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New weirdest stars in the galaxy checked for aliens

There's a bunch of stuff zipping in front of a distant pair of stars, making it a good place to look for E.T.

kic-8462852-small.jpg

Artist's representation of a crumbling Dyson sphere -- a theoretical alien megastructure -- orbiting a star.

Danielle Futselaar/METI International

Something strange is going on around star system HD 139139 (sometimes called  EPIC 249706694), so naturally some scientists have checked to see if it might be the product of some sort of extraterrestrial intelligence. 

The answer so far, for the umpteen-millionth time in a row is: It's probably not aliens.

The weird behavior stems from what's believed to be a pair of stars bound to each other nicknamed the "Random Transiter" (a transit is an astronomy term for when something like a planet passes in front of a star, dimming its brightness slightly). It's reminiscent of KIC 8462852, better known as Boyajian's Star or Tabby's Star, which dims randomly and also gradually over time. Boyajian's Star went viral after astronomers like Pennsylvania  State University's Jason Wright suggested that the ongoing construction of alien megastructures could explain the odd dimming.

Aliens are not a leading explanation for the behavior of Boyajian's Star at this point. We know this in part because SETI (Search for Extra-Terrestrial Intelligence) researchers checked with the help of a teenager.

Naturally, some of those same researchers are now checking the Random Transiter for signs of life, or at least technology created by it. As with Boyajian's Star, astronomers have also observed a number of random transits, or dimming events, of HD 139139. In fact, it was seen dimming randomly by the Kepler Space Telescope 28 times over an 87-day period. 

"The mystery behind the origin of these events makes this system an interesting target for technosignature searches," reads a forthcoming paper in Research Notes of the American Astronomical Society by researchers from the Breakthrough Listen project based at the University of California, Berkeley.

So the team used the Green Bank Radio Telescope in West Virginia to check for radio emissions from the distant star system around 350 light years away from Earth. After listening for three five-minute sessions, there were no signs of life or tech.

"We detect no evidence of technosignatures from EPIC 249706694," they write. 

Even if there are no aliens, the mystery of the Random Transiter remains intriguing. Possible explanations include a huge collection of up to 28 planets orbiting the star, an extremely close-in planet or planets whipping around the two stars via some undetectable pattern, a belt of dust and debris or possibly interstellar objects.

There are problems with some of these explanations, though. And with alien megastructures also now seeming pretty unlikely, the possibilities are only limited to everything that scientists haven't thought of yet. 

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