Subarcsecond mid-infrared imaging of two post asymptotic giant branch 21 micron sources

High-resolution (FWHM 0.4) mid-infrared images have been obtained for two proto planetary nebulae possessing the 21 mum emission feature (IRAS 07134+ 1005 and Z02229+6208). Images through five filters were obtained, covering the 11.3 and 21 mum emission features as well as the adjacent dust continuum. The images of IRAS 07134+ 1005 show a clearly resolved shell structure, but no significant variation in morphology is seen between the different filters. The uniform morphology between the emission features and the continuum suggests that both the carriers of the 11.3 mum aromatic band and the 21 mum feature originate from the material ejected during the asymptotic giant branch phase of evolution.