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Reprinted with permission from Physics Today.
Karl-Heinz Böhm, Professor Emeritus of Astronomy at the University of Washington, died on March 2, 2014.
Karl-Heinz was born September 27, 1923 in Hamburg, Germany and had lived in Seattle since 1968. His father was a merchant seaman who belonged to the association of those who had sailed around The Horn without steam. After high school he joined the German navy and served on submarines until the end of the war. After working in a coal mine, a salt mine and an automobile factory, he resumed his education to obtain an undergraduate degree at the University of Darmstadt in 1947 and at the University of Kiel where he obtained his PhD in Physics in 1954 under the supervision of Professor Albrecht Unsöld. For his thesis he developed a new model of the solar atmosphere in which he showed that the theoretical temperature minimum fell significantly below the empirical temperature minimum. The difference implied that a non-radiative heating mechanism was necessary to maintain the boundary temperature above the calculated minimum at the outer-most levels, i.e. about optical depth 10-3.
Starting in 1954 he spent a year at the Lick Observatory on Mt. Hamilton, California, on an exchange fellowship. At Lick he worked with several astronomers among whom George Herbig had the greatest influence on his future research. Herbig, who worked on star formation over his 70 year career, introduced Karl-Heinz to T Tau stars and Herbig-Haro objects which were the youngest known stars, still contracting to the main sequence. During the next decade he and his wife, Erika Böhm-Vitense, made several productive visits to the University of California at Berkeley. Karl-Heinz worked there with Prof. Louis Henyey, one of the first astronomers to apply digital computers to solve problems in theoretical astrophysics. Their most notable accomplishment, in cooperation with three others, was the development of the “Henyey method” of solving the seven equations in seven unknowns to yield their dependence as a function of depth in stars with masses from below one solar mass to above 100 solar masses. Their program took into account the conversion of hydrogen into helium and subsequently heavier elements which caused the stars to evolve from the main sequence to become red giants.
After returning to Germany to hold faculty positions at Kiel University and then at Heidelberg, the Böhms took advantage of the ready-access to large digital computers in the United States to move to the University of Washington where he became a Professor of Astronomy in 1968. At the University of Washington he taught graduate courses in stellar atmospheres and interiors as well as a particularly valuable course in the physical foundations of stellar and interstellar astrophysics. His lectures were particularly well-prepared and clearly presented because of his thorough knowledge of the subject and by rewriting his lecture notes each time he gave a course even though he could have used his notes from two years before.
Karl-Heinz’s theoretical work in the 1960s and 70s was first concentrated on the interiors and atmosphere of white dwarf stars. His first PhD student was Wilfred Goodson, then an American Air Force officer at Heidelberg whose thesis was on the ionization structure of planetary nebulae. Early students at the University of Washington were Tom Grenfell who later turned to glaciological applications of the theory of radiative transfer, J. Cassinelli, Richard Schwartz, Ed Brugel, Johannes Schmidt-Burck, Alex Raga and Alberto Noriega-Crespo, all on important aspects of the envelopes of the T Tau stars and of contracting stars called Herbig-Haro objects after their discoverers. The H-H objects are high density condensations associated with contracting stars. Their stellar winds generate shocks by interaction with surrounding gas clouds. The emission lines of these objects are excited by the recombination behind ionizing shocks.
Karl-Heinz’s final PhD student was Anthony Goodson whose thesis was published in 1998 on the formation of stellar jets. Tony is the son of Karl-Heinz’s first PhD student, Brigadier General Wilfred Goodson (retired). The record of supervising the theses of a father and a son may well be unequaled.
In his chapter on the Basic Theory of line Formation in Stellar Atmospheres, 1960 (edited by J.L. Greenstein) he pointed out that there is no question as to the need to consider whether or not it is necessary to account for the departures from local thermodynamic equilibrium, but only how great they are.
Starting in 1980 Karl-Heinz observed with J.B. Oke on the 200-inch telescope and the Cassegrain double spectrograph. Their work published with E.W. Brugel and E. Mannery concentrated on the emission lines of H-H objects. As a combined observer and theoretician, Karl-Heinz joined Josef Solf at the German observatory on Calar Alto in Spain to use the spectrograph designed by Solf for additional observations of Herbig-Haro objects and the stars found to be the origins of the stellar winds that provided their ionization energy.
Karl-Heinz was awarded the Physics Prize of the Göttingen Academy of Sciences and has been an External Science Member (and frequent summer visitor) of the Max-Planck Institute für Astronomie, Heidelberg. He has been a Fellow of the AAAS since 1980 and was a Visiting Fellow, JILA, at the University of Colorado 1984/5.
Karl-Heinz and his wife, astrophysicist Erika Böhm-Vitense, have four children: Hans, Manfred, Helga and Eva, the first three of whom work in physical and computer science. We were personally great friends and particularly enjoyed discussing a variety of subjects in naval history.
In preparing this obituary I have been greatly helped by George Herbig’s summary of the Böhm’s contribution to astrophysics in their 70th birthday celebration volume (Wallerstein and Noriega-Crespo 1994).
Submitted by George Wallerstein
Obituary written by: George Wallerstein
BAAS Citation: BAAS, 2015, 47, 003