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Awards and Honors

Astronomical Society of the Pacific awards highest honor to astronomer Robert Kraft

By Françoise Chanut

The Astronomical Society of the Pacific has awarded the 2005 Catherine Wolfe Bruce Gold Medal to Robert P. Kraft, professor emeritus of astronomy and astrophysics and former director of the UC Observatories/Lick Observatory (UCO/Lick). Kraft is the sixth astronomer associated with the Lick Observatory to receive this award, and the fourth associated with UCSC.

Photo of Robert Kraft

Robert Kraft
UCSC Photo Services

The Bruce Medal is the highest honor bestowed by the Astronomical Society of the Pacific (ASP). It recognizes scientists worldwide for fundamental and lifelong contributions to the field of astronomy. Previous recipients include many renowned astronomers, such as 1938 medalist Edwin P. Hubble, who showed the universe is expanding, and 2003 medalist Vera Rubin, who demonstrated the existence of dark matter.

Kraft has received many awards in his long and distinguished career, but he said the Bruce Medal holds special significance. "The Bruce Medal I cherish the most since it has the longest history and is given on a worldwide basis," Kraft said. "The list of recipients contains a lot of my heroes, such as Otto Struve and Jesse Greenstein, and I feel really honored to be on that list."

In announcing the award, the ASP acknowledged Kraft's outstanding research achievements and extensive service to the astronomy community.

Kraft served as director of UCO/Lick from 1981 to 1991. During this time he played a key role in bringing about the W. M. Keck Observatory on Mauna Kea, Hawaii, by committing the resources of Lick Observatory to the construction and instrumentation of the world's first 10-meter telescope, now known as Keck I. Keck I and its twin, Keck II, remain the largest optical and infrared telescopes ever built. UCO/Lick operates the Keck Observatory in cooperation with Caltech and NASA.

Kraft also served as president of the American Astronomical Society from 1974 to 1976 and president of the International Astronomical Union from 1997 to 2000.

As a researcher, Kraft made important contributions to the understanding of novae, stars that undergo a sudden increase in brightness due to massive nuclear explosions. He showed that all novae arise from close binary star systems in which the more evolved star (usually a white dwarf) siphons up hydrogen and helium from its expanding companion. The transferred material forms a disk whose rapid accretion onto the dense white dwarf leads to an explosion. Kraft also established an important rung on the ladder of celestial distances by assessing the contribution of interstellar dust to the dimming of Cepheid variables in the disk of our galaxy. His work on stellar rotation--now a fundamental topic in astronomy textbooks--showed that stars like the Sun spin slower and slower as they age because winds of charged particles carry away their angular momentum.

Kraft became interested in the chemical composition of stars after observing an unusual star named FG Sagittae, which underwent rapid changes in composition and later nearly disappeared behind a cloud of its own soot. He went on to analyze in detail the chemical composition of the oldest stars in our galaxy. This work led to several major contributions, including evidence for deep mixing of elements in red giants, bloated stars at a late stage of their evolution. He also established intriguing differences between the chemical composition of stars in globular clusters and their neighboring field stars.

Kraft, 77, earned his B.S. and M.S. in mathematics from the University of Washington and his Ph.D. in astronomy from UC Berkeley. He rose to prominence in the 1960s as an astronomer at the Mt. Wilson and Palomar Observatories in Pasadena. He joined UC Santa Cruz in 1967 as an astronomer at Lick Observatory and professor of astronomy and astrophysics, after holding assistant professor positions at Indiana University and the University of Chicago.

Soon after joining UC Santa Cruz, Kraft was elected to both the National Academy of Sciences and the American Academy of Arts and Sciences. In 1995, the American Astronomical Society named Kraft the Henry Norris Russell Lecturer for his lifetime achievement in astronomy. Kraft's work currently focuses on the abundance of rare earth elements in globular clusters.

The Astronomical Society of the Pacific was founded in San Francisco in 1889 and has awarded the Catherine Wolfe Bruce Gold Medal most years since 1898. From the outset, the medal was meant for astronomers of any nationality and either gender, and might only be awarded when a suitable candidate was found. The ASP board of directors selects a medalist among candidates nominated each year by the directors of six observatories--three in the United States and three elsewhere in the world. Additional information on the Astronomical Society of the Pacific is available the web at

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