Supernova noticed by astronomers in 1181 might have been a uncommon Kind 1ax that leaves a “zombie star” remnant
In 1181 AD, Chinese and Japanese astronomers noticed that a “guest star” as bright as Saturn briefly appeared in their night sky. In the thousand years since then, astronomers have been unable to pinpoint the origins of this event. New observations have shown that the “guest star” was a supernova, and a strange one at that. It was a supernova that didn’t destroy the star, but left behind a zombie that was still glowing.
“Guest stars” are what modern astronomers today call novae or supernovae, and the brightness of the event in 1181 AD (described as being as bright as Saturn) and its longevity (visible to the naked eye for 185 days) means that it is almost certainly of a supernova. For decades, a pulsar wind nebula in the same region of the sky was thought to be the remnants of this supernova, but new estimates suggest that the age of this nebula is around 7,000 years, far too old to explain the 1181 recordings.
While searching the archives of NASA’s Wide-field Infrared Survey Explorer, a team led by astronomers from the University of Hong Kong discovered an alternate and much stranger possible origin story. Her work was recently published in the preprint journal arXiv.
The astronomers found one of the hottest Wolf-Rayet stars known, which they call the Parker star, named after one of the study directors. Wolf-Rayet stars are massive stars surrounded by hot gas envelopes and are among the brightest stars in the sky.
Around Parker’s star is a nebula called Pa 30. The nebula has an expansion speed of around 1,100 km / s and, due to its current size, was probably formed from a supernova event around 1,000 years ago – exactly on the line of the “guest star”. Observations.
The 1,100 km / s expansion speed is much slower than that of a typical supernova remnant and is usually associated with a rare type of supernova that does not fully detonate its star. That fact would explain the existence of Parker’s star as well – it’s a zombie remnant that should have died a thousand years ago, but it’s still alive.
These type of supernovae are extremely rare, and this observation could mean that this is the only known zombie remnant in the Milky Way. And we wouldn’t know if it weren’t for those astronomical astronomers a thousand years ago.