A wind-shell interaction model for multipolar planetary nebulae

TL;DR

This paper presents a new hydrodynamics model for simulating the formation of multipolar planetary nebulae through wind-shell interactions, challenging previous jet-based explanations and providing insights into nebula morphology and progenitor star mass.

Contribution

The study introduces a novel, user-friendly hydrodynamics code integrated with SHAPE for simulating wind-shell interactions in planetary nebulae formation.

Findings

Secondary lobes can form from wind-shell interactions, not just collimated outflows.

The wind-shell interaction scenario better explains observed nebula shapes.

Progenitor stars are likely more massive based on interaction timescales.

Abstract

We explore the formation of multipolar structures in planetary and pre-planetary nebulae from the interaction of a fast post-AGB wind with a highly inhomogeneous and filamentary shell structure assumed to form during the final phase of the high density wind. The simulations were performed with a new hydrodynamics code integrated in the interactive framework of the astrophysical modeling package SHAPE. In contrast to conventional astrophysical hydrodynamics software, the new code does not require any programming intervention by the user for setting up or controlling the code. Visualization and analysis of the simulation data has been done in SHAPE without external software. The key conclusion from the simulations is that secondary lobes in planetary nebulae, such as Hubble 5 and K3-17, can be formed through the interaction of a fast low-density wind with a complex high density environment, such as a filamentary circumstellar shell. The more complicated alternative explanation of intermittent collimated outflows that change direction, in many cases may therefore not be necessary. We consider that the wind-shell interaction scenario is more likely since the bow-shock shape expected from a strongly cooling bow-shock from jets is different from that of the observed bubbles. Furthermore, the timescales of the wind-wind interaction suggest that the progenitor star was rather massive.