Richards Named Shapley Lecturer by American Astronomical Society

Mercedes T. Richards, professor of astronomy and astrophysics, recently was named a Harlow Shapley Visiting Lecturer in Astronomy by the American Astronomical Society. The Shapley Visiting Lectureship Program sponsors two-day visits by professional astronomers to college campuses, bringing the excitement of modern astronomy and astrophysics to colleges throughout North America, including Canada and Mexico, especially to institutions that do not offer degrees in astronomy.

Shapley Lecturers contribute to the host institution's academic program and intellectual environment in many different ways. They give at least one presentation, the Harlow Shapley Lecture, that is free and open to the general public. They also may engage in a variety of other activities, such as guest teaching; giving a research colloquium or seminar presentation; interacting with students informally; discussing teaching and curriculum with faculty, deans, and administrators; and visiting local primary and secondary schools.

Richards was elected to the nominating committee of the American Astronomical Society in January 2007. She also was elected to the Organizing Committee of the International Astronomical Union's Commission 42 on Binary Stars in August 2006 during the IAU General Assembly, which was held in Prague, Czech Republic. At that historic meeting, Richards was one of only 411 IAU members worldwide to vote on a new definition of planets, which led to the "demotion" of Pluto to the status of "dwarf planet." She was chair of the Scientific Organizing Committee for a meeting on astrotomography at the annual meeting of the International Astronomical Union in Sydney, Australia, in 2003. She was on the teaching faculty during a month-long international Vatican Observatory Summer School for graduate students in 1999. She also has participated in math and science enrichment programs for high-school students from throughout the United States and Canada.

Richards studies binary stars, which are pairs of stars that were formed at the same time, like twins. Although these pairs have the same age, the stars mature at different rates. In close pairs, called interacting binaries, each star affects the evolution of its companion. Richards collects and analyzes observations of gas flows between stars in close binary systems. She also makes computer models and animations that show how these stars interact. Richards was the first astronomer to make clear images of the gravitational flow of gas between the stars in any interacting binary pair.

Since these binaries are too distant to be resolved by the largest optical telescopes, Richards uses an indirect technique called tomography to develop images of the gas flow between the stars. "Tomography uses an object's shadow to infer the size and shape of the object that is producing it," says Richards. In astronomy, the image is derived from numerous spectra, which show a pattern of Doppler shifts. These wavelength shifts are projections of the gas motions that can be used to make an image of the gas flows in the binary stars. While the technique has been used extensively in medicine, geophysics, and archeology, Richards was the first astronomer to apply tomography to the study of a group of binary stars in which the stream of gas flows directly from one star and hits the surface of the companion star. Richards was also the first astronomer to make theoretical hydrodynamic simulations of this special class of binaries. She says, "It is like aiming a water hose at a curved wall and watching the water splash and continue moving away, except that the gas flows in binaries can have speeds of over a million miles per hour."

Richards has served as assistant head and director of the undergraduate program in the Department of Astronomy and Astrophysics since 2003. Prior to joining the Penn State faculty in 2002, Richards served on the faculty of the University of Virginia in Charlottesville from 1987 to 1999 and was a visiting scientist at the Institute for Advanced Study in Princeton, New Jersey in 2000 and 2001. She earned a doctoral degree in astronomy at the University of Toronto, Canada, in 1986, and a master's degree in astronomy at York University in Toronto in 1979. She earned a bachelor's degree in physics at the University of the West Indies in Jamaica in 1977.