Jeffrey L. Linsky - Böcker

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.

Recent research on the solar-stellar system has been triggered by a host of recent observational data, in particular from space based observations. For this conference the major topics selected centered on new measurement capabilities (magnetic fields and infrared, with specific emphasis on the new IRAS results), important classes of stars (F stars, M dwarfs and giants, and pre-main sequence stars), and interesting unanswered questions (the nature of nonthermal phenomena, heating processes, angular momentum evolution, and the existence and cause of the corona/wind dividing line). Each section is opened by two or more invited lectures aimed at a wide audience, including graduate students, and continues with some research papers. The proceedings also record the two general discussions on the role of magnetic fields in cool star atmospheres and the role of monitoring programs for studies of cool stars (see also Lecture Notes in Physics Vol. 292).

The original plans for a meeting to celebrate the second centenary of the As­ tronomical Observatory of Palermo were for a celebration with a double character. The gathering was to have both a historical character, appropriate for a bicenten­ nial, and a technical character, to note and chronicle the new phase of the history of the Observatory, which has prospered in parallel with the development of this fairly recent topic in astronomical research, the physics of stellar and solar coronae. After the untimely death of the Observatory's Director, Giuseppe S. Vaiana (Pippo to his many friends), a number of colleagues and friends insisted that the celebration should nevertheless be held and should be dedicated to this farsighted scientist who stimulated the development of coronal physics from the early x-ray observations of the solar corona to the recognition of coronae as an observable feature of nearly all stars. This memorial dedication did not change the character of the meeting, which was held in Palermo from 22 to 26 June 1992; as his contributions are very alive in the papers presented at the meeting and collected here, Pippo Vaiana has certainly achieved his place in the history of Astronomy.