Miras

Volume 40 number 1 (2012)

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Lee Anne Willson

Iowa State University, Department of Physics and Astronomy, Ames, IA 50011; address email correspondence to lwillson@iastate.edu

Massimo Marengo

Iowa State University, Department of Physics and Astronomy, Ames, IA 50011; address email correspondence to lwillson@iastate.edu

Abstract

Mira variables share essential characteristics: High visual amplitude, periods of hundreds of days, red colors (spectral types M, S, and C), and the presence of emission lines at some phases. They are fundamental mode pulsators, with progenitor masses ranging from <1 to several solar masses. In this review, we summarize what is known from modeling and observational studies, including recent measurements from optical and IR interferometry, and studies involving large samples of stars particularly in the Magellanic Clouds. While we have a good idea of how these stars fit into the big picture of stellar evolution, many important details remain to be settled by a combination of more ambitious models and new observational techniques. Carrying on observations of bright Mira variables will be essential for interpreting observations of large numbers of fainter sources as well as for assessing the completeness and accuracy of the models.