A 900-year-old cosmic mystery surrounding the origins of a famous supernova first spotted over China in 1181AD finally been solved, consistent with an international team of astronomers.
New research published on September 15, 2021 says that a faint, fast expanding cloud (or nebula) called Pa30, surrounding one among the hottest stars in Milky Way galaxy, known as Parker’s Star, fits the profile, location & age of the historic supernova.
There have only been 5 bright supernovae in Milky Way in the last millennium (starting in 1006). Of these, Chinese supernova, which is also known as ‘Chinese Guest Star’ of 1181AD has remained a mystery.
It had been originally seen & documented by Chinese & Japanese astronomers in the 12th century who said it had been as bright as the planet Saturn & remained visible for 6 months.
They also recorded an approximate location in the sky of sighting, but no confirmed remnant of the explosion has even been identified by modern astronomers. The other 4 supernovae are all now well-known to modern-day science and include the famous Crab Nebula.
The source of this 12th century explosion remained a mystery, until this latest discovery made by a team of international astronomers from Hong Kong, United Kingdom, Spain, Hungary & France, including Professor Albert Zijlstra from The University of Manchester. In new paper, astronomers found that Pa 30 nebula is expanding at an extreme velocity of more than 1,100 km per second (at this speed, traveling from the Earth to Moon would take only 5 minutes). They use this velocity to derive an age at nearly 1,000 years, which might coincide with the events of 1181AD.
Prof Zijlstra (Professor in Astrophysics at University of Manchester) explains: “The historical reports place the guest star between 2 Chinese constellations, Chuanshe & Huagai. Parker’s Star fits the position well. That means both the age & location fit with the events of 1181.”
Pa 30 & Parker’s Star have previously been proposed as the results of a merger of 2 White Dwarfs. Such events are thought to lead to a rare & comparatively faint kind of supernova called a ‘Type Iax supernova’.
Prof Zijlstra added: “Only around 10 percent of supernovae are of this type and that they aren’t well understood. The fact that SN1181 was faint but faded very slowly fits this kind. It’s the only such event where we can study both the remnant nebula & the merged star and even have a description of the explosion itself.”
The merging of remnant stars, white dwarfs & neutron stars, give rise to extreme nuclear reactions & form heavy, highly neutron-rich elements like gold & platinum. Prof. Zijlstra said: “Combining all this information like the age, location, event brightness and historically recorded 185-day duration, indicates that Parker’s star & Pa30 are the counterparts of SN 1181. This is the sole Type Iax supernova where detailed studies of the remnant star & nebula are possible. it’s nice to be able to solve both a historical & an astronomical mystery.”
The findings originally published on The Astrophysical Journal.