Dr. Anastasios Nesis died on Friday November 6, 2020.
Dr. Anastasios (Tassos) Nesis grew up in Corinth, Greece. After his school years he completed a two-year military service and then went on to study high frequency technology from 1954–1957. Over the next two years he worked for the army as civilian teacher of high frequency technology. In 1960, with very limited funds, he decided to emigrate to Germany. His journey took him first to Radolfzell where he studied German at the local Goethe-Institut which had just been founded there. His first job was with Telefunken where he worked in the development laboratory. In 1962 his keen interest in the natural sciences prompted him to move to Freiburg to study physics and obtain a second university degree.
In 1967 he started to work on his diploma thesis at Leibniz-Institut für Sonnenphysik (KIS) which at the time was referred to as Fraunhofer-Institut. Under Prof. Dr. Wolfgang Mattig’s supervision and in collaboration with Dr. Peter Mehltretter, Dr. Nesis analysed scientific data obtained with the spectrostratoscope. In the summer of 1968, Dr. Nesis was hired as undergraduate assistant at the institute and in 1970 he completed his graduate degree.
After finishing his thesis, Dr. Nesis worked for a Deutsche Forschungsgemeinschaft (German Research Foundation) project at KIS where he was promoted to staff scientist in 1973. Numerous observation trips to the solar observatory on Capri followed, where he performed observations under the leadership of Prof. Dr. Wolfgang Mattig. During the long waits for perfect seeing, Dr. Nesis studied Italian with the help of a grammar book. He would then practice speaking Italian in the evenings with his friends at the square.
Dr. Nesis was an enthusiastic speaker who enjoyed presenting his scientific results at national and international conferences where he became acquainted with colleagues in Germany and the U.S. It so happened that, at the end of May 1985, he received his PhD not in Freiburg but at the Berlin Institute of Technology where he presented his doctoral thesis on the dynamics of solar granulation in which he was supervised by Prof. Dr. Erwin Sedlmayr.
As soon as the construction of the vacuum-tower telescope on Tenerife was completed, Dr. Nesis used it to conduct spectroscopic observations on the dynamics of granulation. The images he obtained achieved spatial and spectral resolutions that were unprecedented at the time. His primary scientific interests were the development of turbulence, the physical processes of hydrodynamics, and structure formations on the solar surface. Dr. Nesis focused his studies on applying the most recent data analysis methods and on the description of processes as chaotic systems, producing many publications on these issues.
Anastasios Nesis was a dear colleague who remained closely linked to the institute where a small office was always waiting for him. He was very sociable and open, and he enjoyed being in contact with others. Tassos loved discussing science with colleagues at KIS and around the world, especially with young scientists. He had a passion for reading and self-study and he had his own private library containing a collection of specialist publications and degree theses that he bequeathed to the Leibniz-Institut für Sonnenphysik. Tassos was a wonderful colleague and highly respected by everybody, and we are very saddened by his passing.