Wesselink, Adriaan Jan

BornHellevoetsluis, the Netherlands, 7 April 1909

DiedNew Haven, Connecticut, USA, 12 January 1995

Adriaan Wesselink developed new instruments and techniques for the photometric observation of stars, provided powerful methods for the determination of stellar radii, and offered a significant correction to the cosmic distance scale. He was the son of Jan Hendrik Wesselink, a physician, and his wife Adriane Marina Nicolette Stok, a surgical nurse. Wesselink was admitted to the University of Utrecht and studied under Ejnar Hertzsprung and Willem de Sitter . From 1929 to 1946, he held an assistantship at the Leiden Observatory. His doctoral thesis, completed under Hertzsprung’s supervision in 1937, examined the light curve of the eclipsing binary star, SZ Camelopardalis. Wesselink employed an objective grating, which provided multiple diffraction images with precisely known photometric ratios, to obtain the star’s high-resolution light curve. In 1936, he and two colleagues applied another...