Optical tomography of the born-again ejecta of A 58

Abstract

In a born-again planetary nebula (PN), processed H-deficient material has been injected inside the old, H-rich nebula as a result of a very late thermal pulse (VLTP) event. Long-slit spectra have been used to unveil the chemical and physical differences between these two structures, but the ejection and shaping processes still remain unclear. To peer into the morpho-kinematics of the H-deficient ejecta in the born-again PN A\,58, we present the first integral field spectroscopic observations of a born-again PN as obtained with GTC MEGARA. We detect emission from the Halpha , He i iii ii and ii emission lines, which help us unveil the expansion patterns of the different structures. In combination with ALMA and Hubble Space Telescope data we have been able to produce a complete view of the H-deficient ionized and molecular ejecta in A\,58. We propose an hourglass structure for the ionized material, which embraces molecular high-velocity polar components and is simultaneously bisected by an expanding toroidal molecular and dusty structure. Our results leverage the role of a companion in shaping the VLTP ejecta in this born-again PN.