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Hydrostatic Equilibrium

Astronomy  Hydromagnetic wave  Hydrus
04/17/2014

Hydrostatic equilibrium is one of the most important fundamental principles in atmospheric physics and astrophysics.


Hydrostatic Equilibrium
The simple model of any main sequence star is of a dense gas/fluid in a state of hydrostatic equilibrium. The inward acting force, gravity, is balanced by outward acting forces of gas pressure and the radiation pressure.

Hydrostatic equilibrium: gravity compression is balanced by pressure outward.
Greater gravity compresses the gas, making it denser and hotter, so the outward pressure increases.

Hydrostatic equilibrium
A planet's defining physical characteristic is that it is large enough for the force of its own gravity to dominate over the electromagnetic forces binding its physical structure, ...

hydrostatic equilibrium
A balance between the weight of a layer in a star and the pressure that supports it.
hyperbolic
See hyperbolic space.

Hydrostatic Equilibrium
The balance between weight of the material pressing downward on a layer in a star and the pressure in that layer.
I ...

HYDROSTATIC EQUILIBRIUM - Balance between gravity and gas pressure. In the case of a star, gravity originates in mutual gravitational attraction of the entire mass of the star.

Hydrostatic Equilibrium - This is the balance between weight (gravity) and pressure (air pressure or gas pressure). This is like how the old dome on the UNI-Dome worked (and how the Metrodome in Minneapolis works).

Hydrostatic Equilibrium - The balance between the inward directed gravitational force and the outward directed pressure force within a celestial body ...

hydrostatic equilibrium
The balance maintained within a star between the explosive pressure of the core caused by heat and the gravitational attraction of the mass of the star itself.

Hydrostatic equilibrium occurs when compression due to gravity is balanced by a pressure gradient which creates a pressure gradient force in the opposite direction....
, the boundary that separates objects from planethood.

Hydrostatic Equilibrium
A balance between the gravitational force inward and the gas and radiation forces outward in a star.
Hyperbolic Space ...

HYDROSTATIC EQUILIBRIUM
Hydrostatic equilibrium is a stable condition in a star in which the fluid matter within the star is at an equilibrium with respect to all forces, including the inward-pulling force of gravity, ...

Hydrostatic equilibrium :
gravity inwards = pressure outwards
stability : stellar thermostat
Chapter 12: Stellar Evolution ...

Hydrostatic equilibrium gives no net flow in the z-direction:
at density r. For a thin disk, this approaches -GMz/r³ so the disk thickness will be H ~ r/M.

Hydrostatic equilibrium
A state that occurs when compression due to gravity is balanced by a pressure gradient which creates a pressure gradient force in the opposite direction.

Roundness - hydrostatic equilibrium due to mass - not size as I thought I'd made clear before. If it has enough mass to be round its a planet, if not, then not Pluto is round, Ceres is round, Vesta is not quite.

In addition to hydrostatic equilibrium, the interior of a stable star will also maintain an energy balance of thermal equilibrium.

See magnetohydrodynamics. [H76]
Hydrostatic Equilibrium
A balance between the gravitational force inward and the gas and radiation forces outward in a star. [H76]
Hyperbolic Space ...

hydrostatic equilibrium Balance between pressure forces and gravitational forces in a star's layers.

hydrostatic equilibrium 1. The state of a fluid whose surfaces of constant pressure and constant mass (or density) coincide and are horizontal throughout. Complete balance exists between the force of gravity and the pressure force.

dwarf planet A celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape2 , ...

The identity of g* and g is implied by the assumption of hydrostatic equilibrium.

has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and
has cleared the neighbourhood around its orbit ...

First is the hydrostatic balance, also called hydrostatic equilibrium. This determines the structure of the star as the internal pressure gradient balances against the force of gravity.

This balance is called hydrostatic equilibrium. Now pressure is a force per unit area; you exert pressure on a wall if you put your hand on it and push. That pressure force is exerted only over the surface area covered by your hand.

This hydrostatic equilibrium condition usually also applies to changes of density inside the object, so that the density at a place inside the object will depend only on how far it is from the object's center.

In many ways stars are very simple objects; round spheres of gas in hydrostatic equilibrium, hot and dense at the centre, much cooler at the surface and as the Astronomer Royal Sir Martin Rees says, much simpler than ants! ...

The radius of a star is determined by hydrostatic equilibrium which is the balance between the energy generation in the center of the star and gravity that tends to collapse the star.

horizontal branch Region of the H-R diagram where post-main sequence stars again reach hydrostatic equilibrium. At this point, the star is burning helium in its core, and hydrogen in a shell surrounding the core.

Scientifically, stars are defined as self-gravitating spheres of plasma in hydrostatic equilibrium, which generate their own energy through the process of nuclear fusion.

horizontal branch Region of the Hertzsprung-Russell diagram where post-main sequence stars again reach hydrostatic equilibrium. At this point, the star is burning helium in its core, and hydrogen in a shell surrounding the core.

is in orbit around the Sun,
has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape,
has not cleared the neighbourhood around its orbit, and
is not a satellite.

This whole process acts to maintain hydrostatic equilibrium. As the core then contracts, the energy generation increases, causing the sun to become more luminous.

where, most importantly P=pressure and T=Temperature. The outward pressure nearly balances the inward gravitational pull, a condition called hydrostatic equilibrium.

Irregular moons are too far away from their parents to become tidally locked. They also come in various shapes as they are not massive enough to have achieved hydrostatic equilibrium.

It states, "A 'planet' is defined as a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, ...

Instead, as the hydrogen is used up by fusion, the star loses the balance of hydrostatic equilibrium and simply contracts and heats up due to gravity.

See also: See also: Astro, Solar, Sun, Earth, Planet

Astronomy  Hydromagnetic wave  Hydrus
04/17/2014

 
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