Very High Angular Resolution Imaging

The 1990s are proving to be a very exciting p&iod for high angular resolution astronomy. At radio wavelengths a combination of new array instruments and pow erful imaging algorithms have generated images of unprecedented resolution and quality. In the optical and infrared, the great technical difficulties associated with constructing separated-aperture interferometers have been largely overcome, and many new instruments are now operating or are being developed. As these pro grams start to produce observational results they will be able to draw extensively on the experience gained by the radio-interferometry community. Thus it seemed that the time was ripe for a meeting which would bring together workers from all wavelength ranges to discuss the details of the science and art of "Very High Angular Resolution Imaging" . While the main emphasis of Symposium No. 158 was on high resolution tech niques from the radio, mm-wave, infrared and optical bands, it also provided an opportunity for presentation of astronomical results from these techniques. As well as giving our colleagues from the Northern Hemisphere a break from midwinter, the location of the Symposium in Australia recognised the continuing development of astronomical interferometry in this country, especially the recent completion of the Australia Telescope radio array, and the progress toward com missioning of the Sydney University Stellar Interferometer. A number of the par ticipants visited these instruments during the post-symposium tour.

This book offers an essential compendium of astronomical high-resolution techniques. Recent years have seen considerable developments in such techniques, which are critical to advances in many areas of astronomy. As reflected in the book, these techniques can be divided into direct methods, interferometry, and reconstruction methods, and can be applied to a huge variety of astrophysical systems, ranging from planets, single stars and binaries to active galactic nuclei, providing angular resolution in the micro- to tens of milliarcsecond scales. Written by experts in their fields, the chapters cover adaptive optics, aperture masking imaging, spectra disentangling, interferometry, lucky imaging, Roche tomography, imaging with interferometry, interferometry of AGN, AGN reverberation mapping, Doppler- and magnetic imaging of stellar surfaces, Doppler tomography, eclipse mapping, Stokes imaging, and stellar tomography. This book is intended to enable a next generation of astronomers to apply high-resolution techniques. It informs readers on how to achieve the best angular resolution in the visible and near-infrared regimes from diffraction-limited to micro-arcsecond scales.

Over the last decade many efforts have been made to develop high angular resolution techniques in astrophysics. Combined with imaging facilities, they have rapidly proved their efficiency and have already led to major astrophysical results. During the decade to come, astronomers will be offered new, even more sophisticated high angular resolution tools, especially in the IR and optical domains, coupled with much bigger telescopes, either on the ground or in space. In such a context of rapidly evolving techniques and a growing need for higher angular resolution to test theories or discover new objects, the present book reviews both instrumental and scientific aspects. The main questions addressed are: what kind of science will benefit from high angular resolution techniques? How can they best be used? Audience: The book is accessible to students and research workers in both instrumental and astrophysical aspects.

Imaging at high angular resolution (HRA) is a ?ourishing discipline. High performance instruments like the spectro-polarimeter SPHERE at VLT/ESO has recently been implemented. A harvest of splendid results is continuously coming from interferometry with PIONIER, MATISSE, and now GRAVITY (all at VLTI/ESO), VEGA and JouFlu (CHARA), and at longer wavelengths with ALMA at VLTI/ESO and NOEMA/IRAM. The future is already underway with the very close launch of JWST/NASA, and the development of ELT at ESO. HRA provides a unique way to study regions of stellar formation, proto-planetary discs as well as the surfaces of stars and their environments. This volume offers lectures given by world experts in the ?eld during the EvrySchatzman School on Stellar Physics (EES 2017) held in Roscoff, France. The addressed topics include a course of introduction to optical/IR interferometry covering the history and basic principles, a course on diffraction-dominated observational astronomy, and a course presenting the principles and instrumentation of optical long baseline interferometry. This book will be a valuable reference for researchers and students in the coming years.

The 11th International Conference on Medical Imaging and Computer Assisted Intervention, MICCAI 2008, was held at the Helen and Martin Kimmel Center of New York University, New York City, USA on September 6–10, 2008. MICCAI is the premier international conference in this domain, with - depth papers on the multidisciplinary ?elds of biomedical image computing and analysis, computer assisted intervention and medical robotics. The conference brings together biological scientists, clinicians, computer scientists, engineers, mathematicians, physicists and other interested researchers and o?ers them a forum to exchange ideas in these exciting and rapidly growing ?elds. The conference is both very selective and very attractive: this year we - ceived a record number of 700 submissions from 34 countries and 6 continents, fromwhich258papers were selectedfor publication,whichcorrespondsto a s- cess rate of approximately 36%. Some interesting facts about the distribution of submitted and accepted papers are shown graphically at the end of this preface. The paper selection process this year was based on the following procedure, which included the introduction of several novelties over previous years. 1. A ProgramCommittee (PC) of 49 members was recruited by the Program Chairs,to getthenecessarybody ofexpertiseandgeographicalcoverage.All PC members agreed in advance to participate in the ?nal paper selection process. 2. Key words grouped in 7 categories were used to describe the content of the submissions and the expertise of the reviewers.

A few years ago, a real break-through happened in observational astronomy: the un derstanding of the effect of atmospheric turbulence on the structure of stellar images, and of ways to overcome this dramatic degradation. This opened a route to diffraction-limited observations with large telescopes in the optical domain. Soon, the first applications of this new technique led to some outstanding astrophysical results, both at visible and infrared wavelengths. Yet, the potential of interferometric observations is not fully foreseeable as the first long-baseline arrays of large optical telescopes are being built or cOIIllnissioned right now. In this respect a comparison with the evolution of radio-astronomy is tempting. From a situation where, in spite of the construction of giant antennas, low angular resolution was prevailing, the introduction of long baseline and very long baseline interferometry and the rapid mastering of sophisticated image reconstruction techniques, have brought on a nearly routine basis high dynamic range images with milliarcseconds resolution. This, of course, has completely changed our views of the radio sky.

This comprehensive and unique reference work on astro-tomography is based on expanded and suitably edited contributions to the 1st International Workshop on Astro-tomography. The focus is on studying indirect imaging and subsequent reconstruction techniques with applications in all areas of observational astronomy, astrophysics and cosmology. Detailed subject and object indexes, together with a list of useful resources on the Internet, will help the reader to use this book in a most efficient way.