Gemini North telescope reveals gas knots in SN 1181 remnant

Pa 30 is a supernova remnant located 7,500 light-years away in the constellation Cassiopeia. New observations show its expanding debris consists of tiny gas knots rather than smooth streaks. This remnant is thought to be the leftovers of SN 1181, a historic stellar explosion witnessed by medieval astronomers in China and Japan.

Advanced ground-based telescopes have captured unprecedented details of the historic stellar explosion recorded centuries ago. Live Science reported on Oct. 6, 2026, that the Gemini North telescope on Mauna Kea in Hawaii produced an image revealing about 10 times more filamentary structures in Pa 30 than previously seen. Eight surviving texts date the original appearance of SN 1181 between Aug. 4 and 6 of that year, remaining visible as a naked-eye object for 185 days.

This object stands as one of only five Milky Way supernovas witnessed from Earth before optical instruments first appeared in the Netherlands in 1608. Timothy Cunningham, an assistant professor of astronomy and astrophysics at the University of Warwick who led the international research team, noted the rarity of this data.

It’s rare to get this level of detail on a supernova we can date to a specific week in history,
Timothy Cunningham, University of Warwick

Surviving Zombie Star at the Center of Pa 30 Points to Symmetrical Blast

The latest findings, published in The Astrophysical Journal, challenge previous assumptions about how the debris field formed. Cunningham explained the unexpected composition of the expanding material.

The filaments are made of chains of tiny knots rather than smooth streaks, providing new constraints on the nature of the space around the star before it exploded and the physical processes that have shaped the expanding ejecta,
Timothy Cunningham, University of Warwick

Researchers suggest these knot-like structures formed due to variations in temperature or density in the surrounding space as the debris expanded. Pa 30 houses a surviving star sitting nearly at the exact center of the remnant. Standard supernova explosions typically hurl stars far from their original positions, making this central placement a strong indicator that the initial blast was highly symmetrical.

Scientists classify Pa 30 as a Type Iax supernova. Unlike standard Type Ia events that completely obliterate their progenitor stars, a Type Iax event represents a lower-energy, incomplete explosion of a white dwarf. This leaves behind a remnant often called a zombie star, making Pa 30 the sole Type Iax supernova ever discovered.