Vogt-Russell theorem

The Vogt–Russell theorem states that the structure of a star, in hydrostatic and thermal equilibrium with all energy derived from nuclear reactions, is uniquely determined by its mass and the distribution of chemical elements throughout its interior. Although referred to as a theorem, the Vogt–Russell theorem has never been formally proved. The theorem is named after astronomers Heinrich Vogt and Henry Norris Russell, who devised it independently.

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