Gravity darkening in rotating stars

By F. Lara, Michel Rieutord. 2011

191 citations recorded by the source corpus.

Context. Interpretation of interferometric observations of rapidly rotating stars requires a good model of their surface effective temperature. Until now, laws of the form Teff ∝ g βff have been used, but they are only valid for slowly rotating stars. Aims. We propose a simple model that can describe the latitudinal variations in the flux of rotating stars at any rotation rate. Methods. This model assumes that the energy flux is a divergence-free vector that is antiparallel to the effective gravity. Results. When mass distribution can be described by a Roche model, the latitudinal variations in the effective temperature only depend on a single parameter, namely the ratio of the equatorial velocity to the Keplerian velocity. We validate this model by comparing its predictions to those of the most realistic two-dimensional models of rotating stars issued from the ESTER code. The agreement is very good, as it is with the observations of two rapidly rotating stars, α Aql and α Leo. Conclusions. We suggest that as long as a gray atmosphere can be accepted, the inversion of data on flux distribution coming from interferometric observations of rotating stars uses such a model, which has just one free parameter.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/f5fad3ecbc4a97bbacdc1c74c73b8ed385e12385

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Citations in the corpus

Classical Be stars (2013, background): “An alternative to a fixed β , better reproducing the observed distribution of values, has been proposed by Espinosa Lara and Rieutord (2011), where β itself becomes a function of W .”
Improvements to stellar structure models, based on a grid of 3D convection simulations. II. Calibrating the mixing-length formulation (2014, methodology): “For fast rotators, more elaborate models are needed [See, e.g., Espinosa Lara & Rieutord (2011) for analytical 2D work and Augustson et al. (2012) for 3D hydrodynamics simulations], but the behaviour of Smax(Teff , log g) in Fig.”
The Gemini Planet Imager Exoplanet Survey: Giant Planet and Brown Dwarf Demographics from 10 to 100 au (2019, methodology): “A two-dimensional model of the star was constructed using the formalism described in Lovekin et al. (2006) and Espinosa Lara & Rieutord (2011) to account for the latitudinal dependence of the effective temperature and surface gravity, and for the angle between the rotation axis and the observer.”