Cosmic mystery SOLVED after 900 years: Supernova first observed over China in 1181 is identified as Pa30 – a nebula surrounding one of the hottest stars in the Milky Way
- Astronomers have solved 900-year-old mystery about the origin of a supernova
- It was first seen over China in 1181, visible for six months and as bright as Saturn
- A faint, rapidly expanding nebula called Pa30 now identified as an explosion source
- Experts said Pa30 fits the profile, location and age of the 12th-century supernova
A 900-year-old cosmic mystery surrounding the origin of a supernova first observed over China in 1181 has finally been solved.
A faint, rapidly expanding nebula called Pa30 has been identified as the source of the 12th-century explosion, which, according to Chinese and Japanese astronomers, was as bright as the planet Saturn and remained visible for six months.
Experts said Pa30, which surrounds Parker’s star — one of the hottest stars in the Milky Way — fits the profile, location and age of the historic supernova.
Astronomers have solved a 900-year-old mystery surrounding the origin of a supernova first observed over China in 1181. A faint nebula called Pa30 (depicted in three different images with colors showing X-rays) has been identified as the 12th century explosion source
HOW IS A MIST FORMED?
Planetary nebulae are formed when a star larger than our sun begins to die and release a solar wind of gas.
As he ages, the wind becomes more violent and collides with fragments of an ancient star, creating strange shapes.
Later, the star’s outer layers are blown off, exposing the star’s hot core, illuminating the surrounding gas and causing the eerie glow.
Only when the glow starts is the nebula visible to Earth.
Factors such as how the star rotates, what angle it is viewed from, and the chemical makeup of the gas affect the shape of the nebula.
There have been only five bright supernovae in the Milky Way in the past millennium, including the famous Crab Nebula, but the origin of all supernovae except the “Chinese Guest Star” is known.
Despite 12th-century astronomers recording an approximate sky location from the 1181 sighting, no confirmed remnant of the explosion had been identified until now.
The discovery was made by a team of international astronomers from Hong Kong, the UK, Spain, Hungary and France.
In a new research paper, they found that the Pa30 nebula is expanding at an extreme speed of more than 1,100 km per second (at this speed, traveling from Earth to the moon would take just five minutes).
They used this rate to derive an age of about 1000 years, which would coincide with the events of 1181.
Professor Albert Zijlstra, from the University of Manchester, was one of the astronomers involved in the study.
He said: ‘The historical reports place the host star between two Chinese constellations, Chuanshe and Huagai.
“Parker’s Star fits the position well. That means that both the age and the location fit the events of 1181.”
It has previously been suggested that Pa30 and Parker’s Star formed as a result of the merger of two white dwarfs.
A white dwarf is what stars like the sun become at the end of their lives when they have used up all their nuclear fuel.
Such mergers of white dwarfs are thought to lead to a rare and relatively faint type of supernova called a “Type Iax supernova.”
Professor Zijlstra said: ‘Only about 10 percent of supernovae are of this type and they are not well understood.
Professor Albert Zijlstra, from the University of Manchester, said all research indicated that Parker’s star and Pa30 are the counterparts of the 1181 supernova (depicted on a star map)
Images of the nebula were obtained by the Kitt Peak National Observatory telescope (shown)
‘The fact that SN1181 was faint but faded very slowly suits this type.
“It’s the only event where we can study both the remnant nebula and the merged star, and also have a description of the explosion itself.”
The merging of remnant stars, white dwarfs and neutron stars, cause extreme nuclear reactions and form heavy, very neutron-rich elements such as gold and platinum.
Professor Zijlstra added: ‘Combining all this information, such as the age, location, event brightness and historically recorded duration of 185 days, indicates that Parker’s star and Pa30 are the counterparts of SN 1181.
“This is the only Type Iax supernova that allows detailed studies of the remaining star and nebula.
“It’s nice to be able to solve both a historical and an astronomical mystery.”
The research is published in the The astrophysical journal letters.
SUPERNOVAE RISES WHEN A GIANT STAR EXPLODES
A supernova occurs when a star explodes and blasts debris and particles into space.
A supernova only burns for a short time, but can tell scientists a lot about how the universe came to be.
One type of supernova has shown scientists that we live in an expanding universe, one that is growing faster and faster.
Scientists have also determined that supernovae play a key role in the distribution of elements throughout the universe.
In 1987, astronomers spotted a ‘titanic supernova’ in a nearby galaxy that sparkled with the power of more than 100 million suns (pictured)
Two types of supernovae are known.
The first type occurs in binary star systems when one of the two stars, a carbon-oxygen white dwarf, steals matter from its companion star.
Eventually, the white dwarf accumulates too much matter, causing the star to explode, resulting in a supernova.
The second type of supernova occurs at the end of the life of a single star.
When the core of the star runs out, some of its mass flows to the core.
Eventually, the core is so heavy that it can’t bear its own gravity and the core collapses, resulting in another giant explosion.
Many elements found on Earth are created in the cores of stars, and these elements travel onward to form new stars, planets, and everything else in the universe.