Remarkable new images from the James Webb Space Telescope have captured the first-ever view of four dust spirals surrounding the Wolf-Rayet stars in the Apep system.
The mid-infrared imagery is the culmination of years of data collected by the European Southern Observatory’s Very Large Telescope (VLT) in Chile, supported by James Webb observations. Previously, Webb could image only one of the shells, although all four were hypothesized to exist based on VLT data.
Apep’s Spiral Shells
“Looking at Webb’s new observations was like walking into a dark room and switching on the light — everything came into view,” said Yinuo Han, the lead author of one paper and co-author on the other describing the work. “There is dust everywhere in Webb’s image, and the telescope shows that most of it was cast off in repetitive, predictable structures.”
They were formed over the course of centuries by emissions from the two stars, on a 190-year orbit in which they come into close contact for just 25 years, creating the dust seen in the images. Two new papers, recently published in The Astrophysical Journal, bring into focus the remarkable story behind the new imagery.
Also in the mix is a third star that slices through the dust clouds on an even wider orbit. This is difficult to discern in the imagery (seen above), as all three appear as a single point of light. The slicing is evident as a V shape, beginning at 10 o’clock and ending at 2 o’clock around the central point of light. VLT observations revealed the third star in 2018, but how it moved in the system was unknown until now.
“I was shocked when I saw the updated calculations play out in our simulations,” he said. “Webb gave us the ‘smoking gun’ to prove the third star is gravitationally bound to this system.”
An Unusual System
Correlating years of VLT observations with the Webb image allowed the researchers to refine the orbits of Wolf-Rayet stars.
“This is a one-of-a-kind system with an incredibly rare orbital period,” White said. “The next longest orbit for a dusty Wolf-Rayet binary is about 30 years. Most have orbits between two and 10 years.”
Wolf-Rayet stars are extremely rare, with scientists estimating that there may be only a thousand in our entire Galaxy, out of hundreds of billions of stars. Apep is the only known example of two Wolf-Rayets forming a binary system, although a few hundred binaries containing a single Wolf-Rayet have been observed.
The Wolf-Rayet stars of the Apep system are currently somewhere between 10 and 20 times the mass of our sun, the researchers believe, yet at one time they likely were even more massive than the supergiant, which cuts a hole through their dust sheets, coming in somewhere between 40 and 50 times the mass of the Sun.
Producing the Dust Shells
The stellar winds produced by the two stars rush towards each other and mix when their orbits come into proximity. This results in 25 years of carbon-rich dust production, a period vastly longer than in most similar situations. For example, the dust shells of Wolf-Rayet 140 only persist for months. The dust observed in Apep is blasting through space at 1,200 to 2,000 miles per second and at tremendous density. The amorphous carbon composition of the dust enabled Webb to achieve a clear view of the phenomenon with the MIRI instrument.
“Carbon dust grains retain a higher temperature even as they coast far away from the star,” Han said, explaining how the dust shields were so apparent in the imagery.
While the team has accomplished a great deal towards understanding this highly unusual star system, they say their work is not yet complete.
“We solved several mysteries with Webb,” Han said. “The remaining mystery is the precise distance to the stars from Earth, which will require future observations.”
The papers, “The Formation and Evolution of Dust in the Colliding-wind Binary Apep Revealed by JWST” and “The Serpent Eating Its Own Tail: Dust Destruction in the Apep Colliding Wind Nebula,” both appeared in The Astrophysical Journal on November 19, 2025.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.