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upstart writes in with an IRC submission for nothernotherguy:

Three stars, warped rings may show how planets end up moving backward:

The star system in question is named GW Orionis, and it's located in the star-forming region of Orion, about 1,250 light years from Earth. The system is young, still in the process of forming, and consists of three stars. Two of them, both somewhat larger than the Sun (2.5 and 1.4 times its mass), orbit each other closely at roughly the same distance as the Earth is from the Sun. A third star, also slightly larger than the Sun, orbits these two at a distance that's roughly eight times the distance between the Earth and Sun.

But the orbits of the three stars had consequences for the disk of gas and dust that formed around them. This disk also showed up during the imaging campaign, and [...] the results were fairly complex. Images of the disk reveal a complicated pattern of bright and dark patches surrounding the stars, along with at least three different rings of dense material within the disk.

[...] In the model, the outermost rings orbit in a single plane, but the plane doesn't align with the orbital plane of any of the stars. Perhaps more significantly, their orbits are retrograde, in that they orbit the stars in a different direction than the third star orbits the inner two. The third ring, by contrast, is oriented in the same plane as that of the stars. But its center isn't the center of the stars' orbits.

Physically, there should be a single disk of material surrounding all three stars. Instead, there seems to be a large outer disk that's consistent with this. But, closer to the center of the system, the disk is skewed by the off-axis orbits of the stars. There's either a break between the outer and inner ring or, if the material is contiguous, it's distorted as if the inner ring had been pushed up through a thin sheet of plastic.

If the model is correct, this represents the first clear case of what's called "disk tearing," in which the misalignment of the material and the stars creates forces that can break up the disk.

Journal Reference:
Stefan Kraus, Alexander Kreplin, Alison K. Young, et al. A triple-star system with a misaligned and warped circumstellar disk shaped by disk tearing [$], Science (DOI: 10.1126/science.aba4633)

Original Submission