The explosion that lit the skies for 23 days and nights in AD 1054 may have been the explosion of a rare type of supernova, a new study suggests.
On July 4, 1054 – about 700 years before America set off the first fireworks display, a mysterious light exploded in the sky. The explosion was visible around the world, lingered in the daytime sky for almost a month and was visible at night for almost two years, according to NASA.
At the time, Chinese astronomers referred to the mysterious explosion as a “guest star” – a temporary celestial body that seemed to appear out of nowhere, then disappear into nothingness. Yet modern space telescopes like NASA’s Hubble reveal that Earth’s strange “guest” is here (albeit 6,500 light years away).
What remains of that ancient eruption is known today as the Crab Nebula – a massive, rapidly expanding balloon of irradiated gas with a powerful pulsating neutron star at its center. Nebulae like these are the smoldering remnants of once powerful stars that have lost most of their mass in massive supernova explosions.
The Crab, the third supernova
“The Crab supernova is believed to be an electron capture supernova, but because it occurred a thousand years ago, little data is available on the progenitor star and the explosion itself.” said lead study author Daichi Hiramatsu, a researcher. graduate student at the University. of California, Santa Barbara (UCSB), said.
When a star explodes, it usually goes out in one of two ways: a thermonuclear supernova or an iron core collapse supernova.
In between, electron-capturing supernovae, born from stars 8 to 10 times the mass of the Sun – neither too heavy nor too light. Since the 1980s, astronomers have calculated that stars in this transitional mass range could fall victim to a strange pattern of death, where an overwhelming gravitational force crushes the star’s core, causing electrons to collide with them. nucleus in their atomic nuclei, causing the nucleus to collapse.
For a progenitor star that would initially be quite massive, but would lose a lot of mass before the explosion begins, filling the space around it with a jet of gas. When the star’s core finally explodes, it creates a relatively weak, slow explosion that interacts with nearby gas, making it brighter than expected.
Scientists have never found a star that fully meets these criteria – until March 2018, when a star 31 million light years from Earth ceased to exist.
In their new study, the researchers analyzed the star using data from the Hubble and Spitzer space telescopes to match the rest of the supernova (SN 2018zd) with its progenitor star. They discovered that the star and the explosion met all the criteria for the legendary electron-capture supernova.
This research offers scientists a new way to examine the remains of dead stars.