Hogg, Helen Sawyer (1905-1993), an American-born astronomer, became known for her research on variable stars. She discovered more than 250 of these stars, whose light varies in brightness. Hogg chiefly studied variable stars in globular star clusters, which are ball-like groups of stars in the Milky Way Galaxy. Her work included measuring the period of many of these stars. A variable star’s period is the time its light takes to change from bright to dim and back to bright. This information, in certain cases, helps astronomers determine the distance of the star from Earth.
Helen Battles Sawyer was born on Aug. 1, 1905, in Lowell, Massachusetts. She married Frank S. Hogg, a Canadian astronomer, in 1930. She received a Ph.D. degree in astronomy from Radcliffe College in 1931. The first edition of her major work, Catalogue of Variable Stars in Globular Clusters, was published in 1939. In 1935, Hogg joined the faculty of the University of Toronto, where she conducted most of her research. In 1957, Hogg became the first woman to serve as president of the Royal Astronomical Society of Canada. She died on Jan. 28, 1993.
