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Solar radiation pressure strongly affects comet tails. Solar heating causes gases to be released from the comet nucleus, which also carry away dust grains. Radiation pressure and solar wind then drive the dust and gases away from the Sun's direction. The gases form a generally straight tail, while slower moving dust particles create a broader ...
Bartoli in 1876 had derived the existence of radiation pressure from the principles of thermodynamics. Following Bartoli, Boltzmann considered an ideal heat engine using electromagnetic radiation instead of an ideal gas as working matter. The law was almost immediately experimentally verified.
The results can then be applied more generally, for instance, by representing incoherent radiation as a superposition of such waves at different frequencies and with fluctuating amplitudes. We would thus not be considering the instantaneous E ( t ) and H ( t ) used above, but rather a complex (vector) amplitude for each which describes a ...
This is related to radiation pressure tangential to the grain's motion. This causes dust that is small enough to be affected by this drag, but too large to be blown away from the star by radiation pressure, to spiral slowly into the star. In the Solar System, this affects dust grains from about 1 μm to 1 mm in diameter. Larger dust is likely ...
The thermodynamics of a black-body photon gas may be derived using quantum statistical mechanical arguments, with the radiation field being in equilibrium with the atoms in the wall. The derivation yields the spectral energy density u, which is the energy of the radiation field per unit volume per unit frequency interval, given by: [3]
In forming the stellar structure equations (exploiting the assumed spherical symmetry), one considers the matter density (), temperature (), total pressure (matter plus radiation) (), luminosity (), and energy generation rate per unit mass () in a spherical shell of a thickness at a distance from the center of the star.
The radiation zone is stable against formation of convection cells if the density gradient is high enough, so that an element moving upwards has its density lowered (due to adiabatic expansion) less than the drop in density of its surrounding, so that it will experience a net buoyancy force downwards. The criterion for this is:
The radiation stress tensor, as well as several of its implications on the physics of surface gravity waves and mean flows, were formulated in a series of papers by Longuet-Higgins and Stewart in 1960–1964. Radiation stress derives its name from the analogous effect of radiation pressure for electromagnetic radiation.