Leon Mestel FRS. Photo: Lucinda Douglas-Menzies

Tributes have been paid to the eminent University of Sussex astronomer and astrophysicist, Emeritus Professor Leon Mestel FRS, who has died at the age of 90.

Leon was born in Melbourne in August 1927 and was brought up in West Ham before studying mathematics in Cambridge, obtaining his BA in 1948 and his PhD in 1952.

He then obtained fellowships in Leeds and Princeton before returning to Cambridge as a Lecturer in 1955.

After a year as JFK Fellow in Israel, in 1967 he moved to Manchester as Professor of Applied Mathematics, before coming to the University of Sussex in 1973 – where he stayed until his retirement in 2002.

Peter Thomas, Professor of Physics & Astronomy at Sussex, says: “All of those who remember Leon do so with affection. We were all a little in awe of his intelligence and knowledge (he could do The Times crossword in less time than it took to drink a cup of coffee) but he always had a twinkle in his eye and used to amuse us with his anecdotes which, if you knew your classics, often turned out to be a little bit risqué.”

Former Sussex doctoral student Peter Coles, now a professor at Cardiff University, notes Leon’s “prodigious mathematical skill” and his “encyclopaedic knowledge of astrophysics”. Peter recalls in a blog post: “He also had great powers of concentration and the determination to tackle the kind of extremely challenging problems that scared off lesser intellects.” He adds: “His lectures were pretty intense – and, I have to say, not made any easier to understand by his truly terrible handwriting on the blackboard! – but I learned a huge amount from them.”

Leon was a master of magnetohydrodynamics (“every bit as fearsome as it sounds”, says Peter Thomas) and was widely respected for his contributions to the field. He gave the highly regarded Saas Fee lectures on that topic (with Nigel Weiss) in 1974 and wrote the seminal work on Stellar Magnetism in 1999 (second edition 2012).

His ability to solve complex mathematics problems, before the days of computer algebra, were unparalleled.

He is heard to have expressed the opinion that magnetic fields are “the great simplifying force in astrophysics” – though, says Peter Thomas, “I strongly suspect that may have been one of his jokes.”

For his scientific achievements, Leon was elected a Fellow of the Royal Society (FRS) in 1977. The Royal Astronomical Society awarded him both the Eddington Medal (in 1993, for his fundamental work on cosmic magnetism) and its highest honour, the Gold Medal, in 2002.

To be closer to his family, in 2008 Leon moved back to Cambridge, where he died on 15 September.

Leon is survived by his children Leo, Jonathan, Rosie and Ben, as well as four grandchildren.