Scientists Are Closer to Understanding the ‘Alien Megastructure Star’

Stars don’t come much weirder than KIC 8462852, known colloquially as Tabby’s star. You may be more familiar with it as the “alien megastructure star.” Astronomers have been puzzling over the seemingly random dips in brightness from Tabby’s star, and one of the explanations put forward is that aliens have built massive structures in orbit. Well, it looks like the aliens have fired up their giant machinery again. That might give us a chance to figure out what’s going on out there.

Astronomers reported on Thursday last week that KIC 8462852 had entered a dimming period, which offers a unique opportunity to observe it. All previous dimming periods were identified in historic data — it was analyzed long after the anomaly had passed. Unlike many other stellar phenomena, this star’s dips in brightness are not periodic, thus it’s difficult to predict. The announcement of a new dip set off alarm bells in the astronomical community, and those with access to telescopes made plans to take spectrum readings.

KIC 8462852, which lies 1,480 light years away in the constellation Cygnus, was first noted by astronomers in 2015 when data from the planet-hunting Kepler telescope showed a series of dips in brightness. This is how Kepler detects planets, but the dimming from Tabby’s star is not periodic, so a planet was unlikely. A massive swarm of comets close to the star has also been suggested, but there are problems with that hypothesis, too. The alien megastructure angle is obviously an outside chance, but we just don’t know what’s going on yet.

Astronomers used Kickstarter in 2016 to get the funding needed to run a continuous observation of Tabby’s star. That’s why the alarm was sounded as a new dip occurred rather than months later after historic data was reviewed. At the time of this posting, the dip in luminance has ended, but astronomers had several days to scan Tabby’s star and capture its spectra. This could be the key to figuring out what’s going on. The dips in 2016 also happened in clusters, so more could be on the way.

Tabby’s star dip.

Observing the spectra of Tabby’s star during a dimming period lets astronomers determine what sort of molecules are involved. If the strange fluctuations are the result of comets clustered around the star, we’ll be able to detect their telltale signature in the star’s infrared spectrum. No one is entirely sure what we’ll see if there is actually some alien explanation. Perhaps some artificial elements or complex molecules? No one knows what a Dyson Sphere would look like, after all.

In a few months, this mysterious star might be a lot less (or a lot more) mysterious.

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