Known officially as BPM 37093, the star confirms a theory, first raised in the early 1960s, that cool white dwarfs should have a diamond core.
A white dwarf is what small stars, those up to about the size of the sun, turn into when they run out of nuclear fuel and die. The intense pressures at the heart of such dead stars compress the carbon into diamond.

BPM 37093 is a variable white dwarf star of the DAV, or ZZ Ceti, type, with a hydrogen atmosphere and an unusually high mass of approximately 1.1 times the Sun’s. This star’s temperature (~ 11 000 K) and high mass (~ 1.1 M_sun) imply that it should be crystallized throughout most of its core, the exact fraction depending on its core composition. BPM 37093 is the first object where the results of crystallization theory can be probed observationally. If the star is crystallized its pulsation spectrum should differ significantly from non-crystallized pulsating stars.

The star BPM 37093 has been nicknamed Lucy after The Beatles’s hit Lucy in the Sky with Diamonds.