Astronomiske observationer: observatorier, udstyr og metoder

Ken Freeman I would like to pick out a few items that I found particularly interesting. The choice probably reflects my ignorance, because many of these topics are no doubt more known to most of you. I am fairly sure that some of them are basic and important. We will start with the first session. There were three closely related papers on the evolution of massive stars, the formation of open clusters and associations and the IMF. We learned that clusters appear to form in initially bound clouds 6 of masses between 10'+_10 M , but star formation is a destructive process. Most of the gas is@ lost and the remaining stars then find themselves in an unbound system, which naturally disperses on a dynamical time. As a result of this, star formation is typically a fairly inefficient process, at least on the scale of open clusters. However (as Heggie pointed out) it seems to be somewhat more efficient on smaller scales, as evidenced by the fairly high incidence of binary stars. To form a bound cluster requires a higher efficiency of star formation, typically 30% or more, and we see how the three papers of this morning session relate: the initial mass function and the timing of where and when the DB stars form dictate the likely fate of the system.

Ever since the serendipitous discovery of planet Uranus in 1871, astronomers have been hunting for new worlds in the outer regions of our solar system. This exciting and ongoing quest culminated recently in the discovery of hundreds of ice dwarfs in the Kuiper belt, robbed Pluto from its 'planet' status, and led to a better understanding of the origin of the solar system.This timely book reads like a scientific 'who done it', going from the heights of discovery to the depths of disappointment in the hunt for 'Planet X'. Based on many personal interviews with astronomers, the well-known science writer Govert Schilling introduces the heroes in the race to be the first in finding another world, bigger than Pluto.

More than half of all stars in the universe formed and evolved as binary systems and their study is essential for understanding stellar and galactic evolution. The six lectures in this book give both a readable introduction and an up-to-date review of nearly all aspects of  research into binary stars, including the range from common binaries to more exotic systems composed of white dwarfs, neutron stars and black holes.

ELlA M. LEIBOWITZ Director, Wise Observatory Chair, Scientific Organizing Committee The international symposium on "e;Astronomical Time Series"e; was held at the Tel Aviv University campus in Tel Aviv, from December 30 1996 to January 11997. It was organized in order to celebrate the 25th anniversary of the Florence and George Wise Observatory (WO) operated by Tel Aviv University. The site of the 1 meter telescope of the observatory is near the town of Mitzpe-Ramon, some 220 km south of Tel Aviv, at the center of the Israeli Negev highland. There were two major reasons for the choice of Time Series as the sub- ject matter for our symposium. One is mainly concerned with the subject matter itself, and one is related particularly to the Wise Observatory. There is hardly any doubt that astronomical time series are among the most ancient concepts in human civilization and culture. One can even say that astronomical time series preceeded astronomy itself, as the impression of the day /night cycle on Earth is probably the first and most fundamental effect that impress a. human being, or, in fact, most living creatures on this planet. An echo of this idea. can be heard in the Biblical story of Creation, where the concept of night and day preceeds the creation of the astronomical objects.

The systematic study of the planets has experienced a slow but steady progress from the efforts of a single individual (Galileo Galilei, 1564-1642) to nations that individually and collectively create whole agencies and complex infrastructures devoted to the exploration and understanding of our solar system. This quest for knowledge continues in earnest today as we attempt to understand Earth's unique place among its closest neighbors. Known diversities emphasize fractionation processes that may have occurred in the nebula during early solar system formation, and the vastly different evolutionary paths taken by the planets and their satellites. The discovery of similarities and differences among the planets has given rise to a discipline of "e;Comparative Planetology. "e; Here terrestrial properties and giant planet atmospheres are viewed and probed, surface geologies are related to atmospheres and oceans, interior structures are envisioned, magnetic fields mapped, and bizarre differences in satellites and ring systems continue to enlighten, amaze and confound the detectives of planetary science. A science organizing committee with international participation was formed to develop a conference program to address the basic issues and the fundamental processes that are common among the planets. The goals of the meeting were twofold: first the production of a reference source on comparative planetology for academia, and second, the provision of an impetus for NASA to begin a program devoted to this emerging science discipline. The conference program accommodated seventeen invited papers and nineteen poster presentations.

"e;You will hold in your hands the proceedings of the last conference ever on integral-?eld spectroscopy."e; So the daring statement that we, organizers, made at the end of an extremely interesting and busy week of conference in October 2005. Indeed, the quality and diversity of the contributions in this book indicated that integral-?eld spectroscopy had evolved into a mature technique. Future books would not be dedicated to the technique as such but to the science achieved with '3D-spectroscopy,' that is a dedicated book after thisone,assemblingscienceresultsacrosssomany?elds,isunlikelytoappear again (or have you seen a proceeding dedicated to 'long-lit spectroscopy' recently?). In a sense this is very encouraging. The idea of this conference was an o?springoftheResearchandTrainingNetwork(RTN)'Euro3D'sponsoredby the European Commission. The goal of this network was to promote integr- ?eld spectroscopy from an technique for experts to a common user utility for astronomical research. When we ?rst talked about this conference the VLT, for example, was not yet equipped with any integral-?eld spectrograph. We were wondering whether anyone would actually attend the conference in 4 years' time and would have anything to report upon. We were rewarded for our optimism and very positively surprised about the progress made in the years after that. A progress, of course, driven by theadventofsomanyintegral-?eldspectrographsaroundtheworld,installed on 4m to 8-10m class telescopes. Many of these instruments are referred to in the present book. Yet, this is explicitly not a book dedicated to technical issues,butfocusingonthescience.Thus,thenameoftheconference,Science Perspectives for 3D Spectroscopy.

In the history of science the opening up of a new observational or experimental window is always followed by an increase in knowledge of the subject concerned. This is also the case with the subject of this book, ultraviolet radiation (hereafter UV). In principle, the ultraviolet range might be just one more of these windows, of no particular importance. However, the energy per UV photon provides the main peculiarity, its magnitude being great enough to produce important ch- ical reactions in the atmospheres of planets and satellites, thereby a?ecting the transmission of this radiation to the ground. The Sun is the main natural source of UV radiation in the Solar System and our planet is the body where its in?uences can be best tested and the only one where its relation with life can be studied. However, the terrestrial atmosphere blocksmostofthephotonsinthiselectromagneticrangeandastronomershavehad to develop various techniques (balloons, planes and rockets) to cross this barrier and access the information. These tools have been used in parallel to investigate the physical properties of the terrestrial atmosphere and the interaction of its constituents with light. This book will addresses most of these topics.