What is Stellar Evolution?

Overview

The process of stellar evolution begins when a cloud of gas and dust in space collapses under its own gravity, forming a new star. As the star forms, it enters a phase called the main sequence, where it spends most of its life fusing hydrogen into helium in its core. This stage can last billions of years, depending on the star's mass, and is crucial for the stability and energy output of the star. As the hydrogen in the core gets depleted, the star undergoes significant changes. For larger stars, this leads to expansion into a red giant, where helium fusion begins, and eventually results in a supernova explosion. In contrast, smaller stars like our Sun will shed their outer layers to form a planetary nebula, leaving behind a dense core known as a white dwarf. Understanding stellar evolution is important because it explains how elements are created and distributed in the universe. For example, the heavy elements found on Earth were formed in the interiors of massive stars and spread through space when these stars died. This cycle of birth, life, and death of stars is fundamental to the structure and evolution of galaxies in the universe.