Astrophysicists have proposed supernova classes known as electron-capture for 40 years, but have not been able to prove their existence. But now, astronomers from 25 institutes have come together to provide evidence of such a phenomenon in natural astronomy. Moreover, their work makes the case that one of the most famous supernovae of all time belongs to this category. There are two main types of supernovae known: giant stars that go through a major collapse when the external forces of their fusion can no longer overcome gravity and the white dwarf pulls enough to create thermonuclear explosions in their neighbors. There are definite and proposed subclasses between the two, but the electronic-capture supernovas will be an original third class.
The core-broken supernova must be at least 10 times the mass of the Sun, which creates the pressure to mimic the iron that comes to form their cores. The theory behind electron-capture supernovae is that they involve 8-10 solar masses, which have oxygen-neon-magnesium cores and never produce their own iron. If the pressure at the center of these stars is so great that the electrons around these atoms get trapped in the neon and magnesium nuclei and the space between the atoms shrinks, the theory goes that instead of becoming a white dwarf as a light star, the core began to explode violently and the explosion will start again.
After Kenny Chi Nomoto, a professor at the University of Tokyo, proposed the concept in 1980, astronomers tried to model how an electronic-capture supernova would look and in particular how it would differ from the known type. Daiichi Hiramatsu, a graduate student at the University of California, Santa Barbara, identified six distinctive features of the electronic-capture supernova anticipated with the creation of large quantities of explosive emitters and chemical structures and components prior to the explosion.
Hundreds of recorded supernova Hiramatsu have a few of these features after checking a few records, but one that ticks all the boxes; SN 2018zd. “We started by asking, ‘Is this weird?’ Hiramatsu said in a statement. “We then examined every aspect of the SN 2018zd to see if they could all be explained in the electron-capture view.”
