Leiden University Obituary

Adriaan Blaauw was the Nestor of Dutch astronomy, a role he fulfilled with visible relish. Never short of a story (or the time to tell it), he loved to talk about astronomy, to anyone. Famous for his ground- breaking research on OB associations and runaway OB stars, and for co-editing Volume 5 (on galactic structure) of the 'Stars and Stellar Systems' series in 1965, he also contributed greatly to astronomy as the chair of the group that defined the input catalogue for the HIPPARCOS mission. His mind was sharp until the end, and many of us will remember conversations over the years in which a recent research result was met with a gracious and genuine complement, accompanied by a probing question delivered with a twinkle in the eyes. These were always moments to treasure, and many students of astronomy, young and old, have enjoyed them. But the fondest memory will be for the warmth of his personality - it is hard to imagine a kinder man.

Adriaan Blaauw was born in Amsterdam 1914, and after meeting Willem de Sitter studied in Leiden from 1932 onwards. While still a student he moved to Groningen as an assistant to van Rhijn, where he obtained his PhD (cum laude) in 1946 on a study of the Scorpio Centaurus Cluster. In 1945 he again joined the staff in Leiden, before becoming associate professor at Chicago's Yerkes Observatory in 1953.

He returned to the Netherlands in 1957 as director of the Kapteyn Institute in Groningen, where he started to build up the present institute. In the meantime he was deeply involved in the foundation of ESO, the European Southern Observatory, initially as its (part-time) scientific director. In 1970 he left Groningen to become the second Director-General. During his tenure he oversaw the move of the organization from Hamburg to Geneva, and the completion of the 'flagship' 3.6m telescope on La Silla. After his term at ESO he became full professor in Leiden, a position he held until his retirement in 1981. He served as president of the International Astronomical Union from 1976 to 1979. His talents as a diplomat served him well, as he succeeded into bringing China back into the IAU.

During his career Adriaan Blaauw saw astronomy change almost out of all recognition. The expansion of the universe, galaxy evolution, the distance scale, stellar evolution, stellar populations, quasars, and many other phenomena were all discovered or eludicated during his lifetime. Space observatories, radio telescopes and computers appeared over the same period, and continue to grow more and more powerful, as do optical telescopes including those of ESO. Earlier this year Adriaan visited Paranal Observatory again, where he could see the progress for himself - by all accounts the twinkle in his eyes, as he asked the astronomers about their observations, was as bright as ever.

Adriaan continued to enjoy good health well into his 90's, and he remained a regular visitor to Leiden. After his retirement he moved back to his historic farm near Groningen and took an emeritus professor appointment at the Kapteyn institute, where he continued to interact with students and staff alike. In this period he saw the HIPPARCOS satellite deliver spectacular results (thanks in no small part to his own contributions and encouragement). History and historical perspective were among his great passions, so not only did he produce an Early History of ESO around 1990 , but he also became involved in researches into the history of the Blaauw family from 17th century sources from Graft in the province of North Holland, where his roots lie. He also invested much energy in setting up the archives of the IAU, making frequent trips to Paris in his trusted small Volvo and producing a History of the IAU in 1994.

In 2004 Adriaan wrote up some of his reminiscences in the Annual Reviews of Astronomy and Astrophysics, and they make great reading. The warmth and humour, the respect and wit, as well as a true historical view, are very inspiring.

We have lost a dear friend, who will be remembered fondly and with admiration for many years. May he rest in peace.

Koen Kuijken Jan Lub