'Alien megastructures' orbiting distant star are most likely comets, as expected By Loren Grush on November 29, 2015 11:00 am @lorengrush
(NASA)Last month, the online world went into a tizzy over the possibility of intelligent alien life lingering near a distant star in our galaxy. The star in question is called KIC 8462852, and the reason it caused such a ruckus is because it exhibits strange dimming behavior that doesn't follow a particular pattern. It means one or more large objects are passing front of the star, periodically blocking light in an atypical routine. Of the many theories that were proposed to explain this, one incredibly unlikely scenario was blown out of proportion: a swarm of alien megastructures, built by an intelligent civilization, orbited the star to harness its energy.
Well, that theory is pretty much bunk now (if it wasn't already). The dimming is most likely caused by a swarm of comets that are traveling along a very eccentric orbit around KIC 8462852, according to a new study that will soon be published in the journal Astrophysical Journal Letters. The comet theory has been the leading explanation for the star's behavior all along, but this new research, based on data from NASA's Spitzer Space Telescope, further confirms the idea.
To reach this comet conclusion, researchers from Iowa State University used Spitzer to study KIC 8462852 in infrared light. An excess of infrared wavelengths would indicate that warm bodies are present around the star. For example, if colliding asteroids or impacting planets were behind the dimming, they'd create a bunch of warm dust and debris that would glow at infrared wavelengths.
Astronomers studied KIC 8462852 in the infrared back in 2010, and didn't see an excess of light wavelengths then. But that was before this weird dimming behavior was seen by NASA's Kepler spacecraft, once in 2011 and again in 2013. Kepler only observed the star in the visible light spectrum, so the researchers wanted to see if the infrared measurements might have changed in the last five years.
But just as before, 2015 observations of KIC 8462852 didn't show an excess of infrared light, indicating there's probably a family of cold comets traveling a strange path around the star. It's likely that one large comet — the head of the family — passed by in 2011, followed by a string of comet fragments in 2013. The researchers noted, however, that more observations of the star are needed to confirm the comet theory.
To be fair, the researchers didn't exactly deny that alien megastructure theory. But as most astronomers know, suggesting aliens as the answer to unexplained astronomical phenomenon is always the last resort.
http://www.theverge.com/2015/11/29/9801480/kepler-alien-megastructure-probably-just-comets
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