Agop TERZAN (1927-2020)


Agop Terzan is one of the most important persons of Armenian Diaspora and French astronomy. The stellar clusters revealed by Terzan and named after him are known to all astronomers. With his perennial activity and essential results he has a serious contribution in observational astrophysics.


Agop Terzan was born on October 31, 1927 in Constantinople (Istanbul). He graduated from the Constantinople University (he got his Bachelor degree on Mathematics in 1945 and Masters on Astronomy in 1949) and worked as a teacher of mathematics at Central Lyceum of Istanbul. In 1956 he moved to France. In 1957-1959 Terzan worked as a teacher of mathematics at technical lyceum and in 1959-1965 as an assistant astronomer, later as a scientist. In 1967-1998 he worked at the Lyon Observatory, in 1982-1983 he was the Deputy Director of that observatory. In 1965 he was awarded a doctorate of mathematical sciences by Lyon University; in 1980 he was awarded a professorship.


Terzan's works mainly refer to variable stars, stellar clusters and problems of physics of stars. Since 1963 he made observations by a number of most significant telescopes of the world. He discovered 710 variable stars in the immediate vicinity of 14 globular clusters, 11 new globular clusters (named Terzan 1, etc. till Terzan 11), 158 diffuse nebulae, 124 galaxies (from which 25% appeared to be active galaxies of Sy2 type), 4430 red variable stars in direction to the Galactic center (including 458 ones which were later identified with the IRAS infrared sources), 1428 high proper motion stars ( > 0''.1 per year). 26 planetary nebulae, 122 diffuse galaxies in direction to the center of Our Galaxy. Later it was found out that those galaxies discovered by Terzan formed the cluster of galaxies of Ophiucus constellation, as well as the super-cluster of Sagitterius-Ophiucus, which was essentially discovered due to Terzan. On the basis of the observations recently made by European astronomers it was found out that Terzan 5 cluster was one of the main formations of the center of Our Galaxy; on its basis the Galaxy was formed. In essence it is the protogalaxy, which formed its central part (bulge) joining the Milky Way.


As a result of the above mentioned works Terzan published more than 100 scientific papers in the most important astronomical journals. Terzan also has a serious contribution in the working out of astronomical devices (devices and photometers for comparing eclipses). He also has a considerable contribution in editorial and administrative works.


Terzan is a member of International Astronomical Union (1967), European Astronomical Society and French National Astronomy Committee. In 1968-1978 he was the Head of Lyon Astronomical Society. He was awarded a Henry Rey prize of the French Astronomical Society (1977), prizes of French Ministry of Education (1979) and a number of medals. He was a Corona Prize winner of the French Academy of Sciences (1988).


Agop Terzan visited Armenia for many times, including his official missions to the Byurakan Astrophysical Observatory in 1971, 1973, 1977, 1984 and 1989 on purpose of participating in conferences and scientific discussions.



Globular clusters Terzan 1, Terzan 3, and Terzan 7