Dust, not alien megastructures, likely behind weird dimming of 'Tabby's Star'

New research finds the 'weirdest star in the galaxy' might not be nearly as weird as the clouds of dust that obscure it.

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Eric Mack
3 min read

Odd clouds of dust may be responsible for the weirdest star in the galaxy's weird behavior.


The so-called "weirdest star" in the galaxy -- it's also known as the "WTF" star, Boyajian's Star, Tabby's Star and KIC 8462852 -- remains a mystery, but its weird dimming behavior likely can't be explained by aliens. Unless, perhaps, they're incredibly tiny.

New research presented at a meeting of the American Astronomical Society (AAS) in Denver on Tuesday suggests a dusty explanation. 

A team of teenage students from the Thacher School, a private boarding high school in Ojai, California, trained the school's newly renovated observatory on the star beginning in April 2017 to study its enigmatic dips in brightness.

Boyajian's Star has a tendency to dip randomly and erratically throughout the year and has also been slowly dimming overall for more than a century. A swarm of comets, large clouds of dust and even alien megastructures have been suggested as possible culprits for haphazardly blocking the star's light.

The students from Thacher believe their data shows that not only is dust the most likely explanation, but that different types of dust are passing in front of the star.  

"Long-term dimming and short-term dimming may be caused by completely independent phenomena happening at the same time," Thacher School rising senior Yao Yin told reporters at AAS. 

She says there could be types of dust that differ, either in the size of the grains or in their chemical make-up. One possibility is that some fairly recent collision or other event produced the dust and it hasn't had enough time to become well mixed. Or perhaps completely different events produced the different kinds of dust. Or some of the dust may not even be that near the star.

"For all we know there could be microscopic aliens. Realistically we're not very sure," added Alejandro Wilcox, also a student researcher at Thacher. "It could be much closer to us than it is to Tabby's Star."

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Yin and Wilcox are part of a large international collaboration of citizen scientists and professionals studying the star at direction of the star's namesake Dr. Tabetha Boyajian at Louisiana State University. Boyajian herself also believes dust is a likely explanation for the star's dips in brightness.

Arizona State University post-doctoral researcher Eva Bodman is part of the collaboration and presented her own findings alongside Yin and Wilcox. She says what can be said for sure is that any dust cloud obscuring the star is extremely complex.

"I think of it as like a clumpy, amorphous cloud," Bodman said. 

Analysis of light data from Boyajian's star reveals the presence of clouds of very fine dust passing in front of it.

"This dust is more like a misty cloud ... than the dust you find in your home," Bodman explained, likening it to smoke particles.

Bodman says that any more fine-grained dust near the star would have to be newly created because small grain sizes would be blown away by its stellar wind relatively quickly. She added that the century-long dimming appears to be caused by the larger grains that are able to stick around longer. But beyond that, it's hard to discern much else about the composition of the dust and how it's being created with any certainty.

"The star is still a mystery," Bodman said.

The mystery may not last forever, though, with new space telescopes on the horizon and young astronomers like Yin and Wilcox on the rise.

"With the [James Webb Space Telescope] and TESS coming up, we'll get more oddities like this," said Yin. "And we'll certainly learn much more about the universe."

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