Adams, Walter S. (Walter Sydney), 1876-1956

Adams was the astronomer of stellar spectroscopy at Mount Wilson Observatory, 1904-1923, and Director, 1923-1946.

Astronomer.

Walter Sydney Adams (1876-1956, APS 1915), astronomer, explored the uses of spectroscopy, investigated sunspots and the rotation of the Sun, the velocities and distances of thousands of stars, and planetary atmospheres. Adams served as acting director and director of Mount Wilson Observatory from 1909 until 1946.

Walter Adams was born in the village of Kessab near Antioch in Northern Syria in 1876. His parents Lucien Harper Adams and Nancy Dorrance Francis Adams were missionaries under the American Board of Commissioners for Foreign Missions. The boy received his earliest education, which focused on theology, geography, history and the classics, at home. In 1885 the family moved to Derry, New Hampshire. There Adams attended first the local public school and then Pinkerton Academy, a private high school. When his father was sent back to Syria in 1890, Walter enrolled at St. Johnsbury Academy in northern Vermont. Due largely to health reasons, he subsequently spent a year on a Massachusetts farm. He then studied at Phillips Academy, Andover, where he deepened his knowledge of mathematics, physics, and chemistry. Upon graduation in 1894 he enrolled at Dartmouth College where he studied under the astronomy professor Edwin B. Frost (1866-1935, APS 1909), graduating in 1898.

In 1898 Frost accepted an invitation by George Ellery Hale (1868-1938, APS 1902) to take charge of the department of stellar spectroscopy at Yerkes Observatory in Williams Bay, Wisconsin, which had a 40 inch refractor, the largest refracting telescope in the world. Adams accompanied Frost to Chicago in order to gain practical experience and attend graduate school at the University of Chicago, where he studied celestial mechanics and learned practical astrophysical technique at Yerkes. At Chicago he studied under the astronomers Forest R. Moulton (1872-1952, APS 1916) and Kurt Laves (1866-1944), and the mathematician Oskar Bolza (1857-1942). At the Yerkes Observatory he worked closely with Hale and also with Frost, with whom he collaborated in a radial velocity program for stars of early spectral type. They found that many of the stars were spectroscopic binaries with large ranges in velocity.

In 1899 Adams published his first research contribution on “The polar compression of Jupiter.” The following year he departed for Munich, Germany, to complete a Ph.D. under the astronomers Hugo von Seeliger (1849-1924) and Karl Schwarzschild (1873-1916), returning to Chicago in 1901 to become computer and general assistant at Yerkes and also taught astrophysics at Chicago.

In 1904 Hale invited Ferdinand Ellerman (1869-1940), George Willis Ritchey (1864-1945) and Adams to join him in the task of establishing a new observatory on Mt. Wilson in the hills above Pasadena in California, with funding from the Carnegie Institution. Adams accepted, and from 1904 to 1909, he served as Assistant Astronomer. He subsequently was acting director from 1909 to 1923, and director from 1923 to 1946. Adams worked closely with Hale in the planning and building of the observatory situated on the then barely accessible Mount Wilson, where equipment had to be carried up by burro. Construction of the 60-ft. solar tower telescope and 60-inch stellar telescope took nearly two years. Adams subsequently oversaw the completion of the 100-inch reflecting telescope and, late in his career, the 200-inch telescope at Mt. Palomar.

In addition to substantial administrative work, Adams continued to carry out studies on radial velocities. He made fundamental empirical contributions to understanding how and why spectra could be used to reveal the conditions of stellar atmospheres, helping to establish the means by which spectra could be used to discern the temperature, pressure, and density of stars. His spectroscopic observations also helped to confirm the presence of two fundamental classes of stars, giants and dwarfs. Furthermore, he and his colleague Arnold Kohlschütter (1883-1969) discovered the use of spectral parallax (a comparison of the intrinsic versus observed brightness of stars) in determining the distance to stars. Adams and Kohlschütter published their first joint paper on the spectroscopic method of determining a star’s phallax in 1914, shortly before Kohlschütter had to return to Germany. In a number of papers written with other researchers, including Alfred H. Joy (1882-1973), Milton La Salle Humason (1891-1972), and Ada M. Brayton, Adams developed this method more fully. In recognition of his efforts, Adams was elected to the American Philosophical Society in 1915. In addition, he was awarded the Gold Medal of the Royal Astronomical Society in 1917, and the Draper Medal of the National Academy of Sciences in 1918.

In 1925, Adams reached the peak of public acclaim when his observation of the gravitational field around Sirius corroborated Albert Einstein's theory of relativity. In 1928 the Astronomical Society of the Pacific awarded Adams the Bruce Medal. Later in his career, he devoted his attention to the analysis of planetary atmospheres, reporting the presence of carbon dioxide on Venus in 1932 and trace amounts of oxygen on Mars in 1934. Furthermore, he used Doppler displacement to study the rotation of the sun.

After his retirement from Mt. Wilson in 1946, Adams worked as a research associate of the Carnegie Institute of Washington (1946-1948), and of the California Institute of Technology (1947-1948). He thus maintained a close working relationship with the observatory from its founding in 1904 to its merger with the Mt. Palomar Observatory in 1947.

Adams was the recipient of many awards and honors. In addition to the Gold, Bruce, and Draper Medals, he was awarded the Prix Janssen of the Société Astronomique de France (1926), and the Janssen Medal of the French Academy of Sciences (1935). In 1947 he was the Henry Norris Russell Lecturer of the American Astronomical Society. He received honorary degrees from Chicago, Columbia, Dartmouth, Pompona, Princeton, and Southern California. He was a Foreign Associate or Member of the Royal Astronomical Society (1914), the Royal Swedish Academy (1935), the Institut de France (1945), and the Royal Society (1950). In addition to the APS he was also a member of the National Academy of Sciences and served as president of the Astronomical Society of the Pacific (1923), of the American Astronomical Society (1931-1934), and of the Pacific Division of the American Association for the Advancement of Science (1929). He was Vice-President of the International Astronomical Union (1935-1948) and also acted as its General Secretary (1940-1945). A crater on Mars minor planet #3145 were named after him.

In 1956 Adams died of cerebral thrombosis in Pasadena. He was twice married. His first wife Lilian M. Wickham died in 1922. He was survived by his second wife, Adeline Miller, and two children.