AAS 197, January 2001
Session 46. Variable Stars
Display, Tuesday, January 9, 2001, 9:30am-7:00pm, Exhibit Hall

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[46.17] An Investigation of Period Changes for Four RS CVn Stars: UV Psc, YY Gem, CG Cyg, and XY UMa

S.B. Hughes (College of Wooster), J.R. Sowell (Georgia Tech), D.S. Hall (Vanderbilt), R.M. Williamon (Fernbank)

Recently acquired times of minimum for four RS CVn binaries, all with periods under a day, are presented. Times of minimum for UV Psc, YY Gem, CG Cyg, and XY UMa have been measured for decades. These observations have been collected, and the (O - C) curves for each system have been examined for period changes. The curves for UV Psc and YY Gem showed a linear deviation, and improved periods have been computed. CG Cyg and XY UMa, though, appear to have experienced true changes in their periods. An additional 11.1-year periodic variation has been found in the (O - C) data of XY UMa. The mechanism for the period variations remains uncertain.

SBH acknowledges support from the NSF's Research Experiences for Undergraduates (REU) Program, administered through the Georgia Institute of Technology. JRS wishes to thank the Fund for Astrophysical Research, which made possible the purchase of a computer used to analyze these data.

The author(s) of this abstract have provided an email address for comments about the abstract: jim.sowell@physics.gatech.edu

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