Sergei Alexandrovich Zhevakin Scientist
Sergei Alexandrovich Zhevakin(Russian: Серге́й Александрович Жевакин) (April 11, 1916 – February 21, 2001) was a Russian astronomer.Zhevakin is credited for identifying ionized helium as the valve for the heat engine that drives the pulsation of Cepheid variable stars.