The Structure and Evolution of Stars

Abstract

Having expressed the mean molecular weight, the opacity, and the rate of energy generation in terms of our five unknown quantities and the hydrogen and helium content, we can follow the astrophysical engineer in his star-building venture. As we have already noted, he starts out with a given amount of material (the mass of the star) and the available volume for the star. He must now decide how much of this total material is hydrogen and how much is helium. Everything else is lumped together in what is left over. This gives him a numerical value for the mean molecular weight, which can be substituted directly in the equations that guide him.

Silently one by one, in the infinite meadows of heaven Blossomed the lovely stars, the forget-me-nots of the angels.

—HENRY WADSWORTH LONGFELLOW, Evangeline