Secular Evolution in Mira and Semiregular Variable Pulsations (Abstract)

Volume 33 number 1 (2005)

Matthew Templeton

Janet A. Mattei

Abstract

(Abstract only) The Mira and semiregular variables are pulsating stars in very advanced stages of evolution, and they exhibit a wide variety of pulsation behavior. It is suspected that a small fraction of these variables (including R Aql, R Hya, T UMi, and LX Cyg) exhibit large secular period changes because of structural readjustments from recent thermal pulses. Analysis of secular period changes and other changes in pulsation behavior may therefore be useful in studies of the evolution of these stars. The American Association of Variable Star Observers (AAVSO) International Database (ID) contains data on over 1,500 Mira and semiregular variables. Data for these stars span nearly a century in some cases, making it possible to study the evolution of the pulsation behavior over time. We present preliminary results of a study of period change in these stars using data from the AAVSO ID, and discuss the consequences of our results on models of Mira and semiregular variable star evolution.