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Michael Stark, assistant professor of physics, will talk about “Quasi-Periodic Oscillations in X-Ray Stars” noon Friday in Gagnon Lecture Hall (room 100) of Hugel Science Center.
Free pizza will be provided at the event, which is sponsored by Physics Club.
Stark is principally interested in the study of compact objects that are the final stages in the lives of stars much more massive than earth’s sun. These objects include black holes and neutron stars. The study of these stars is complicated by the fact that they have no internal source of heat, so they do not emit radiation in the same way as most visible stars. When these objects are isolated, they often emit very little detectable radiation. However, many of these objects exist in binary systems with more typical stars and can be studied through their interaction with their binary companion.
The radiation produced in neutron star and black hole binary systems is very bright at X-ray energies. Since X-rays do not penetrate the earth’s atmosphere, Stark observes these systems using X-ray astronomy satellites operated by NASA, the European Space Agency, and the Japanese Institute for Space and Astronautical Science. These observations are sometimes complemented by simultaneous observations with ground-based telescopes.
Stark uses precise timing of changes in brightness of the X-ray emission of these sources to study their rotation and their orbital motion about their binary companion. He also studies the changes in the hot gas in the space surrounding the compact objects. He is currently interested in Cygnus X-3, an X-ray emitting binary system in the constellation Cygnus, and GRO J1744-28, the Bursting Pulsar, a unique source located near the center of the Milky Way. Stark collaborates in these studies and in the study of other transient X-ray sources with scientists at NASA’s Goddard Space Flight Center and the Middle East Technical University in Ankara, Turkey.
He has involved Lafayette students in his research, such as Trustee Scholarship recipient Malinda Saia ’04 (Turnersville, N.J.), a physics major and EXCEL Scholar who assisted in work to understand the orbital motion of Cygnus X-3.
Stark’s graduate work involved the analysis of data from an Extensive Air-shower Array in the high desert of New Mexico. This experiment and others like it use the earth’s atmosphere as a detector for the highest energy radiation in the universe. The source of this radiation is not completely understood, but some of it comes from the compact object sources Stark still studies.
Stark earned a bachelor’s degree in physics from Harvey Mudd College in 1987 and a Ph.D. in cosmic ray astrophysics from University of Maryland in 1994.
He is a member of American Astronomical Society and its High Energy Astrophysics Division, as well as American Physical Society and its Division of Astrophysics, Forum on Physics and Society, and Forum on Education.
Before joining the Lafayette faculty in 2001, Stark taught at Denison University in Granville, Ohio, and Marietta College in Marietta, Ga. Prior to those positions, he conducted research at University of Maryland and Goddard Space Flight Center.