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Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Pa 30 is a nebula surrounding an exceptionally hot stellar remnant in the constellation Cassiopeia. It is the leading candidate for the remnant of the supernova recorded in 1181, and its expanding filaments and unusual surviving star point to a rare, incomplete thermonuclear explosion. The identification is strongly supported by the evidence, though the precise explosion pathway and the star’s powerful wind are still being studied.
What is Pa 30?
Pa 30 is the name of a nebula and the stellar remnant at its center; the system is also catalogued as IRAS 00500+6713. The central object is sometimes called Parker’s star. Unlike the compact remnant left by many supernovae, this system appears to contain a surviving star surrounded by material ejected in an explosion.
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Why is Pa 30 linked to the supernova of 1181?
Chinese and Japanese historical accounts describe a bright “guest star” that appeared in 1181. Astronomers have proposed that Pa 30 is the remnant of that event because its expansion age and sky position fit the historical record. The connection is a strong research identification, not a direct observation of the explosion itself.
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- Ritter and colleagues’ 2021 analysis inferred an expansion age of about 1,000 years, consistent with an event in 1181.
- The authors placed Pa 30 within 3.5 degrees of the position reported in the historical accounts.
- Their spectroscopy found a nebular shock moving at approximately 1,100 km/s. This is the shock speed, not the much faster wind associated with the central star.
In a 2024 study using integral-field spectroscopy, researchers mapped the nebula’s structure and motion in three dimensions. They reported ejecta consistent with ballistic expansion, a cavity inside the remnant, and a sharp inner edge to the filaments aligned with the outer edge of a bright infrared ring. They also found a strong asymmetry in ejecta along the line of sight. The study’s authors concluded, “Our analysis provides strong confirmation that the explosion originated from SN 1181.” Read the 2024 study.
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What do the star and nebula look like?
Pa 30 was first identified in infrared archival data. Optical observations later revealed striking filaments extending outward from the central source, giving the nebula a radial, flower-like appearance. Different wavelengths reveal different parts of the system: infrared observations show nebular structure, X-rays reveal emission from the broader nebula and central source, and visible light highlights heated sulfur in the filaments.
In NASA’s composite image, colors distinguish data from different wavelengths; they are not a literal representation of how Pa 30 would look to the human eye. NASA’s 2023 explainer describes the central star as about 200,000°C and reports a wind speed of up to 16,000 km/s. Those figures refer to the hot star and its wind, not to the slower nebular shock measured by Ritter and colleagues. NASA’s Pa 30 explainer describes the multiwavelength view.
What kind of explosion could leave a star behind?
The leading broad explanation is a subluminous Type Iax thermonuclear supernova. In this kind of event, the explosion may not completely destroy the white dwarf. A bound stellar remnant can survive, surrounded by expelled material—an interpretation that helps explain why Pa 30 has both a nebula and a central star.
The 2021 identification paper proposed that the event began with a merger of two white dwarfs; NASA’s public explainer also summarizes a merger scenario. The unusual remnant, however, does not by itself settle the progenitor’s history or the exact physics of the explosion.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Why is the central star’s wind still a puzzle?
The central star’s reported wind is far faster than the measured nebular shock, and explaining how and when that wind began remains an active problem. A 2026 model by Sato and colleagues proposes that carbon-rich material may have fallen back onto the surviving white dwarf after a pure-deflagration explosion. In the model, delayed carbon ignition could help explain a wind that began centuries after the explosion. The calculation requires a hot post-explosion white-dwarf core near 6 × 108 K; this is a model condition, not a directly measured temperature.
The model offers a possible explanation rather than a settled account. Its authors say “the driving mechanism of the fast wind remains uncertain,” and discuss other possibilities, including a helium-star companion. The details of Pa 30’s origin therefore remain open even though its association with SN 1181 is strongly supported.
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