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Small cyclic variations in the frequencies of acoustic modes are expected to be a common phenomenon in solar-like pulsators, as a result of stellar magnetic activity cycles. The frequency variations observed throughout the solar and stellar…

Solar and Stellar Astrophysics · Physics 2015-06-12 A. R. G. Santos , M. S. Cunha , J. J. G. Lima

Gravity-mode asteroseismology has significantly improved our understanding of mixing in intermediate mass stars. However, theoretical pulsation periods of stellar models remain in tension with observations, and it is often unclear how the…

Solar and Stellar Astrophysics · Physics 2023-06-28 Vincent Vanlaer , Conny Aerts , Earl P. Bellinger , Jørgen Christensen-Dalsgaard

We derive the perturbation equations for relativistic stars in scalar-tensor theories of gravity and study the corresponding oscillation spectrum. We show that the frequency of the emitted gravitational waves is shifted proportionally to…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Hajime Sotani , Kostas D. Kokkotas

A brief review of the stability of rotating relativistic stars is followed by a more detailed discussion of recent work on an instability of r-modes, modes of rotating stars that have axial parity in the slow-rotation limit. These modes may…

General Relativity and Quantum Cosmology · Physics 2008-11-26 John L. Friedman , Keith H. Lockitch

Stars are changing entities in a constant evolution during their lives. At non-secular time scales (from seconds to years) the effect of dynamical processes such as convection, rotation, and magnetic fields can modify the stellar…

Solar and Stellar Astrophysics · Physics 2019-07-09 S. Mathur , J. Ballot , R. A. Garcia

Thanks to their high quality, new and upcoming asteroseismic observations - with CoRoT, Kepler, and from the ground... - can benefit from the experience gained with helioseismology. We focus in this paper on solar-like oscillations, for…

Astrophysics · Physics 2008-04-02 J. Ballot , T. Appourchaux , T. Toutain , M. Guittet

The internal gravity waves far field exited by a non-local perturbation sources was considered. A separate wave mode asymptomatic presentation was constructed, describing the wave field key features depending on the source geometry.

Fluid Dynamics · Physics 2009-11-18 Vitaly V. Bulatov , Yuriy V. Vladimirov

Knowledge of the geometry of pulsational modes is a prerequisite for seismic modelling of stars. In the case of slowly pulsating B-type (SPB) pulsators, the simple zero-rotation approach so far used for mode identification is usually not…

Solar and Stellar Astrophysics · Physics 2015-06-24 W. Szewczuk , J. Daszyńska-Daszkiewicz

We investigate inertial mode oscillations of slowly and uniformly rotating, isentropic, Newtonian stars. Inertial mode oscillations are induced by the Coriolis force due to the star's rotation, and their characteristic frequencies are…

Astrophysics · Physics 2016-08-30 Shijun Yoshida , Umin Lee

Sharp structural variations induce specific signatures on stellar pulsations that can be studied to infer localised information on the stratification of the star. This information is key to improve our understanding of the physical…

The spectrum of oscillation modes of a star provides information not only about its material properties (e.g. mean density), but also its symmetries. Spherical symmetry can be broken by rotation and/or magnetic fields. It has been…

Solar and Stellar Astrophysics · Physics 2018-04-25 Shyeh Tjing Loi , John C. B. Papaloizou

Asteroseismology allows us to probe the physical conditions inside the core of red giant stars. This relies on the properties of the global oscillations with a mixed character that are highly sensitive to the physical properties of the…

Solar and Stellar Astrophysics · Physics 2015-11-18 B. Mosser , M. Vrard , K. Belkacem , S. Deheuvels , M. J. Goupil

A method for obtaining asteroseismological information of a Gamma Doradus oscillating star showing at least three pulsation frequencies is presented. This method is based on a first-order asymptotic g-mode expression, in agreement with the…

Astrophysics · Physics 2009-11-10 A. Moya , J. C. Suarez , P. J. Amado , S. Martin-Ruiz , R. Garrido

Context: Mode identification has remained a major obstacle in the interpretation of pulsation spectra in rapidly rotating stars. Aims: We would like to test mode identification methods and seismic diagnostics in rapidly rotating stars,…

Solar and Stellar Astrophysics · Physics 2017-05-24 D. R. Reese , F. Lignières , J. Ballot , M. -A. Dupret , C. Barban , C. van 't Veer-Menneret , K. B. MacGregor

Dynamics of sine-Gordon kinks in the presence of rapidly varying periodic perturbations of different physical origins is described analytically and numerically. The analytical approach is based on asymptotic expansions, and it allows to…

Strong magnetic fields in relativistic stars can be a cause of crust fracturing, resulting in the excitation of global torsional oscillations. Such oscillations could become observable in gravitational waves or in high-energy radiation,…

Astrophysics · Physics 2009-11-06 Neophytos Messios , Demetrios B. Papadopoulos , Nikolaos Stergioulas

We calculate non-axisymmetric oscillations of uniformly rotating polytropes magnetized with a purely toroidal magnetic field, taking account of the effects of the deformation due to the magnetic field. As for rotation, we consider only the…

Solar and Stellar Astrophysics · Physics 2015-06-24 Hidetaka Asai , Umin Lee , Shijun Yoshida

Asteroseismology, the study of stellar vibration, has met with great success, shedding light on stellar interior structure, rotation, and magnetism. Prominently known as $\delta$ Scutis, intermediate-mass main-sequence oscillators that…

Solar and Stellar Astrophysics · Physics 2024-10-01 Subrata Kumar Panda , Shravan Hanasoge , Siddharth Dhanpal , Vageesh D. C

We examine the potential of asteroseismology for exploring the internal rotation of white dwarf stars. Data from global observing campaigns have revealed a wealth of frequencies, some of which show the signature of rotational splitting.…

Astrophysics · Physics 2009-10-31 Steven D. Kawaler , Takashi Sekii , Douglas Gough

Oscillation properties are usually measured by fitting symmetric Lorentzian profiles to the power spectra of Sun-like stars. However the line profiles of solar oscillations have been observed to be asymmetrical for the Sun. The physical…

Solar and Stellar Astrophysics · Physics 2018-05-02 O. Benomar , Mjo. Goupil , K. Belkacem , T. Appourchaux , M. B. Nielsen , M. Bazot , L. Gizon , S. Hanasoge , K. R. Sreenivasan , B. Marchand
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