One of the most important things we know about stars is that their lifespans end one day. Every star has a lifetime, and when that time expires, one of the most violent explosions in space occurs; supernova. Supernovas are when stars explode violently, and these explosions release energy on a massive scale. The resulting energy causes a bright light to form in space.
The amount of mass that stars have gives information about how they will die. There were two types of supernovae known so far in this regard. The first is a core collapse supernova, which occurs when a star more than 10 times the mass of the Sun runs out of fuel and its core collapses into a black hole or neutron star.
The other is a supernova that happens in binary star systems, when one of the two stars is a white dwarf with a mass of up to 8 times the mass of the Sun. In such supernovas, the white dwarf constantly steals matter from the other star and eventually explodes.
We are now certain that a third type exists: the electron capture supernova.
A new study published in Nature Astronomy on June 28, 2021 confirms important information by revealing the first example of a type of supernova predicted 40 years ago. In 1980, Ken’ichi Nomoto of the University of Tokyo conducted studies in which he pointed to a third type of supernova, called electron capture supernova. Three years of research on a supernova observed in March 2018 confirmed Nomoto’s prediction.
Supernova 2018zd began to be studied in detail after the first observations in March 2018. Archival images from the Hubble Space Telescope and Spitzer Space Telescope have revealed a faint object likely to be a star before the explosion. The supernova is located about 31 million light-years away in galaxy NGC2146 and is a relatively close supernova to our Earth.
In addition to the data sets created with the data obtained from the telescopes, the researches made in the past years about the electron capture supernova also played an important role in this study. The researchers found that all of the features likely to be found in a possible electron capture supernova are found in the newly observed Supernova 2018zd.
The study also solved a millennial mystery:
As the calendars showed the year 1054, a supernova occurred in the Milky Way. According to Chinese records, this supernova was so bright that it remained visible for 23 days during the day and about two years at night. The resulting remnant was the Crab Nebula.
The Crab Nebula was one of the strongest candidates for an electron capture supernova in years, but uncertainties in the studies prevented it from being considered a definitive conclusion. The new result confirms that the event that created the Crab Nebula was an electron capture supernova.
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