Roger Victor Emile Cayrel (born 4 December 1925, Bordeaux

Bordeaux

Bordeaux is a port city on the Garonne River in the Gironde department in southwestern France.The Bordeaux-Arcachon-Libourne metropolitan area, has a population of 1,010,000 and constitutes the sixth-largest urban area in France. It is the capital of the Aquitaine region, as well as the prefecture...

, France) is a French astronomer

Astronomer

An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...

. His main interests are stellar atmosphere

Stellar atmosphere

The stellar atmosphere is the outer region of the volume of a star, lying above the stellar core, radiation zone and convection zone. It is divided into several regions of distinct character:...

s, galactic chemical evolution and metal-poor stars.

He attended the Lycée Michel-Montaigne in Bordeaux and studied physics at the École normale supérieure

École normale supérieure

An école normale supérieure or ENS is a type of publicly funded higher education in France. A portion of the student body who are French civil servants are called Normaliens....

 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

Canada-France-Hawaii Telescope

The Canada–France–Hawaii Telescope is located near the summit of Mauna Kea mountain on Hawaii's Big Island at an altitude of 4,204 meters , and is one of the observatories that comprise the Mauna Kea Observatory...

 (CFHT, 1974–1980), president of the IAU

IAU

IAU may refer to:*International Astronomical Union*International American University*International American University College of Medicine*International Association of Universities*International Association of Ultrarunners...

 commission on stellar atmospheres (1973–1976) and head of the Bureau des Longitudes

Bureau des Longitudes

The Bureau des Longitudes is a French scientific institution, founded by decree of 25 June 1795 and charged with the improvement of nautical navigation, standardisation of time-keeping, geodesy and astronomical observation. During the 19th century, it was responsible for synchronizing clocks...

 (1995–1996).

Cayrel has ben a corresponding member of the Académie des Sciences since 1988. He was awarded the Prix Jules Janssen

Prix Jules Janssen

The Prix Jules Janssen is the highest award of the French Astronomical Society. Created in 1897 and awarded annually, it is usually given in alternate years to a French astronomer, and to an astronomer of another nationality. It is distinct from the Janssen Medal , which is awarded by the French...

 of the French Astronomical Society in 2001.

Cayrel and his colleagues discovered thorium

Thorium

Thorium is a natural radioactive chemical element with the symbol Th and atomic number 90. It was discovered in 1828 and named after Thor, the Norse god of thunder....

 and uranium

Uranium

Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...

 in the ultra-metal-poor halo star BPS CS31082-0001, which was named Cayrel's Star

Cayrel's Star

BPS CS31082-0001, named Cayrel's Star, is an old Population II star located in a distance of 4 kpc in the Galactic Halo. It belongs to the class of ultra-metal-poor stars , especially the very rare subclass of neutron-capture enhanced stars. It was discovered by Tim C...

 to honour him. From the thorium and uranium content, an age of 12.5 Billion years could be calculated.

Since 1954, he has been married to the Italian astronomer Giusa de Strobel.