This May Be the First Planet Found Orbiting 3 Stars at Once


“‘Star Wars’ missed a trick,” said Rebecca Nealon from the University of Warwick in England, a co-author on the paper.

Scientists have been on the lookout for a planet orbiting three stars, and found potential evidence in another system, GG Tau A, located about 450 light years from Earth. But the researchers say the gap in GW Ori’s gas and dust ring makes it a more convincing example.

“It may be the first evidence of a circumtriple planet carving a gap in real time,” said Jeremy Smallwood from the University of Nevada, Las Vegas, lead author of the new paper.

William Welsh, an astronomer at San Diego State University, said the researchers “make a good case. If this turns out to be a planet, it would be fascinating.”

Alison Young from the University of Leicester in England who has argued that GW Ori’s stars caused the gap in the system’s disk, rather than a planet, notes that observations from the ALMA telescope and Very Large Telescope in Chile in the coming months could end the debate.

“We’ll be able to look for direct evidence of a planet in the disk,” Dr. Young said.

If the planet hypothesis is confirmed, the system would reinforce the idea that planet formation is common. Several worlds, known as circumbinary planets, are already known to orbit two stars at once. But circumtriple planets have been harder to come by — despite estimates that at least a tenth of all stars cluster in systems of three or more. Yet their possible existence suggests that planets spring up in all sorts of places, even here in this most bizarre of systems.

“Three stars is not enough to kill planet formation,” Dr. Nealon said.

That suggests that exoplanets are likely to arise in more and more unusual locations. “What we’ve learned is any time planets can form, they do,” said Sean Raymond, an astronomer from the University of Bordeaux in France who was not involved in the paper.


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