Hydrostatic equilibrium is one of the most important fundamental principles in atmospheric physics and astrophysics.
Hydrostatic equilibrium: gravity compression is balanced by pressure outward.
Greater gravity compresses the gas, making it denser and hotter, so the outward pressure increases.
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.
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, leading to a state of hydrostatic equilibrium.
A balance between the weight of a layer in a star and the pressure that supports it.
See hyperbolic space.
The balance between weight of the material pressing downward on a layer in a star and the pressure in that layer.
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. Gas pressure is produced by nuclear reactions that heat the star's gas.
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
Hyperbola - A curved path that does not close on itself. A body moving with a speed greater than escape velocity follows a hyperbola ...
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.
A balance between the gravitational force inward and the gas and radiation forces outward in a star.
Hyperbolic Space ...
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, the out-ward pulling buoyancy due to pressure differentials, ...
Hydrostatic equilibrium :
gravity inwards = pressure outwards
stability : stellar thermostat
Chapter 12: Stellar Evolution ...
Hydrostatic Equilibrium Spacetime Frequencies Degeneracy Pressure Diffraction Irregular Galaxies Tsunami Newton's Law Solar Cycle Supermassive Black Holes The Sun Tachyons Asteroids Nuclear Fission Power Absorption Equinox Homogeneity Radius Measurements
Curious Minds Online ...
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.
The mass flow rate (accretion rate in a steady state) must by mass conservation be constant with radius ...
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. Hydrostatic equillibrium is responsible for keeping stars from imploding and for giving planets their spherical shape.
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.
the gas is in hydrostatic equilibrium -- which might be a decent approximation in some clusters, but is clearly not in others (such as Stephan's Quintet). If it is, then
where Mint is the mass interior to the radius R ...
In addition to hydrostatic equilibrium, the interior of a stable star will also maintain an energy balance of thermal equilibrium. There is a radial temperature gradient throughout the interior that results in a flux of energy flowing toward the exterior.
HYDROSTATIC EQUILIBRIUM: This refers to the balancing of forces in a fluid (fluid=hydro, static=stationary, equilibrium=balance).
See magnetohydrodynamics. [H76]
A balance between the gravitational force inward and the gas and radiation forces outward in a star. [H76]
Hyperbolic Space ...
Hydrostatic equilibrium has been achieved. Also, the rate at which energy is produced in the core has balanced the rate at which energy is transported to the surface of the star and radiated away into space. Thermal equilibrium has been established.
hydrostatic equilibrium Balance between pressure forces and gravitational forces in a star's layers. hyperbola Open-ended curve of a conic section formed by the intersection of a plane with a right-circular cone at any angle between the axis of the cone and its slant edge.
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. See hydrostatic equation. 2.
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 , (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.
The identity of g* and g is implied by the assumption of hydrostatic equilibrium.
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.
Pamela: This is gravitational hydrostatic equilibrium on a different scale and in a different way. In this case when you have small bodies, the chemical structures, the everyday bonds between the minerals allow asteroids that look like potatoes.
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. If this is so, the object is called spherically symmetric.
One proposal would have defined a planet as "a celestial body that (a) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (b) is in orbit around a star, and is neither a star nor a satellite of a planet".
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, and
has cleared the neighbourhood around its orbit
(official IAU definition dated 24 August 2006) plutoid a celestial body that ...
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.
where, most importantly P=pressure and T=Temperature. The outward pressure nearly balances the inward gravitational pull, a condition called hydrostatic equilibrium.
Age: 1--3 yrs
R ~ 50 Rsun
Tcore = 150,000K
Tsurface = 3500K
Energy Source: Gravity
This whole process acts to maintain hydrostatic equilibrium. As the core then contracts, the energy generation increases, causing the sun to become more luminous. A little-known fact is that the sun is approximately 140% as luminous now as it was when it was born.
The spherical part is important because objects become spherical when they attain a state known as hydrostatic equilibrium, meaning they are large enough for their own gravity to pull them into a round shape. This is a characteristic of planets and not of shapeless asteroids and Kuiper Belt Objects.
A celestial body orbiting the Sun that is massive enough to be rounded by its own gravity but has not cleared its neighboring region of planetesimals and is not a satellite. It has to have sufficient mass to overcome rigid body forces and achieve hydrostatic equilibrium.
Most stars will pass through this region at some time in their lives: they become pulsating variables of some type when they have a small imbalance in the gravitational force and the outward internal pressure so that they are not in hydrostatic equilibrium.
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. At this point, it is no longer a main-sequence star (since it is no longer fusing hydrogen), but becomes a "white dwarf.
charged particles, such as free protons, alpha particles and beta particles, as well as a steady stream of neutrinos. It is the internal pressure of this nuclear fusion process that prevents the Sun from collapsing further under its own gravity (known as a state of hydrostatic equilibrium).
See also: Astro, Solar, Sun, Earth, Planet