de Vaucouleurs, Gérard Henri
Born Paris, France, 25 April 1918
Died Austin, Texas, USA, 7 October 1995
Gérard de Vaucouleurs surveyed, classified, and cataloged galaxies in the Northern Hemisphere and Southern Hemisphere, and created a complex Galaxy classification system that differed from Edwin Hubble ’s system and was more useful scientifically.
Vaucouleurs grew up in Paris. Nothing is known of his father; he adopted his mother’s maiden name. Vaucouleurs showed a boyhood interest in astronomy, observing the Moon with a borrowed nautical telescope from the balcony of his family’s apartment. With a telescope later given to him by his mother, he became an expert visual observer, timing lunar occultations and mapping the visible appearances of the planets. With his home-made map of Martian surface features, the young amateur astronomer measured the rotation rate of Mars with an accuracy unsurpassed until the 1960s Mariner spacecraft missions to the planet made further improvements possible.
Vaucouleurs studied astronomy, physics, mathematics, optics, photography, and spectroscopy at the University of Paris where he received an undergraduate degree in 1939. He joined amateur astronomer Julien Péridier at the latter’s Le Houga Observatory to continue his planetary work, but the onset of World War II forced the closing of the observatory a few months later. Vaucouleurs served in the French army artillery for 19 months before the French capitulation in May 1941. He then returned to Le Houga, where in addition to continuing his lifelong studies of Mars, he took up double stars and variable stars. As a research scholar at the Sorbonne Physics Research Laboratory (1943–1945) and the Institut d’Astrophysique (1945–1950), Vaucouleurs earned a doctoral degree in 1949, defending a dissertation on molecular (Rayleigh) scattering and depolarization of light in liquids and gases. In 1944, he married Antoinette Pietra, an accomplished astronomer in her own right, who for the next 43 years would collaborate with him in many of his astronomical researches.
The Vaucouleurs immigrated to England where he was on the staff of the University of London’s Mill Hill Observatory. In 1951 the couple moved to Australia when Gérard was awarded a fellowship to do planetary research at the Australian National University’s Mount Stromlo Observatory. There he earned a second doctor of science degree, for research in molecular physics, optics, photography, astronomy, and astrophysics. During this time Vaucouleurs also served as observer-in-charge of the Yale-Columbia Southern Station in Canberra.
At Mount Stromlo, Vaucouleurs took advantage of the fact that the southern sky remained relatively unexplored by large telescopes or photography; little was known about the 1,000 of galaxies visible from the Southern Hemisphere. From 1952 to 1956 Vaucouleurs surveyed bright southern galaxies, and reobserved the 1,300 galaxies in the Shapley-Ames Catalog, measuring the brightnesses and radial velocities of 100 of galaxies and determining their distances. Using his measurements, he mapped clusters of galaxies that aggregated to form what Vaucouleurs called the “Local Supercluster.” In 1953 Vaucouleurs pointed out that most of the bright galaxies were distributed along a relatively narrow belt at an angle of roughly 90° to the plane of the Milky Way. He interpreted this distribution as the perspective effect of looking edge-on at a great disk of galaxies tens of millions of light-years across. At the time, few astronomers took Vaucouleurs’s Local Supercluster model seriously. However, it is now generally accepted that galaxies are distributed in great sheets or bubbles of large-scale structure separated by large voids in intergalactic space.
From 1953 to 1956 Vaucouleurs made a detailed study of the Magellanic Clouds with Frank Kerr , discovering that the Milky Way’s neighbors, previously regarded as irregular and chaotic in their form and motions, actually showed spiral structure and rotated. These studies resulted in the first accurate determination of the masses of the clouds; Vaucouleurs classified both clouds as barred spirals with a specific type of asymmetry. Vaucouleurs was also the first astronomer to classify the Milky Way as a barred spiral galaxy.
In 1957, Vaucouleurs came to the United States, where he would live for the rest of his life. After brief stints at the Lowell Observatory in Flagstaff, Arizona, and the Harvard College Observatory, Vaucouleurs joined the faculty of the University of Texas, Austin, in 1960. He became a naturalized citizen in 1962, and was named a full professor in 1965. At McDonald Observatory near Fort Davis, Texas, Vaucouleurs took photographs and made photometric and spectroscopic measurements of 1,000 of galaxies. For his survey, Vaucouleurs also designed and built a Fabry-Perot interferometer. With his data, he mapped the shape of the visible Universe with unprecedented accuracy, separating spiral galaxies according to their two major morphological components – the central bulge and the disk.
With his wife Antoinette and other collaborators, Vaucouleurs was an indefatigable cataloger of galaxies, publishing three Reference Cataloguesof bright galaxies in 1964, 1976, and 1991 (the last published after Antoinette’s death in 1987), and other valuable galaxy cataloges including databases of those objects that appeared in the southern sky. His catalogs were not mere compilations or lists, but contained much original data on angular sizes, magnitudes, colors, and radial velocities (redshifts) that Vaucouleurs gathered himself with the world’s largest telescopes. He also applied a critical eye to data from other sources incorporated into his galaxy catalogs, carefully weighing it for its relative reliability.
Vaucouleurs devised a complex alternative to Hubble’s scheme for classifying galaxies based on their morphologies. Vaucouleurs used many different parameters including the averaged surface brightness of the galaxy, its photometric brightness at different wavelengths, the ratio of the galaxy’s HI content to its magnitude, and the ratio of a galaxy’s central bulge to its disk. He developed formulae relating galaxies’ angular dimensions to their luminosity profiles, discovering the “r1/4” law that empirically defines the surface brightness distribution for elliptical galaxies.
Intensely interested in the cosmic distance scale – the absolute distances separating galaxies and clusters of galaxies in the Universe – Vaucouleurs questioned and revised the standard distance indicators and developed many new ones. He believed in spreading the risks by averaging the effects of many different distance indicators to cancel out systematic and statistical errors. Vaucouleurs’ measurements of Galaxy distances led him to continue supporting a H0value near 100 km s?1Mpc?1(the majority view between about 1955 and 1970) after others had adopted values of 50–75. He was a propornent of hierarchical or fractal structure in the Universe, and of a non?zero cosmological constant, so that his large value of H was not in contradiction with the best estimates of the age of the Universe. His work and that of other proponents of the “short distance scale” (H0values in the range of 80–100 km s?1Mpc?1) stood in sharp contrast to the work of Allan Rex Sandage (born: 1926), Gustav Tammann, and others who favored values of H0nearer 50 km s?1Mpc?1, the “long distance scale.” The precise value of H0remains somewhat uncertain in 2006, but seems to fall between 57 (Sandage) and 71 (Hubble Space Telescope key project).
Vaucouleurs received the Royal Astronomical Society’s 1980 Herschel Medal and the American Astronomical Society’s 1988 Henry Norris Russell Prize and lectureship. In 1986, he was elected a member of the United States National Academy of Sciences.
Vaucouleurs was survived by his second wife, the former Elysabeth Bardavid of Paris, France, whom he had known for a number of years and married in 1988.
- Burbidge, E. Margaret (2002). “Gérard de Vaucouleurs.” Biographical Memoirs, National Academy of Sciences82: 99–113.Google Scholar
- Capaccioli, M. and H. G. Corwin, Jr. (1989). Gerard and Antoinette de Vaucouleurs: A Life for Astronomy. Singapore: World Scientific Press.Google Scholar
- Vaucouleurs, Gérard de (1953). A Revision of the Harvard Survey of Bright Galaxies. Canberra: Australian National University.Google Scholar