SHAPING THE GLOWING EYE PLANETARY NEBULA, NGC 6751

Abstract

NGC 6751 is a highly structured multiple-shell planetary nebula (PN) with a bipolar outflow. In this work, we present a comprehensive set of spatially resolved, high spectral resolution, long-slit spectra and deep imaging from San Pedro Martir, Gemini, the Hα composite full sky survey and archive images from the Hubble Space Telescope and Spitzer. This material allows us to identify all the main morphological components and study their detailed kinematics. We find a thick equatorial structure fragmented into multiple knots that enclose a fast expanding bubble with a filamentary surface structure. The knotty ring is surrounded by faint emission from a disk-like envelope. Lobes with embedded filaments form a bipolar outflow. The equatorial ring is tilted with respect to the line of sight and with respect to the bipolar outflow. A spherical halo surrounds the PN and there is material further out identified as a fragmented outer halo. This information is used to derive a three-dimensional morpho-kinematic model using the code SHAPE that closely replicates the observed image and long-slit spectra of the nebula, providing a fair representation of its complex structure. NGC 6751 is located close to the galactic plane and its large-scale surrounding environment is shown to be a gas-rich region. We find indications that the PN is interacting with the interstellar medium. Emission components from an extended nebulosity located a couple of arcminutes away from the nebula have radial velocities that are inconsistent with the rest of NGC 6751 and are confirmed as originating from the ambient material, not related to the PN, in agreement with a previous suggestion.