Optical tomography of the born-again ejecta of A 58

¹ Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía s/n, Granada 18008, Spain
e-mail: borjamm@iaa.es
² Department of Space, Earth, and Environment, Chalmers University of Technology, Onsala Space Observatory, 3992 Onsala, Sweden
³ Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Antigua Carretera a Pátzcuaro 8701, Ex-Hda San José de la Huerta, Morelia, 58089 Michoacán, Mexico

Received: 9 November 2023
Accepted: 26 January 2024

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 Hα, He I, [O III], [N II] and [S 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.