Planetary nebulae with Wolf-Rayet-type central stars -- II. Dissecting the compact planetary nebula M2-31 with GTC MEGARA

TL;DR

This study uses advanced integral field spectroscopy to reveal the detailed morphology, kinematics, and plasma components of the planetary nebula M2-31, including the reclassification of its central star as a [WO4]-type Wolf-Rayet star.

Contribution

It provides the first detailed 2D spatial segregation of plasma components and a comprehensive morphological and kinematic analysis of M2-31 using GTC MEGARA data.

Findings

Revealed bipolar outflows and a toroidal structure in M2-31.

Detected multiple plasma components through spatial segregation of emission lines.

Reclassified the central star as a [WO4]-type Wolf-Rayet star.

Abstract

We present a comprehensive analysis of the compact planetary nebula M2-31 investigating its spectral properties, spatio-kinematical structure and chemical composition using GTC MEGARA integral field spectroscopic observations and NOT 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 M2-31 that discloses a fast spectroscopic bipolar outflow along position angles 50$^\circ$ and 230$^\circ$, 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 2D map of the C II line implies the presence of multiple plasma components. The deep NOT ALFOSC observations allowed us to detect broad WR features from the central star of M2-31, including previously undetected broad O VI lines that suggest a reclassification as a [WO4]-type star.