2007ApJ...670.1347C

Asymmetries and motions in the dust shell surrounding Mira A (ο Ceti) are reported. Measurements were taken with the UC Berkeley Infrared Spatial Interferometer (ISI), a three-element interferometer operating at 11.15 µm. At the time of these observations, it was in a linear, east-west configuration with a maximum baseline of 12 m and thus had a resolution of better than 100 mas. Three years of data (2003-2005) are presented and permit observation of the movement of dust shells over time. Fits are made to the visibility and closure-phase curves, which are then used to create one-dimensional profiles of the dust shells. Asymmetries in the circumstellar dust have been observed, and several possible explanations for these asymmetries are explored.