Core Collapse Supernova
Stars have different masses, colors brightness, and lifespan. Our star the sun is a small type of star called the yellow dwarf. The sun has a massive amount of energy nearly 3.8×10^26 watts. Only 2 billion of the sunlights lits up half of the earth. We will need 20 billion of the largest nuclear weapons and 10000 asteroid impacts (chicxulub) to fully outshine the sun. Still, some stars are millions of time brighter that does not fuse only hydrogen and helium but also carbon, neon, oxygen, silicon, iron. stars over 25 solar masses explode in a gigantic explosion called a supernova.
After stars become old they will go through all types of cores from hydrogen to helium to carbon to neon to oxygen to silicon to iron. After that iron cannot fuse to a heavier element so fusion stops gravity wins against fusion that makes the stars to collapses. The core collapses from 5000 km to 20 km causing a sudden increase in density that moves the particles 5 times closer than atomic nuclei.
Electrons and protons collide forming neutrons according to Newtons’ 2nd law of physics. The neutrons and protons push against gravity. Causing the core to increase to 50 km and a shock wave travels through the immense pressure that breaks the neutron into protons and electrons and antineutrinos.
Then the gravity pushes back again causing electrons and protons to collide and make a positron and a neutrino.
In such a way the temperature inside increases to 100 to 500 billion degrees. And if the stars are massively more than 100 solar masses and are more than 5 million solar brightness then the core will be 67 trillion degrees temperature.
After that, the neutrinos will break the atoms apart and the star will explode into a supernova. A supernova releases more energy in a second than the sun in 10 billion years before the supernova if gravity wins then the remnant will be a black hole. If the sub-atomic particles then the remnant will be a neutron star.