AST 309 Chapter Notes - Chapter 3: Low Mass, Solar Mass, Protostar
Document Summary
Stable main sequence stars maintain equilibrium by producing energy through nuclear fusion in their cores. The ability to generate energy by fusion defines a star. 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. This rate of hydrogen use means that eventually the sun (and all other stars) will run out of central fuel. Stars come with many different masses, ranging from 1/12 solar masses (msun) to roughly 100 200 msun. There are far more low-mass than high-mass stars. The most massive main-sequence stars (spectral type o) are also the most luminous and have the highest surface temperature. The lowest-mass stars on the main sequence (spectral type m or l) are the least luminous and the coolest. A galaxy of stars such as the milky way contains enormous amounts of gas and dust enough to make billions of stars like the sun.
