Classes of Stars 2

Classes of Stars 2

Stars are broadly classed into the spectral types O, A, B, F, G, K, and M. This classification was done before astronomers realized that the spectral type, or composition, is directly related to the temperature and size of a star. We now know that O-type stars are the biggest, hottest stars, while M-type stars are the smallest and coolest. This applies only to stars that are on the main sequence, that is, stars which have fully ignited and are still burning mostly hydrogen. [TB] {EA}