English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We develop a physical framework for interpreting high-resolution images ofpre planetary nebule ("prePNe") with pairs of candle shaped lobes. We usehydrodynamical models to infer the historical properties of the flows injectedfrom the nucleus that shape the lobes into standard forms. First, we find asuitable set of parameters of a fast, collimated, tapered flow that is activelyreshaped by an exterior slow AGB wind and that nicely fits the basic shape,kinematics, mass, and momenta of this class of prePNe. Next we vary the mostinfluential parameters of this "baseline" model-such as density, speed, andgeometry-to see how changes in the flow parameters affect the nebularobservables after 900y. Several generic conlusions emerge, such as the injectedflows that create the hollow candle-shaped lobes must be light, "tapered", andinjected considerably faster than the lobe expansion speed. Multi-polar andstarfish prePNe probably evolve from wide angle flows in which thin-shellinstabilites corrugate their leading edges. We show how the common linearrelationship of Doppler shift and position along the lobe is a robust outcomethe interaction of tapered diverging streamlines with the lobes' curved walls.Finally we probe how magnetic fields affect the basline model by adding atoroidal field to the injected baseline flow. Examples of prePNe and PNe thatmay have been magnetically shaped are listed. We conclude that the light,field-free, tapered baseline flow model is an successful and universal pardigmfor unravelling the histories of lobe formation in prePNe.

Models of the Mass-Ejection Histories of pre Planetary Nebulae, III. The Shaping of Lobes by post-AGB Winds