- Astronomers have solved a 900-year-old mystery about the origin of a supernova
- It was first observed over China in 1181, visible for six months and as bright as Saturn
- A faint, rapidly expanding nebula named Pa30 has now been identified as the source of the explosion
- Experts say Pa30 is compatible with the profile, location and age of a 12th-century supernova
The 900-year-old cosmic mystery surrounding the origin of the 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 a 12th-century explosion, which Chinese and Japanese astronomers described as bright as Saturn and remained visible for six months.
Experts said Pa30, which surrounds Parker’s star – one of the hottest stars in the Milky Way – is compatible with the profile, location and age of the historic supernova.
Astronomers have solved a 900-year-old mystery about the origin of the first supernova observed over China in 1181. A faint nebula named Pa30 (depicted in three separate images with colors showing X-ray emission) has been identified as a 12th-century eruption. Source
How does a nebula form?
Planetary nebulae are formed when a star larger than our Sun begins to die and releases a solar wind of gas.
As it grows the wind becomes more violent and collides with the pieces of the older star, creating strange shapes.
Later, the outer layers of the star are blown off and the hot core of the star is exposed, illuminating the surrounding gas and causing the eerie glow.
The nebula is visible to Earth only once it begins to glow.
Factors such as how the star rotates, at what angle it is viewed and the chemical composition of the gas affect the size of the nebula.
There have been only five bright supernovae in the Milky Way over the past millennium, including the famous Crab Nebula, but all but the origin of the ‘Chinese guest star’ is well known.
Despite 12th-century astronomers recording an approximate location in the sky of 1181 sightings, no confirmed remnants of the eruption had yet been identified.
The discovery was made by a team of international astronomers from Hong Kong, Britain, Spain, Hungary and France.
In a new research paper, they found that the Pa30 nebula is expanding at a peak velocity of more than 1,100 km per second (at this speed, it would take only five minutes to travel from Earth to the Moon).
He used this velocity to derive an age of about 1,000 years, which would coincide with the events of 1181.
Professor Albert Zijlstra of the University of Manchester was one of the astronomers involved in the research.
He said: ‘Historical reports place the guest star between the two Chinese constellations, Chuanshe and Huagai.
‘Parker’s star fits in well. This means that both the age and the location fit with the events of 1181.’
It was previously suggested that Pa30 and Parker’s star formed as a result of the merger of two white dwarfs.
A white dwarf is what Sun-like stars become at the end of their lives when they have used up all their nuclear fuel.
Such merger events of white dwarfs are believed to lead to a rare and relatively faint type of supernova, known as a ‘Type IX supernova’.
Professor Zijlstra said: ‘Only about 10 percent of supernovae are of this type and are not well understood.
Professor Albert Zijlstra of the University of Manchester said that all research indicates that Parker’s star and Pa30 are equivalent to the 1181 supernova (pictured on a star chart).
Images of the nebula were obtained by the Kitt Peak National Observatory Telescope (shown)
‘The fact that SN 1181 was faint but faded very slowly, thus fits.
‘This is the only event where we can study both the remaining nebula and the merged star, and get the details of the explosion.’
The merger of leftover stars, white dwarfs and neutron stars, gives rise to extreme nuclear reactions and forms heavy, highly neutron-rich elements such as gold and platinum.
Professor Zijlstra added: ‘Combining all this information such as age, location, brightness of the event and the historically recorded 185-day period, it shows that Parker’s star and Pa30 are equivalent to SN 1181.
‘This is the only type Iax supernova where detailed study of remnant stars and nebulae is possible.
‘It’s nice to be able to solve both historical and astronomical mysteries.’
research has been published in The Astrophysical Journal Letters.
A supernova occurs when a giant star explodes
A supernova occurs when a star explodes, dropping debris and particles into space.
A supernova only burns for a short time, but it can tell scientists a lot about the beginning of the universe.
A one-of-a-kind supernova has shown scientists that we live in an expanding universe, which is expanding at an ever-increasing rate.
Scientists have also determined that supernovae play an important role in distributing elements throughout the universe.
In 1987, astronomers observed a ‘Titanic supernova’ in a nearby galaxy, blazing with the power of more than 100 million suns (pictured)
There are two known types of supernovae.
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 a single star’s lifetime.
As the star runs out of nuclear fuel, some of its mass flows into its core.
Eventually, the core is so heavy that it cannot stand the force of its own gravity and the core collapses, resulting in another massive explosion.
Many of the elements found on Earth are formed in the core of stars and these elements travel to form new stars, planets and everything else in the universe.