Stellar evolution refers to the sequence of changes or transformations that a star undergoes over the course of its lifetime. It is a fundamental concept in astrophysics and describes the various stages and processes through which stars evolve from their formation to their eventual demise.
In the early stages of stellar evolution, stars are born from vast clouds of gas and dust called nebulae. These clouds eventually collapse under their own gravity, giving rise to protostars. As the protostars continue to contract, they heat up and eventually reach a point where nuclear fusion ignites in their cores. This marks the onset of the star's main sequence phase, where it will spend the majority of its life.
Throughout this main sequence phase, stars generate energy by fusing hydrogen atoms into helium in their cores, producing vast amounts of heat and light. The duration of this phase depends on the star's mass, with more massive stars burning through their fuel more rapidly.
After exhausting their hydrogen fuel, stars undergo various subsequent evolutionary phases, such as expanding into red giants or supergiants, depending on their mass. These giants release outer layers of gas into space, often forming planetary nebulae, leaving behind a dense core known as a white dwarf.
For stars considerably more massive than our Sun, the final stages of stellar evolution can lead to explosive events like supernovae, neutron star or black hole formation. The remnants of these powerful stellar explosions scatter enriched materials back into space, contributing to the formation of new stars and solar systems.
The study of stellar evolution enables scientists to understand the life cycles of stars, their chemical compositions, and their contributions to the overall structure and evolution of the universe.
