The lowest-mass stars on the main sequence (spectral type M or L) are the least luminous and the coolest. The most massive main-sequence stars (spectral type O) are also the most luminous and have the highest surface temperature.There are far more low-mass than high-mass stars. Stars come with many different masses, ranging from 1/12 solar masses ( M Sun) to roughly 100–200 M Sun.This rate of hydrogen use means that eventually the Sun (and all other stars) will run out of central fuel. Each second in the Sun, approximately 600 million tons of hydrogen undergo fusion into helium, with about 4 million tons turning into energy in the process.The ability to generate energy by fusion defines a star. Stable (main-sequence) stars such as our Sun maintain equilibrium by producing energy through nuclear fusion in their cores.Describe how advancing waves of star formation cause a molecular cloud to evolveĪs we begin our exploration of how stars are formed, let’s review some basics about stars discussed in earlier chapters:.
By the end of this section, you will be able to:
