What is stellar evolution?

Stellar evolution refers to the comprehensive process a star undergoes throughout its lifetime, including its formation, main sequence phase, and eventual death. This journey starts from a molecular cloud, where gravity causes gas and dust to condense into a protostar. Once the conditions are right, nuclear fusion begins, allowing the star to shine and evolve through various stages depending on its initial mass.

As the star ages, it will pass through different phases such as the main sequence, where it spends the majority of its life fusing hydrogen into helium, then often expands into a red giant or supergiant, and ultimately ends its life cycle as a white dwarf, neutron star, or black hole. Each of these stages involves significant changes in the star's structure, temperature, brightness, and chemical composition. Understanding stellar evolution is fundamental in astrophysics as it explains the lifecycle of stars and their contributions to the universe, including the formation of heavier elements that are crucial for planet formation and the development of life.