Reports of an "alien megastructure" causing strange dimming at a faraway planet appear to be wrong, as NASA thinks it's probably dust.
It was perhaps the most bizarre object of study in space for scientists – a star that is seen unusual dips in brightness that caused some to posit many outlandish theories, including the possibility of some sort of alien megastructure. But NASA now thinks that Boyajian’s Star, or Tabby’s Star, is experiencing these dips simply because of dust rather than anything extraordinary.
KIC 8462852, as it is known, had been seen dimming up to 20 percent over a matter of days, while also showing longer-term dimming trends. It’s strange behavior for any star around our sun’s size, prompting speculations some sort of advanced civilization had built a megastructure around it to harvest its energy.
But researchers at NASA determined that there was less dimming in the infrared light from the star than the ultraviolet light, which rules out an alien megastructure which would not explain different dimming of wavelengths. Instead, it’s probably a cloud of dust orbiting the star every 700 days, scientists think.
“Called KIC 8462852, also known as Boyajian’s Star, or Tabby’s Star, the object has experienced unusual dips in brightness — NASA’s Kepler space telescope even observed dimming of up to 20 percent over a matter of days. In addition, the star has had much subtler but longer-term enigmatic dimming trends, with one continuing today,” reads the NASA statement. “None of this behavior is expected for normal stars slightly more massive than the Sun. Speculations have included the idea that the star swallowed a planet that it is unstable, and a more imaginative theory involves a giant contraption or “megastructure” built by an advanced civilization, which could be harvesting energy from the star and causing its brightness to decrease.
“A new study using NASA’s Spitzer and Swift missions, as well as the Belgian AstroLAB IRIS observatory, suggests that the cause of the dimming over long periods is likely an uneven dust cloud moving around the star. This flies in the face of the “alien megastructure” idea and the other more exotic speculations.”