Mysterious Dimming Of ‘Alien Megastructure’ Star May Be Caused By Dust Cloud

Posted: Oct 8 2017, 9:14am CDT | by , Updated: Oct 8 2017, 9:20am CDT, in News | Latest Science News

 
Mysterious Dimming of ‘Alien Megastructure’ Star may be Caused by Dust Cloud
Credit: NASA/JPL-Caltech

New study make it far less likely that Tabby's star is surrounded by a vast structure built by an alien civilization

Scientists have proposed a new explanation for the mysterious dimming of Alien meagastructure or Tabby’s star.

Using observations from NASA's Spitzer and Swift missions, researchers suggests that the unusual dips in brightness are likely caused by a cloud of dust moving around the star. That dismisses the possibility of a vast structure around the star built by an alien civilization and supports a relatively natural cause.

"This pretty much rules out the alien megastructure theory, as that could not explain the wavelength-dependent dimming," said lead study author Huan Meng from University of Arizona, Tucson. "We suspect, instead, there is a cloud of dust orbiting the star with a roughly 700-day orbital period."

Tabby's Star, also called KIC 8462852 or Boyajian's Star, has baffled scientists ever since its discovery in October 2015. The star is located about 1,480 light years away from Earth and goes through strange and sudden fluctuations in the brightness. At one point in time, it was even observed dimming more than 20 percent, which cannot be attributed to a planet passing between the object and our Earth. Since that time, various explanations have been presented, ranging from large asteroids to a debris disc to an alien megastructure that harvest’s the star’s energy. But none of those speculations had come close to being provable.

However, observations indicated that something irregular likely passes in front of the star and temporarily blocked some of the light coming from it.

So what makes dust the reason behind these unusual dimming?

Researchers believe that the objects causing the long-period dimming of Tabby's Star can be no more than a few micrometers in diameter. When they observed light changes of Tabby's Star in ultraviolet using Swift and in infrared using Spitzer, as well as in visible light in AstroLAB IRIS observatory almost throughout the last year, they determined the blocking particles must be bigger than interstellar dust, small grains that could be located anywhere between Earth and the star.

Circumstellar dust or dust that orbits a star is not so small it would blow away and also not so big it would uniformly block light of an object.

"From our study, we can say that the cause of the long-term dimming should be circumstellar dust grains larger than those in interstellar dust, but we cannot say what the source of the dust is," said Meng. "It could be a swarm of comets, a recent planetary impact or residuals from billions of years of planet formation."

This is currently considered the best explanation, although others cannot be ruled out altogether.

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