How are supernovas formed?

Answer 1

To understand a supernova, understand that a star, like our sun, will continue to burn fuel, such as hydrogen into helium for our sun. This process is a constant fight between the outwards pressure of the nuclear fusion and the inwards pressure of the gravity of the mass of the sun.

As long as the sun has enough energy (e.g. fuel) to burn in order to balance the inwards pressure, the sun can exists.

however, when the (hydrogen) fuel runs low, the inwards pressure of the strong gravity may overtake the outwards pressure of the nuclear reaction creating an implosion or collapse of the star.

In larger stars, this collapse can squeeze the molecules so tight that the star explodes in a supernova.

This typically happens when a significant portion of the core is burned into lead which creates very dramatic gravitational pull due to the increased mass together with a relatively low supply of hydrogen.

Answer 2

Supernovas are formed in two main ways. First, in a binary star system, when one star becomes a white dwarf and accretes matter from its companion, it can reach a critical mass and undergo a thermonuclear explosion, creating a Type Ia supernova. Second, in a massive star, once nuclear fusion in its core stops, the core collapses under gravity and then rebounds, resulting in a massive explosion and the formation of a Type II supernova.