Long-Term VRI Photometry of 89 (V441) Herculis (Abstract)

Volume 28 number 2 (2000)

John R. Percy

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

Akos Bakos

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 4500 days of VRI photometry of the peculiar high-latitude F2Ibe supergiant 89 (V441) Her, from the AAVSO photoelectric photometry program and from a robotic photometric telescope. We detected the previously-known photometric period of 65.2 days, and also the 283-day period which was previously observed in radial velocity only. We have determined the relative amplitudes and phases of light, color, and radial velocity for each period. The 65.2-day period appears to be due to pulsation. The nature of the 283-day period is less clear; its possible origin will be discussed. We have constructed the best available (O-C) diagram; it suggests that the 65.2-day period is increasing on a time scale of a few hundred years.