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Our understanding of stars has grown significantly due to recent advances in asteroseismology, the stellar analog of helioseismology, the study of the Sun's acoustic wave oscillations. Using ground-based and satellite observatories to measure the frequency spectra of starlight, researchers are able to probe beneath a star's surface and map its interior structure. This volume provides a wide-ranging and up-to-date overview of the theoretical, experimental and analytical tools for carrying out front-line research in stellar physics using asteroseismological observations, tools and inferences. Chapters from seven eminent scientists in residence at the twenty-second Canary Islands Winter School of Astrophysics examine the interior of our Sun relative to data collected from distant stars, how to measure the fundamental parameters of single field stars, diffusion processes, and the effects of rotation on stellar structures. The volume also provides detailed treatments of modeling and computing programs, providing astronomers and graduate students a practical, methods-based guide.

Astroseismology --- Astero-seismology --- Asteroseismology --- Extraterrestrial seismology --- Stellar oscillations

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Studying pulsation spectra through asteroseismology allows probing the inner structure of stars. Core helium burning stars, specifically subdwarf type B stars, have been observed to harbour pressure and gravity mode pulsations, allowing respectively to probe the envelope and core of such stars. In particular, observations show a dichotomy in gravity modes pulsation spectra, with sometimes structures called trapped modes, which induce variable period spacings between observed periods, and other times no trapped modes at all, with a rather smooth pulsation spectra showing more or less constant spacings instead. In this master thesis, we model subdwarf type B stars with both 4th generation static models and evolutionary models, using the STELUM and PULSE codes. Through this, we aim to gain insights on the influence of core helium burning on the pulsation spectra. We highlight as well the influence of the chemical and thermal structures on the behavior of pulsation spectra, in particular the mass of the core and envelope, as well as the thermal gradients prescriptions. A clear distinction is made between evolutionary and static models. The latter are studied first, and we discuss the origin of trapped modes from chemical transitions and temperature gradients in such models. In evolutionary models, we focus on the overshooting and semi-convection phenomena, which are not found in static models, and study their impact on the chemical and thermal structure of the star, as well as on the pulsation spectra. This master thesis gives the theoretical basis of pulsation spectra computed from current available stellar models of subdwarf B stars, now to be compared in detail with observations of such stars, in particular those observed by the Kepler and TESS satellites.

asteroseismology --- astrophysics --- sdB stars --- numerical simulations --- Physique, chimie, mathématiques & sciences de la terre > Aérospatiale, astronomie & astrophysique

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Astroseismology --- Helioseismology --- Solar dynamics --- Solar seismology --- Astero-seismology --- Asteroseismology --- Extraterrestrial seismology --- Stellar oscillations --- Helioseismology - Congresses. --- Astroseismology - Congresses.

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Stars --- Astrogeology --- Stellar oscillations --- Seismology --- European Helio- and Asteroseismology Network --- Convection, Rotation and Planetary Transits (CoRoT) Telescope --- Evolution and Seismic Tools Activity (ESTA) Team

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This volume presents a timely snapshot of the state of helio- and asteroseismology in the era when the SOHO/MDI instrument is about to be replaced by SDO/HMI and the CoRoT space mission is yielding its first long-duration light curves of thousands of stars. The articles and topics in this book are inspired by two seminal conferences, HELAS II and SOHO19/GONG 2007, but contributions from other experts have been commissioned as well. For example, three key papers were invited to describe the current status of asteroseismology, global helioseismology, and local helioseismology. These papers provide a framework for the other contributions and together they form a complete description of our understanding of pressure waves in the Sun and other stars. This volume is aimed at solar physicists and astronomers specializing in helio- and asteroseismology.

Seismology --- Astroseismology. --- Astero-seismology --- Asteroseismology --- Seismography --- Physics. --- Astrophysics. --- Astrophysics and Astroparticles. --- Astronomical physics --- Astronomy --- Cosmic physics --- Physics --- Natural philosophy --- Philosophy, Natural --- Physical sciences --- Dynamics --- Extraterrestrial seismology --- Stellar oscillations --- Geophysics --- Earthquakes