Toward Precision Cosmochronology: A New C/O Phase Diagram for White Dwarfs

Understand

The continuous cooling of a white dwarf is punctuated by events that affect its cooling rate.

• Probably the most significant of those is the crystallization of its core, a phase transition that occurs once the C/O interior has cooled down below a critical temperature.
• This transition releases latent heat as well as gravitational energy due to the redistribution of the C and O ions during solidification, thereby slowing down the evolution of the white dwarf.
• The unambiguous observational signature of core crystallization - a pile-up of objects in the cooling sequence - was recently reported.