huvudsekvensens

Huvudsekvensen, in astronomy, refers to the longest and most stable stage of a star's life. During this phase, stars fuse hydrogen into helium in their cores, releasing vast amounts of energy. Our Sun is currently a main-sequence star. The position of a star on the main sequence is determined by its mass. More massive stars are hotter, brighter, and bluer, while less massive stars are cooler, dimmer, and redder. The duration of a star's main-sequence lifetime is also dependent on its mass; massive stars burn through their fuel much faster and have shorter main-sequence lifetimes than low-mass stars. The study of the main sequence is fundamental to understanding stellar evolution, as it provides a baseline for comparing stars of different ages and masses. Stars leave the main sequence when they exhaust the hydrogen fuel in their cores, initiating further evolutionary stages such as becoming red giants or white dwarfs. The Hertzsprung-Russell diagram is a key tool used by astronomers to visualize and study the main sequence, plotting stellar luminosity against surface temperature.