Stability of Stars

A star is formed when a cloud of gas and dust (a nebula), collapses under its own gravitational pull. This causes the density and temperature at the core to increase, initiating nuclear fusion.
Stars are held in equilibrium by two opposing forces: the inward pull of gravity and the outward push of radiation pressure from nuclear fusion.
The life cycle of a star is determined by its mass. Larger stars have shorter life spans because they burn through their fuel more quickly.
As a star exhausts its hydrogen fuel, it begins to fuse helium and other heavier elements at its core. Each stage of fusion releases less energy, increasing the star’s size and causing it to cool and become a red giant.
If a star is sufficiently large, the supernova explosion that occurs at the end of its life will be forceful enough to create a neutron star or a black hole. Smaller stars end their lives as white dwarfs.
Black holes are regions of space where gravity is so strong that nothing, not even light, can escape. They are detected via their strong gravitational effects on surrounding objects.
Neutron stars are the remnants of supernova explosions. They are incredibly dense - one teaspoon of neutron star material would weigh about a billion tonnes on Earth.
White dwarfs are the remnants of less massive stars. They are incredibly hot but very faint because of their small size.
A binary star system is made up of two stars orbiting a common centre of mass. If a white dwarf is in a binary system with a more massive star, it can pull matter from its companion, resulting in a supernova.
The process of star death recycles star material back into the universe where it may form new stars and planets, a concept known as the Stellar Life Cycle.