4 The lifecycles of stars

The Hertzsprung-Russell diagram has so far allowed us to classify the stars according to temperature and luminosity, and has also shown a pattern in the masses of stars, with more massive stars being hotter and more luminous, and smaller stars being relatively cooler and less luminous.

The diagram is also helpful in understanding the lifecycles and evolution of stars. You will start by taking a closer look at the main sequence, which is the central diagonal band running the length of the diagram, and is the part of the diagram occupied by stars in the main, stable part of their lifetime.