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Born on this day
Liam Brady
Born Liam Brady, Irish footballer
7th week in year
13 February 2019

Important eventsBack

The Harvard-Smithsonian Center for Astrophysics announces the discovery of the universe's larges13.2.2004

Wikipedia (25 Feb 2013)

The Harvard–Smithsonian Center for Astrophysics (CfA) is one of the largest and most diverse astrophysical institutions in the world,[citation needed] where scientists carry out a broad program of research in astronomy, astrophysics, earth and space sciences, and science education. The center's mission is to advance knowledge and understanding of the universe through research and education in astronomy and astrophysics.

The center was founded in 1973 as a joint venture between the Smithsonian Institution and Harvard University. It consists of the Harvard College Observatory and the Smithsonian Astrophysical Observatory. The center's main facility is located between Concord Avenue and Garden Street, with its mailing address and main entrance at 60 Garden Street, Cambridge, Massachusetts. Beyond this location there are also additional satellite facilities elsewhere around the globe. The current director of the CfA, Charles R. Alcock, was named in 2004. The director from 1982 to 2004 was Irwin I. Shapiro.

V886 Centauri (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. Like other white dwarfs, V886 Centauri is thought to be composed primarily of carbon and oxygen, which are created by thermonuclear fusion of helium nuclei in the triple-alpha process.

In the 1960s, it was predicted that as a white dwarf cools, its material should crystallize, starting at the center. When a star pulsates, observing its pulsations gives information about its structure. V886 Centauri was first observed to be a pulsating variable in 1992, and in 1995 it was pointed out that this yielded a potential test of the crystallization theory. 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 V886 Centauri had crystallized. Other work gives a crystallized mass fraction of between 32% and 82%. Any of these estimates would result in a total crystalline mass in excess of 5×1029 kilograms.

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.

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