900 years after its first description, this supernova has just been found

A team of astronomers was able to observe the remains of a supernova described in Chinese and Japanese texts from the 12th century.

Solving a cold case, by uncovering a rare astronomical phenomenon: this is the nice double coup achieved by an international team of astronomers led by Andreas Ritter and Quentin Parker, from the University of Hong Kong. The enigma was located in the constellation of Cassiopeia, under the name SN 1181, a supernova described in Chinese and Japanese texts between 1181 and 1182. For six months, SN 1181 shone as brightly as the planet Saturn, before disappearing. Observers were actually witnessing the destruction of a massive star at the end of its life, one of the most energetic events in the universe. But no trace of the tremendous explosion had been spotted again until now. However, a supernova leaves a remnant: a nebula of gas that is a remnant of the star. Those of the supernovae of 1006, 1054, 1572 and 1604 have all been found. It is now done with SN 1181.

A discovery that opens another track

It is the discovery in 2013 of Pa30, a nebula in full expansion located in the vicinity of SN 1181, which puts astronomers on the track. But they also had to verify that its formation was contemporary with the supernova. This they did by studying the dynamics of the nebula, whose results have just been published in The Astrophysical Journal Let-ters . Our data show that the gas is expanding at a very high speed: 1100 km/s," says Quentin Parker. This corresponds to an explosion that took place about 1000 years ago, which is consistent with the supernova SN 1181.

Even better: the nebula leads astronomers to the still hot corpse of the supernova: 200,000 °C, a record! It is a Wolf-Rayet type star, which is in the heart of Pa30.

A supernova of type Iax

It is in the center of the Pa 30 nebula (above, seen in false colors) that was found the corpse of the explosion of a star (opening of the article, artist's view) observed in the twelfth century.

In 2019, a publication had hypothesized that the star and the nebula would be from the collision of two white dwarfs, themselves corpses of stars. This cataclysm constitutes a supernova of type Iax, rare. Is this the case for SN 1181? "Taken together, the age, the location, the luminosity described at the time and the duration of six months show that the star and the nebula Pa30 are the consequences of SN1181," says Andreas Ritter. Astronomers thus have the possibility to study a supernova of type Iax, thanks to a collaboration carried out nine centuries apart!

source : ( https://www.sciencesetavenir.fr/espace/astrophysique/900-ans-apres-sa-premiere-description-cette-supernova-vient-d-etre-retrouvee_158592 )