J320 (PN G190.3−17.7) as a poly-polar planetary nebula surrounded by point-symmetric knots

Abstract

Spatially resolved, long-slit spectra obtained with the Manchester echelle spectrometer of the planetary nebula J320 have been compared with Hubble Space Telescope and ground-based images. The morphology and kinematics of the nebular core have been convincingly modelled using the Xshape code. Two and possibly three bipolar lobes, expanding at ≈ 46 km s−1 but with different axial orientations, have been found to constitute the bright central nebula. These are found to be surrounded by two sets of point-symmetric, high-speed knots reminiscent of those that could be generated by a bipolar, rotating, episodic jet. Another isolated knot exists but without a counterpart. The sequence and nature of the periodic ejections that have given rise to this complex structure are considered in view of the most recent theories of the shaping and evolution of planetary nebulae.