grandson of O. W. Struve. His early spectroscopic studies were on rapidly rotating stars. In the late 1930s, with the American astronomer Christian Thomas Elvey (1899–1970), he built a spectrograph for studying nebulae. They discovered interstellar hydrogen concentrated near the galactic plane, and also detected ionized hydrogen (see h ii region). Struve also studied binary stars (as had his predecessors), stellar evolution, and the origin of planetary systems.