Helio- and asteroseismology study the interior of the Sun and other stars, by means of observations of oscillations on their surfaces. The last 10 years in the study of the solar interior, to a has witnessed a very rapid evolution point where we can now contemplate investigating the physical state of matter, or the details of rotation and other large-scale motion, in the Sun. The stellar studies are in some respects at the point of the solar studies 10 years ago, but appear poised to take off. Thus the time was deemed ripe for lAO Symposium No 123, to assess the present status of this work, and plan for its future development. Apart from the seismic data, few observations are available to provide information about stellar interiors. Detailed studies, by spectral analysis, can be made of stellar surface properties, including atmospheric temperature and chemical composition. However, the stellar radiative spectrum is almost entirely fixed by the mass, luminosity, radius and surface rotation of the star, and contains essentially no other information about the interior. An important test of stellar evolution theory is provided by observations of stel lar clusters, whose members can reasonably be assumed to have the same age and chemical composition. The location of such stars in a HR diagram, where luminosity is plotted against the effective temperature, can roughly be understood in terms of stellar evolution calculations.

This book discusses the methods used in helio- and asteroseismology for the collection, analysis and interpretation of data. It is the first comprehensive discussion of helioseismic and asteroseismic methodology, collecting techniques from over 300 research papers spread out over decades, with a critical discussion and inter-comparison. It enables the reader to follow the path of inference from the collection of the data at the telescope through to the understanding gained in terms of the modeling of solar and stellar physics and stellar evolution.By focusing on how results are obtained, rather than on the results themselves, this book provides the essential background needed to understand this field, which is rapidly advancing due to the availability of modern observing facilities both on the ground and in space. The material is accessible for advanced undergraduates and post-graduates, and provides an essential resource for researchers in the field./a

This collection of papers offers a timely snapshot of helio- and asteroseismology in the era when SOHO/MDI instrument is about to be replaced by SDO/HMI and when the CoRoT space mission is yielding its first long-duration light curves of thousands of stars.

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.

The history of modern helioseismology is only ten years old. In 1975 F-L Deubner separated for the first time the spatial and temporal pro perties of the solar five-minute oscillations, and was thus able to measure the dispersion relation for high-degree acoustic modes (p modes). The diagnostic value of these observations was appreciated immediately. Indeed, by comparing the observed relation with computations that had already been carried out by R.K. Ulrich, and subsequently by H. Ando and Y. Osaki, it was recognised that contemporary solar models that had been constructed with the low observed neutrino flux in mind were too hot in their outer layers. Moreover, their convection zones were too shallow. Since that time the observations have improved. There is now good reason to suppose that a sufficiently careful analysis will lead to a direct determination of the helium abundance in the solar convection zone, especially when foreseeable further improvements in the observations have been achieved. The data will also provide useful diagnostics of the uncertain equation of state of partially ionized plasmas, and they might also enable us to measure the large-scale structure of the convec tive flow.

The cover picture of this volume displays one of the most advanced products of he lioseismic research: a view into the deep interior of the sun, revealing its distinctly non-uniform rotation throughout the entire depth of the convection zone. Just over 20 years ago, the first successful helioseismic experiment disclosed an increase of ro tation velocity in the uppermost one dozen megameters below the photosphere. The stunning progress in depth and detail highlighted by the cover diagram (and by others shown in this volume as well) was made possible by considerable advances in instru mentation, by the development of powerful analytical tools and, foremost, by the involvement of new brains of enthusiastic proselytes and newcomers to the field, in creasing nearly exponentially in number every year. New branches of research widened the scope of "uranoseismology", as e. g. time-distance seismology (the promising av enue towards small-scale and short-time variability), atmospheric seismology (a new look at strange phenomena we have all ways seen, but hardly understood), and finally the growing observational assault on hundreds of individual stars which are either manifestly or supposedly oscillating -i. e. asteroseismology. The formation of numer ous solar and stellar observing networks and, ultimately, space missions like SOHO have greatly promoted the potential of this science. This steady progress was accompanied by workshops, colloquia, and symposia in quick succession.