Carbon detonation
Encyclopedia
Carbon detonation is the violent re-ignition of thermonuclear fusion
in a dead star
, which produces a Type Ia supernova
. A white dwarf
undergoes carbon detonation only if it has a normal binary
companion which is close enough to the dwarf star to dump sufficient amounts of matter onto the dwarf, expelled during the process of the companion's own late stage evolution
.
If the companion supplies enough matter to the dead star, the white dwarf's internal pressure and temperature will rise high enough to fuse the previously unfusable carbon
in the white dwarf's core. Carbon detonation generally occurs when the accreted matter pushes the white dwarf's mass close to the Chandrasekhar limit
of roughly 1.4 solar mass
es.
Computer simulations show that the fusion front proceeds as a series of turbulent, expanding "bubbles" that exhibit Rayleigh–Taylor instability. The turbulence of the unstable fusion front makes it ragged, and the high surface area of the ragged front results in an extremely rapid "burn", known as a "thermonuclear flame". This rapid "burn" erupts explosively through the dwarf star's surface, which is seen as a type Ia supernova.
Nuclear fusion
Nuclear fusion is the process by which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. This is usually accompanied by the release or absorption of large quantities of energy...
in a dead star
White dwarf
A white dwarf, also called a degenerate dwarf, is a small star composed mostly of electron-degenerate matter. They are very dense; a white dwarf's mass is comparable to that of the Sun and its volume is comparable to that of the Earth. Its faint luminosity comes from the emission of stored...
, which produces a Type Ia supernova
Type Ia supernova
A Type Ia supernova is a sub-category of supernovae, which in turn are a sub-category of cataclysmic variable stars, that results from the violent explosion of a white dwarf star. A white dwarf is the remnant of a star that has completed its normal life cycle and has ceased nuclear fusion...
. A white dwarf
White dwarf
A white dwarf, also called a degenerate dwarf, is a small star composed mostly of electron-degenerate matter. They are very dense; a white dwarf's mass is comparable to that of the Sun and its volume is comparable to that of the Earth. Its faint luminosity comes from the emission of stored...
undergoes carbon detonation only if it has a normal binary
Binary star
A binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...
companion which is close enough to the dwarf star to dump sufficient amounts of matter onto the dwarf, expelled during the process of the companion's own late stage evolution
Stellar evolution
Stellar evolution is the process by which a star undergoes a sequence of radical changes during its lifetime. Depending on the mass of the star, this lifetime ranges from only a few million years to trillions of years .Stellar evolution is not studied by observing the life of a single...
.
If the companion supplies enough matter to the dead star, the white dwarf's internal pressure and temperature will rise high enough to fuse the previously unfusable carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
in the white dwarf's core. Carbon detonation generally occurs when the accreted matter pushes the white dwarf's mass close to the Chandrasekhar limit
Chandrasekhar limit
When a star starts running out of fuel, it usually cools off and collapses into one of three compact forms, depending on its total mass:* a White Dwarf, a big lump of Carbon and Oxygen atoms, almost like one huge molecule...
of roughly 1.4 solar mass
Solar mass
The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...
es.
Computer simulations show that the fusion front proceeds as a series of turbulent, expanding "bubbles" that exhibit Rayleigh–Taylor instability. The turbulence of the unstable fusion front makes it ragged, and the high surface area of the ragged front results in an extremely rapid "burn", known as a "thermonuclear flame". This rapid "burn" erupts explosively through the dwarf star's surface, which is seen as a type Ia supernova.
See also
- Nuclear fusionNuclear fusionNuclear fusion is the process by which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. This is usually accompanied by the release or absorption of large quantities of energy...
- Helium flashHelium flashA helium flash is the runaway fusion of helium in the core of low mass stars of less than about 2.25 solar masses and greater than about 0.5 solar mass, or on the surface of an accreting white dwarf star. They may also occur in the outer layers of larger stars in shell flashes...
, a similar, although less cataclysmic sudden initiation of fusion