Imaging the Radio Photosphere of Mira
Matthews et al present new measurements of the millimeter wavelength continuum emission from the long period variable Mira (o Ceti) at frequencies of 46, 96, and 229 GHz based on observations obtained with the VLA and ALMA. The stellar disk is resolved, and the measurements indicate a decrease in the size of the radio photosphere at higher frequencies, as expected if the opacity decreases at shorter wavelengths. The shape of the radio photosphere is found to be slightly elongated, with a flattening of ~10 – 20%. The data also reveal evidence for brightness non-uniformities on the surface of Mira at radio wavelengths. Mira's hot companion, Mira B was detected at all three observed wavelengths, and the radius of its radio-emitting surface was measured to be 2 x 1013 cm. These data highlight the power of the VLA and ALMA for the study of the atmospheres of evolved stars.
View Paper: New Measurements of the Radio Photosphere of Mira Based on Data from the JVLA and ALMA, L.D. Matthews (Haystack), M.J. Reid (CfA), and K.M. Menten (MPIfR), 2015 ApJ, 808, 36 (20 July 2015).
