Astrophysics (Index)About

Eddington luminosity

(Eddington limit)
(maximum luminosity at which radiation force overcomes gravity)

The Eddington luminosity (or Eddington limit) is a maximum limit on the luminosity of a star or other astronomical body. It is the point beyond which the gravitational force inward is overwhelmed by the outward force of the radiation pressure, and it depends upon the mass. If it were surpassed, the radiation pressure would push material out of the star, reducing its mass and thus bringing its luminosity down to the limit. It represents an upper bound on the luminosity of stars in hydrostatic equilibrium, though they generally are not close to this upper bound.

Eddington luminosity is also relevant to accretion and its resulting luminosity: its formula is used to derive the characteristics of black holes from the luminosity of the resulting quasars. The Eddington accretion rate is the accretion rate at which a black hole reaches Eddington luminosity.

The terms super-Eddington luminosity and super-Eddington accretion indicate these limits are exceeded, which has the implication that the object is undergoing a phenomenon with a short timescale, since with time, it should reach hydrostatic equilibrium. Supernovae fall under this category.

Further reading:

Referenced by pages:
accretion rate
black hole accretion rate (BHAR)
direct collapse black hole (DCBH)
mass-luminosity relation
Salpeter timescale
supermassive black hole (SMBH)
SMBH formation
X-ray burster (XRB)