It radiates heat and light, and every other part of the electromagnetic spectrum, such as radio waves, micro-waves, X-rays, gamma-rays and ultra-violet radiation. The proportions vary according to the mass and age of the star.
The energy of stars comes from nuclear fusion. This is a process that turns a light Ikhemikali into another heavier element. Stars are mostly made of hydrogen and helium. They turn the hydrogen into helium by fusion. When a star is near the end of its life, it begins to change the helium into other heavier chemical elements, like I-carbon and I-oxygen. Fusion produces a lot of energy. The energy makes the star very hot. The energy produced by stars radiates away from them. The energy leaves as electromagnetic radiation.
Birth of a star[tshintsha | Yenza izilungiso kokubhaliweyo]
A star begins as a collapsing cloud of material made mostly of hydrogen, with helium and tiny amounts of heavier elements. Once the stellar core is dense enough, some of the hydrogen is changed into helium through nuclear fusion. The energy moves away from the core by a combination of radiation and convection. The star's radiation stops it from collapsing further under its own gravity. Once the hydrogen fuel at the core has been used up, those stars with at least 0.4 times the mass of the Sun expand to become a red giant.
Imithombo[tshintsha | Yenza izilungiso kokubhaliweyo]
- Bahcall, John N. 2000. "How the Sun shines". Nobel Foundation. http://nobelprize.org/nobel_prizes/physics/articles/fusion/index.html. Retrieved 2006-08-30.