James Webb Telescope Reveals Four Coiled Dust Shells Around Wolf-Rayet Star System Apep

Updated on: November 20, 2025 | By: Jameswebb Discovery Editorial Team

James Webb Space Telescope Reveals Four Serpentine Dust Shells Spiraling Around Apep

NASA’s James Webb Space Telescope has just delivered one of the most breathtaking and scientifically important images of 2025: a crisp mid-infrared portrait of the Wolf-Rayet binary system Apep that, for the first time, shows four complete coiled dust shells spiraling outward like cosmic smoke rings. Previous ground-based observations had only ever detected a single shell. Webb has not only tripled that count but also confirmed the presence and gravitational influence of a third massive star that is literally carving holes through the expanding dust.This discovery, published in two companion papers in The Astrophysical Journal (Han et al. and White et al., 2025), marks the clearest view yet of one of the Milky Way’s most exotic and violent stellar systems.Webb MIRI image of Apep showing four coiled dust shells

Four serpentine dust shells spiral away from the central stars in this James Webb Space Telescope MIRI image. The innermost shell resembles a backward lowercase “e.” The fourth shell is extremely faint and visible only at the extreme edges of the frame. 

What Makes Apep So Special?

Apep (catalog name 2XMM J160050.8–514245) is the only known galactic system that contains two carbon-rich Wolf-Rayet stars (WC8 type) in a wide binary orbit, accompanied by a massive supergiant companion. Wolf-Rayet stars are extremely rare — only about 1,000 are thought to exist in the entire Milky Way — and systems with two of them are virtually unique.These stars are in the final, dramatic phase of their lives. Having already shed their outer hydrogen envelopes through ferocious stellar winds, they are now burning helium and heavier elements at their cores, blazing at temperatures exceeding 50,000 K and ejecting material at speeds of 2,000–3,000 km/s.What makes Apep truly extraordinary is the extremely long orbital period of the central Wolf-Rayet binary: approximately 190 years — by far the longest known for any dusty Wolf-Rayet system. The next longest is roughly 30 years; most produce dust on 2–10 year cycles (e.g., WR 140, WR 104).Every 190 years, the two Wolf-Rayet stars swing close to each other for about 25 years. During this prolonged “skirmish,” their powerful winds collide, compress, and cool, forming dense carbon-rich dust that is launched outward at 1,200–2,000 miles per second (2–3 million mph). The result is a new dust shell roughly every two centuries.

Why Could Only Webb See All Four Shells?

Earlier infrared observations (especially with ESO’s VISIR instrument on the Very Large Telescope) revealed the bright innermost pinwheel-like plume and hinted at extended structure, but could only confidently trace one complete shell.Webb’s Mid-Infrared Instrument (MIRI) changed everything. Carbon dust stays relatively warm even at large distances from the stars, glowing brightly at mid-infrared wavelengths (especially 7–25 μm) that are completely absorbed by Earth’s atmosphere. From space, MIRI can detect this extremely faint emission with unprecedented sensitivity and resolution.As Yinuo Han (Caltech), lead author of one of the new papers, said:

“Looking at Webb’s new observations was like walking into a dark room and switching on the light — everything came into view. There is dust everywhere in Webb’s image, and the telescope shows that most of it was cast off in repetitive, predictable structures.”

The four shells visible in the new image were produced over the last ~700–800 years, perfectly matching the expected timeline for a ~190-year orbital period with extended dust-production episodes.

The Third Star: The Cosmic Knife That Carves the Dust

The central stars appear as a single overexposed pinpoint in the MIRI image, but researchers have known since 2018 VLT spectroscopy that there is a hotter, more massive supergiant companion in a much wider orbit. Webb’s data provided the smoking gun.Look closely at the shells: each one has a distinctive V-shaped cavity pointing roughly from 10 o’clock to 2 o’clock relative to the center. These cavities line up perfectly across all four shells, proving they were carved by the same object — the third star.As the dust shells expand, the fast-moving supergiant (orbit yet to be fully characterized) punches through them like a knife, creating funnel-shaped holes that are visible in every layer.Ryan White (Macquarie University), lead author of the companion paper, described the moment the team realized what they were seeing:

“I was shocked when I saw the updated calculations play out in our simulations. Webb gave us the ‘smoking gun’ to prove the third star is gravitationally bound to this system.”

Future of Apep: Supernovae and Possible Gamma-Ray Bursts

Both Wolf-Rayet stars, now estimated at 10–20 solar masses each (having lost most of their original mass), will end their lives in spectacular core-collapse supernovae within the next few hundred thousand years — cosmically very soon.Because they are rapidly rotating and have lost their hydrogen envelopes, either (or both) could produce a long-duration gamma-ray burst — one of the most energetic explosions in the universe — when they die. The supergiant companion (likely 40–50 solar masses) will also eventually explode.When that happens, the multiple dust shells will be illuminated and shocked, potentially creating one of the most spectacular supernova remnants in our galaxy.

Why This Discovery Matters

• First clear detection of multiple historical dust-ejection episodes in a very long-period Wolf-Rayet binary

• Definitive proof of a bound triple system with a dust-carving third star

• Best laboratory yet for studying colliding-wind dust formation of carbon dust on century-long timescales

• Critical data for calibrating models of massive-star evolution and supernova/GRB progenitors

As Han summarized:

“We solved several mysteries with Webb. The remaining mystery is the precise distance to the stars from Earth, which will require future observations (likely with Gaia or future data releases or VLBI radio measurements).”

James Webb Space Telescope continues to rewrite our understanding of the most extreme stellar systems in the universe. Apep — named after the Egyptian serpent god of chaos — has proven a perfectly fitting name for one of the most beautifully violent objects in our galaxy. Stay tuned to jameswebbdiscovery.com for daily updates on every new JWST science result.