In the past decade, indirect (Doppler) imaging techniques have opened up a whole new discipline in stellar astronomy, providing increasingly detailed photometric, magnetic, and chemical inhomogeneity images of stellar surfaces. Furthermore, new optical interferometers are already being used with sophisticated interferometer techniques to image stellar surface structures more directly, and in the future the ESO VLT Interferometer and other instruments will extend these capabilities enormously. These developments are highlighted in the first two sections of this book. The large number of recent results, ground-based and space-based, and the lack of a generally accepted dynamo theory with predictive power for the stars and the Sun, result in an ever-growing complexity of interpretation of individual results. The IAU Symposium 176 on Stellar Surface Structure' consequently focused on spatially resolved stellar observations throughout the H-R diagram, from O- and B-stars to late M-stars. Two further sections in this book summarize the current observational data on surface inhomogeneities in stellar photospheres, chromospheres, and coronae. Finally, a special section is devoted to next generation model atmospheres.

In the past decade, indirect (Doppler) imaging techniques have opened up a whole new discipline in stellar astronomy, providing increasingly detailed photometric, magnetic, and chemical inhomogeneity images of stellar surfaces. Furthermore, new optical interferometers are already being used with sophisticated interferometer techniques to image stellar surface structures more directly, and in the future the ESO VLT Interferometer and other instruments will extend these capabilities enormously. These developments are highlighted in the first two sections of this book. The large number of recent results, ground-based and space-based, and the lack of a generally accepted dynamo theory with predictive power for the stars and the Sun, result in an ever-growing complexity of interpretation of individual results. The IAU Symposium 176 on Stellar Surface Structure' consequently focused on spatially resolved stellar observations throughout the H-R diagram, from O- and B-stars to late M-stars. Two further sections in this book summarize the current observational data on surface inhomogeneities in stellar photospheres, chromospheres, and coronae. Finally, a special section is devoted to next generation model atmospheres.

Celebrating the centenary of George Ellery Hale's discovery of magnetic fields in sunspots, IAU Symposium 273 reviews the recent advances made in the fields of solar and stellar magnetism. Sunspots are responsible for the time-varying properties of the Sun, including the solar irradiance. Combined study of the spots on the Sun and on other stars provides a greater understanding of sunspot formation and behaviour on a long-term basis. On the other hand, stellar observations can be best understood by using detailed properties of the Sun as a reference point. This volume contains reviews and research articles from solar and stellar astronomers on the recent findings of solar and stellar magnetism using observational, theoretical and simulation studies of the Sun and the stars to approach the subject in a unified manner. Its findings are useful to advanced students and researchers in solar and stellar astronomy.

Die Sonne ist ein ziemlich durchschnittlicher Stern, der sich vor allem durch seine geringe Entfernung zur Erde auszeichnet. Bei naherer Betrachtung entpuppt sich die Sonnenoberflache jedoch als wahrer "Hexenkessel" mit Magnetfeldern aller Art, Sonnenflecken, Plasmaeruptionen und plotzlichen Explosionen, die alle einen fundamentalen Einfluss auf unseren Planeten haben, einen Einfluss, den wir erst mit modernster Astronomie messen und verstehen gelernt haben. Dieses Buch erklart die spannenden Innenwelten, die physikalischen Grundlagen und Funktionsweisen der Sonne und der anderen aktiven Sterne. Die aktuellsten Forschungsergebnisse und neuestes Datenmaterial werden fundiert, aber auch fur Laien verstandlich, aufbereitet und mit uber 200 Bildern, teilweise Aufnahmen mit dem Hubble Weltraumteleskop, illustriert."