The Magellanic Clouds

The first book to provide a synthesised and comprehensive account of the Magellanic Clouds.

On March 28 and 29, 1969, at the occasion of the dedication of the European Southern Observatory, some 90 astronomers from all over the world gathered at the ESO headquarters at Santiago de Chile for discussing problems of the Magellanic Clouds. They came from Argentina, Australia, Chile, Mexico, South Mrica and the United States as well as from Europe; these latter, naturally, mostly from the member states ofESO. The choice of the subject was an obvious one. When erecting the European Southern Observatory as a joint effort in European astronomy, it was agreed from the beginning that the field of research should be the southern sky, so far hardly explored with large telescopes. Among the objects to be investigated, the Magellanic Clouds rank highest, together with the galactic centre region and the southern spiral structure. Being located ten times closer than the nearest large stellar systems accessible to northern observers, and containing a stellar population ranging in age from the oldest down of star formation, the Clouds provide an ideal laboratory for research on to the stage current problems in astrophysics. Yet, most of the northern observational astronomers were hardly acquainted with the Magellanic Clouds; naturally, they are used to think in terms of research projects that can be conducted at their observatories. A survey of the status of knowledge and research on the Clouds therefore appeared in order now that the first- medium size- telescopes of ESO came into operation.

Symposium 148 "The Magellanic Clouds and their Dynamical Interaction with the Milky Way" was the first IAU Symposium held in Australia since 1973. In all, 23 countries were represented by 149 participants. The Symposium was held from July 9 to 13, 1990 at Womens College, the University of Sydney. The last symposium on the Magellanic Clouds' was held in 1983 in Ttibingen, Germany. Since then new ground-and satellite-based instruments have become available. A range of results from these instruments were presented at IAU Symposium 148 and are published in these proceedings. IAU Symposium 148 was timed to coincide with the commissioning of the Australia Telescope, and indeed, a few of the first results from that instrument were presented at this Symposium Over the next decade the Australia Telescope is destined to make a major impact on Magellanic Cloud research. Papers are arranged in five main sections reflecting the Symposium timetable: • Large-Scale Structure and Kinematics • Star Formation and Clustering • Stellar Evolution • The Interstellar Medium • The LMC-SMC-Galaxy System These are preceeded by both the introduction to and the summary of the Symposium. Questions and answers from the oral sessions are reproduced at the end of each section.

Around the beginning of the sixteenth century, Portuguese and Dutch sailors first ventured into southern seas. With their keen navigational interest in the skies, they noted the continuous presence of two cloud-like features, not far from the almost immediately Southern Pole. The first literature mention of these 'clouds' was in the journal written in 1520 by the Italian navigator Pigafetta on the first circumnavigation of the globe by Magalhaes (c/. Pigafetta et ai. , 1962). In honour of this exploit, the objects have since become known as the Magellanic Clouds, although the Dutch name 'Kaapsche Wolken' (Cape Clouds - after the Cape of Good Hope) has also been in use for centuries. The Large and Small Magellanic Clouds are dwarf irregular galaxies, orbiting our own Milky Way Galaxy, presently at distances of 53 and 63 kpc respectively (Humphreys, 1984) . . They are the galaxies nearest to us: most other Local Group galaxies are of order ten times more distant. The LMC and SMC are also the prototypical blue dwarf irregulars, representatives of a class of objects in which several hundred more distant objects are now known. Their masses are a few per cent of the mass of the Milky Way Galaxy, but they are relatively gas-rich and appear to be, at the present epoch, forming stars at a more prodiguous rate than our Galaxy (c/. Lequeux, 1984).