Magnetic Nested-wind Scenarios for Bipolar Outflows: Pre-planetary and YSO nebular shaping

TL;DR

This study uses 2.5D MHD and HD simulations to explore how nested wide-angle winds influence the morphology of bipolar outflows in young stellar objects and planetary nebulae, revealing distinct structural features.

Contribution

It introduces detailed MHD and HD simulation results of nested wind systems, highlighting their impact on outflow morphology and emission features, relevant to planetary nebula and YSO evolution.

Findings

Nested MHD winds produce distinct morphological differences from single winds.

Nested HD winds mainly cause geometric distortions without topological change.

Nested MHD winds exhibit on-axis emission knots absent in HD simulations.

Abstract

We present results of a series of magnetohydrodynamic (MHD) and hydro- dynamic (HD) 2.5D simulations of the morphology of outflows driven by nested wide-angle winds - i.e. winds which eminate from a central star as well as from an orbiting accretion disk. While our results are broadly relevent to nested wind systems we have tuned the parameters of the simulations to touch on issues in both Young Stellar Objects and Planetary Nebula studies. In particular our studies connect to open issues in the early evolution of Planetary Nebulae. We find that nested MHD winds exhibit marked morphological differences from the single MHD wind case along both dimensions of the flow. Nested HD winds on the other hand give rise mainly to geometric distortions of an outflow that is topologically similar to the flow arising from a single stellar HD wind. Our MHD results are insensitive to changes in ambient temperature between ionized and un-ionized circumstellar environments. The results are sensitive to the relative mass-loss rates, and to the relative speeds of the stellar and disk winds. We also present synthetic emission maps of both nested MHD and HD simulations. We find that nested MHD winds show knots of emission appearing on-axis that do not appear in the HD case.