The origin of the planetary nebula M 116: A morpho-kinematic and chemical analysis

We investigated the origin of the Planetary Nebula (PN) M 116 using narrow-band optical imaging, and high- and low-resolution optical spectra to perform a detailed morpho-kinematic and chemical studies. M 116 is revealed to be a multipolar PN that predominantly emits in [Oa III] in the inner part of the nebula and [Na II] in the lobes. A novel spectral unsharp masking technique was applied to the position-velocity (PV) maps to reveal a set of multiple structures at the centre of M 116 spanning radial velocities from 40 km s1 to 20 km s1, with respect to the systemic velocity. The morpho-kinematic model indicates that the deprojected velocity of the lobe outflows are ¥100 km s1, and particularly the larger lobes and knots have a deprojected velocity of 350 km s1; the inner ellipsoidal component has a deprojected velocity of 29 km s1. A kinematical age of ~8700 yr has been obtained from the model assuming a homologous velocity expansion law and a distance of 6.2 ± 1.9 kpc. The chemical analysis indicates that M 116 is a Type I PN with a central star of PN (CSPN) mass in the range of 0.618 0.713 M and an initial mass for the progenitor star between 2.0 and 3.0 M (depending on metallicity). An Teff 140 000 K and log(L/L) = 2.3 was estimated using the 3MdB photoionisation models to reproduce the ionisation. stage of the PN. All of these results have led us to suggest that M 116 is an evolved PN, contrary to the scenario of proto-PN suggested in previous studies. We propose that the mechanism responsible for the morphology of M 116 is related to the binary (or multiple star) evolution scenario.