White Dwarf Star Enters Its Crystallization Era, Turning Into A 'Cosmic Diamond'

"In this work we present the discovery of a new Sirius-like quadruple system at 32 parsecs distance, composed of a crystallizing white dwarf companion to the previously known triple HD 190412," write an international team of astronomers led by Alexander Venner of the University of Southern Queensland in Australia.

"By virtue of its association with these main sequence companions, this is the first crystallizing white dwarf whose total age can be externally constrained, a fact that we make use of by attempting to empirically measure a cooling delay caused by core crystallization in the white dwarf."