Diffraction limited near-infrared imaging of the Red Rectangle by bispectral analysis

Abstract

We present a new method for infrared speckle imaging mainly based on the bispectral analysis algorithm applied to extended objects. The eciency of the reconstruction procedure is increased by a relaxation process making use of redundancies in the pupil plane. The method is applied to near- and mid-infrared data sets of the Red Rectangle (CRL 915) inK,L 'a nd M-bands leading to diraction limited maps of the post-AGB (Asymptotic Giant Branch) bipolar nebula. Studying the morphology of the Red Rectangle at sub-second of arc scale allows to decompose the near and mid-infrared broadband spectrum in two parts: the radiated light from the central part of the nebula and the radiated light from the lobes to the north and south. This decomposition indicates that, in addition to scattering of the light from a central source, thermal extended emission from warm dust may also be important at arsecond and subarcsecond scales in this bipolar nebula.