Interferometric observations of six Mira-type stars: R Aqr, CIT 3, Cyg, WAql, R Leo, and U Ori are reported. All measurements were made by UC Berkeley's Infrared Spatial Interferometer (ISI ), which is comprised of three 1.65 m telescopes using a heterodyne detection system currently operating at 11.15 m. All data were taken in a nonredundant east-west linear configuration of telescopes, at a variety of spatial frequencies, with baselines of up to 12 m. By fitting a smooth curve to the closure phase data, as a function of the shortest baseline, the phases of individual visibility measurements can be determined. With curves of the visibility and phase, one-dimensional images are then constructed by an inverse Fourier transform. These images show significant changes in the stars and surrounding dust between the years 2003 and 2004 indicating nonconstant gas emission. They also show significant and varied types of asymmetry, including asymmetries that may be caused by companions, asymmetric stars, or asymmetric dust emission.

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Asymmetries and motions in the dust shell surrounding Mira A (o Ceti) are reported. Measurements were taken with the UC Berkeley Infrared Spatial Interferometer (ISI), a three-element interferometer operating at 11.15 m. 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)(2004)(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.

The unusual source IRC +10216 is the brightest stellar object at mid-infrared wavelengths in the northern hemisphere. Adding to its distinctiveness, the dust around IRC +10216 almost completely enshrouds the star and has an extremely complex distribution. We report the imaging of IRC +10216 at 11.15 m with three telescopes and the closure phase at two different stellar phases. Three-baseline interferometry data from a linear array of telescopes is used to create a one-dimensional image of the star and circumstellar dust. The two epochs over which data have been taken provide information at different position angles, which yields some insight into the two-dimensional structure of IRC +10216. Specifically, we observe two areas of peaked intensity. The first is 66 AE 4 mas to the west and 160 AE 51 mas to the south of the star, and the second is 227 AE 8 mas to the east and 94 AE 57 mas to the south. These two features can explain most of the observed asymmetry.