gravitational collapse

Also found in: Dictionary, Thesaurus, Wikipedia.

gravitational collapse:

see black holeblack hole,
in astronomy, celestial object of such extremely intense gravity that it attracts everything near it and in some instances prevents everything, including light, from escaping.
..... Click the link for more information.

gravitational collapse

Contraction of a body arising from the mutual gravitational pull of all its constituents. Although there are several examples of such contraction processes in astronomy, ‘gravitational collapse’ usually refers to the sudden collapse of the core of a massive star at the end of nuclear burning, when its internal gas pressure can no longer support its weight. For a massive star this may initially result in a supernova explosion, removing much of the star's mass. The eventual degree of gravitational collapse is determined by the mass that remains after a supernova, or after any other form of mass loss. The three most likely end-products (in order of increasing mass) are white dwarfs, neutron stars, and black holes.

Gravitational Collapse


(in astronomy), the catastrophically rapid compression of a star under the action of gravitational attraction.

According to existing astronomical conceptions, gravitational collapse plays a decisive role in the late stages of the evolution of massive stars. During the billions of years of its prior existence, a star is in equilibrium: the forces of gravitational attraction, which tend to compress the star’s material, are balanced by the forces of hot gas pressure, which counteract compression. Thermonuclear reactions proceeding in the star’s central regions at temperatures of tens of millions of degrees are the sources of the star’s radiant energy. After several billion years, the star’s nuclear sources of energy are exhausted. Meanwhile, the star continues to lose energy, radiating light into space from its surface and neutrinos from its interior. This leads to a very slow contraction of the star’s central regions. If the star’s mass is not less than 1.2 solar masses, then the density and pressure in the star’s central regions increase so much that nuclear reactions begin to occur involving the breakdown of complex nuclei, during which an enormous amount of heat is absorbed. This leads to the following: with the increase in the density of the gas the forces of hot gas pressure do not rise as fast as the gravitational forces, the equilibrium between these forces is upset, and under the influence of gravity, now not balanced by the force of gas pressure, the star tends to contract—gravitational collapse occurs.

The process takes a fraction of a second, but in this time the density of the central parts of the star increases to that of the atomic nucleus, about 1014 g/cm3. Now the already powerful repulsive forces of the nuclear particles pressing on each other slow or even halt the compression of matter in the star’s central regions. The falling outer layers of the star encounter the layers that have come to rest, and an outward-traveling shock wave is generated, which is reinforced by neutrinos emanating from the interior and by the detonation of the remnants of the nuclear “fuel” in the star’s envelope. The star’s outer layers are ejected into space. This ejection process is observed as the explosions of supernovas. The core remaining after the ejection of the envelope of a star with a mass not exceeding 2 solar masses is a neutron star. Astronomers observe such stars as sources of pulsating radio emission—pulsars.

If the mass of the star’s core is large (greater than 2 solar masses), then the repulsion of the nuclear particles is not able to withstand the gravity, and the star’s core, after rapid cooling, will continue to contract. In this case, its gravitational field increases so much that the effects of the general theory of relativity begin to play a role, and no force can any longer halt the contraction. This stage of a star’s evolution is called relativistic gravitational collapse. When the star’s radius becomes equal to a critical value (determined by the star’s mass and equal to 3 M0 km, where M0 is the star’s mass expressed in solar masses), the gravitational field no longer releases radiation or particles. Such a celestial object is called a black hole or frozen star.


Zel’dovich, Ia. B., and I. D. Novikov. Teoríia tiagoteniia i evoliutsiia zvezd. Moscow, 1971.


gravitational collapse

[‚grav·ə′tā·shən·əl kə′laps]
The implosion of a star or other astronomical body from an initial size to a size hundreds or thousands of times smaller.
References in periodicals archive ?
Similarly, light leaving the surface of a body undergoing gravitational collapse, at the instant that it passes its event horizon, takes an infinite amount of observer time to reach an observer, however far that observer is from the event horizon.
Mixmaster gravitational collapse is a very simple model, admits Svend Erik Rugh of the Niels Bohr Institute in Copenhagen, Denmark.
To obtain a model for a star and for the gravitational collapse thereof, it follows that the solution to Einstein's field equations must be built upon some manifold without boundary.
Furthermore, the conventional conception of gravitational collapse is demonstrably false.
Singularities associated with gravitational collapse appear frequently in the solutions of Einstein's equations, even though nature doesn't countenance such bizarre features.
That may be why, when gravitational collapse proceeds, the resulting objects inevitably halt their growth at just the right size to sustain nuclear fusion.
As to how they are formed, theories include the gravitational collapse of a large star, collision between galaxies or the sheer density of material present shortly after the Big Bang.
Stars spring to life from the gravitational collapse of massive clouds of gas and dust.
Practically all of our galaxy's 200 to 400 billion stars, including the sun, were born through the gravitational collapse of diffuse clouds of dust and gas sprinkled across the Milky Way by previous generations of long-dead stars.
Much theoretical effort has gone in to understanding the gravitational collapse of protostar but the question of gravitational instability of partially-ionized gaseous medium in the presence of radiative heat-loss function is of particular interest in cosmogony.
The first concerns the special Schwarzschild case of a black hole with its critical limit of gravitational collapse.
Papers address high-mass star formation by gravitational collapse of massive cores, the binarity of Eta Carinae, metallicity-dependent Wolf-Rayet winds, and an overview of cosmic infrared background and Population III, among other topics.