A thermonuclear supernova is the explosion of a white dwarf star after it has gained mass from another star in a binary galaxy, a binary star. These white dwarfs are the dense cores of ash left after a bright star – a star about 8 times the mass of the Sun – reached the end of its life.
A supernova explosion in an iron core occurs when a massive star — whose mass is more than 10 times the mass of the Sun — runs out of nuclear fuel and its iron core collapses, resulting in a black hole or neutron star.
Between these two main types of supernovae – there are still many subdivisions – there are electron-capturing supernovae. These stars stop fusion reactions if their cores are made of oxygen, neon, and magnesium – they’re not heavy enough to make iron.
Gravity is constantly trying to squeeze a star, and what prevents most stars from collapsing is either fusion in the core caused by an opposing force, or, in cores where fusion has stopped, the atoms in the core cannot be brought together close to each other. .
In an electron-capturing supernova, some of the electrons in the oxygen, neon, and magnesium nuclei of their atomic nuclei are hit in a process called electron capture. This removal of electrons causes the star’s core to collapse under its own weight, capturing the supernova’s electron.
If the star was a little more massive, it’s possible that the elements in its core have fused into heavier elements, extending its life. So it’s kind of in reverse mode: the star isn’t light enough to escape the collapse of its core and isn’t heavy enough to extend its life and subsequently die in a different way.
This is the theory that has been formulated since 1980 by Kenichi Nomoto of the University of Tokyo and other scientists. Over the years, theorists have made predictions about what to look for when searching for electron-trapping supernovae and their precursors, giant super-closed sub-stars.
The stars must have had a lot of mass, much of it was lost before the explosion, and that mass near the dying star must have an unusual chemical composition. Then, the electron-capturing supernova should have a weak explosion, give little radioactive precipitation, and have neutron-rich elements in its core, as electrons are squeezed into atomic nuclei and many protons turned into neutrons.