In 1181, a bright new star appeared in the constellation Cassiopeia. This star was actually a supernova or an exploding star. Chinese and Japanese astronomers noted this event.
For many years, scientists have searched for the remnants of this explosion. In 2013, amateur astronomer Dana Patchick discovered a nebula called Pa 30, which was found to be the leftover material from the supernova.
In 2023, astronomers spotted strange, dandelion-like filaments in the remnants. Using advanced tools at a Hawaiian observatory, they have created a 3D map of these filaments and measured how fast they are moving away from the explosion site.
Caltech professor of physics Christopher Martin, who led the team that built KCWI, said, “A standard image of the supernova remnant would be like a static photo of a fireworks display. KCWI gives us something more like a ‘movie’ since we can measure the motion of the explosion’s embers as they streak outward from the central explosion.”
The 1181 supernova happened when a white dwarf star exploded unusually, leaving behind a “zombie star.” This type of explosion, a Type Iax supernova, was fainter than typical supernovae, matching what historical records described. The debris from this explosion forms the Pa 30 nebula we see today.
Scientists know that the supernova created glowing filaments of sulfur in the nebula, but they are still figuring out how and when they formed. To study the supernova’s structure in 3D, astronomers used an instrument called KCWI, which breaks light into different colors for each part of an image.
This helped them measure the movement of the filaments. They found that material moving toward us appears blue (blue-shifted), while material moving away looks red (red-shifted).
The study of the 1181 supernova used a technique similar to how we hear sound changes when a firetruck passes by. As the truck approaches, the sound gets higher; as it moves away, the sound gets lower.
For this research, astronomers utilized the KCWI instrument’s “red arm,” which was recently added to improve its capabilities. This new part doubled the range of light it can capture, allowing for detailed observations of the Pa 30 nebula.
The findings showed that the filaments from the explosion move outward at about 1,000 kilometers per second. The material in these filaments is expanding consistently, meaning it hasn’t changed speed since the explosion, helping scientists pinpoint the explosion to around 1181.
The 3D mapping also revealed a large empty space inside the nebula and suggested that the explosion wasn’t perfectly symmetrical.
Tim Cunningham, a NASA Hubble Fellow at the Center for Astrophysics |Harvard & Smithsonian (CfA), said, “As to how the filaments formed after the blast, the scientists are still puzzled. A reverse shock wave may be condensing surrounding dust into filaments, but we don’t know yet. The morphology of this object is very strange and fascinating.”
Journal Reference:
- Tim Cunningham, Ilaria Caiazzo, Nikolaus Z. Prusinski et al. Expansion Properties of the Young Supernova Type Iax Remnant Pa 30 Revealed. The Astrophysical Journal Letters. DOI 10.3847/2041-8213/ad713b
