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The core's not really a diamond. We already discuss the crystallized mass fraction, total mass, and atmosphere.
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'''BPM 37093''' is a [[variable star|variable]] [[white dwarf]] [[star]] of the DAV, or [[Pulsating white dwarf|ZZ Ceti]], type, with a [[hydrogen]] atmosphere and an unusually high mass of approximately 1.1 times the [[Sun]]'s. It is about 50 [[light-year]]s from Earth, in the constellation [[Centaurus]], and vibrates; these pulsations cause its [[luminosity]] to [[variable star|vary]].<ref name="arxiv04" /><ref name="simbad" /> 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]].<ref name="rln">[http://spiff.rit.edu/classes/phys230/lectures/planneb/planneb.html Late stages of evolution for low-mass stars], Michael Richmond, lecture notes, Physics 230, [[Rochester Institute of Technology]], accessed online [[May 3]], [[2007]].</ref>
'''BPM 37093''' is a [[variable star|variable]] [[white dwarf]] [[star]] of the DAV, or [[Pulsating white dwarf|ZZ Ceti]], type, with a [[hydrogen]] atmosphere and an unusually high mass of approximately 1.1 times the [[Sun]]'s. It is about 50 [[light-year]]s from Earth, in the constellation [[Centaurus]], and vibrates; these pulsations cause its [[luminosity]] to [[variable star|vary]].<ref name="arxiv04" /><ref name="simbad" /> 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]].<ref name="rln">[http://spiff.rit.edu/classes/phys230/lectures/planneb/planneb.html Late stages of evolution for low-mass stars], Michael Richmond, lecture notes, Physics 230, [[Rochester Institute of Technology]], accessed online [[May 3]], [[2007]].</ref>

Since the "star" may be composed entirely of crystallized carbon it would be a diamond with roughly the same mass as our sun. In diamond terms, it is a weight of 10 billion, trillion carats.


In the 1960s, it was predicted that as a white dwarf cools, its material should [[crystallize]], starting at the center.<ref name="metcalfe1">Testing White Dwarf Crystallization Theory with Asteroseismology of the Massive Pulsating DA Star BPM 37093, T. S. Metcalfe, M. H. Montgomery, and A. Kanaan, ''Astrophysical Journal'' '''605''', #2 (April 2004), pp. L133&ndash;L136. {{bibcode|2004ApJ...605L.133M}}</ref> When a star pulsates, observing its pulsations gives information about its structure. BPM 37093 was first observed to be a pulsating variable in 1992<ref>The discovery of a new DAV star using IUE temperature determination, A. Kanaan, S. O. Kepler, O. Giovannini, and M. Diaz, ''Astrophysical Journal Letters'' '''390''', #2 ([[May 10]], [[1992]]), pp. L89&ndash;L91. {{bibcode|1992ApJ...390L..89K}}</ref>, and in 1995 it was pointed out that this yielded a potential test of the crystallization theory.<ref>The Status of White Dwarf Asteroseismology and a Glimpse of the Road Ahead, D. E. Winget, ''Baltic Astronomy'' '''4''' (1995), pp. 129&ndash;136. {{bibcode|1995BaltA...4..129W}}</ref> In 2004, Travis Metcalfe and a team of researchers at the [[Harvard-Smithsonian Center for Astrophysics]] estimated, on the basis of these [[asteroseismology|asteroseismological]] observations, that approximately 90% of the mass of BPM 37093 had crystallized.<ref name="metcalfe1" /><ref name="lucy">[http://news.bbc.co.uk/2/hi/science/nature/3492919.stm BBC News: Diamond star thrills astronomers]</ref><ref>[http://cfa-www.harvard.edu/press/pr0407.html Press release], 2004, Harvard-Smithsonian Center for Astrophysics.</ref><ref name="arxiv04">Whole 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 Astrophysics'' '''432''', #1 (March 2005), pp. 219&ndash;224. {{bibcode|2005A&A...432..219K}} {{doi|10.1051/0004-6361:20041125}}.</ref> Other work gives a crystallized mass fraction of between 32% and 82%.<ref name="Brassard">P. Brassard, G. Fontaine, Asteroseismology of the Crystallized ZZ Ceti Star BPM 37093: A Different View, ''Astrophysical Journal'' '''622''', #1, pp. 572&ndash;576. {{bibcode|2005ApJ...622..572B}}</ref> Any of these estimates would result in a total crystalline mass in excess of 5{{e|29}} [[kilogram]]s.
In the 1960s, it was predicted that as a white dwarf cools, its material should [[crystallize]], starting at the center.<ref name="metcalfe1">Testing White Dwarf Crystallization Theory with Asteroseismology of the Massive Pulsating DA Star BPM 37093, T. S. Metcalfe, M. H. Montgomery, and A. Kanaan, ''Astrophysical Journal'' '''605''', #2 (April 2004), pp. L133&ndash;L136. {{bibcode|2004ApJ...605L.133M}}</ref> When a star pulsates, observing its pulsations gives information about its structure. BPM 37093 was first observed to be a pulsating variable in 1992<ref>The discovery of a new DAV star using IUE temperature determination, A. Kanaan, S. O. Kepler, O. Giovannini, and M. Diaz, ''Astrophysical Journal Letters'' '''390''', #2 ([[May 10]], [[1992]]), pp. L89&ndash;L91. {{bibcode|1992ApJ...390L..89K}}</ref>, and in 1995 it was pointed out that this yielded a potential test of the crystallization theory.<ref>The Status of White Dwarf Asteroseismology and a Glimpse of the Road Ahead, D. E. Winget, ''Baltic Astronomy'' '''4''' (1995), pp. 129&ndash;136. {{bibcode|1995BaltA...4..129W}}</ref> In 2004, Travis Metcalfe and a team of researchers at the [[Harvard-Smithsonian Center for Astrophysics]] estimated, on the basis of these [[asteroseismology|asteroseismological]] observations, that approximately 90% of the mass of BPM 37093 had crystallized.<ref name="metcalfe1" /><ref name="lucy">[http://news.bbc.co.uk/2/hi/science/nature/3492919.stm BBC News: Diamond star thrills astronomers]</ref><ref>[http://cfa-www.harvard.edu/press/pr0407.html Press release], 2004, Harvard-Smithsonian Center for Astrophysics.</ref><ref name="arxiv04">Whole 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 Astrophysics'' '''432''', #1 (March 2005), pp. 219&ndash;224. {{bibcode|2005A&A...432..219K}} {{doi|10.1051/0004-6361:20041125}}.</ref> Other work gives a crystallized mass fraction of between 32% and 82%.<ref name="Brassard">P. Brassard, G. Fontaine, Asteroseismology of the Crystallized ZZ Ceti Star BPM 37093: A Different View, ''Astrophysical Journal'' '''622''', #1, pp. 572&ndash;576. {{bibcode|2005ApJ...622..572B}}</ref> Any of these estimates would result in a total crystalline mass in excess of 5{{e|29}} [[kilogram]]s.

Revision as of 23:23, 9 June 2009

BPM 37093
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Centaurus
Right ascension 12h 38m 49.93s[1]
Declination −49° 48′ 01.2″[1]
Apparent magnitude (V) 14.0[1]
Characteristics
Spectral type DAV4.4[2]
Variable type DAV (ZZ Ceti)[2]
Astrometry
Radial velocity (Rv)−12[2] km/s
Parallax (π)61.0 ± 9.4 mas[3]
Distanceapprox. 53 ly
(approx. 16 pc)
Details
Mass1.10[4] M☉
Luminosity0.001[3] L☉
Surface gravity (log g)8.81 ± 0.05[5] cgs
Temperature11730 ± 350[5] K
Other designations
V886 Cen, V886 Centauri, GJ 2095, LFT 931, LHS 2594, LTT 4816, WD 1236-495[1]

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. It is about 50 light-years from Earth, in the constellation Centaurus, and vibrates; these pulsations cause its luminosity to vary.[4][1] 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.[6]

Since the "star" may be composed entirely of crystallized carbon it would be a diamond with roughly the same mass as our sun. In diamond terms, it is a weight of 10 billion, trillion carats.

In the 1960s, it was predicted that as a white dwarf cools, its material should crystallize, starting at the center.[7] When a star pulsates, observing its pulsations gives information about its structure. BPM 37093 was first observed to be a pulsating variable in 1992[8], and in 1995 it was pointed out that this yielded a potential test of the crystallization theory.[9] In 2004, Travis Metcalfe and a team of researchers at the Harvard-Smithsonian Center for Astrophysics estimated, on the basis of these asteroseismological observations, that approximately 90% of the mass of BPM 37093 had crystallized.[7][10][11][4] Other work gives a crystallized mass fraction of between 32% and 82%.[5] Any of these estimates would result in a total crystalline mass in excess of 5×1029 kilograms.

Body-centered cubic lattice

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.[12] Since a diamond also consists of crystallized carbon, the star BPM 37093 has been nicknamed Lucy after The Beatles's hit Lucy in the Sky with Diamonds.[10]


References

  1. ^ a b c d e BPM 37093, query result in SIMBAD. Accessed on line April 1, 2008.
  2. ^ a b c A Catalog of Spectroscopically Identified White Dwarfs, George P. McCook and Edward M. Sion, Astrophysical Journal Supplement 121, #1 (March 1999), pp. 1–130. CDS ID III/210.
  3. ^ a b Photometric and Spectroscopic Analysis of Cool White Dwarfs with Trigonometric Parallax Measurements, P. Bergeron, S. K. Leggett, María Teresa Ruiz, Astrophysical Journal Supplement 133, #2 (April 2001), pp. 413–449. Bibcode:2001ApJS..133..413B
  4. ^ a b c Whole 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 Astrophysics 432, #1 (March 2005), pp. 219–224. Bibcode:2005A&A...432..219K doi:10.1051/0004-6361:20041125.
  5. ^ a b c P. Brassard, G. Fontaine, Asteroseismology of the Crystallized ZZ Ceti Star BPM 37093: A Different View, Astrophysical Journal 622, #1, pp. 572–576. Bibcode:2005ApJ...622..572B
  6. ^ Late stages of evolution for low-mass stars, Michael Richmond, lecture notes, Physics 230, Rochester Institute of Technology, accessed online May 3, 2007.
  7. ^ a b Testing White Dwarf Crystallization Theory with Asteroseismology of the Massive Pulsating DA Star BPM 37093, T. S. Metcalfe, M. H. Montgomery, and A. Kanaan, Astrophysical Journal 605, #2 (April 2004), pp. L133–L136. Bibcode:2004ApJ...605L.133M
  8. ^ The discovery of a new DAV star using IUE temperature determination, A. Kanaan, S. O. Kepler, O. Giovannini, and M. Diaz, Astrophysical Journal Letters 390, #2 (May 10, 1992), pp. L89–L91. Bibcode:1992ApJ...390L..89K
  9. ^ The Status of White Dwarf Asteroseismology and a Glimpse of the Road Ahead, D. E. Winget, Baltic Astronomy 4 (1995), pp. 129–136. Bibcode:1995BaltA...4..129W
  10. ^ a b BBC News: Diamond star thrills astronomers
  11. ^ Press release, 2004, Harvard-Smithsonian Center for Astrophysics.
  12. ^ Crystallization of carbon-oxygen mixtures in white dwarfs, J. L. Barrat, J. P. Hansen, and R. Mochkovitch, Astronomy and Astrophysics 199, #1–2 (June 1988), pp. L15–L18. Bibcode:1988A&A...199L..15B
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