Arne Slettebak

Arne Edwin Slettebak (August 8, 1925 – May 20, 1999) was a naturalized American astronomer who served as chair of the astronomy department at the Ohio State University from 1962 to 1987 and director of the Perkins Observatory from 1959 to 1978. Slettebak was born in the Free City of Danzig before emigrating to the United States at a young age.

His principal research interests were in stellar rotation and Be stars, and he published over 90 papers, abstracts and articles over his career. The asteroid 9001 Slettebak, discovered in 1981, was named in his honour.

Early life and education
Arne Edwin Slettebak was born in the Free City of Danzig (in modern day Gdansk, Poland) on August 8, 1925 to Norwegian parents. His family emigrated to the United States in 1927, and he gained citizenship in 1932. He studied at the University of Chicago, graduating with a BS degree in physics in 1945 before obtaining a PhD in astronomy in 1949. His doctoral dissertation, which he completed under the guidance of William Wilson Morgan, was concerned with the rotational velocities of O-type and B-type stars. As a graduate student, he also worked on parts of what became the Morgan-Keenan system together with Morgan's other doctoral students Nancy Grace Roman and William P. Bidelman.

Career
After receiving his PhD in 1949, Slettebak joined the Ohio State University as an instructor the same year. He became full professor in 1959 when he assumed the role of director of the Perkins Observatory from Geoffrey Keller, a position he would hold until 1978. That same year, he also took over directorship of the McMillin Observatory from Allen Hynek.

Slettebak was instrumental in the re-establishment of a separate astronomy department in November 1962, of which he became chair, holding this position for 25 years until 1987. In 1964, he supervised the department's move from the McMillin Observatory, which had been deemed too small, to its current location atop the Smith Physics Laboratory. He also helped forge an agreement between the Ohio State University, Ohio Wesleyan University and Lowell Observatory to move the 69-inch Perkins telescope from Perkins Observatory to Lowell in Flagstaff, Arizona, where it was upgraded and would serve as the department's primary research instrument until 1998.

Slettebak also held Fulbright fellowships in Hamburg and Vienna as well as visiting professorships in Vienna and Strasbourg.

He retired from the department in 1994, becoming Professor Emeritus. In 2015, the Ohio State University's planetarium was renamed the Arne Slettebak Planetarium in honour of his legacy.

Research
One of Slettebak's main research interests was the rotation of stars. This topic had been in a 'golden age' during the 1930s as a result of observational evidence from Otto Struve and Grigory Shajn but was abandoned for nearly 15 years after Pol Swings established that axial rotation in close binaries with short periods is approximately or perfectly synchronized with the orbital motion. After the World War II, interest in the field was renewed, in particular as a result of Slettebak, who published a series of papers on the topic starting in 1949. He assembled the main results pertaining to the field in the period between 1930 and 1970, finding that the distribution of rotational velocities along the main sequence increases from low values in F-type stars to a maximum in B-type stars.

His other principal interest was in Be stars, for which he organised multiple commissions at the International Astronomical Union and was active in other conferences.

Personal life
Slettebak married Constance Lorraine Pixler, a music graduate from the College of Wooster, on August 28, 1949; the couple had a daughter and a son. He died on May 20, 1999 at the age of 73 after a brief illness.