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Interpretation of interferometric observations of rapidly rotating stars requires a good model of their surface effective temperature. Until now, laws of the form T_eff \propto g_eff^{\beta} have been used, but they are only valid for…

Solar and Stellar Astrophysics · Physics 2011-09-15 Francisco Espinosa Lara , Michel Rieutord

Context.Interpretation of light curves of many types of binary stars requires the inclusion of the (cor)relation between surface brightness and local effective gravity. Until recently, this correlation has always been modeled by a power law…

Solar and Stellar Astrophysics · Physics 2015-06-11 Francisco Espinosa Lara , Michel Rieutord

In this paper we develop a calculation code to account for the effects carried by fast rotation on the observed spectra of early-type stars. Stars are assumed to be in rigid rotation and the grid of plane-parallel model atmospheres used to…

Astrophysics · Physics 2007-05-23 Y. Fremat , J. Zorec , A. -M. Hubert , M. Floquet

To the best of our knowledge, there are no specific calculations of gravity-darkening exponents for white dwarfs in the literature. On the other hand, the number of known eclipsing binaries whose components are tidally and/or rotationally…

Solar and Stellar Astrophysics · Physics 2021-04-28 A. Claret

Recent interferometric data have been used to constrain the brightness distribution at the surface of nearby stars, in particular the so-called gravity darkening that makes fast rotating stars brighter at their poles than at their equator.…

Solar and Stellar Astrophysics · Physics 2020-03-17 Raphaël Raynaud , Michel Rieutord , Ludovic Petitdemange , Thomas Gastine , Bertrand Putigny

In this lecture I discuss the bulk surface heterogeneity of rotating stars, namely gravity darkening. I especially detail the derivation of the omega-model of Espinosa Lara & Rieutord (2011), which gives the gravity darkening in early-type…

Solar and Stellar Astrophysics · Physics 2016-09-07 Michel Rieutord

We apply a von Zeipel gravity darkening model to corotating binaries to obtain a simple, analytical expression for the emergent radiative flux from a tidally distorted primary orbiting a point-mass secondary. We adopt a simple Roche model…

Solar and Stellar Astrophysics · Physics 2015-06-04 Helen E. White , Thomas W. Baumgarte , Stuart L. Shapiro

Mechanisms influencing absorption line profiles of fast rotating stars can be sorted into two groups; (i) intrinsic variations sensitive to temperature and pressure, and (ii) global effects common to all spectral lines. I present a detailed…

Astrophysics · Physics 2009-11-10 Ansgar Reiners

In this paper, we discuss the influence of the gravitational darkening effect on the emergent spectrum of a fast-rotating, flattened neutron star. Model atmosphere codes always calculate spectra of emergent intensities and fluxes emitted…

High Energy Astrophysical Phenomena · Physics 2022-02-16 A. Majczyna , J. Madej , A. Różańska , M. Należyty

We assume that stars may undergo surface differential rotation to study its impact on the interpretation of $V\!\sin i$ and on the observed distribution $\Phi(u)$ of ratios of true rotational velocities $u=V/V_\rm c$ ($V_\rm c$ is the…

Solar and Stellar Astrophysics · Physics 2017-06-21 J. Zorec , Y. Frémat , A. Domiciano de Souza , F. Royer , L. Cidale , A. -M. Hubert , T. Semaan , C. Martayan , Y. R. Cochetti , M. L. Arias , Y. Aidelman , P. Stee

The spectral energy distribution (SED) of a non-spherical star could differ significantly from the SED of a spherical star with the same average temperature and luminosity. Calculation of the SED of a deformed star is often approximated as…

Astrophysics · Physics 2009-11-11 C. C. Lovekin , R. G. Deupree , C. I. Short

We use the kinematic data of the stars in eight dwarf spheroidal galaxies to assess whether $f(R)$ gravity can fit the observed profiles of the line-of-sight velocity dispersion of these systems without resorting to dark matter. Our model…

Astrophysics of Galaxies · Physics 2023-01-18 Ivan de Martino , Antonaldo Diaferio , Luisa Ostorero

The observed flat rotation curves of galaxies require either the presence of dark matter in Newtonian gravitational potentials or a significant modification to the theory of gravity at galactic scales. Detecting relativistic Doppler shifts…

Astrophysics of Galaxies · Physics 2012-02-15 Alan Cooney , Dimitrios Psaltis , Dennis Zaritsky

The effect of gravitational darkening on models of the thermal structure of Be star disks is systematically studied for a wide range of Be star spectral types and rotation rates. Gravitational darkening causes a reduction of the stellar…

Solar and Stellar Astrophysics · Physics 2015-05-30 M. A. McGill , T. A. A. Sigut , C. E. Jones

Using 2D models of rotating stars, the interferometric measurements of alpha Eri and its fundamental parameters corrected for gravitational darkening effects we infer that the star might have a core rotating 2.7 times faster than the…

Astrophysics · Physics 2016-08-15 J. Zorec , Y. Frémat , A. Domiciano De Souza

I model the effect of rapid stellar rotation on a planet's insolation. Fast-rotating stars have induced pole-to-equator temperature gradients (known as gravity-darkening) of up to several thousand Kelvin that affect the star's luminosity…

Earth and Planetary Astrophysics · Physics 2016-12-07 John P. Ahlers

Thermal evolution of neutron stars is studied in the $f(R)=R+\alpha R^{2}$ theory of gravity. We first describe the equations of stellar structure and evolution for a spherically symmetric spacetime plus a perfect fluid at rest. We then…

General Relativity and Quantum Cosmology · Physics 2023-06-08 Martín Nava-Callejas , Dany Page , Mikhail V. Beznogov

Gyrochronology and recent theoretical findings are used to reduce the number of input parameters of differential rotation models. This eventually leads to a theoretical prediction for the surface differential rotation as a function of only…

Solar and Stellar Astrophysics · Physics 2015-06-04 L. L. Kitchatinov , S. V. Olemskoy

We use Doppler imaging techniques to determine the dependence of starspot rotation rates on latitude in an homogeneous sample of young, rapidly-rotating solar analogues. A solar-like differential rotation law is used, where the rotation…

Astrophysics · Physics 2009-11-10 J. R. Barnes , A. Collier Cameron , J. -F. Donati , D. J. James , S. C. Marsden , P. Petit

As the disk formation mechanism(s) in Be stars is(are) as yet unknown, we investigate the role of rapidly rotating radiation-driven winds in this process. We implemented the effects of high stellar rotation on m-CAK models accounting for:…

Solar and Stellar Astrophysics · Physics 2017-08-30 I. Araya , C. E. Jones , M. Curé , J. Silaj , L. Cidale , A. Granada , A. Jiménez
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