Crystallization of binary ionic mixtures in dense stellar plasmas

The crystallization diagrams of arbitrary dense binary ionic mixtures are examined within the framework of the density-functional theory of freezing. The behavior of the phase diagram is shown to depend strongly on the charge ratio in the mixture. As the charge ratio Z1/Z2 is lowered, the phase diagram evolves from a spindle shape into an azeotropic phase diagram and finally into a eutectic phase diagram. This has important consequences on the crystallization of trace elements in White Dwarfs, and on the subsequent gravitational energy release, leading to a substantial modification of the cooling history of these stars. (Author)