He received a bachelor's degree in Engineering Physics from Cornell University in 1954. He was in Leiden for 1955, before going to Harvard University, where he received a master's degree in 1957. His dissertation on "The Novae Outburst", supervised by R.N. Thomas,[1] resulted in a PhD from the University of Colorado in 1958.[1][2] He was subsequently employed as a postdoc at the National Bureau of Standards,[1] the Paris Observatory in 1959–60, Princeton University in 1960–62 (assistant professorship),[2] at the Institute for Advanced Study,[1] and Indiana University (1962–63).[2]
He became a Professor of Astrophysics at the Kapteyn Astronomical Institute of the University of Groningen from 1963, a position he was offered by Adriaan Blaauw. He was Chairman of the Department of Astronomy in 1969–1982.[1] He retired with a pension in 1997,[2] and he was subsequently an Emeritus Professor.[1]
His main research focus was planetary nebulae, about which he wrote a textbook. He published around 400 papers, which received over 10,000 citations during his lifetime.[1] He also discovered a planetary nebula, which was later given the name of Po 1.
He was editor-in-chief of the Bulletin of the Astronomical Institutes of the Netherlands from 1963 until 1969, when the journal merged with other national journals to become the Astronomy and Astrophysics journal; he was subsequently an editor of that journal until 1976, when he transitioned to editing the 'Letters' edition of the journal, a role he kept until 1998, while also being an editor of The Astronomy and Astrophysics Review from 1990 until 1999.[1]
He supervised 22 PhD students, including Harm Habing, Klaas de Boer and Jacqueline van Gorkom.[1]
He was a member of Academia Europaea from 1989.[2]
