ANNOUNCEMENTS

Adriaan Blaauw at 80 S.R. POTTASCH, Kapteyn Laboratorium, Groningen, Netherlands

On 12 April 1994, Adriaan Blaauw mation of the occurrence of stellar Orion OBI Association with four sub­ celebrated his 80th birthday. He neither groups of recent formation, (2) the dis­ groups formed over the past 12 mil­ looks nor acts this age: he still spends covery of the process of sequential star lion years. much of his time actively engaged in formation, and (3) his work on the class 3. Regarding the runaway stars, it was scientific work. His impact on (Euro­ of early-type stars with anomalously already know in the early 1930's that pean) astronomy has been great and it high velocities, the "runaway" stars. early-type stars have small random is useful to examine it more closely. These investigations would bear fruit velocities. However, about 10 % of also in studies of the star formation pro­ the 0 stars have high radial velocities cess. which did not fit into the universal Short Sketch of his Career 1. In the late 1940's, there was property of slow moving luminous Adriaan was born in Amsterdam in accumulating evidence that besides stars. The possibility that these mo­ 1914. In 1932 he began his studies of the majority of stars with ages of the tions were due to undiscovered spec­ Astronomy at Leiden University. He be­ order of that of the solar system, to be troscopic binaries was ruled out, as came an "Assistant" at the Kapteyn In­ counted in billions of years, the ages was the possibility that they were due stitute in Groningen in 1938, although he of the most massive stars in the to systematic atmospheric motions. A was officially still a student at Leiden, Galaxy would have to be counted in study of the proper motions indicated obtaining his "doctoraal" degree there in millions of years only. The evidence that at least some of these stars had 1941. He spent the war years in was based, on the one hand, on the transverse motions which were Groningen, moving to a staff position at new understanding of stellar nuclear equally large. Adriaan concluded that Leiden in October 1945. He defended energy sources (closely related to these high velocities were real mo­ his thesis "A study of the Scorpio-Cen­ work on nucleosynthesis in the years tions in space. taurus Cluster" in 1946 at Groningen during and immediately after the Sec­ How had these motions originated (advisor, P.J. van Rhijn). In 1948 Adriaan ond World War) and, on the other and why was there a clear-cut became Associate Professor of As­ hand, on the study of the structures dichotomy between fast and slow tronomy at Leiden University. He re­ and equilibrium conditions of loose moving stars? An important clue was signed from this position in 1953 to stellar groups, the Stellar Associa­ that these runaway stars were mostly accept a similar position at the Universi­ tions. Adriaan studied known OB­ single stars. Adriaan suggested that ty of Chicago (Yerkes Observatory) Associations and identified new ones these stars had originally been part of where he remained for four years. Dur­ (the Sea-Cen, the Per OBII, the Lac a massive binary system which had ing the last year of his stay he was also OBI Associations), and provided di­ suddenly been disrupted because the Associate Director of Yerkes and Mac­ rect confirmation of these very young primary of the system became a Donald Observatories. ages by means of investigations of supernova, so that the component At the end of 1957 Adriaan returned to their internal motions. These revealed was released at a velocity of the order the Netherlands as Professor at a general expansion, confirming that of the orbital velocity. This relatively Groningen University and Director of the they are unbound systems that must simple solution was first published in Kapteyn Institute, which he remained have been born only millions of years 1961. An interesting aspect of these until 1970. His growing involvement with ago. An important implementation of studies is that for nearby runaway ESO (see below) led to his formal "half­ these various lines of evidence was stars with accurate proper motions it time" appointment as Scientific Director that star formation in the Galaxy must is possible to identify the OB Associa­ of ESO in 1968. In 1970 he reversed still be going on today. tion from which the star originated. In these associations, becoming Director 2. His study of the structures and stellar such cases the epoch of the super­ General of ESO and part-time Professor content of the OB Associations re­ nova explosion can be fixed with high at Groningen. This situation lasted five vealed that these consist of spatially accuracy (of the order of several years, after which Adriaan returned to separated subgroups, separated in tenths of a million years) and it is also the Netherlands, but this time as Pro­ age by intervals of several millions of possible to determine the distance, fessor at Leiden. He retired from there in years, and this led him to the conclu­ and hence the absolute magnitude of 1981 to settle in his beautiful, centuries sion that star formation occurs step­ the star with high accuracy. These old, farmhouse in the province of wise. The process has since become studies therefore also bear fruit in Drenthe, not far from Groningen Univer­ known as "sequential star formation", other ways, for instance for stellar sity. Here he became Advisor to the and is now recognized as a general astrophysicists working on models of Department of Astronomy, a function characteristic of the formation of atmospheres of early-type stars. A which he actively fulfils at present. massive stars. In many cases there is recent example is his study of the close association of the youngest of bright runaway star Zeta Puppis. these subgroups with the interstellar Scientific Research in Astronomy molecular cloud medium from which Some Details on the Association Adriaan's name is mostly associated the association has emerged. Exam­ withESO with investigations on massive stars, the ples are the Sco-Cen Association o and B-type Stars. Of these we with at least four subgroups formed Discussion about the need for a joint summarize (1) the observational confir- over the last 15 million years, and the European observatory in the southern 62 hemisphere first began to take form af­ began to feel that their work was not Mention must also be made of ter the last war. In 1953 at a conference widely read and some were considering Adriaan's work for the international on galactic structure in Groningen (IAU publishing their best work in the Astronomical Union, of which he Symposium 1), informal talks were held Astrophysical Journal. The initiative to was President from September 1976 to the day before the conference began merge the national journals came, as August 1979. He is especially remem­ among various European astronomers might be expected, from their editors, bered for his efforts to include China about the possibilities. Adriaan took part especially J.-L. Steinberg and myself. A and the vast majority of Chinese as­ in these discussions but just after this meeting took place in April 1968 of tronomers as members of the IAU. conference he accepted the position at astronomers from Belgium, Denmark, These efforts bore fruit as Chinese Yerkes Observatory. Because he ex­ France, Germany and the Netherlands membership was confirmed at the Pa­ pected to remain there he took no fur­ to prepare a possible merger. it was tras meeting in 1982. A discussion of the ther part in the ESO planning until the immediately clear that scientifically the details of these negotiations as well as a end of 1957, at which time he returned difficulties of such a merger were rela­ general history of the IAU has just been to Europe as Professor of Astronomy tively minor (but not non-existent). A completed by Adriaan and should be (and Director of the Kapteyn Institute) at much greater problem were the financial available before the General Assembly Groningen. Although a "statement of and administrative aspects. If the same of this year. intent" had been signed in 1954, only procedure had been followed as by the limited progress was made in the early creation of ESO, a journal might have years. Positive was the beginning of site been formed many years before. Non-Astronomical Scientific testing in South Africa. The financial Adriaan, as ESO representative at the Activity basis remained weak and dependent on meeting, suggested circumventing the voluntary contributions of the future difficult procedure. He offered the ser­ Adriaan has also been scientifically member states. In October 1957 the vices of ESO as "legal person" respon­ active in a field quite different from committee of astronomers which was sible for the financial and administrative astronomy: the early history of farmers­ meeting periodically (about once a year) state of the journal. This would make it settlements. It started with research on to discuss the project assumed a more easy for national governments to make the history of the structure and inhabit­ formal form with the appointment of a financial contributions to an internation­ ants of the 17th-century farmhouse he Chairman (Oort) and a Secretary al organization, since an official treaty acquired and restored in the 1960's. (Bannier). In May 1959 Adriaan suc­ already eXisted. A Board of Directors This gradually developed into his sys­ ceeded Bannier as Secretary of this with representatives of the sponsoring tematically investigating aspects of the "provisional council" until succeeded by countries was set up, which took over history of a nearby village, typical for the Heckmann in 1963. During this period the financial and administrative dealings settlements in the north-east of the substantial progress had been made in of the journal. The editors were then Netherlands. These studies were based the organization of ESO, leading to the only responsible for the scientific deal­ on archival data in Dutch State Archives. signing of the Convention in Oc­ ings of the journal. The Board fixed gen­ After having published several articles in tober 1962. eral policy (e.g. which languages were professional History Journals, he pub­ Adriaan continued to be involved in acceptable, who were to be the editors) lished a book on the village Westervelde the development of ESO. At the begin­ but was not involved in the processing in 1987, in which he covered cultural, ning of 1968 this was formalized by his of articles. Adriaan was elected the first agricultural and social aspects in the appointment as Scientific Director of Chairman of the Board of Directors in 17th, 18th and 19th century. This study ESO. This was a "half-time" function October 1968 and held the position until has turned out to be useful in courses and he combined it with his work in March 1979. When he resigned, the on legal anthropology at Groningen Uni­ Groningen by driving to and from Ham­ journal was well established and both versity. burg (where ESO had its headquarters financially and scientifically "healthy". at the time). In January 1970 he succeeded Heckmann as Director Gen­ Concluding Remarks eral. His position at Groningen became Other European and International "part-time" and he remained Director The picture describes an internatio­ Activities General of ESO until the beginning of nal, and especially European-oriented 1975 and continued as advisor for some Since 1981 Adriaan has been associ­ astronomer. The European orientation time after that. He is the author of ated with the Hipparcos satellite project, has partly to do with the fact that "ESO's Early History" which was pub­ as Chairman of the Scientific Evaluation astronomy has turned rapidly to large lished in 1991. Committee. In this position he has work­ projects which can no longer be ed closely with the scientists who have supported by individual institutes or Astronomy and Astrophysics: designed and built the instrument. In even small countries. It has partly to do a European Journal particular he has advised on many with larger historical (and political) aspects of the scientific programme. changes. The founding of Astronomy and This association was "natural" since Finally, I personally would like to Astrophysics took place in 1968 for es­ Adriaan's scientific research is closely thank Adriaan for one of his minor deci­ sentially the same reasons ESO was related to the Hipparcos goal. The fruits sions: his invitation in 1962 to me to formed: the individual European coun­ of this association will only be known in come to Groningen, without which I tries could not compete in this case with detail in the coming years as the Hippar­ would not have become a "European" the large American journals. Europeans cos data are released for publication. astronomer.

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