2021MNRAS.508.2254R

We present a comprehensive analysis of the compact planetary nebula M 2-31 investigating its spectral properties, spatio-kinematical structure, and chemical composition using Gran Telescopio Canarias (GTC) Multi-Espectrografo en GTC de Alta Resolucion para Astronomia (MEGARA) integral field spectroscopic observations and Nordic Optical Telescope(NOT) Alhambra Faint Object Spectrograph and Camera (ALFOSC) medium-resolution spectra and narrow-band images. The GTC MEGARA high-dispersion observations have remarkable tomographic capabilities, producing an unprecedented view of the morphology and kinematics of M 2-31 that discloses a fast spectroscopic bipolar outflow along position angles 50^* and 230^*, an extended shell, and a toroidal structure or waist surrounding the central star perpendicularly aligned with the fast outflows. These observations also show that the C II emission is confined in the central region and enclosed by the [N II] emission. This is the first time that the spatial segregation revealed by a two-dimensional map of the C II line implies the presence of multiple plasma components. The deep NOT ALFOSC observations allowed us to detect broad Wolf-Rayet (WR) features from the central star of M 2-31, including previously undetected broad O VI lines that suggest a reclassification as a [WO4]-type star.