Existing stellar evolution theory models believe that massive stars in the universe will occur at the end of the main sequence star stage, at this moment the star will release energy equivalent to the sun's tens of billions of years of nuclear fusion energy, a large amount of material in the star is instantly thrown out, as if fireworks were set off in the universe, astronomers have long discovered the remnants of supernova explosions in the universe, and have observed supernova explosions from the Magellan Nebula SN1987A blue supergiant. But a real-time spectacle of red supergiant supernova explosions has not been detected, but in the summer of 2020, the scene came.
On January 8, 2022, southern metropolis daily and other media said that an astronomical research team composed of Northwestern University and the University of California, Berkeley said that they had observed the collapse of a red supergiant into a type II supernova after a supernova explosion for the first time in the summer of 2020, from which they intuitively understood the characteristics of the red supergiant supernova explosion.
Red supergiants are main sequence stars with a mass of at least 4 times more than the Sun in their later years, and the stars will expand very largely at this time, because when a star with a mass higher than 4 times the mass of the Sun re-initiates hydrogen fusion outside the helium nucleus, the energy released outside the nucleus does not increase significantly, but the radius increases many times, becoming a red supergiant, such as Betelgeuse on the constellation Orion is a red supergiant, its mass is about 11.6 times that of the Sun, but its volume is about 500 million times that of the Sun.
The red supergiant that the researchers found is located in the NGC 5731 galaxy, about 120 million light-years away from us, at the beginning it did not show strong signs of explosion, but the star looks a little "throbbing", and there is a strong radiation revealed, but suddenly it is bright, the researchers carefully observed the stellar changes in the next 130 days, its process is very active, its explosion type is classified as a type II supernova event, The incident was also labeled SN2020tlf.
The event was observed by the Deep Imaging and Multi-Object Spectrometer of the Keck Observatory in Hawaii and the Near-Infrared Echelet Spectrometer, with a luminosity of hundreds of millions of times that of the Sun, like a large firework blooming in the universe. Magdey, an astronomy professor at Northwestern University, said: "We have never confirmed such intense activity in a red supergiant star, which is really not the usual spectacular!" We saw it produce such bright radiation, then collapse and burn until now. ”
Lead author Wayne said: "This event provides a breakthrough in the understanding of massive stars before they die, helping us to directly detect the prenovae activity of red superstars, which have never been observed in an ordinary type II supernova before, and this is the first time we have seen an explosion of a red supergiant." “
Type II supernova, also known as nuclear collapse supernova, is the result of a violent explosion caused by internal collapse of massive stars, only red supergiants with a mass of more than 9 times the sun will appear such a phenomenon, some experts believe that observing such events will greatly affect how we define the last months of star evolution, solving some mysteries about how massive stars spend the last moments of their lives.
Resources:
Southern Metropolis Daily January 8, 2022 article "Scientists for the first time witnessed the rapid collapse of a massive star and exploded into a supernova in real time"