Long-Term VRI Photometry of Rho Cassiopeiae (Abstract)

Volume 28 number 2 (2000)

John R. Percy

University of Toronto, Erindale Campus, Department of Astronomy, Mississauga, Ontario L5L 1C6, Canada

David Kolin

University of Toronto, Erindale Campus, Department of Astronomy, Mississauga, Ontario L5L 1C6, Canada

Gregory Henry

University of Toronto, Erindale Campus, Department of Astronomy, Mississauga, Ontario L5L 1C6, Canada

Abstract

(Abstract only) We report over 5700 days of VRI photometry of the yellow hypergiant variable star rho Cassiopeiae, from the AAVSO photoelectric program and from a robotic photometric telescope. The (V-I) color curve is generally in phase with the light curve on time scales of a few hundred days, but there is a 4000-day variation in color which is absent from the light curve. The approximate ratio of (V-I)/V is 0.46. The most conspicuous period in the light curve, autocorrelation diagram, and power spectrum is about 830 days, but there are also less conspicuous variations on time scales of 200 to 500 days. Since the most recent comprehensive analysis of the light curve of rho Cas found a dominant period of 300 days, we conclude that the behavior of the star is quite variable with time.