Distribution of dust about Omicron Ceti and Alpha Orionis based on 11 micron spatial interferometry

Visibilities of Omicron Ceti and Alpha Orionis have been measured at a wavelength of 11 microns by a two-element heterodyne interferometer with maximum baseline spacings of 4 and 13 m. The measurements show that dust extends to within about 3 stellar radii of the oxygen-rich star Omicron Ceti, the temperature there being near 1200 K. While the majority of dust near Alpha Orionis is in a shell of inner radius 0.90 arcsec, where the temperature is about 300 K, a region very near the star producing 11 microns radiation appears to be present. This may be represented as a stellar envelope of diameter 0.063 arcsec which is not transparent at 11 microns wavelengths.