Discovery of an Edge-on Dust Disk around the [WC10] Central Star CPD −56°8032

We present Hubble Space Telescope ultraviolet and optical Space Telescope Imaging Spectrograph spectroscopy of the [WCL] planetary nebula central star CPD -56°8032, obtained during its latest light-curve minimum. The UV spectrum shows the central star's continuum light distribution to be split into two bright peaks separated by 0 10. We interpret this finding as due to an edge-on disk or torus structure that obscures direct light from the star, which is seen primarily via its light scattered from the disk's rims or lobes. CPD -56°8032 is an archetype of dual dust chemistry [WCL] planetary nebulae, which exhibit strong infrared emission features from both carbon-rich and oxygen-rich materials, and for which the presence of a disk harboring the O-rich grains had been suggested. Our direct observation of an edge-on occulting dust structure around CPD -56°8032 provides strong support for such a model and for binary interactions being responsible for the correlation between the dual dust chemistry phenomenon in planetary nebulae and the presence of a hydrogen-deficient [WCL] Wolf-Rayet central star.