During his doctoral work, Delhaye acquired training from the world's leading specialists in galactic dynamics, Jan Oort in Leiden in 1948 and Bertil Lindblad in Stockholm in 1949.
[4] In 1971 Delhaye resigned from the Paris Observatory to head from 1971 to 1979 the newly formed Institut National d'Astronomie et de Géophysique (INAG) of the CNRS.
During his years at the Paris Observatory and then at the INAG, he also held an appointment from 1966 to 1976 as maître de conférences (MCF) at the École polytechnique.
[1] He contributed a chapter Solar Motion and Velocity Distribution of Common Stars to the 1965 book Galactic Structure, edited by Blaauw and Schmidt.
[10] In 1987 he received the Prix Jules Janssen with a laudation citing not only his research, but also his teaching, helping French astronomers, and furthering international scientific cooperation.