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We consider the perturbations of a relativistic star as an initial-value problem. Having discussed the formulation of the problem (the perturbation equations and the appropriate boundary conditions at the centre and the surface of the star)…

General Relativity and Quantum Cosmology · Physics 2016-08-25 Gabrielle Allen , Nils Andersson , Kostas D. Kokkotas , Bernard F. Schutz

Mixed modes seen in evolved stars carry information on their deeper layers that can place stringent constraints on their physics and on their global properties (mass, age, etc...). In this study, we present a method to identify and measure…

Solar and Stellar Astrophysics · Physics 2015-06-15 O. Benomar , T. R. Bedding , B. Mosser , D. Stello , K. Belkacem , R. A. Garcia , T. R. White , C. A Kuehn , S. Deheuvels , J. Christensen-Dalsgaard

We present the results of the first theoretical non-radial non-adiabatic pulsational study of M dwarf stellar models with masses in the range 0.1 to 0.5M_solar. We find the fundamental radial mode to be unstable due to an \epsilon mechanism…

Solar and Stellar Astrophysics · Physics 2015-05-30 C. Rodríguez-López , J. MacDonald , A. Moya

We present a comprehensive analysis of high-resolution, far-UV HST/STIS, FUSE, and optical spectra of 17 O stars in the SMC. Our analysis is based on NLTE metal line-blanketed model atmospheres calculated with our NLTE code TLUSTY. We…

Astrophysics · Physics 2009-11-10 Sara R. Heap , Thierry Lanz , Ivan Hubeny

High precision asteroseismic data provide a unique opportunity to test input microphysics such as stellar opacities, chemical composition or equation of state. These tests are possible because pulsational frequencies as well as amplitudes…

Solar and Stellar Astrophysics · Physics 2015-06-18 Przemysław Walczak , Jadwiga Daszyńska-Daszkiewicz

In previous attempts to perform seismic modelling of pulsating subdwarf-B stars, various mode identification techniques are used with uncertain results. We investigated a method so far neglected in sdB stars, but very successful for Main…

Astrophysics · Physics 2007-05-23 C. Schoenaers , A. E. Lynas-Gray

Among A-type main-sequence variables, pulsations of $\delta$ Sct and $\gamma$ Dor variables are driven in the He II ionization zone, while H-ionization zone and strong magnetic fields seem to play roles in the excitation of high-order…

Solar and Stellar Astrophysics · Physics 2013-09-30 Hideyuki Saio

The detection of pulsational frequencies in stellar photometry is required as input for asteroseismological modelling. The second short run (SRa02) of the CoRoT mission has provided photometric data of unprecedented quality and…

We examine pulsational stability of low $m$ $r$ modes in SPB stars by calculating fully nonadiabatic oscillations of uniformly rotating stars, where $m$ is an integer representing the azimuthal wave number around the rotation axis. $R$…

Astrophysics · Physics 2009-11-13 Umin Lee

Rapidly spinning neutron stars are known to harbour pulsation modes that may become unstable and grow in amplitude by emitting gravitational radiation. Among the various stellar modes, the f-mode is the one typically considered as a…

Solar and Stellar Astrophysics · Physics 2015-05-28 Erich Gaertig , Kostas Glampedakis , Kostas D. Kokkotas , Burkhard Zink

Subdwarf B stars show chemical peculiarities that cannot be explained by diffusion theory alone. Both mass loss and turbulence have been invoked to slow down atomic diffusion in order to match observed abundances. The fact that some sdB…

Solar and Stellar Astrophysics · Physics 2015-05-30 Haili Hu , Christopher A. Tout , Evert Glebbeek , Marc-Antoine Dupret

Aims: We investigate from a theoretical perspective if space asteroseismology can be used to distinguish between different thermal structures and shapes of the near-core mixing profiles for different types of coherent oscillation modes in…

Solar and Stellar Astrophysics · Physics 2019-08-20 Mathias Michielsen , May G. Pedersen , Kyle C. Augustson , Stéphane Mathis , Conny Aerts

Tidal interaction in a coalescing neutron star binary can resonantly excite the g-mode oscillations of the neutron star when the frequency of the tidal driving force equals the intrinsic g-mode frequencies. We study the g-mode oscillations…

Astrophysics · Physics 2015-06-24 Dong Lai

Pulsational properties of 1.8 M$_{\odot}$ stellar models covering the latest stages of contraction toward the main sequence up to early hydrogen burning phases are investigated by means of linear nonadiabatic analyses. Results confirm that…

Astrophysics · Physics 2009-11-06 Marian Suran , MarieJo Goupil , Annie Baglin , Yveline Lebreton , Claude Catala

We consider the pulsational properties of white dwarf star models with temperatures appropriate for the ZZ Ceti instability strip and with masses large enough that they should be substantially crystallized. Our work is motivated by the…

Astrophysics · Physics 2009-10-31 M. H. Montgomery , D. E. Winget

Evolutionary models for massive stars, accounting for rotational mixing effects, do not predict any core-processed material at the surface of B dwarfs with low rotational velocities. Contrary to theoretical expectations, we present a…

Astrophysics · Physics 2009-11-13 T. Morel , S. Hubrig , M. Briquet

We present new results for pulsating neutron stars. We have calculated the eigenfrequencies of the modes that one would expect to be the most important gravitational-wave sources: the fundamental fluid f-mode, the first pressure p-mode and…

General Relativity and Quantum Cosmology · Physics 2009-10-30 Nils Andersson , Kostas D. Kokkotas

We review the present-day methods of mode identification applied to main sequence pulsators focusing on those that make use of multicolour photometry and radial velocity data. The effects which may affect diagnostic properties of these…

Solar and Stellar Astrophysics · Physics 2011-12-13 J. Daszyńska-Daszkiewicz , A. A. Pamyatnykh

In this paper we demonstrate how pulsating white dwarfs can be used as an astrophysical laboratory for empirically constraining convection in these stars. We do this using a technique for fitting observed non-sinusoidal light curves, which…

Astrophysics · Physics 2009-11-13 M. H. Montgomery

The recent detection of both pressure and high-order gravity modes in the classical B-type pulsator Gamma Pegasi offers promising prospects for probing its internal structure through seismic studies. To aid further modelling of this star,…

Solar and Stellar Astrophysics · Physics 2021-03-17 C. P. Pandey , T. Morel , M. Briquet , K. Jayakumar , S. Bisht , B. B. Sanwal