NASA's Spitzer Space Telescope sheds light on "alien megastructure" star

Artists impression of a comet family passing in front of KIC 8462852(Credit: NASA/JPL-Caltech)

KIC 8462852 recently attracted a lot of attention owing to speculation that dramatic dips in the star's light that were detected in 2011 and 2013 by NASA's Kepler spacecraft were due to the presence of vast superstructures created by an advanced alien race. But a new study centering around analysis of data collected by NASA's Spitzer Space Telescope suggests that the mysterious objects occulting the star KIC 8462852 aren't the creations of little green men, but in fact a family of comets.

This alien megastructure theory that recently made news across the globe prompted SETI to task its Allen Telescope Array (ATA) to take readings on the peculiar star. But so far, the ATA has come up empty, leaving the tantalizing mystery as to the cause of the unusual readings open for debate.

From the outset the majority of the scientific community had stuck to more level ground, instead pointing to possible clouds of debris created from an impact between two large bodies, or the presence of comets as the leading causes of the occultation.

If the strange occultation observed around KIC 8462852 were to be the result of debris from colliding planetoids or asteroids passing in front of the star, then the fragments would be at temperatures that would cause them to emit infrared light. Therefore, the theory could be tested by taking aim at the star with an infrared telescope.

Previous observations carried out by Kepler had detected the phenomenon in the visible light spectrum, and so to test the collision theory astronomers analyzed infrared data collected by the Spitzer space telescope, which had by chance taken readings on KIC 8462852 earlier this year.

An analysis of the data failed to find any excess of infrared light that would point toward planetary/asteroid debris as the cause of the dimming. This lack of evidence places the theory that the dimming of light from KIC 8462852 was caused by a family of comets traveling in a highly eccentric orbit.

This theory is supported by the lack of infrared light picked up in the Spitzer data, as, unlike the warmer impact fragments that would result from a collision, the presence of comets would be nigh on impossible to detect.

In order to explain the unusual occultation pattern, astronomers assert that an enormous lead comet could have been responsible for the original dimming of light detected in 2011, while the 2013 event was the result of a swarm of lesser comets following in the giant's wake.

While this seems like the most likely explanation, the new evidence pointing to the comet theory is far from conclusive, with further observation needed to reveal the source of the occultation.

"We may not know yet what's going on around this star," says Massimo Marengo of Iowa State University who led this latest study. "But that's what makes it so interesting."

A paper on the findings has been accepted for publication in the Astrophysical Journal Letters.

Source: NASA


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