A Dyson Swarm, which could be the formation of the so-called alien megastructure [Illustration by Vexedent]
Unfortunately, no, it's still probable that we haven't stumbled upon the discovery of an alien civilization. The star in the so-called alien megastructure likely has a Saturn-like planet with wobbly rings orbiting it. This is probably what's causing the strange, irregular dimming that caught the eye of astronomers in 2015.
This star is called Tabby's star, named after Dr. Tabetha Boyajian, the astronomer who first noticed the strange dimming. Dr. Boyajian and her team found that the star, then known as KIC 8462852, had been dimming in an inexplicable way for a few years. Some people put forward the theory that the strange dimming may be an indication of an advanced alien civilization. However, researchers now say that a gas giant with wobbly rings may be the culprit behind the strange dimming, which is of course a more plausible, if not somewhat disappointing, explanation. The planet and its rings may be causing the irregular dimming as they pass in front of the star.
A young star surounded by a protoplanetary disc, which could also explain the irregular dimming [Illustration by the European Southern Observatory (ESO)]
When the planet passes in front of the star, its rings are the first to block the light of the star. The planet itself then passes by, creating even more of a dimming before its rings block the light again.
However, wouldn't this still create a regular pattern of dimming? The researchers say that no, this situation won't. If the planet's rings are at a different angle every time the planet passes in front of the star, this may possibly create irregular dimming. “We found that tilted ringed structures undergo short-term changes in shape and orientation that are manifested as strong variations of transit depth and contact times, even between consecutive eclipses,” the researchers explain in the paper.
The researchers tested their theory by simulating a light curve from a ringed planet. In the simulations, the distance of the planet from Tabby's star is one-tenth the distance of the Earth from the sun. At that distance, the gravity of the star would tug at the rings and make them wobble. As the rings wobble, they cause irregular dimming.
Scientists hadn't been completely cold to the idea that an alien megastructure was causing the dimming. However, other explanations, including this one, are more plausible.
Comet fragments may also be causing the irregular dimming, but this may be unlikely. [Illustration by NASA/JPL-Caltech]
Another explanation for the irregular dimming was that a family of comets were destroyed near the star. This explanation was also deemed possible, and some scientists considered it to be the most accurate. However, scientists discovered that no debris were emitting infrared light around the star. Thus, scientists have ruled out the possibility that comet fragments were causing the dimming.
The wobbly-ringed planet is the newest, most possible explanation to date. However, there are already those who are questioning whether or not this explanation can sufficiently explain the phenomenon. Some think that even a wobbly-ringed planet would still be causing some regular dimming.
Even the scientists that proposed the wobbly-ringed planet theory acknowledge that they may be wrong. However, their work can show how certain mechanisms alter light curves. The alien megastructure theory may still be possible, but the wobbly-ringed planet theory is more probable.
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