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J.R. Percy, A.G. Bakos (U. Toronto), G.W. Henry (Tennessee State U.)
We report 4500 days of VRI photometry of the peculiar high-latitude F2Ibe star 89 (V441) Her, from a robotic photometric telescope, and from the American Association of Variable Star Observers photoelectric photometry program. 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 and ascribed to binarity. 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 - probably radial. The nature of the 283-day variations is unclear; we discuss possible origins, based on models of the system. We have determined times of maxima from our data, and 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.
Supported by NASA, NSF, NSERC Canada, and the AAVSO Photoelectric Photometry Program.