Hyron Spinrad, a University of California, Berkeley, astronomer who doggedly searched the skies for the most distant galaxies in hopes of understanding the fate of the universe, died Dec. 7 in Walnut Creek, California, after a long illness. Spinrad, a professor emeritus and former chairman of astronomy, was 81.
During his career, Spinrad set numerous galactic distance records as he used telescopes at UC’s Lick Observatory in California, Kitt Peak National Observatory in Arizona and the Keck Observatory operated by UC and Caltech in Hawaii to peer farther and farther into space in search of galaxies that could offer clues to their evolution and the evolution of the universe.
In the 1970s and ‘80s, astronomers were looking for observational evidence of galaxy evolution, and finding the most distant galaxies was the main challenge. Spinrad thought that bright radio galaxies, the most distant objects then observable, might hold the key.
“He was one of the preeminent extragalactic observational astronomers of his generation, the last of his kind,” said former student S. George Djorgovski, now a professor of astronomy at the California Institute of Technology.
Thanks to the advent of CCDs, or charge coupled devices – sensitive light detectors now common in all digital cameras – Spinrad was able to find faint, distant radio galaxies that existed when the universe was only one-third its current age. He was the first to prove, in 1985, that giant radio galaxies evolve over time. Unfortunately, this means they vary in brightness, making them ill-suited as so-called ‘standard candles’ to measure the geometry and age of the universe.
A decade later, supernovas turned out to be that long-sought standard candle – peaking at the same brightness no matter how distant – allowing astronomers and physicists at UC Berkeley and elsewhere to measure the universe and discover that it is expanding faster and faster, with no sign of stopping.
The bright radio galaxies Spinrad discovered are now suspected of having massive black holes at the center, gobbling up interstellar gas and releasing enormous amounts of energy.
z=5 or bust!
In his research, Spinrad relied on spectroscopy, which involves splitting light from distant objects into its component colors to learn about the objects’ physical characteristics. The spectra of galaxies can be used to determine the redshift – that is, how much the light has been stretched or reddened because the galaxy is moving away from us – and estimate its distance, since more distant objects recede from Earth faster than closer objects.
“He introduced us to his favorite game, baseball, and we had a softball team, the Spiral Arms, of faculty and students that occasionally played against each other,” said Imke de Pater, a UC Berkeley professor of astronomy and also a former department chair. “We were, in Hy’s words, one big happy family.”
According to his colleagues, “z=5 or bust!” was Spinrad’s mantra – z is the letter astronomers use for redshift – and he eventually was the first to find galaxies that far away. He was co-author of a 2012 paper reporting a galaxy at z=7.2. The current record redshift is 8.6, corresponding to just 600 million years after the Big Bang and more than 13 billion light-years from Earth.
Spinrad also used spectroscopy to investigate planetary atmospheres and comets. In 1963, while at the Jet Propulsion Laboratory in Pasadena, he discovered water vapor in the atmosphere of Mars. In 1984, he made the first spectroscopic examination of Halley’s Comet as it barely became visible approaching the sun for its once-every-76-years visit in 1986.
Spinrad was born Feb. 17, 1934, in Brooklyn, New York, to Manny and Ida Spinrad. He moved with his family to San Francisco when he was 12 and commuted across town to attend George Washington High School. He honed his baseball skills on the streets of the city and pitched for UC Berkeley while earning an undergraduate degree in astronomy in 1955. After a stint in the U.S. Army, he returned to UC Berkeley for his Ph.D. in astronomy in 1961.
From 1961 until 1964, he worked as a senior scientist at JPL, where he helped develop instrumentation for the first flybys of Venus and Mars. He joined the UC Berkeley faculty in 1964 and retired in 2004.
“Hy was chairman of our department when I was hired, and his door was always open,” said de Pater. “He was usually there — hidden behind his terminal and piles of books — ready to give advice, as a colleague and mentor.”
While normally laid-back, Spinrad could bounce around with nervous energy when observing, anxious that the weather would turn bad and ruin an evening of observing, Djorgovski said.
“He knew more about the weather than any meteorologist, and he was eager to get things done,” he said. “He was an artist of the telescope. It was really cool and exciting to work all night observing and then find spectra of galaxies that would turn out to be the most distant known.”
Even after his retirement, Spinad never lost his love for teaching astronomy, delivering lectures in the middle stages of his illness.
“Work was never work for my dad. It was a passion,” said his daughter, Tracy Spinrad, a professor at Arizona State University.
Spinrad was a member of the National Academy of Sciences and was honored with the 1986 Heineman Prize for outstanding work in astrophysics. Asteroid 3207 Spinrad was named for him.
Spinrad is survived by his wife, Bette (Abrams) of Walnut Creek, whom he met while an undergraduate at UC Berkeley; sons Michael of Greenbrae, California, and Robert of Palm Springs, and daughter, Tracy, of Tempe, Arizona; seven grandchildren and one great-grandchild.
Donations in Spinrad’s memory can be made to the Student Observation Fund at UC Berkeley or Hospice of the East Bay.