Theoretical gravity darkening as a function of optical depth: A first approach to fast rotating stars

DOI: 
10.1051/0004-6361/201527336
Publication date: 
01/04/2016
Main author: 
Claret A.
IAA authors: 
Claret A.
Authors: 
Claret A.
Journal: 
Astronomy and Astrophysics
Publication type: 
Article
Volume: 
588
Pages: 
Number: 
A15
Abstract: 
Aims. Recent observations of very fast rotating stars show systematic deviations from the von Zeipel theorem and pose a challenge to the theory of gravity-darkening exponents (β1). In this paper, we present a new insight into the problem of temperature distribution over distorted stellar surfaces to try to reduce these discrepancies. Methods. We use a variant of the numerical method based on the triangles strategy, which we previously introduced, to evaluate the gravity-darkening exponents. The novelty of the present method is that the theoretical β1 is now computed as a function of the optical depth, that is, β1 ? β1(τ). The stellar evolutionary models, which are necessary to obtain the physical conditions of the stellar envelopes/atmospheres inherent to the numerical method, are computed via the code GRANADA. Results. When the resulting theoretical β1(τ) are compared with the best accurate data of very fast rotators, a good agreement for the six systems is simultaneously achieved. In addition, we derive an equation that relates the locus of constant convective efficiency in the Hertzsprung-Russell (HR) diagram with gravity-darkening exponents. © ESO 2016.
Database: 
SCOPUS
ADS
WOK
SCOPUS
URL: 
https://ui.adsabs.harvard.edu/#abs/2016A&A...588A..15C/abstract
ADS Bibcode: 
2016A&A...588A..15C
Keywords: 
Binaries: eclipsing; Stars: evolution; Stars: rotation