Arne Slettebak

Arne Edwin{{cite news|newspaper=Athol Daily News|date=August 18, 1949|page=3|url=https://www.newspapers.com/article/athol-daily-news-wedding-of-arne-sletteb/150498657/|access-date=July 2, 2024|title=Daughter of Former Athol Pastor Will Become Bride Sunday|via=Newspapers.com}} Slettebak was born in the Free City of Danzig (in modern-day Gdańsk, Poland) on August 8, 1925, to Norwegian parents.{{sfn|Pogge|Newsom|2000|pp=1686–1687}} His family emigrated to the United States in 1927, and he gained American citizenship in 1932.{{sfn|Pogge|Newsom|2000|pp=1686–1687}} He studied at the University of Chicago, graduating with a BS degree in physics in 1945 and obtaining a PhD in astronomy in 1949.{{sfn|Pogge|Newsom|2000|pp=1686–1687}} 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.{{Cite web |title=Alumni: Arne E. Slettebak, 1949 |url=https://astro.uchicago.edu/alumni/arne-e-slettebak-1949.php |access-date=December 14, 2023|publisher=University of Chicago |url-status=live |archive-url=https://web.archive.org/web/20231214201105/https://astro.uchicago.edu/alumni/arne-e-slettebak-1949.php |archive-date=December 14, 2023}}{{sfn|Slettebak|1949}} As a graduate student, he worked as a research assistant at the Yerkes Observatory conducting astronomical spectroscopy investigations.{{cite news|newspaper=The Columbia Record|title=Astronomical Lectures Set At University|url=https://www.newspapers.com/article/the-columbia-record-arne-slettebak-lectu/151900628/|date=March 20, 1961|access-date=July 24, 2024|page=12|via=Newspapers.com}} He also contributed to parts of what became the Morgan-Keenan system together with Morgan's other doctoral students Nancy Grace Roman and William P. Bidelman.{{sfn|Osterbrock|1997|p=305}}

{{Multiple image

| image1 = McMillin Observatory taken spring of 1971.jpg

| alt1 = A photo of the building housing the McMillin observatory taken in 1971.

| caption1 = Site of the McMillin Observatory pictured in 1971

| image2 = Perkins Observatory.JPG

| alt2 = A photo of the main facade of the Perkins Observatory with two trees in front of it.

| caption2 = Main facade of the Perkins Observatory

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After receiving his PhD, Slettebak joined the Ohio State University as an instructor the same year.{{sfn|Pogge|Newsom|2000|pp=1686–1687}} He became assistant professor in 1950 and held a Fulbright fellowship at the Hamburg Observatory for the 1955–56 academic year, where he conducted research on the structures of galaxies.

He was promoted to associate professor in 1958 and then full professor in 1959 when he assumed the role of director of the Perkins Observatory from Geoffrey Keller;{{sfn|Jossem|1969|pp=70, 102}}{{cite news|url=https://www.newspapers.com/article/the-daily-sentinel-tribune-slettebak-pro/151899939/|access-date=July 24, 2024|title=OSU Board Upholds Oath|newspaper=The Daily Sentinel-Tribune|date=December 12, 1959|page=2|via=Newspapers.com}} he would hold this position until 1978.{{sfn|Pogge|Newsom|2000|pp=1686–1687}} Also in 1959, he took over directorship of the McMillin Observatory from J. Allen Hynek.{{sfn|Jossem|1969|pp=70, 102}}{{sfn|Wenning|2020|p=18}}

Slettebak was a major force in the re-establishment of a separate astronomy department, which was approved in November 1962.{{sfn|Jossem|1969|p=69}} He became chair of the newly independent entity and remained in this position until 1987.{{sfn|Pogge|Newsom|2000|pp=1686–1687}} From 1964 to 1968, he supervised the department's move from the McMillin Observatory, whose building had been deemed too small and unsafe, and Orton Hall to its current location at the Smith Physics Laboratory.{{efn|Instruction and research at the McMillin Observatory had already diminished significantly, mainly because its 12.5-inch refracting telescope was too small and had, by 1931, been dwarfed by 69-inch telescope present at the Perkins Observatory.{{sfn|Wenning|2020|p=16}}}}{{sfn|Wenning|2020|p=18}}{{Cite web|date=April 15, 2015|title=OSU Planetarium to be named for Professor Arne Slettebak |url=https://astronomy.osu.edu/news/osu-planetarium-be-named-professor-arne-slettebak|access-date=December 15, 2023|publisher=The Ohio State University|archive-url=https://web.archive.org/web/20240604121250/https://astronomy.osu.edu/news/osu-planetarium-be-named-professor-arne-slettebak|archive-date=June 4, 2024|url-status=live}}

He also helped forge an agreement between the Ohio State University, Ohio Wesleyan University and Lowell Observatory to move the Perkins Observatory's 69-inch reflecting telescope to Lowell in Flagstaff, Arizona.{{sfn|Pogge|Newsom|2000|pp=1686–1687}} A 16-inch Schmidt telescope and a 32-inch reflector were donated to Perkins and replaced the 69-inch telescope.{{cite news|newspaper=The Plain Dealer|title=Giant Scope Readied for Arizona Trip|page=4|date=March 4, 1961|url=https://www.newspapers.com/article/the-plain-dealer-perkins-telescope-trans/151929204/|via=Newspapers.com|access-date=July 24, 2024}} After its transfer, the telescope's optics were upgraded to a 72-inch mirror and it was used jointly by the two universities and the observatory.{{efn|Perkins Observatory was already owned by Ohio Wesleyan University and jointly operated with the Ohio State University prior to the transfer.{{cite news|newspaper=The Marion Star|title=New Observatory To Be Built At Perkins South of Delaware|page=12|date=March 18, 1960|url=https://www.newspapers.com/article/the-marion-star-perkins-telescope-transf/151929414/|via=Newspapers.com|access-date=July 24, 2024}}}}{{sfn|Pogge|Newsom|2000|pp=1686–1687}}{{cite news|newspaper=Arizona Daily Sun|first=William|last=Hoyt|title=5th Largest Reflector To Locate Here|page=1|date=January 7, 1960|url=https://www.newspapers.com/article/arizona-daily-sun-perkins-telescope-tran/151931559/|via=Newspapers.com|access-date=July 24, 2024}} It continued serving as the primary research instrument for Ohio State's astronomy department until 1998.{{efn|In 1998, Ohio State ended its partnership with Ohio Wesleyan and Lowell Observatory, and the 72-inch mirror was sold to Lowell.{{cite web|title=America's observatory enters a new age|url=https://www.astronomy.com/science/americas-observatory-enters-a-new-age/|first=David J.|last=Eicher|date=May 18, 2023|website=Astronomy.com|access-date=July 24, 2024|archive-url=https://web.archive.org/web/20240221052250/https://www.astronomy.com/web/20240221052250/https://www.astronomy.com/science/americas-observatory-enters-a-new-age/|archive-date=February 21, 2024|url-status=live}}{{cite web|url=https://astronomy.osu.edu/outreach/about-osu-astronomy|title=About OSU Astronomy|publisher=The Ohio State University|archive-url=https://web.archive.org/web/20240703033618/https://astronomy.osu.edu/outreach/about-osu-astronomy|archive-date=July 3, 2024|url-status=live|access-date=July 24, 2024}}}}{{sfn|Pogge|Newsom|2000|pp=1686–1687}}

Slettebak held another Fulbright fellowship for the 1974–75 academic year, this time at the University of Vienna.{{cite web|title=Arne Slettebak|website=Fulbright Program|url=https://fulbrightscholars.org/grantee/arne-slettebak-0|archive-date=July 23, 2024|archive-url=https://web.archive.org/web/20240723233321/https://fulbrightscholars.org/grantee/arne-slettebak-0|url-status=live|access-date=July 24, 2024}} During his career, he also undertook visiting professorships in Vienna and Strasbourg.{{sfn|Pogge|Newsom|2000|pp=1686–1687}} He was a councilor of the American Astronomical Society from 1964 to 1967 and served on several commissions of the International Astronomical Union, including as president of Commission 45 (Stellar Classification) from 1979 to 1982.{{sfn|Pogge|Newsom|2000|pp=1686–1687}}{{cite web|url=https://www.iau.org/administration/membership/individual/12898/|title=Arne Slettebak|access-date=July 25, 2024|publisher=International Astronomical Union|archive-date=May 22, 2024|archive-url=https://web.archive.org/web/20240522112347/https://www.iau.org/administration/membership/individual/12898/|url-status=live}}

From 1961 to 1978, Slettebak represented Ohio State on the board of directors of the Association of Universities for Research in Astronomy, and was chair of its scientific committee between 1970 and 1973.{{sfn|Pogge|Newsom|2000|pp=1686–1687}}{{cite magazine|page=31|date=2004|publisher=The Ohio State University|title=Arne Slettebak|access-date=July 31, 2024|magazine=Department of Astronomy Magazine|url=https://www.astronomy.ohio-state.edu/Pubs/Astronomy_04.pdf|archive-url=https://web.archive.org/web/20240330093326/https://www.astronomy.ohio-state.edu/Pubs/Astronomy_04.pdf|archive-date=March 30, 2024|url-status=live}} He retired from the astronomy department in 1994, becoming professor emeritus.{{sfn|Pogge|Newsom|2000|pp=1686–1687}} In 2015, the Ohio State University planetarium was renamed the Arne Slettebak Planetarium in honour of his legacy.

File:HRDiagram.png (visible here as a prominent diagonal band from upper left to lower right) increase from low values in F-type stars to a maximum in B-type stars.]]

Slettebak's main research interests were stellar rotation, spectroscopy and the study of Be stars; for the latter subject, he organised multiple colloquia at the International Astronomical Union.{{sfn|Pogge|Newsom|2000|pp=1686–1687}}

The topic of stellar rotation had been in a 'golden age' during the 1930s after Otto Struve and his collaborators provided conclusive observational evidence for axial rotation in single stars.{{sfn|Hearnshaw|1990|p=199}}{{sfn|Tassoul|2000|p=3}} However, after Pol Swings determined that the axial rotation of binary stars close to each other and with short periods tends to be approximately or perfectly synchronized with orbital motion, the field was abandoned for nearly 15 years.{{sfn|Tassoul|2000|pp=3–4}}

After World War II, interest in measurements of stellar axial rotation was revitalised by Slettebak, who published a series of papers on the topic starting in 1949.{{sfn|Tassoul|2000|p=4}}{{sfn|Hearnshaw|1990|pp=199–200}} He made extensive measurements of the rotational velocities of stars, initially making use of Struve and Grigory Shajn's graphical model during the 1950s and 60s,{{sfn|Tassoul|2000|p=4}} and subsequently with numerical models.{{sfn|Pogge|Newsom|2000|pp=1686–1687}}{{sfn|Diaz|González|Levato|Grosso|2011|p=1}} One of his research projects was conducted jointly with Case Institute of Technology and sponsored by the Office of Naval Research.

Slettebak measured Be stars with axial rotational velocities of over 400–500 km/s, which averaged 150 km/s more than B-type stars as a class.{{sfn|Hearnshaw|1990|pp=199, 332}}{{sfn|Tassoul|2000|p=12}} He discovered groups of stars that had very low rotational velocities,{{sfn|Hearnshaw|1990|p=200}} and also found both that stars at a later stage of their life were slower than dwarf stars and that metallic-line stars had much smaller rotational velocities than average dwarf stars.{{sfn|Hearnshaw|1990|pp=200, 349}} Slettebak's data was used by Allan Sandage to show that the lower rotational velocities above the main sequence were consistent with theories of stellar evolution.{{sfn|Hearnshaw|1990|p=349}}

Later in his career, Slettebak compiled the main results of statistical studies on stellar rotation conducted between 1930 and 1970, determining that the distribution of rotational velocities for stars along the main sequence increases from low values in F-type stars to a maximum in B-type stars.{{sfn|Tassoul|2000|p=12}}

In 1955 and 1958, he conducted research in astronomical spectroscopy at the Mount Wilson and Palomar observatories in California. Slettebak remained active in research even after retirement, publishing the last of his more than 90 papers, abstracts and articles in 1998.{{sfn|Pogge|Newsom|2000|pp=1686–1687}}

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.{{cite magazine|publisher=University of Chicago|title=Deaths: 1940s and 1950s|volume=92|number=4|date=April 2000|magazine=The University of Chicago Magazine|department=Class Notes|url=https://magazine.uchicago.edu/0004/class-notes/deaths_40s-50s.html|url-status=live|access-date=July 2, 2024|archive-date=June 20, 2010|archive-url=https://web.archive.org/web/20100620093352/http://magazine.uchicago.edu/0004/class-notes/deaths_40s-50s.html}} He died on May 20, 1999, at the age of 73 in Worthington, Ohio, after a brief illness.{{sfn|Pogge|Newsom|2000|pp=1686–1687}} Pixler died in 2006 at the age of 82.{{cite news|newspaper=The Columbus Dispatch|url=https://www.legacy.com/us/obituaries/dispatch/name/constance-slettebak-obituary?id=28252734|date=December 10, 2006|title=Constance Slettebak Obituary|archive-date=July 24, 2024|archive-url=https://web.archive.org/web/20240724114306/http://web.archive.org/screenshot/https://www.legacy.com/us/obituaries/dispatch/name/constance-slettebak-obituary?id=28252734|via=Legacy.com|access-date=July 24, 2024|url-status=live}}

{{notelist}}

{{reflist}}

{{refbegin}}

• {{cite journal|date=July 1, 2011|last1=Diaz|first1=C. G.|last2=González|first2=J.F.|last3=Levato|first3=H.|last4=Grosso|first4=M.|url=https://www.aanda.org/articles/aa/pdf/2011/07/aa16386-10.pdf|doi=10.1051/0004-6361/201016386|journal=Astronomy & Astrophysics|display-authors=1|title=Accurate stellar rotational velocities using the Fourier transform of the cross correlation maximum|volume=531|issue=July 2011|arxiv=1012.4858 |bibcode=2011A&A...531A.143D |article-number=A143}}
• {{cite journal|last1=Pogge|first1=Richard|last2=Newsom|first2=Gordon|date=December 1, 2000|title=Arne Slettebak (1925–1999)|url=https://baas.aas.org/pub/arne-slettebak-1925-1999/release/1|journal=Bulletin of the American Astronomical Society|volume=32|issue=4|pages=1686–1687|bibcode=2000BAAS...32.1686P}}
• {{cite web|last=Jossem|first=E. Leonard|date=November 1969|title=History of the Department of Physics 1873 – 1970|url=https://physics.osu.edu/sites/default/files/2023-11/history_of_dept._of_physics.pdf|access-date=December 15, 2023|publisher=The Ohio State University|archive-url=https://web.archive.org/web/20231215002721/https://physics.osu.edu/sites/default/files/2023-11/history_of_dept._of_physics.pdf|archive-date=December 15, 2023|url-status=live}}
• {{cite book|last=Hearnshaw|first=John B. |url=https://books.google.com/books?id=iCs4AAAAIAAJ&dq=arne+slettebak&pg=PA199|title=The Analysis of Starlight: One Hundred and Fifty Years of Astronomical Spectroscopy|publisher=Cambridge University Press|year=1990|isbn=978-0-52-139916-6 |edition=Revised paperback|author-link=John Hearnshaw|via=Google Books}}
• {{cite book|last=Osterbrock|first=Donald E.|url=https://www.nasonline.org/publications/biographical-memoirs/memoir-pdfs/morgan-w-w.pdf|title=William Wilson Morgan|author-link1=Donald Edward Osterbrock|pages=289–313|year=1997|publisher=National Academies Press|location=Washington D.C.|archive-date=May 28, 2014|archive-url=https://web.archive.org/web/20140528073923/https://www.nasonline.org/publications/biographical-memoirs/memoir-pdfs/morgan-w-w.pdf|url-status=dead|access-date=July 21, 2024}}
• {{cite journal|last=Slettebak|first=Arne|date=November 1949|title=On the Axial Rotation of the Brighter O and B Stars|url=https://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1949ApJ...110..498S&defaultprint=YES&filetype=.pdf|journal=The Astrophysical Journal|volume=110|pages=498–514|bibcode=1949ApJ...110..498S|doi=10.1086/145226}}
• {{cite book|last=Tassoul|first=Jean-Louis|url=https://books.google.com/books?id=yWh0MR_xCg8C&q=slettebak|title=Stellar Rotation|publisher=Cambridge University Press|year=2000|isbn=978-1-13-942832-3|via=Google Books}}
• {{Cite web|last=Wenning|first=Carl J.|date=December 19, 2020|title=Emerson McMillin and his Astronomical Observatory|url=https://astronomy.osu.edu/sites/default/files/2024-07/emerson_mcmillin_observatory_Dec2020.pdf|archive-url=https://web.archive.org/web/20240723225009/https://astronomy.osu.edu/sites/default/files/2024-07/emerson_mcmillin_observatory_Dec2020.pdf|archive-date=July 23, 2024|access-date=July 23, 2024|publisher=The Ohio State University}}

{{refend}}

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{{DEFAULTSORT:Slettebak, Arne}}

Category:1925 births

Category:1999 deaths

Category:American astronomers

Category:American people of Norwegian descent

Category:People from Gdańsk

Category:Ohio State University faculty

Category:University of Chicago alumni