Subarcsecond Mid-Infrared Imaging of Two Post-Asymptotic Giant Branch 21 Micron Sources

Abstract

High-resolution (FWHM 0.4") mid-infrared images have been obtained for two proto-planetary nebulae possessing the 21 μm emission feature (IRAS 07134+1005 and Z02229+6208). Images through five filters were obtained, covering the 11.3 and 21 μm 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 μm aromatic band and the 21 μm feature originate from the material ejected during the asymptotic giant branch phase of evolution. This paper is based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Particle Physics and Astronomy Research Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), CNPq (Brazil), and CONICET (Argentina). The observations were made with the mid-infrared camera OSCIR, developed by the University of Florida with support from the National Aeronautics and Space Administration and operated jointly by Gemini and the University of Florida Infrared Astrophysics Group.