[Fe III] emission lines in the planetary nebula NGC 2392

TL;DR

This study presents spectroscopic observations of NGC 2392, revealing [Fe III] lines that suggest a bipolar structure similar to Mz 3, and constructs a 3D model to understand its morphology and formation.

Contribution

The paper provides new spectroscopic data and a 3D morpho-kinematic model to interpret the structure and formation of NGC 2392, highlighting its similarity to bipolar nebulae.

Findings

Detection of [Fe III] lines in the inner region.

Inner and outer regions resemble bipolar nebula features.

Physical conditions differ between regions.

Abstract

NGC 2392 is a young double-shell planetary nebula (PN). Its intrinsic structure and shaping mechanism are still not fully understood. In this paper we present new spectroscopic observations of NGC 2392. The slits were placed at two different locations to obtain the spectra of the inner and outer regions. Several [Fe III] lines are clearly detected in the inner region. We infer that NGC 2392 might have an intrinsic structure similar to the bipolar nebula Mz 3, which also exhibits a number of [Fe III}] lines arising from the central regions. In this scenario, the inner and outer regions of NGC 2392 correspond to the inner lobes and the outer outflows of Mz 3, respectively. We construct a three-dimensional morpho-kinematic model to examine our hypothesis. We also compare the physical conditions and chemical composition of the inner and outer regions, and discuss the implications on the formation of this type of PN.