Amazing stuff!
"... The supernova was spotted by Chinese and Japanese astronomers in 1181, when it was visible gleaming from the Cassiopeia constellation for 6 months. They dubbed it the “guest star”. It’s one of just 5 confirmed galactic supernovae seen during human history.
The remaining nebula went unspotted until 2013, and was only formally identified as the 1181 supernova’s source in 2021. ..."
"... The 1181 supernova is thought to have occurred when a thermonuclear explosion was triggered on a dense dead star called a white dwarf. Typically, the white dwarf would be completely destroyed in this type of explosion, but in this case some of the star survived, leaving behind a sort of “zombie star.” This type of partial explosion is called a Type Iax supernova. “Because this was a failed explosion, it was fainter than normal supernovae, which has been shown to be consistent with the historical records,” ..."
From the abstract:
"The recently discovered Pa 30 nebula, the putative type Iax supernova remnant associated with the historical supernova of 1181 AD, shows puzzling characteristics that make it unique among known supernova remnants. In particular, Pa 30 exhibits a complex morphology, with a unique radial and filamentary structure, and it hosts a hot stellar remnant at its center, which displays oxygen-dominated, ultrafast winds. Because of the surviving stellar remnant and the lack of hydrogen and helium in its filaments, it has been suggested that Pa 30 is the product of a failed thermonuclear explosion in a near- or super-Chandrasekhar white dwarf, which created a subluminous transient, a rare subtype of the Ia class of supernovae called type Iax. We present here a detailed study of the 3D structure and velocities of a full radial section of the remnant. The Integral Field Unit observations, obtained with the new red channel of the Keck Cosmic Web Imager spectrograph, reveal that the ejecta are consistent with being ballistic, with velocities close to the free-expansion velocity. Additionally, we detect a large cavity inside the supernova remnant and a sharp inner edge to the filamentary structure, which coincides with the outer edge of a bright ring detected in infrared images. Finally, we detect a strong asymmetry in the amount of ejecta along the line of sight, which might hint at an asymmetric explosion. Our analysis provides strong confirmation that the explosion originated from SN 1181."
Dandelion Supernova Revealed in 3-D (original news release) "New observations probe a sphere of filaments around a dead star"
Figure 1. Lower panel: narrowband image obtained from stacking all the KCWI-red channel cubes and integrating over the wavelength range 6680–6750 Å, covering the maximally blue- and redshifted [S ii] emission features.
Upper panel: the black and white image shows the [S ii] narrowband data from R. A. Fesen et al. (2023), obtained with the Hiltner telescope at Kitt Peak. ... 
In 1181, astronomers in China and Japan recorded a new star in the sky, a rare supernova explosion. The remains of that supernova, called SN 1181, are depicted here in this artist’s animation, which flies around the remnant as it appears today in one moment in time.
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