Periodic Phenomena and Evolution in Cataclysmic Binaries

Principal Investigator (PI) Patterson leads the Center for Backyard Astrophysics (CBA), a worldwide collaboration between amateur and professional astronomers to monitor Cataclysmic Variables (CVs). CVs are two stars in a tight orbit, one star is a white dwarf (WD) and the other is a star similar to our sun. The WD steals material from the outer layers of its companion causing rapid and varying changes in the observed brightness. The amateur astronomers coordinate their efforts to monitor the CVs throughout the year and conduct intense observing campaigns during outbursts to further our understanding of these complex binary star systems. The CBA is a well-established group and will continue to provide precise photometric orbital and disk precession periods, and accurate data on flickering and outbursts for approximately 120 CVs. The members coordinate observations from a wide range of longitude to ensure near day-long coverage of CVs during outbursts. The concerted team effort and dedication over the past 25 years has resulted in over 150 publications. A major result was the discovery of superhump signals from SU Uma-type dwarf novae. The superhump may be caused by periodic tidal stressing of the WD disk and the team will continue their investigation of these strange phenomena.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.