Researchers got a clear look at the 1181 supernova remains, which feature giant gas chains. The surviving star sits at the center of this debris cloud, called Pa 30. Ilaria Caiazzo said, "The supernova that created Pa 30 was a Type Iax supernova, a peculiar kind of explosion."

Debris around the surviving star of the 1181 supernova forms chains of giant knots, and the star lies almost exactly at its center.

A supernova usually marks the end of a star. In 1181, Japanese, Chinese and Arabic astronomers recorded one that wasn't quite the end: a scorching leftover star, now ringed by long, straight streaks of gas.

New telescope images show those streaks aren't smooth. They're chains of knots, each one wide enough to hold Neptune's orbit about ten times over.

The images also put the surviving star almost exactly at the center of the debris. A centered star means the blast gave it almost no push, a clue to how the explosion played out.

Tim Cunningham of the University of Warwick led the work with Ilaria Caiazzo of the Institute of Science and Technology Austria. Cunningham did the research while at the Harvard & Smithsonian Center for Astrophysics.

Astronomers call the debris cloud Pa 30, and it's the only one of its kind known in the Milky Way.

A supernova recorded in 1181

Observers in three cultures noted down the explosion. Its remains weren't identified until 2013, when volunteer sky watchers spotted an unknown cloud in archived infrared images. The cloud was later tied to the old record; it lies about 7,500 light-years from Earth.

The star that exploded was a white dwarf, the dense, Earth-sized core a star leaves behind once it has used up its fuel.

In an interview with Earth.com, Caiazzo explained why something survived. "The supernova that created Pa 30 was a Type Iax supernova, a peculiar kind of explosion in which a white dwarf is not completely destroyed, leaving behind a partially burned stellar remnant," she said.

The leftover star is extremely hot, about 360,000°F (200,000°C). It also blows out a wind at roughly 10,000 miles per second (16,000 kilometers per second).

Straight streaks are rare in debris

Most supernova debris is a churned-up mess. Pa 30 looks more like a burst of fireworks, with straight streaks pointing out from the center. An earlier study found the gas has been flying outward at a steady speed since the explosion.

"No other known supernova remnant shows such long, straight filaments; most have a much more chaotic structure," Caiazzo said. "Understanding how these filaments formed is one of the big open questions about Pa 30."

To get a sharper look, the team used the Gemini North telescope on Mauna Kea in Hawaii. In mid-2025, the telescope gathered nearly seven hours of images. Its filters passed only the light that glowing sulfur and oxygen give off.

Knots run along the streaks

The sulfur images showed about ten times as many streaks as earlier pictures had. Up close, most streaks broke into a string of knots.

Each knot is about 60 billion miles (100 billion kilometers) across. The knots are similar in size along each streak and from one streak to the next. Their spacing looks fairly regular too.

The oxygen glow, faint and fuzzy in earlier images, turned out to come from the same streaks as the sulfur.

The knots give modelers something new to match. One idea is that the streaks rippled where fast-moving debris slid past thinner gas, and that the gas then cooled and clumped.

Another, in which the star's wind shaped the streaks, has trouble explaining why the debris moves outward so steadily.

"We have now discovered that the filaments are not smooth, but are instead made up of individual knots," Caiazzo said. "That gives us an important new clue about how the explosion unfolded and how the ejected material evolved afterward."

The surviving star barely moved

Computer simulations of this kind of explosion often start the blast off to one side of the white dwarf. A lopsided blast should push the surviving star the other way. Simulations predict speeds of up to about 370 miles per second (600 kilometers per second).

"Because momentum has to be conserved, an asymmetric explosion should give the surviving star a 'kick' in the opposite direction - much like an astronaut throwing an object in one direction and being pushed the other way," Caiazzo told Earth.com.

The team traced where the streaks point back to. The cloud's center matched the star's position almost exactly, so the star's sideways speed can't be more than about 9 miles per second (14 kilometers per second).

If the push could have gone in any direction, its total speed is almost certainly below about 60 miles per second (94 kilometers per second).

"That tells us that it cannot have received a large kick, and therefore that the explosion must have been actually quite symmetric," Caiazzo said.

What remains unknown

The knots are only barely sharp enough to measure. Streaks that overlap along the line of sight also make their spacing hard to pin down.

The star's motion toward or away from Earth hasn't been measured directly. Spectra so far cover only about a tenth of the cloud.

What blew up in the first place is still open. Researchers have proposed two white dwarfs merging, and Caiazzo said the other possibility is a white dwarf pulling material from a companion star.

Her team now has observing programs on the James Webb and Hubble space telescopes. Combined with simulations, she said, those images could show what the system looked like before 1181 and what the surviving star will become.

Cunningham said similar remains of exploding stars may still be hiding in the Milky Way, since reliable records go back only about a thousand years.

Explosions of this type also show up as points of light in distant galaxies, but Pa 30 is the one close enough to study in this detail.

The full study was published in the journal The Astrophysical Journal.

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