For more than a year, a so-called ‘alien megastructure’ star has baffled scientists. The star KIC 8462852, also known as Tabby’s star, has a mass 1.5 times bigger than our Sun. It is located about 1,480 light years away. The star gained worldwide attention in 2015 when astronomers led by Tabetha Boyajian of Yale University spotted something incredibly odd about it.

Alien Megastructure Star
Image Source: Skeeze / Pixabay

Is KIC 8462852 surrounded by an alien megastructure?

Scientists observed sudden dips in its brightness. Within just a few days, its brightness dipped as much as 22% before going back to normal. The mystery deepened further in January 2016 when a review of old photographic plates showed that the star’s brightness dipped 14% between 1890 and 1989. That’s a far too short timeframe, in space terms, for a known natural dimming.

The star faded another 3% over a period of four years when NASA’s Kepler space telescope was observing it. These unnatural fluctuations in brightness sparked speculations that the star KIC 8462852 might be surrounded by an alien megastructure. The alien megastructure hypothesis says an advanced civilization might have built a giant structure around the star to capture solar energy to meet its massive energy demand.

The star might be returning to its normal state

A new study conducted by Brian Metzger and his colleagues at the Columbia University proposes that KIC 8462852 might have gobbled one or more of its own planets. The study will be published in the Monthly Notices of the Royal Astronomical Society on Monday. It helps explain the dips in the brightness of the star.

Brian Metzger said if a planet got knocked by a comet out of its orbit and plunged into its host star, it would temporarily brighten up the star. Depending on the size of the planet, the star could take anywhere between 200 years and 10,000 years to burn away the planet’s matter before it starts dimming. It’s possible that astronomers started observing the star towards the end of this period. It could explain the 14% dip in brightness over 100 years. It means the star is just returning to its normal state.

Challenging the alien megastructure theory

Researchers believe that the planet might have left behind giant debris, which may include its moon, which somehow couldn’t be sucked in. These pieces might be orbiting the star. And when they pass in front of the star, they cause sudden dips in the brightness. If this theory is true, such collisions could be more common than astronomers expected.

Metzger hopes that the next time Kepler observes the dips, astronomers would be able to find signs of debris passing close to the star. Such transits should last only a few days. Jason Wright of Pennsylvania State University told New Scientist that the planet-gobbling theory is a strong one, and it could challenge the alien megastructure theory.