IFU spectroscopy of southern PNe: III

TL;DR

This study uses integral field spectroscopy to analyze four southern Galactic planetary nebulae, revealing their ionization, chemical composition, morphology, and kinematics, and challenging previous classifications of their emission lines.

Contribution

It provides detailed spatially resolved spectroscopic data for four PNe, clarifies their excitation classes and chemical types, and questions the origin of certain emission lines and the WELS classification.

Findings

Hen2-29 is of Peimbert Type I (He and N rich)

M3-6 is a low excitation planetary nebula

Recombination lines of CII, CIII, CIV, NIII are nebular in origin

Abstract

In this paper we describe integral field spectroscopic observations of four southern Galactic Planetary Nebulae (PNe), M3-4, M3-6, Hen2-29 and Hen2-37 covering the spectral range, 3400-7000 A. We derive the ionisation structure, the physical conditions, the chemical compositions and the kinematical characteristics of these PNe and find good agreement with previous studies that relied upon the long-slit technique in their co-spatial area. From their chemical compositions as well as their spatial and kinematic characteristics, we determined that Hen2-29 is of the Peimbert Type I (He and N rich), while the other three are of Type II. The strength of the nebular He II line reveals that M3-3, Hen2-29 and Hen2-37 are of mid to high excitation classes while M3-6 is a low excitation planetary nebula (PN). A series of emission-line maps extracted from the data cubes were constructed for each PN to describe its overall structure. These show remarkable morphological diversity. Spatially resolved spectroscopy of M3-6, shows that the recombination lines of CII, CIII, CIV and NIII are of nebular origin, rather than arising from the central star as had been previously proposed. This result increases doubts regarding the weak emission-line star (WELS) classification raised by Basurah et al. (2016). In addition, they reinforce the probability that most genuine cases of WELS are arise from irradiation effects in close binary central stars (Miszalski 2009).