Hot Flashes on Miras?

Volume 30 number 1 (2002)

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Lee Anne Willson

Abstract

Short-time-scale variations have been reported for a few Miras, including sudden 0.2-magnitude or more brightening in the visual lasting from a few hours to a few days. Are these flashes real? Are they hot? What are they? Almost all the natural time scales for variation in the atmosphere and wind of a Mira variable are months to years. What could cause such short-term variations? One intriguing possibility is that the variations are associated with the interaction of a Jovian planet with the time-dependent outflow of a Mira wind. Here we discuss observable features of such an interaction in terms of order-of-magnitude estimates and phenomenology, and make one clear prediction requiring observational followup. Future work needs to include both theoretical calculations and the development of systematic methods for searching for such events.