Emily Chan
In 1181 AD, during the Genpei War, a mysterious star appeared in Asia’s skies for a brief time before disappearing again. For 843 years, the cosmic event was a source of confusion for astronomers.
No one knew what it really was or why it had shown up. But in 2021, researchers managed to track down its location. Still, the cause of the event is unclear.
A team of scientists used computer modeling techniques and observational analysis to reconstruct the event, now called supernova (SN) 1181.
They discovered that it was a supernova triggered by two white dwarfs colliding with each other in a rare occurrence.
The structure of the remnant white dwarf and the impact of the collision were left behind. Then, 20 to 30 years ago, high-speed stellar winds started blowing from the surface of the remnant white dwarf. This discovery could help astronomers gain a better understanding of supernova varieties.
“There are many accounts of this temporary guest star in historical records from Japan, China, and Korea. At its peak, the star’s brightness was comparable to that of Saturn,” said Takatoshi Ko, the lead author of the study from the Department of Astronomy at the University of Tokyo.
For about 180 days, the star remained visible until it gradually dimmed and could no longer be detected by the human eye.
Because of how old the remnant of the SN 1181 explosion is now, it is very dark, which made it hard to find.
White dwarfs are small, dense stars that are created when stars with masses similar to the sun’s die by exhausting all their nuclear fuel.
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