Planetary Nebulae Shaped By Common Envelope Evolution

TL;DR

This study demonstrates through simulations that Common Envelope Evolution can produce aspherical, bipolar planetary nebulae when impacted by fast stellar winds, highlighting its role in nebula shaping.

Contribution

The paper shows that CEE can generate highly bipolar nebulae with morphology depending on wind momentum, confirmed via high-resolution 3D simulations.

Findings

CEE produces aspherical, bipolar outflows.

Fast wind momentum influences bipolar morphology.

Symmetry breaking occurs between lobes.

Abstract

The morphologies of planetary nebula have long been believed to be due to wind shaping processes in which a fast wind from the central star impacts a previously ejected envelope. Asymmetries assumed to exist in the slow wind envelope lead to inertial confinement shaping the resulting interacting winds flow. We present new results demonstrating the effectiveness of Common Envelope Evolution (CEE) at producing aspherical envelopes which, when impinged upon by a spherical fast stellar wind, produce highly bipolar, jet-like outflows. We have run two simple cases using the output of a single PHANTOM SPH CEE simulation. Our work uses the Adaptive Mesh Refinement code AstroBEAR to track the interaction of the fast wind and CEE ejecta allowing us to follow the morphological evolution of the outflow lobes at high resolution in 3-D. Our two models bracket low and high momentum output fast winds. We find the interaction leads to highly collimated bipolar outflows. In addition, the bipolar morphology depends on the fast wind momentum injection rate. With this dependence comes the initiation of significant symmetry breaking between the top and bottom bipolar lobes. Our simulations, though simplified, confirm the long-standing belief that CEE can plan a major role in PPN and PN shaping.