12 April 1914 - 1 December 2010
Professor A. Blaauw, a prominent astronomer and investigator in the field of young stars and stellar groups and one of the greatest scientific leaders within the Netherlands and within worldwide astronomy.
Adriaan Blaauw studied in Leiden with W. de Sitter, E. Hertzsprung and J.H. Oort. In 1938 he became a research assistant at the Kapteyn Astronomical Laboratory in Groningen where he obtained his doctorate, cum laude, in 1946. His dissertation, supervised by P.J. van Rhijn, was a study of the Scorpio-Centaurus Cluster, a large group of young stars moving together through the Galaxy. A year earlier he had been appointed "conservator" at the Leiden Observatory where he became a Lecturer in 1948. In 1953 he received an appointment at the Yerkes and MacDonald Observatories, at that time one of the most important centers of astronomical research, and in 1956 he became Associate Director of that institute.
Blaauw's research in these years focussed on the properties of young massive stars and on the groups where they are found. He demonstrated that such groups expand, and the lifetime determined from the motion of the aging groups is consistent with the age determined from the spectra. In this way it is possible to specify the place and time of formation of these groups out of the gas clouds between the stars. Blaauw discovered that some massive stars, the "runaways", can disappear from their birthplace with velocities approaching 100 km/s. In 1957 Blaauw returned to Groningen as Professor and director of the Kapteyn Astronomical Laboratory. This institute had been created in the years between 1890 and 1920 by Jacobus Kapteyn. Kapteyn, using statistical methods, had achieved world fame with his studies of the structure of the Milky Way, but since that time the institute had lost its leading position. By coming to the Kapteyn Laboratory Blaauw made the leap from a great observatory in the United States to a small, old institute in a provincial Dutch city. He renewed the research program and the equipment, strongly increased size and range of the staff, and brought the Kapteyn Laboratory back to the forefront of scientific research. In addition to modern optical methods, radio astronomy and space research came to play a primary role, and the institute itself developed into a major center of research in the international astronomical community. Blaauw's own research culminated in a seminal paper in which he explained runaway stars as a product of double star systems wherein one component explodes as a supernova and the other is flung out of its orbit at great speed. Blaauw followed this up with a highly cited review paper on young stellar groups. In addition, he edited, together with Maarten Schmidt, a book about the structure of the Milky Way. For many years this volume remained the best source of information on this subject.
Many organizations have called upon Blaauw's great managerial talents. For four years (1964-1968) he was the Dean of the Faculty of Mathematics and Natural Sciences in Groningen. For seven years (1958-1965) he was secretary of the Netherlands Foundation for Radio Astronomy, which operated the radio telescope in Dwingeloo and prepared the construction of the Westerbork Synthesis Radio Telescope. At the same time he was the key figure for the preparation and building of the European Southern Observatory (ES0), which is the large European astronomical facility in the southern hemisphere. In 1968 Blaauw became the Scientific Director of ESO and from 1970 until 1975 he was Director-General. During this period ESO grew into a mature, stable organization with a range of different telescopes coming into service; in particular, the large 3.6-m aperture telescope was planned and developed.
After his years at ESO Blaauw was appointed Professor in Leiden. From 1976 until 1979 he was President of the International Astronomical Union (IAU). With his great diplomatic skill he negotiated the return of China to the IAU (China had left the Union in 1961 in protest against the admission of Taiwan). Within the Netherlands he became the first Chair of the ZWO Foundation ASTRON, which played a dominant role in the coordination of astronomical research between the various universities in Holland. He also assumed a leading function in the consortium that specified the scientific program for the satellite HIPPARCOS to be constructed by the European Space Agency, ESA. This instrument subsequently measured with great accuracy the positions of 120 000 stars.
After his retirement in 1981, Blaauw returned to the Kapteyn Institute in Groningen. In his later years he wrote books on the history of the IAU and of ESO, as well as historical studies of the characteristic farms in the province of Drenthe. He remained active in research on young stellar groups, on "runaways" and their relationship with pulsars and supernovae, and he played an active role in scientific discussions at the Kapteyn Institute. Up to his final months he gave numerous interviews and presentations on the history of Dutch and worldwide astronomy.
For his contributions to Dutch astronomy and to society Blaauw was made a Knight in the Order of the Netherlands Lion, and a member of the Royal Dutch Academy of Sciences, as well as various foreign academies. He received many additional honorary awards. His organizational and managerial successes were due to a large degree to his amiable, balanced character, his broad overview and his calm manner of presenting his ideas. He gave his collaborators great freedom and strong support; he had an enormous positive influence on his students and his doctoral candidates. He led the Kapteyn Institute forward in an entirely democratic way long before the movement of 1968 forcibly had such influence on the universities. His special personal qualities have borne rich fruit.