gravitational instability

gravitational instability

The tendency for fluctuations in an inhomogeneous medium to grow because of self-gravitation. It is opposed by pressure forces. The critical length-scale beyond which such condensations collapse is known as a Jeans length, and the Jeans mass it encloses eventually forms a stable gravitationally bound system. The Jeans length is thus often taken as a characteristic length-scale for gravitational collapse; an interstellar cloud larger than the Jeans length will fragment into clumps with this characteristic size. See also galaxies, formation and evolution.

gravitational instability

[‚grav·ə′tā·shən·əl ‚in·stə′bil·əd·ē]
(mechanics)
Instability of a dynamic system in which gravity is the restoring force.
References in periodicals archive ?
Thus, the drop in solar radiation caused conditions for gravitational instability in the thin surface layer.
"This is a major step towards our understanding of how stars and planets form and evolve," says Vorobyov, "If we can prove that most stars undergo such episodes of brightening caused by disk gravitational instability, this would mean that our own Sun might have experienced several such episodes, implying that the giant planets of the Solar system may in fact be lucky survivors of the Sun's tempestuous past."
"If we can prove that most stars undergo such episodes of brightening caused by disk gravitational instability, this would mean that our own sun might have experienced several such episodes, implying that the giant planets of the solar system may in fact be lucky survivors of the sun's tempestuous past," Eduard Vorobyov, an author of the study from the Astrophysical Department of Vienna University, said in a (http://www.eurekalert.org/pub_releases/2016-02/uov-bs020516.php) statement.
Boss' new model demonstrates how a phase of marginal gravitational instability in the gas disk surrounding a proto-sun, leading to an outburst phase, can explain all of these findings.
In the gravitational instability model, some of the gas and dust suddenly clumps and collapses, simultaneously creating a planet's core and atmosphere.
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.
This theorem is applicable exactly to the case of the gravitational instability of the cosmic clouds.
Further, the gravitational instability of oceanic islands indicates that collapses could imperil major cities bordering the ocean basins (McGuire, 1996).
The other possibility is that the very early solar nebula was massive enough to go through periods of gravitational instability, as described earlier.
There has been considerable uncertainty about how systems of planets form, with two leading models, called core accretion and gravitational instability. Planetary properties, such as the composition of a planet's atmosphere, are clues as to whether a system formed according to one model or the other.
There has been uncertainty about how planets in other solar systems formed, with two leading models, called core accretion and gravitational instability. When stars form, they are surrounded by a planet-forming disk.