With World War II ending, but the draft continuing in England, Alexander Dalgarno began his studies at University College London. Deferment from military service was an attractive fringe benefit; deciding on an academic discipline was another matter.
“I chose mathematics because I thought I could perform adequately without having to work very hard,” he wrote in “A Serendipitous Journey,” an autobiographical essay that the Annual Review of Astronomy and Astrophysics published in 2008. “After one semester I discovered how wrong I was. I began to work in earnest and I seem never to have stopped.”
Starting in 1952, he published some 750 papers over the next 61 years, colleagues estimated, and continued his research and collaborations even after a Parkinson’s disease diagnosis. “One of his most remarkable achievements was that he touched on so many fields and he did it over so many years,” said Hossein Sadeghpour, director of the Institute for Theoretical Atomic Molecular and Optical Physics at the Harvard-Smithsonian Center for Astrophysics, which Dr. Dalgarno helped found.
The serendipitous intellectual journey Dr. Dalgarno described in the essay “is how this man saw himself. He would apply himself to any problem in science he could make a contribution to,” said Sadeghpour, adding that “he certainly was a rarity in this respect.” Called the “father of molecular astrophysics” during a 2008 symposium to honor his career and work, Dr. Dalgarno received awards over the years that recognized his contributions to a wide range of scientific disciplines.
Dr. Dalgarno, the Phillips professor of astronomy emeritus at Harvard University, where he formerly chaired the astronomy department, died April 9 of complications from Parkinson’s disease. He was 87 and had lived in Cambridge.
“There is no greater figure than Alex in the history of atomic physics and its applications,” the late David Bates, who was a Queen’s University Belfast professor, and the late George Victor, formerly of the Harvard-Smithsonian Center for Astrophysics, wrote in 1988 for the journal Advances in Atomic and Molecular Physics.
In 2013, the Franklin Institute in Philadelphia awarded Dr. Dalgarno the Benjamin Franklin Medal “for his many fundamental contributions to the development of the field of molecular astrophysics, which led to a better understanding of interstellar space, including the giant molecular clouds that are the birthplaces of stars and planets.”
His other awards included the Royal Astronomical Society’s Gold Medal (1986), the Royal Society of Chemistry’s Spiers Memorial Award (1992), and the American Geophysical Union’s Fleming Medal (1995). He received the Hughes Medal in 2002 from the Royal Society of London “for his contributions to the theory of atomic and molecular process, and in particular its application to astrophysics.”
Throughout Dr. Dalgarno’s teaching career, which began in the 1950s at Queen’s University Belfast, his office door remained open nearly all the time.
Anyone from colleagues to undergraduates could knock, walk in, and discuss ideas. Some encounters in his office, or at conferences and symposiums, led to collaborations and papers that stepped away from his principal research pursuits.
“He was amazingly prolific,” said Michael McElroy, who is the Gilbert Butler professor of environmental science at Harvard’s school of engineering and applied sciences and was one of Dr. Dalgarno’s early graduate students in Belfast. “He wrote an enormous amount of papers by any conceivable measure. He wrote with great discipline, but also with great clarity.”
In the 1970s, Dr. Dalgarno was asked to edit Astrophysical Journal Letters. He intended to stay a few years, but remained for 29. “I was intrigued by the thought of editing what was or could be the leading journal in the world in astrophysics,” he wrote in “A Serendipitous Journey,” adding that “it seemed a very good way to learn astrophysics and so it turned out, though I learned still more about people.”
During his tenure, “he became chief judge and traffic cop of astrophysics literature,” said James Moran, an astrophysics professor in Harvard’s department of astronomy. In that role, he added, Dr. Dalgarno resolved disputes among researchers “with tremendous grace and ease. It was just amazing.”
That Dr. Dalgarno managed to do so much in so many areas mystified many colleagues. “He was somehow a legend,” said James Babb, staff scientist at the Smithsonian Astrophysical Observatory, “but also an enigma in some sense: How does he do it?”
Neal Lane, a former science adviser to President Bill Clinton, spoke at the 2008 symposium honoring Dr. Dalgarno and described how he managed to make his work days look effortless while teaching in Belfast. Dr. Dalgarno arrived at 10 a.m., stepped out for coffee around 11, had lunch at 1 p.m., took a break at 4 to play squash, and often attended a dinner party at night. “The following morning, Alex might hand you a handwritten draft of the paper he had written sometime before sunrise,” Lane said, and each word was “carefully considered.”
Born in London, Dr. Dalgarno was a twin; he and his sister were the youngest of five children whose parents were from Aberdeen, Scotland. Their father was an insurance company executive, the family lived in London during the Blitz bombings of World War II, and “we were eventually comfortably middle class,” he wrote.
Accepted into the special honors mathematics program at University College London, he graduated with a bachelor’s degree and was finishing his doctorate in physics when Bates recruited him to be an assistant lecturer at Queen’s University Belfast. “I made friends across the university,” he wrote in his autobiographical essay. “The famous poet, Philip Larkin, was one of them.”
In 1957, he married Barbara Kane and they had four children. Their marriage ended in divorce.
Through the Fulbright grant program, he worked and conducted research at the Massachusetts Institute of Technology during part of 1954. Aside from a sabbatical year in the early 1960s at Geophysics Corporation of America, he spent his entire career in academia. Dr. Dalgarno moved to Harvard in 1967.
A service has been held for Dr. Dalgarno, who in addition to his former wife, of Belfast, leaves two daughters, Penelope of Ipswich, England, and Rebecca of Nottingham, England; two sons, Piers of Belfast and Fergus of Warrington, England; seven grandchildren; a great-grandchild; and his longtime companion, Fern Creelan. He also leaves his second former wife, Emily Dalgarno of Watertown, and her son, Andrew Izsak.Bryan Marquard can be reached at email@example.com.