Astronomers: ‘Alien Megastructure’ Star Has Nothing to do with Aliens

Astronomers started checking out a novel star a few years ago called KIC 8462852. A series of fluctuations in the star’s brightness brought up a number of interesting possibilities. Perhaps the star had dust clouds or gaggles of comets that periodically blocked out the light. That’s interesting in an expected way, but the proposal that made KIC 8462852 famous was pretty radical. Astronomer Jason Wright suggested it may be home to alien “megastructures” that blocked some of the light. It makes for a good headline, but now we have good evidence there are no alien megastructures to be found.

The first team to study KIC 8462852’s unusual periodic dimming was led by Louisiana State University astronomer Tabetha Boyajian. Her work on the star led to it being informally nicknamed “Tabby’s Star.” In that first round of observations, light output from the star dipped by nearly 1 percent and stayed that way for a week. Subsequent drops were even larger, which is outside what you’d expect from an object like a planet passing in front of a star. Even if it was a planet, they don’t tend to stay in one place for a week at a time.

This strange behavior is what led Wright to coyly suggest aliens were building giant structures around Tabby’s Star. This explanation was always a long shot, but it was endlessly fun to speculate about. Now, a study led by none other than Tabetha Boyajian with more than 100 co-authors including astronomer Jason Wright, has been completed. The result? It’s just some dust. Well, a lot of dust.

The team conducted a new series of observations of KIC 8462852, which is 50 percent larger than the sun and about 1,200 light years away. This marks the first time a dimming event was observed in real time. All previous analysis of KIC 8462852 involved looking at data that had been captured in the past. The so-called “Elsie” series of light dips started in May 2017 and were studied in detail via the Las Cumbres Observatory in California. The team found that some wavelengths of light continued to shine at full intensity during the dips, which makes the alien megastructure hypothesis much harder to swallow. Any solid structure would presumably be fully opaque.

The most likely explanation for the observations is a massive dust cloud, and that could still be pretty interesting. Not alien megastructure interesting, but what is? Tabby’s Star could have been the site of a large planetary collision 1,000 years ago that scattered fragmentary remains throughout the solar system in a highly elliptical orbit. If this is true, the team expects another dimming event to happen in June 2019.