More than 800 years ago, in 1181, Chinese and Japanese astronomers witnessed an unusual phenomenon – a bright star shone in the sky for six months and then suddenly disappeared. They were the first to record the supernova explosion on paper. In our time, this phenomenon, known as SN 1181, has become an astronomical mystery that modern scientists are trying to solve.
In 2021, a team of researchers from the University of Manchester, guided by the observations of an amateur astronomer from Los Angeles, determined the possible place of origin of SN 1181. It is a nebula located in the constellation Cassiopeia at a distance of about 7,000 light years. In general, a Type Ia supernova, to which SN 1181 belongs, destroys the white dwarf star that caused the explosion.
However, SN 1181 was not a typical event. Instead of complete destruction, it left behind a “zombie star” that still orbits in the core of the Cassiopeia Nebula. This unusual phenomenon indicates that SN 1181 was a rare Type Iax supernova caused by the merger of two white dwarfs. This led to the formation of a star devoid of the usual elements such as hydrogen and helium.
A study published in July 2023 in The Astrophysical Journal led by Takatoshi Ko of the University of Tokyo confirmed the Type Iax of this supernova using computer modeling. They found two shockwave models, one of which indicated that the “zombie star” may have re-exploded within the last 100 years, despite being dead.
According to the researchers, a possible scenario is that the explosion left enough debris that later fell back onto the white dwarf star, causing a second explosion.
Astronomers are now pointing their most powerful telescopes at the remnant of SN 1181 to unravel its mysteries. They include the Subaru Telescope in Hawaii and the Very Large Array radio observatory in New Mexico. They can provide the necessary data to understand what reignited this star and unravel its mystery.
Earlier we reported on how a supernova made it possible to determine the distance to a distant galaxy.
According to techspot.com
