Why don’t all stars eventually turn into black holes?
It’s all to do with mass. During its life, a star exists in a balance between the force of gravity, which pulls its material towards its centre, and the outward pressure that material exerts when compressed. Towards the end of a star’s life, the balance between these two forces shifts in favour of gravity. This often happens because the star runs out of nuclear fuel, resulting in less outward radiation pressure and less gas pressure.
However, as gravity becomes more important, it compresses the material at the centre, heating it and increasing the outward pressure once more. In more massive stars, gravity ultimately wins and compresses the star until it is as dense as physically possible, resulting in a black hole. On the other hand, less massive stars have weaker gravitational pulls, and in the end a new balance is struck which allows these stars to support themselves against gravity indefinitely as a dead ball of nuclear ash. Occasionally, something even more unusual happens. For stars in a certain mass range, no new balance is struck, but no black hole is formed. In these cases, the star explodes entirely, scattering its matter in all directions and
leaving absolutely nothing ‘stellar’ behind.