AAVSO: American Association of Variable Star Observers

High Angular Resolution Observatons of Miras

Volume 25 number 2 (1997)

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Margarita Karovska
Harvard-Smithsopnian Center


The results of high angular resolution observations of Mira, the prototype star of the class of Mira-type variables, are reviewed, including the detection of substanial asymmetries in its atmosphere. Because of these asymmetries and the effect of the extended atmosphere, it is difficult to determine a photospheric diameter, a crucial parameter for establishing the effective temperature scale and the mode of pulsation. This parameter could be derived using accurate measurements of the diameter and the brightness distribution across the stellar disk as a function of wavelength and pulsation phase, in conjunction with detailed model atmosphere calculations.