Each ring was formed when the stellar winds from the two stars collided as they approached one another, compressing the gas and generating dust. About every eight years, the stars’ orbits bring them together; the dust loops serve as timekeepers, much like the growth rings on a tree trunk.

“We’re looking at over a century of dust production from this system,” said Ryan Lau, an astronomer at NSF’s NOIRLab and lead author of a new study about the system, published today in the journal Nature Astronomy.

Transforming gas into dust is somewhat like turning flour into bread: It requires specific conditions and ingredients. The most common element found in stars, hydrogen, can’t form dust on its own. However, because Wolf-Rayet stars shed so much mass, they also eject more complex elements like carbon, which are typically found far inside a star. Like when two hands knead dough, the heavy elements in the wind are compressed where the winds from both stars meet after cooling as they travel through space.

James Webb telescope has enhanced NASA’s capabilities

Speaking about the capability of the James Webb telescope in capturing minute details, Lau added, “The image also illustrates just how sensitive this telescope is. Before, we were only able to see two dust rings, using ground-based telescopes. Now we see at least 17 of them.”

The Mid-Infrared Instrument (MIRI) on Webb, in addition to the telescope’s overall sensitivity, makes it uniquely suited to study the dust rings, or shells, as Lau and his colleagues refer to them because they are thicker and wider than they appear in the image. Infrared light, which has a spectrum of wavelengths that are invisible to the human eye, is detected by Webb’s scientific equipment.

Due to its ability to detect longer infrared wavelengths than Webb’s other instruments, MIRI is frequently able to see cooler objects, including the dust rings. The dust’s composition, which was mostly made up of material ejected by a type of star called a Wolf-Rayet star, was also revealed by MIRI’s spectrometer.

About Wolf-Rayet stars

A Wolf-Rayet star is a dying O-type star that was born at least 25 times as massive as our Sun and is on the verge of collapsing into a black hole. A Wolf-Rayet star produces powerful winds that propel massive amounts of gas into space as it burns hotter than when it was young. This process may have caused the Wolf-Rayet star in this pair to lose more than half of its initial mass.

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While some other Wolf-Rayet systems are known to produce dust, none are known to produce rings. Because the orbit of the Wolf-Rayet star in WR 140 is elongated rather than circular, a special ring pattern develops. The gas isn’t under enough pressure to form dust until the stars are relatively close to one another — about the same distance as between the Earth and the Sun — and their winds collide. Wolf-Rayet binaries can continuously produce dust when their orbits are circular.