Adriaan Wesselink

Adriaan Jan Wesselink (April 7, 1909 – January 12, 1995) was a Dutch astronomer who worked successively in the Netherlands, South Africa, and the United States. He specialised in observing and understanding the characteristics of stars, particularly variable stars.

Early life Adriaan Wesselink was born on 7 April 1909 in Hellevoetsluis in the Netherlands. His father was a medical doctor and his mother was a nurse. Inspired by his parents, Adriaan Wesselink developed an interest in science.

Wesselink studied physics, mathematics and astronomy at Utrecht University, leading to the award of a bachelor of science degree.

In 1950 Adriaan Wesselink was appointed chief assistant of the Radcliffe Observatory in Pretoria. The observatory was equipped with a 1.9-metre (74-inch) aperture reflecting telescope, then the largest telescope in the southern hemisphere. A new spectrograph was commissioned in 1951 and Wesselink set to work studying the radial velocities of hot, luminous stars in the Milky Way to improve knowledge about the rotation of the disk of the Galaxy. He also carried out photoelectric photometry of stars in the Magellanic Clouds. In collaboration with A. D. Thackeray, he discovered RR Lyrae variable stars in the Magellanic Clouds, which provided much improved measurements of the distances to these two nearby galaxies.

Research in the United States In 1964 Wesselink was appointed a research associate in the astronomy department of Yale University, and in 1965 became a senior research astronomer there. Yale and Columbia universities had established a southern-hemisphere station at El Leoncito near San Juan in Argentina. Wesselink became closely involved in the work from the observatory.

Wesselink worked on many projects relating to stars. These included calculations of the surface brightnesses and radii of stars.

Later years Adriaan Wesselink retired in 1977. He died in New Haven, Connecticut, on 12 January 1995.