In the 1960s, it was predicted that as a white dwarf cools, its material shouldcrystallize, starting at the center.[8] When a star pulsates, observing its pulsations gives information about its structure. BPM 37093 was first observed to be a pulsating variable in 1992,[1] and in 1995 it was pointed out that this yielded a potential test of the crystallization theory.[9] In 2004, Antonio Kanaan and a team of researchers of theWhole Earth Telescope estimated, on the basis of theseasteroseismological observations, that approximately 90% of the mass of BPM 37093 had crystallized.[6][8][10] Other work gives a crystallized mass fraction of between 32% and 82%.[11] Any of these estimates would result in a total crystalline mass in excess of 5×1029 kilograms. As the white dwarf has a radius of 4,000 kilometres (2,500 mi), this means that the core of BPM 37093, nicknamedLucy, is likely one of the largest diamonds in the local region of the universe.[12][13]
Body-centered cubic lattice
Crystallization of the material of a white dwarf of this type is thought to result in abody-centered cubic lattice of carbon and/or oxygen nuclei, which are surrounded by aFermi sea of electrons.[14]
InJohn C. Wright's science fiction novelCount to a Trillion and its sequels, V886 Centauri is called the "Diamond Star", after the crystalline carbon core. In the story of the novel, it becomes the destination of the first human interstellar journey after it is discovered that the star, a ten-decillion-carat diamond of degenerate matter, is not matter at all, but antimatter. An alien artifact called "The Monument" is found orbiting it, which increases human knowledge of mathematics immensely.
^abWhole Earth Telescope observations of BPM 37093: a seismological test of crystallization theory in white dwarfs, A. Kanaan, A. Nitta, D. E. Winget, S. O. Kepler, M. H. Montgomery, T. S. Metcalfe, et al.,Astronomy and Astrophysics432, #1 (March 2005), pp. 219–224.Bibcode:2005A&A...432..219Kdoi:10.1051/0004-6361:20041125.
^abTesting White Dwarf Crystallization Theory with Asteroseismology of the Massive Pulsating DA Star BPM 37093, T. S. Metcalfe, M. H. Montgomery, and A. Kanaan,Astrophysical Journal605, #2 (April 2004), pp. L133–L136.Bibcode:2004ApJ...605L.133M
^The Status of White Dwarf Asteroseismology and a Glimpse of the Road Ahead, D. E. Winget,Baltic Astronomy4 (1995), pp. 129–136.Bibcode:1995BaltA...4..129W
^P. Brassard, G. Fontaine, Asteroseismology of the Crystallized ZZ Ceti Star BPM 37093: A Different View,Astrophysical Journal622, #1, pp. 572–576.Bibcode:2005ApJ...622..572B
^Crystallization of carbon-oxygen mixtures in white dwarfs, J. L. Barrat, J. P. Hansen, and R. Mochkovitch,Astronomy and Astrophysics199, #1–2 (June 1988), pp. L15–L18.Bibcode:1988A&A...199L..15B
