James W. Truran, pioneer in nuclear astrophysics and beloved colleague, 1940-2022

Pioneering scientist helped explain how stars and stellar explosions produced the elements of the universe

Prof. Emeritus James W. Truran, who helped lay the foundations for our understanding of how virtually all elements of the universe were created in stars and stellar explosions, died March 5. He was 81.

A leading figure in the field of nuclear astrophysics, the University of Chicago scientist specialized in understanding the various ways that stars burn and explode, and the elements these processes produce. These processes shape the modern-day universe, affecting the lives of later stars and the formation of planets, including ours.

“Jim was a pioneer with an astounding breadth and depth of knowledge in nuclear astrophysics; but he was also an incredibly kind and friendly colleague and mentor,” said Donald Lamb, a longtime friend and colleague of Truran’s and the Robert A. Millikan Distinguished Service Professor Emeritus in Astronomy and Astrophysics at UChicago. “He was a treasure.”

Born in 1940 in Brewster, New York, Truran received his bachelor’s degree from Cornell in 1961 and his Ph.D. from Yale in 1966. He spent time at NASA’s Goddard Institute for Space Studies, Caltech, Lawrence Livermore National Laboratory, and Yeshiva University, and was on faculty at the University of Illinois Urbana-Champaign from 1973 to 1991. He spent the rest of his career at the University of Chicago, where he was appointed in the Department of Astronomy and Astrophysics.

When Truran began his research, astrophysicists were still struggling to understand how the elements in the universe are produced. All elements except hydrogen and helium are created in stars, either by steady burning or when a massive star explodes. His research laid the foundations for much of our current understanding of how these processes produce the elements we see.

Truran proposed a new explanation of how some pairs of stars can undergo brilliant outbursts called novae that serve as factories for producing heavy elements—a process called “nucleosynthesis.” This process is incredibly important for understanding the history and evolution of galaxies.

“His idea was highly controversial at the time, but his calculations showed it was not only reasonable but likely,” said Lamb. The theory is now widely accepted among scientists.

Truran also predicted the nuclear reactions in certain star pairs that undergo a stupendous explosion called a “Type Ia supernova” would produce enormous amounts of radioactive nickel—enough to explain the incredible brightness of these events, which outshine an entire galaxy. This early work laid the foundation for the use of these supernovae as one of the most important tools of modern cosmology; they are used to measure distance.

Truran worked with Lamb and others at the Flash Center for Computational Science, which led to the discovery of an entirely new possible explanation of how Type Ia supernovae explode. (The center officially moved from UChicago to the University of Rochester in 2021.)

Colleagues and students remember Truran as a friendly collaborator and exceptionally kind mentor. “He knew that graduate school is stressful at a time when you’re far from home, and so he was always incredibly supportive and welcoming,” said Michael Zingale, PhD’00, a student of Truran’s who is now an associate professor at SUNY Stony Brook. “He went out of his way to make sure that I met everyone and knew everyone. In my mind, he was the perfect adviser.”

Truran’s collaborators spanned the world. “Some scientists prefer to work alone, but the way Jim worked was by continuous interaction with others,” said astrophysicist Jean Audouze, a research director at the Institut d'Astrophysique de Paris and close friend and colleague of Truran’s for decades. “Jim was not only a brilliant scholar, but a rare human in his kindness. It was the luck of my life to have the chance to be a friend of his.”

“He was one of the most honorable people I knew. He always did the right thing. Through all his achievements, he never forgot about everyone in the pipeline after him,” said Aparna Venkatesan, PhD’00, cosmologist and professor of physics and astronomy at the University of San Francisco who worked with Truran as a mentee and collaborator. “Through the dozens of young people—including many women and minorities—who he unfailingly mentored and kept in the field through letters he wrote, jobs he helped us land, or conferences he got us invited to, he has been a huge part of keeping our field diverse and inclusive.”

Truran received a Guggenheim Fellowship in 1979, and was a fellow of the American Academy of Arts and Sciences and the American Physical Society. He was also a co-recipient of the Carl Sagan Memorial Award. He served as the vice president of the Aspen Center for Physics and on its board of trustees.

In 2020, he received the American Astronomical Society’s Laboratory Astrophysics Prize, and the following year the American Physical Society awarded him the prestigious Hans A. Bethe Prize for “distinguished contributions across the breadth of nuclear astrophysics, galactic chemical evolution and cosmochronology.”

Outside of his scholarship, Truran was a passionate tennis player and devoted to his family. He is survived by his wife Carol; his three daughters Elaina, Diana and Anastasia; grandchildren Emma, Hunter, Marina and Boden; and great-granddaughter Felicity.

Donations in his memory may be made to the Aspen Center for Physics.