Posted on Nov 22, 2018
In 2016 a group of astronomers from Pennsylvania State University released a preprint that cited star KIC 8462852’s “bizarre light curve” as “consistent with” a swarm of alien-constructed megastructures. This ordinary F star soon went viral as “the most mysterious star in the universe” as Yale astronomer Tabetha Boyajian described KIC 8462852, popularly known as Tabby’s star.
“The dips found by Kepler are real. Something seems to be transiting in front of this star and we still have no idea what it is,” said German astronomer Michael Hippke.
But follow-up research led by Huan Meng, an astronomer at the University of Arizona concluded that a microscopic dust ring originating from circumstellar material found in the star system is causing the dimming and brightening exhibited by KIC 8462852. “It cannot be anything from the interstellar medium,” says Meng — meaning the object(s) at the focus of this investigation is definitely within the planetary system of Tabby’s star.
Now, astronomers using the VISTA telescope in the Atacama Desert in northern Chile have discovered a star whose odd dimming and brightening of light are reminiscent of Tabby’s star.
The team spotted the object in data that were part of a larger survey of the galaxy’s center called the VISTA Variables in the Vía Láctea, or VVV. Instead of brightening, this star suddenly dimmed. The team called it VVV-WIT-07, for “What is this?”
Saito and his colleagues plan to follow up on the star with more powerful telescopes, like the 8.1-meter Gemini telescope or the Atacama Large Millimeter Array, both in Chile.
“If this phenomenon is the same as what’s happening with Tabby’s star, then we can’t invoke an elaborate explanation for what’s happening in both systems,” Boyajian says. “If you’re starting to see stars similar to this all over the place, then it’s got to be a really common thing that happens in nature. That’s really cool.”
The new star’s behavior is is baffling, says astronomer Roberto Saito of the Federal University of Santa Catarina in Florianópolis, Brazil. He and his colleagues reported the star’s flickering November 6 on arXiv.org.
“We don’t know what the object is,” he says. “And that’s interesting.” The star could have some sort of orbiting debris that periodically blocks the starlight, but Saito and colleagues say they need more observations to figure out if that’s possible or if the flicker is caused by something else.
From 2010 to 2018, the star’s brightness waxed and waned with no set pattern similar to that of Tabby’s star, except VVV-WIT-07’s light dropped by up to 80 percent, while Tabby’s star dimmed by only about 20 percent.
Because VVV-WIT-07 is located in the plane of the galaxy, the view from Earth to the star is full of dust, making it hard to make out details such as the star’s distance or what kind of star it is. If it’s a young variable star, for instance, then its light dips might be internal.
“Pretty much everything’s on the table for it right now,” Boyajian says. “We need more data.”
Image credit: JPL/Caltech comets converging on a star.