On 24 July 2026, Semih Filiz successfully defended his doctoral thesis entitled "Spectral Evolution of Hot Hydrogen-Rich White Dwarfs" at the Institute for Astronomy and Astrophysics of the University of Tübingen. His research provides important new insights into the atmospheric evolution of hot white dwarfs, the final evolutionary stage of the vast majority of stars in our Galaxy. 

In his thesis, Mr. Filiz combined state-of-the-art stellar atmosphere modelling with ultraviolet, optical, and photometric observations to investigate the transition between DAO and DA white dwarfs. His work demonstrates that these two classes occupy distinct evolutionary regions and identifies the temperature at which the transformation occurs, resolving a longstanding discrepancy between theoretical predictions and previous observations. The research also sheds new light on the interplay between gravitational settling, radiative levitation, and stellar winds in shaping white dwarf atmospheres, while providing improved constraints on stellar atmosphere models and the evolution of compact stars.

Dr. Filiz is also the last of a remarkable cohort of 19 doctoral students supervised by Prof. Klaus Werner, whose scientific leadership has had a profound impact on the field of white dwarf astrophysics and on the training of generations of young researchers. 

The Institute warmly congratulates Dr. Semih Filiz on this outstanding achievement and wishes him every success in his future scientific career.