Born in
Bordeaux, France, he attended the
Lycée Michel-Montaigne in Bordeaux and studied physics at the
École normale supérieure and the
Faculté des sciences de Paris. Beside his scientific work, he had a number of high-ranking posts in the management of science: director of the
Canada-France-Hawaii Telescope (CFHT, 1974–1980), president of the
IAU commission on stellar atmospheres (1973–1976) and head of the
Bureau des Longitudes (1995–1996). Cayrel was a corresponding member of the
Académie des Sciences from 1988 to 2021. He was awarded the
Prix Jules Janssen of the
Société astronomique de France (Astronomical Society of France), in 2001. Cayrel and his colleagues discovered
thorium and
uranium in the ultra-metal-poor halo star BPS CS31082-0001, which was named
Cayrel's Star to honour him. From the thorium and uranium content, an age of 12.5 Billion years could be calculated. Since 1954, he was married to the Italian astronomer
Giusa de Strobel. ==References==