BPM 37093 (V886 Centauri) 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. It is 48 light-years (15parsecs) from Earth in the constellation Centaurus and vibrates; these pulsations cause its luminositytovary.[3][5] Like other white dwarfs, BPM 37093 is thought to be composed primarily of carbon and oxygen, which are created by thermonuclear fusion of helium nuclei in the triple-alpha process.[8]
BPM 37093
Alight curve for V886 Centauri, adapted from Kanaan et al. (1992)[1]
12h38m 49.78112s[2]
−49° 48′ 00.2195″[2]
14.0[3]
Characteristics
DAV4.4[4]
DAV (ZZ Ceti)[4]
Radial velocity (Rv)
−12[4] km/s
Proper motion (μ)
RA: -557.111 mas/yr[2]
Dec.: -74.036 mas/yr[2]
Parallax (π)
48.39 ± 0.01 ly
(14.836 ± 0.004 pc)
Details
0.0057 R☉
Surface gravity (log g)
Database references
ARICNS
In the 1960s, it was predicted that as a white dwarf cools, its material should crystallize, starting at the center.[9] 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.[10] In 2004, Antonio Kanaan and a team of researchers of the Whole Earth Telescope estimated, on the basis of these asteroseismological observations, that approximately 90% of the mass of BPM 37093 had crystallized.[5][9][11][12] Other work gives a crystallized mass fraction of between 32% and 82%.[7] 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, nicknamed Lucy, is likely one of the largest diamonds in the local region of the universe.[13][14]
Crystallization of the material of a white dwarf of this type is thought to result in a body-centered cubic lattice of carbon and/or oxygen nuclei, which are surrounded by a Fermi sea of electrons.[15]