would not leave any infrared signatures that could be detected.
Marango says that more studies and observations are needed to settle the mystery of KIC 8462852, although his study does help to rule out one more possible explanation.
This leaves the original study’s conclusions as the still-favored theory (click here to read our original article about that study), that the aperiodic dimming of the start is probably because of a swarm of comets. On the other hand, some will certainly point out, it also doesn’t rule out the possibility of an alien megastructure…
Stay tuned, as they say, since this mystery still has a long way to go before it’s completely solved!
Source: NASA.gov – “Strange Star Likely Swarmed by Comets”
Featured Image Source: Illustration of comet swarm by NASA/JPL-Caltech