The life cycle of a star begins in a nebula and ends in a black hole. The lifespan of a star depends on its mass. The more massive it is, the shorter it lives. This ‘long’ and ‘short’ however, is in millions and billions of years! Now you know how long the life cycle of a star is!
Stars are born, stars grow old, stars die. The life cycle of a star is actually its ‘struggle to live’ fighting the gravitational pull and internal pressure. A majority of the life of a star is spent in the main sequence stage. Most stars, specifically our Sun, fuse hydrogen into helium and helium into heavier elements like carbon, oxygen up to even iron and nickel. Stars exhaust their energy during this process.
Stars go through a series of changes during their lifespan. The process is known as stellar evolution, during which they change in their structure, composition, and appearance. Very massive stars live for a few million years, while those with lesser mass live for trillions of years.
It won’t be wrong to say that a star is a sizzling mass of gas. It is composed of the inner core where the process of fusion takes place and an outer gaseous shell.
The core is hot and dense, acting as the gravitational center of a star. The outer shell, made of hydrogen and helium, facilitates the transfer of heat from the core of the star to its surface. Light and heat energy is released into space from the surface of the star. Here’s more on the stages in the life cycle of a star.