Morphological study of the nested planetary nebula Hubble 12

TL;DR

This study uses Hubble and CFHT imaging to analyze the complex nested bipolar structures of the planetary nebula Hubble 12, revealing multiple mass-ejection events and suggesting commonality among similar nebulae.

Contribution

It provides a detailed 3D model of Hb 12's morphology and discusses its mixed chemistry and potential cool companion, advancing understanding of planetary nebula structures.

Findings

Identification of three pairs of bipolar structures

Presence of an arc-shaped filament near the waist

Evidence of multiple mass-ejection events

Abstract

We present a visible-infrared imaging study of young planetary nebula (PN) Hubble 12 (Hb 12; PN G111.8-02.8) obtained with Hubble Space Telescope (HST) archival data and our own Canada-France-Hawaii Telescope (CFHT) measurements. Deep HST and CFHT observations of this nebula reveal three pairs of bipolar structures and an arc-shaped filament near the western waist of Hb 12. The existence of nested bipolar lobes together with the presence of H2 knots suggests that these structures originated from several mass-ejection events during the pre-PN phase. To understand the intrinsic structures of Hb 12, a three-dimensional model enabling the visualisation of this PN at various orientations was constructed. The modelling results show that Hb 12 may resemble other nested hourglass nebulae, such as Hen 2-320 and M 2-9, suggesting that this type of PN may be common and the morphologies of PNs are not so diverse as is shown by their visual appearances. The infrared spectra show that this PN has a mixed chemistry. We discuss the possible material that may cause the unidentified infrared emissions. The analyses of the infrared spectra and the spectral energy distribution suggest the existence of a cool companion in the nucleus of this object.