High Resolution Infrared Spectroscopy In Astronomy

Two specialized new instruments for ESO's VLT, VISIR and CRIRES, spawned the idea for this workshop. CRIRES is a dedicated very high resolution infrared spectrograph; VISIR features a high resolution spectroscopic mode. Together, the instruments combine the sensitivity of an 8m-telescope with the now well-established reliability of VLT-facility instruments. High resolution here means that lines in cool stellar atmospheres and HII-regions can be resolved. The astrophysical topics discussed in this rather specialized workshop range from the inner solar system to active galactic nuclei. There are many possibilities for new discoveries with these instruments, but the unique capability, which becomes available through high-resolution infrared spectroscopy, is the observation of molecular rotational-vibrational transitions in many astrophysical environments. Particularly interesting and surprising in this context, many papers on modeling and laboratory spectroscopy at the workshop appear to indicate that astronomical observations are lagging a bit behind in this field. The papers are an interesting mix of reports from existing high resolution facilities, reports on modeling efforts of synthetic spectra and reports on laboratory spectra. In this sense, a fruitful exchange between molecular physics and astronomy was again accomplished and is documented in this volume.

Spectroscopy of the Earth's Atmosphere and Interstellar Medium focuses on the characteristics of the electromagnetic spectrum of the Earth's atmosphere in the far-infrared and microwave regions. It discusses the modes of observation in field measurements and reviews the two techniques used in the spectral region. Organized into six chapters, this volume begins with an overview of the effect of water-vapor absorption, followed by a discussion on the two frequently used method for deriving atmospheric parameters from high-resolution infrared atmospheric spectra, namely, the equivalent width (EW) technique and the nonlinear least-square fitting (NLSF). Other chapters consider the mechanisms by which interstellar clouds are formed. In addition, the book explores the composition of interstellar clouds, ion-molecule reactions, and the formation of stars. This book will be useful to anyone involved in, or interested in learning more about the field of atmospheric spectroscopy, including scientists, aeronomers, astronomers, astrophysicists, and students.

Many satellites have recently been launched or are in preparation, which operate in the microwave to IR ranges, the main objective being to observe the earth's atmosphere or interstellar clouds. Analysis of the data they supply requires extensive laboratory work because we still only have sufficiently accurate data (line positions, intensities, and profiles) for only a few species. Furthermore, the observer community is making increasing calls for laboratory data, as new development open up new observational possibilities (such as submillimeter observation). Research on these subjects involves many different areas of specialisation in fields of research that generate a wealth of data. In Spectroscopy from Space the people responsible for field observations explain which results they are expecting from their measurements and how laboratory people can help them to analyse their satellite data. Laboratory spectroscopists explain why what they can do now, and what kinds of experiment and theoretical development that might undertake to meet the needs of the remote sensing community. The problems of distributing reliable laboratory data in a timely way are also addressed.

The last major conference on infrared astronomy was the IAU Symposium No. 96 in June 1980. Since then, the discipline has continued to mature and to contribute to all branches of astrophysics. One particular area of growth has been in spectroscopic capabilities at all infrared wavelengths. The purpose of the Symposium in Toledo was to review the scientific questions to be addressed via infrared spectroscopy and to provide, in the proceedings, a useful summary of the field. The sensitivity of infrared spectroscopic observations is still generally limited by detector characteristics or by thermal background radiation. However in recent years improvements in detector technology together with developments in spectroscopic instrumentation have made possible both quite detailed spectroscopy of the brighter members of many classes of galactic sources and also begun to open up some infrared spectroscopy of extragalactic sources. The potential of the field in the next decade or two is clear. The lRAS mission has completed one of the pre-requisites, namely an all-sky photometric survey. Major space missions utilising cryogenic infrared telescopes have been approved in Europe (ISO) and seem likely in the USA (SIRTF); plans for space submillimeter telescopes are firming up. On the ground large telescopes optimized for infrared observations are now in operation at high altitude sites and specialized submillimeter facilities are under construction. The particular advantages of planned, very large telescopes for infrared observations are widely accepted.

Proceedings of the 132nd Symposium of the International Astronomical Union, held in Paris, France, June 29-July 3, 1987

Thoroughly illustrated and clearly written, this handbook offers graduate students and active researchers a practical guide to astronomical spectroscopy.