The Structure of the Prototype Bipolar Protoplanetary Nebula CRL 2688 (Egg Nebula): Broadband, Polarimetric, and H2 Line Imaging with NICMOS on the Hubble Space Telescope

摘要: High-resolution near-infrared (1.65-2.1 μm) images and 2 μm polarimetric of the inner 195 × 193 region bipolar protoplanetary nebula CRL 2688, taken with newly installed Near-Infrared Camera Multiobject Spectrometer (NICMOS) aboard Hubble Space Telescope (HST), are reported. The NICMOS reveal a wealth structure also seen in HST Wide Field Planetary but not detected previous, ground-based imaging studies. In particular, we detect system concentric arcs centered on, twin "searchlight beams" emanating from, obscured central star. show two sharply bounded spindle-shaped polar cavities point-symmetric structure, 2.122 H2 S(1) v = 1-0 emission-line image clearly resolves sharp interface between high-velocity outflow that produces these surrounding slow forms extended nebula. bright equatorial emission into distinct components elucidates their detailed morphologies. We have discovered, within dark lane bifurcates lobes compact source unpolarized light. Our polarimetry shows this is post-asymptotic giant branch star illuminates nebula; conclude companion