| definition |
A theorem that establishes a relation between the radiative flux at some colatitude
on the surface of a rotating star and the local effective gravity (which is a function
of the angular velocity and colatitude). For a rotating star in which centrifugal
forces are not negligible, the equipotentials where gravity, centrifugal force, and
pressure are balanced will no longer be spheres. The theorem states that the radiative
flux is proportional to the local effective gravity at the considered colatitude,
F(θ) ∝ g_eff (θ)α, where α is the gravity darkening coefficient. As a consequence,
the stellar surface will not be uniformly bright, because there is a much larger flux
and a higher effective temperature at the pole than at the equator (T_eff (θ) ∝ g_eff
(θ)β, where β is the gravity darkening exponent. In massive stars this latitudinal
dependence of the temperature leads to asymmetric mass loss and also to enhanced average
mass loss rates.
|
|
