Stellar rotation
type: Concept
related: von Zeipel theorem

von Zeipel theorem
type: Concept
contributor: AAS Frey.Katie
contributor: AAS Frey.Katie Admin
modified: 2020-11-24T17:31:52.824Z
modified: 2020-11-19T16:59:12.832Z
alternative label: von Zeipel's theorem
broader: Analytical mathematics
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.
related: Stellar rotation

Analytical mathematics
type: Concept
narrower: von Zeipel theorem