Prof Malcolm Walmsley, who has died aged 75, made an enormous contribution to the science of star formation and interstellar medium in the course of a long and distinguished career. That career took him from Trinity College Dublin to the United States, Germany, Italy and ultimately full circle back to the Dublin Institute of Advanced Studies, where, in retirement, he worked closely with a group of scientists early in their careers.
His former colleagues Karl Menten and Riccardo Cesaroni, writing in the international scientific journal Nature, said that although he was a "supremely confident and successful scientist, he always shared his ideas freely. He was a very modest and selfless person who actually flinched when addressed as professore in Florence."
He was born in Ranchi, northeast India, where his father James, originally from Co Down, worked for the Indian civil service and his mother Molly Eason (of the famous Dublin bookshop family) taught English. When India became independent, the family moved to Dublin, where he attended St Stephen’s School, Goastown, before boarding at Campbell College, Belfast. In 1959, he entered Trinity College Dublin from where he graduated with first-class honours in mathematics and natural sciences.
In 1964, he went to the University of California at San Diego, where he obtained a PhD in the area of theoretical physics, specifically the theory of extragalactic radio sources and planetary nebulae.
Research fellowship
He met his first wife, Colette Mappa, who was on a scholarship from Bordeaux, at San Diego, and they moved to the Max Planck Institute for Radio Astronomy in Bonn, West Germany, in 1969, where he had secured a two-year research fellowship.
He spent 25 years in Bonn, where his theoretical expertise and access to a new 100m radio telescope at Effelsberg proved a recipe for success. Together with international colleagues he began to apply the new techniques of microwave molecular spectroscopy to the investigation of the nature of the dense gas between stars in our galaxy.
Among his most important contributions, the discovery in the constellation Taurus of a dense cloud with rich chemistry, which was named Taurus Molecular Cloud 1, has become the benchmark for studies of the early stages of star formation. Other pivotal studies included the analysis of spectra of simple molecules, such as ammonia or methanol, to measure the physical properties of interstellar molecular groups.
In the following years, in Germany and afterwards in Italy, he played a leading role in raising a new generation of young astronomers and developing microwave observational astronomy.
His wife died in 1986, and he and their two children remained in Bonn until 1994, when he was given a professorship at the University of Cologne.
Astrochemistry
He married Antonella Natta, also an astrophysicist, in 1992, and in 1995 they moved to Arcetri Astrophysical Observatory in Florence to pursue further research into the early stages of star formation, making important contributions to the fast-developing field of astrochemistry.
International colleagues celebrated his 65th birthday with a one-day international scientific conference in Bonn.
He formally retired in 2008, but retained until 2014 his role as editor of Astronomy and Astrophysics, one of the leading international journals in the field. He returned to Dublin and to a role in the Dublin Institute for Advanced Studies.
His interests were extremely wide-ranging. He was fluent in four languages (English, French, German and Italian) and was deeply versed in literature and history, much of which he could read in the original language.
The year before he died he wrote a letter to his grandchildren about his life in science. “Curiosity is an important human characteristic,” he began and, paraphrasing Newton, he described how lucky he felt to have the opportunity to “turn over bright pebbles on the seashore”.
He is survived by wife Antonella, his children Paul and Emilie, stepson Alessandro, sisters Elizabeth Ryder and Joanna Crooks, and granddaughters Madeleine, Violette and Isabella.