Eddington luminosity

As Eddington limit or Eddington limit ( after the British physicist Sir Arthur Stanley Eddington ) is called in astrophysics the natural limit of the luminosity. It is the largest river of energy that can be transported by a hydrostatic gas stratification mittls radiation to pass before the radiation pressure overcomes the hydrostatic pressure. Radiation pressure comes about by scattering of the radiation by free electrons, the Thomson scattering. The luminance of a particular object, wherein the hydrostatic pressure would be overcome by the radiation pressure is Eddington luminosity.

The Eddington limit is thus the maximum luminosity that can have a star in hydrostatic equilibrium, without becoming unstable and repel its outer layers. Nevertheless, stellar winds are however already in stars significantly below the limit before. While viewing Eddington strictly applies only approximately at stars that give off a stellar wind and therefore are not in hydrostatic equilibrium; However, the Thomson scattering has the property of not to depend on the depth in the star in stars. Because the energy release region inside the star but is much smaller than the region that is affected by the stellar wind, the Eddington limit is nevertheless a meaningful limit. Note, however, that the Eddington limit is derived one-dimensional and time-independent - that is, it is both possible that a star only temporarily exceed the limit without being destroyed, and that a two-dimensional interaction of stellar wind and radiation total a luminosity excess of the limit allows. The latter is drawn, for example, the outbursts of η Carinae into consideration.

Significantly, the Eddington limit is also in accretion of matter onto a compact object such as a black hole, because when the luminosity exceeds the Eddington limit, the associated radiation pressure is so high that the infalling material is pushed outward. But so that the power supply is cut off at the same time so that the luminance drops below the Eddington limit and the material can flow back. This process can be repeated periodically.

The Eddington limit is a function of the mass of the object that accretes the surrounding material:

It is

• The maximum of the brightness, which can be caused by accretion
• The mass of the compact object
• The mass of the Sun
• The luminosity of the sun.