BPM 37093
469673
219994398
2008-06-17T20:15:08Z
Spacepotato
271631
Better source for luminosity; remove radius (inconsistent with other values)
{{Starbox begin|name={{SIMBAD link|BPM+37093|BPM 37093}}}}
{{Starbox observe|epoch=[[J2000.0]] ([[International Celestial Reference System|ICRS]])
|constell=[[Centaurus (constellation)|Centaurus]] |
ra={{RA|12|38|49.93}}<ref name="simbad">{{SIMBAD link|BPM+37093|BPM 37093}}, query result in [[SIMBAD]]. Accessed on line [[April 1]], [[2008]].</ref> |
dec={{DEC|-49|48|01.2}}<ref name="simbad" />|
appmag_v=14.0<ref name="simbad" />}}
{{Starbox character |
class=DAV4.4<ref name="villanovar4">[http://adsabs.harvard.edu/abs/1999ApJS..121....1M A Catalog of Spectroscopically Identified White Dwarfs], George P. McCook and Edward M. Sion, ''Astrophysical Journal Supplement'' '''121''', #1 (March 1999), pp. 1–130. [[Centre de Données astronomiques de Strasbourg|CDS]] ID [http://vizier.u-strasbg.fr/viz-bin/Cat?III/210 III/210].</ref> |
variable=DAV (ZZ Ceti)<ref name="villanovar4" /> }}
{{Starbox astrometry
| radial_v=−12<ref name=villanovar4 />
|parallax=61.0
|p_error=9.4
|parallax_footnote=<ref name="bergeron">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}}</ref>
}}
{{Starbox detail
| mass=1.10<ref name=arxiv04 />
| radius=
| luminosity=0.001<ref name=bergeron />
| temperature=11730 ± 350<ref name=Brassard />
| metal=
| gravity=8.81 ± 0.05<ref name=Brassard />
| rotation=
| age= }}
{{Starbox catalog|names=V886 Cen, V886 Centauri, GJ 2095, LFT 931, LHS 2594, LTT 4816, WD 1236-495<ref name=simbad />
}}
{{Starbox end}}
'''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>
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–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–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. 129–136. {{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. 219–224. {{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. 572–576. {{bibcode|2005ApJ...622..572B}}</ref> Any of these estimates would result in a total crystalline mass in excess of 5{{e|29}} [[kilogram]]s.
[[Image:Lattice body centered cubic.svg|thumb|left|150px|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.<ref>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}}</ref> 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]]''.<ref name="lucy" />
<br clear="left" />
==References==
{{reflist}}
==External links==
* [http://jumk.de/astronomie/special-stars/bpm-37093.shtml BPM 37093 (Diamond Star)]
[[Category:Centaurus constellation]]
[[Category:Pulsating white dwarfs]]
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