Biographical Memoirs Volume 78 (2000) / Chapter Skim
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Robert Julius Trumpler
Robert Julius Trumpler
Pages 276-297
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From page 277... ...
The document itself is an indicator of his character. The handwritten manuscript resembles a copper plate engraving.
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write at home. From summer excursions in the Swiss Alps with his father en cl two oIcler brothers Trumpler gainecl a great love of nature, particularly the high mountains.
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carefully to discussions, he saicI, en cl macle his own observations of the worIcl around him. He observed contradictions between what religion taught en c!
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degree magna cum laude in 1910 under the direction of Professor l. Ambronn.
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or_ ~ Trumpler was invited to the Lick Observatory as a Martin Kellogg fellow in 1919 and was appointed assistant astronomer in 1920. With a position in a major American observatory, Trumpler cleciclecl that his future was in the Unitecl States.
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W Campbell recognized Trumpler as an exceedingly accurate and skillful observer and chose him as his collaborator for the 1922 Lick-Crocker Eclipse Expedition to WalIal, Australia.
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In 1925 Trumpler usecl the catalog of star clusters he was developing to write a paper entitled "Spectral Types in Open Clusters." It presented ciata from the HR diagrams for 52 clusters. Trumpler founcl that there were two types of clusters.
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They clicl not, distant clusters of any one type seemed to have diameters larger than nearby clusters of the same type. Exhaustive analysis of the ciata for possible causes of this discrepancy left Trumpler with only two possibilities: clusters clicl increase in size with distance (a situation that is not physically reasonable)
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most favorable galactic clusters wouIcl have been missecl in all the observational surveys that hacl been macle up to that time, en cl fainter clusters wouic! be uncletectable at distances of 2,000 parsecs or less.
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stucliecl in the 1930 paper were locatecl within a few kiloparsecs from the Sun, they clicl not outline the galaxy. One may note from the drawing in Trumpler's paper that, by 1940, the accepted distance to the center of the galaxy was settling clown at 10,000 parsecs en cl its location was in the direction to the center of the system of globular clusters.
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Raclial velocities can, for example, provicle a means of separating cluster members from non-members as in Trumpler's 1938 investigation of the star cluster in Coma Berenices. This stucly is an excellent example of the huge effort requires!
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of his major work on clusters. One, at the request of the Solar Parallax Commission of the International Astronomical Union, involvecl observations of Eros at the opposition of 1931 as part of the international campaign to measure the solar parallax.
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his many intellectual interests, but was much more outgoing. While at Pittsburgh at the Allegheny Observatory, they founcl en cl joined the Unitarian Church, which fitter!
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A clam on Isabel Creek some 5 miles from the observatory proviclecl swimming on hot summer clays. In summer there were graduate students from Berkeley en cl sometimes visiting astronomers.
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An arrangement between the Lick Observatory en cl the Berkeley Department of Astronomy macle it possible for periodic exchanges of personnel to occur. An astronomer from Lick wouIcl spencl a semester teaching at Berkeley, a professor from Berkeley wouic!
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the upper division course in practical astronomy, a fielcl in which he had worked throughout his career: setting up and testing instruments, measuring photographic plates, etc. He also clevelopecl a graduate course in statistical astronomy (galactic structure)
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spencling time at Santa Cruz en cl Rio clef Mar, where they wouIcl walk on the beach. On one occasion, when they were returning their house key to the rental agent, they learner!
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AM GRATEFUL TO Dorothy Schaumberg, librarian at the Mary Lea Shane Archives at Lick Observatory, and to Tenny Mun at the National Academy of Sciences for information on several dates. I thank Alar Toomre for helpful suggestions relating to early drafts of this biographical memoir.
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35:15863. Historical note on the problem of light deflection in the Sun's gravitational field.
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Observations of Eros made at the Lick Observatory during the opposition of 1931 with a preliminary determination of the solar parallax.
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Statistical Astronomy. Berkeley and Los Angeles: University of California Press.
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