Gemini North Reveals Pearl-Like Knots in the Remnant of a Supernova Witnessed in the Year 1181

Republished from NOIRLab, the U.S. National Science Foundation's National Optical-Infrared Astronomy Research Laboratory, where it first appeared as a press release on 2026-10-06. NOIRLab press-release texts and images are released under the Creative Commons Attribution 4.0 International licence; the text is reproduced here unchanged apart from formatting. Credit: NOIRLab. Read the original for the latest version and any updates.

The Gemini North telescope located on Maunakea in Hawai‘i has revealed the most detailed view yet of Pa 30, the likely remnant of the historic supernova seen in the year 1181. The new observations reveal that its famous “firework” filaments are not smooth streaks, but chains of tiny knots.

No, this is not a firework display. This is Pa 30 — the likely remnant of the historic supernova witnessed in the year 1181, now captured here in unprecedented detail by the Gemini North telescope, one half of the International Gemini Observatory, partly funded by the U.S. National Science Foundation (NSF) and operated by NSF NOIRLab. This image was captured with the Gemini Multi-Object Spectrograph (GMOS), and it shows that the remnant’s unmistakable firework-shaped ejecta take a cascading knot-like structure.

The historic supernova, named SN 1181, is one of only five supernovae in the Milky Way that were observed from Earth before the invention of the telescope. Eight separate texts show that Chinese, Japanese, and Arabic astronomers first observed the supernova between 4 and 6 August 1181. The supernova remained visible in the constellation Cassiopeia for 185 days. According to what we know about how stars end their lives, the colossal explosion would have left something behind. Pa 30, a system composed of a blue central star and surrounding firework-shaped shell, is the top candidate for this supernova remnant.

Pa 30 was only discovered in 2013 through a citizen science campaign to find planetary nebulae in Wide-field Infrared Survey Explorer (WISE) data. It was the 30th nebula found by American amateur astronomer Dana Patchick. Follow-up imaging on the KPNO 2.1-meter Telescope and the Hiltner 2.4-meter Telescope, both located at NSF Kitt Peak National Observatory (KPNO), a Program of NSF NOIRLab, revealed faint, diffuse nebular emission and remarkable radial filaments threading the nebula in a nearly perfect sphere. Based on its estimated age and brightness, scientists consider Pa 30 to be the likely remnant of SN 1181.

Analysis of the new observations from Gemini North, which was led by Timothy Cunningham (Center for Astrophysics — Harvard & Smithsonian) and Ilaria Caiazzo (Institute of Science and Technology Austria), reveals about ten times more filamentary structure in Pa 30 than previously seen. It also shows that the radial filaments are made of consistent chains of tiny knots of gas, rather than smooth streaks as previously thought. This knotty structure suggests that there may have been thermal or density variations in the circumstellar medium that shaped the supernova ejecta as it expanded radially away from the explosion.

Pa 30 is unique among all known supernova remnants. The central star remaining after the explosion, IRAS 00500+6713, is extremely hot, with a temperature of about 200,000°C (~360,000°F). It also possesses very fast stellar winds that move at around 16,000 kilometers per second (~10,000 miles per second).

Surviving remnant stars are expected to be “kicked” away during the powerful supernova explosion. However, the central star of Pa 30 appears almost exactly centered in the remnant. This curious configuration implies that the explosion was quite symmetrical, and it rules out a large kick that could have knocked the star off-center. From this, the researchers conclude that SN 1181 was an extremely rare Type Iax supernova. Unlike the standard high-energy explosions of Type Ia supernovae that wipe out their stars, Type Iax supernovae are lower-energy, incomplete explosions that leave behind a surviving remnant star. Pa 30 is the only known Type Iax remnant in the Milky Way.

The story of SN 1181 is one of humans working together, across time and space, to understand the changing Universe. As new astronomical questions arrive every day, SN 1181 invites us to wonder what mysteries remain unsolved from the distant past.