KIC 8462852, also known as Tabby’s Star or the infamous ‘alien megastructure star,’ is peculiar because the star’s light seems to dim by highly eccentric amounts at unpredictable intervals. What’s more is astronomers don’t fully understand why this happens.
The whole ‘alien megastructure star’ nickname came about when an odd conspiracy theory suggested that an advanced alien civilization had built a massive Dyson sphere-like object around the system’s host star. As you might come to expect, astronomers have been working on a more realistic theory – one that’s truer to science and doesn’t involve an advanced alien civilization harvesting its host star for energy.
While the star’s brightness dips vary, it can purportedly dim by as much as 22% at a time, and this is far too substantial for a transiting exoplanet or any other currently-known theories to explain. But recent observations just might’ve given astronomers a critical clue that they’ve been searching for.
According to the latest hypothesis, it’s possible that Tabby’s Star’s gravity yanked an exomoon away from one of its orbiting exoplanets. That moon could now be drifting closer to the star, and as this happens, its outer layers evaporate after coming in contact with the star’s powerful stellar radiation. Consequently, the exomoon is creating a gaseous cloud that encircles the star, and that cloud would then block various amounts of starlight depending on the amount of shedded material.
This hypothesis is still just that — a hypothesis. Fortunately, the idea is a lot more plausible than the idea of an alien megastructure orbiting the star, and some astronomers think that similar circumstances could be happening with other stars with similar, albeit not as intense, dimming behavior.
It should be interesting to see how astronomers proceed with this idea and whether it will hold any water in the long run.