New Theory Suggests Mysteriously Dimming Star Could Be Consuming a Stolen Exomoon

Tabby's Star has been dimming for decades, puzzling astronomers and scientists around the world.
Fabienne Lang
A hypothetical uneven ring of dust orbiting Tabby's StarNASA/JPL-Caltech

The star named KIC 8462852, or Tabby's Star has baffled astronomers for over a century. Also known as Boyajian's Star, after the assistant professor of physics and astronomy at Louisiana State University, Tabetha Boyajian, who first discovered it.

The star sometimes dims in brightness for a few days or weeks, before returning to its original brightness.

Astronomers have been guessing what the reasons behind the dimmings could be, and have just added one more theory to the lineup: that the star is eating up an exomoon stolen from another planet. 


Tabby's Star's details

Located over 1,000 light-years away, the star is 50% larger than our Sun, and 1,000 degrees hotter. So far, it's the only star of its kind. 

Over the past century, Tabby's Star has been slowly dimming in brightness and has exhibited dimming anywhere between a few days to a few weeks at a time, before returning to its brighter luster. 

Categorized as an F-type star, it should not be dimming in brightness. 

So, astronomers have been scratching their heads figuring out what could be causing the dimming, with theories ranging from something blocking it, or simply space dust being in the way. 

More recently, however, scientists from Columbia University have pointed at another theory: a thick ring of debris is growing and orbiting the star.

The findings of the Columbia University scientists, Brian Metzger, Miguel Martinez, and Nicholas Stone, were published recently in Monthly Notices of the Royal Astronomical Society.

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According to the researchers, the debris is coming from an exomoon — a moon that used to orbit a planet outside our Solar System. 

The star has stolen an exomoon

On top of the abovementioned debris, scientists believe that Tabby's Star has also stolen an exomoon from a nearby planet that no longer exists. 

Due to the strong radiation from the star, it has stripped the exomoon's outer layer, which is made up of gas, ice, and rock. Other large particles are thrust into orbit, ending up in a dust disk surrounding the star. 

This could be an explanation as to why the star keeps dimming and brightening again. 

Researchers are looking for other stars with similar dimming behaviors, which may help figure out this enigma.