metallicitet

Metallicitet is a term used in astronomy to describe the abundance of chemical elements heavier than hydrogen and helium in a celestial object. These heavier elements are often referred to as "metals" by astronomers, regardless of their actual chemical properties. The universe's initial composition after the Big Bang consisted almost exclusively of hydrogen and helium, with trace amounts of lithium. The heavier elements, such as carbon, oxygen, iron, and silicon, were forged in the cores of stars through nuclear fusion and dispersed into the interstellar medium through stellar winds and supernova explosions.

Therefore, metallicitet is a measure of how enriched a star, galaxy, or gas cloud is with these elements produced by previous generations of stars. Younger stars and galaxies, formed from more recently processed gas, tend to have higher metallicitet compared to older, more primitive objects. Astronomers measure metallicitet by analyzing the spectral lines of light emitted or absorbed by celestial objects. The presence and intensity of spectral lines corresponding to heavier elements provide quantitative information about their abundance. Metallicitet is a crucial parameter for understanding stellar evolution, galaxy formation, and the chemical history of the universe. It influences properties like stellar mass, temperature, and lifespan.