High - resolution imaging of the bipolar nebula Red Rectangle Evidence for unstable mass transfer in a close binary system ?

We present the first diffraction-limited specklemasking bispectrum observations of the central part of the Red Rectangle at optical wavelengths (λ ∼ 656 nm and λ ∼ 800 nm). The results confirm infrared observations which show that the object is a bipolar nebula. The dark lane separating the two lobes is probably produced by an obscuring dust disk slightly inclined with respect to the line of sight. The fainter northern lobe appears not to be reddened by the disk. This implies an upper limit of the outer disk radius of about 200 AU. We propose that the observed nebula is the result of recent mass ejection induced by unstable mass transfer from an AGB star to a close companion.