Models of the Mass-ejection Histories of Pre-planetary Nebulae. III. The Shaping of Lobes by Post-AGB Winds

Abstract

We develop a physical framework for interpreting high-resolution images and kinematics of pre-planetary nebulae (“prePNe”). We use hydrodynamical models to infer the historical properties of fast collimated nuclear flows (“jet”) that successfully form hollow, candle-shaped lobes over ≈103 yr, including the density, momenta, and geometry of the jet and its environment. Next we vary the most influential parameters of this “baseline” model to investigate how changes in the flow parameters affect the model outcomes after 900 yr. Several generic conclusions emerge, such as the injected flows that create the hollow lobes must be light, “tapered,” and injected considerably faster than the lobe expansion speed. Multipolar and starfish prePNe probably evolve from wide-angle flows in which thin-shell instabilities corrugate their leading edges. We show how the common linear correlation of Doppler shift and position along the lobe is a robust outcome of the interaction of tapered diverging streamlines with the lobes’ curved walls. Finally, we probe how modest toroidal magnetic fields added to the fast flow affect the outcome of the baseline model. We conclude that the light, field-free, tapered baseline flow model is not only a successful and universal paradigm for unraveling the histories of lobe formation in prePNe, but also provides a comprehensive, inclusive framework for understanding the details of the shapes, sizes, and internal kinematics of their edges.

Common Envelope Shaping of Planetary Nebulae. II. Magnetic Solutions and Self-collimated Outflows

“…We prove that, independently of the type of wind source, the resulting winds behave as "tapered" flows during the initial phases of proto-PNe, in agreement with previous studies in the literature (Lee & Sahai 2003;Balick et al 2019). Although the calculations presented by Zou et al (2019) also show a similar result, we showed in paper I that non-magnetic spherical winds cannot be collimated to form tapered flows or jets.…”

“…Taking into account that the remnant of the primary star is hot and able to form a line-driven wind, what we have to study in this scenario is a whole "wind soup," which is the sum of all winds. This total outflowing wind has been already assumed and modeled as a "tapered" flow by Lee & Sahai (2003) and more recently by Balick et al (2019). One of the main topics of this article is to show that this total wind behaves, indeed, as a tapered flow due to the presence of a circumbinary disk, which acts as an obstacle.…”

Space Velocity and Time Span of Jets in Planetary Nebulae

“…This interaction will slow down their expansion velocities, resulting in a "low-speed" population of jets. In the most extreme cases of light and wide opening angle outflows, they can get trapped within the nebular envelopes as regions of enhanced density that expand with the PN (Balick et al 2019a). The subsequent interaction of this imprint on the AGB wind with the fast post-AGB wind and strong D-type ionization fronts would shape the PN and may even speed up these features as they are entrained with the nebular envelope (Sahai & Trauger 1998;Soker 2002;Lee & Sahai 2003;Huarte-Espinosa et al 2012).…”

Shaping Planetary Nebulae with Jets and the Grazing Envelope Evolution

“…The early recognition that jets play major roles in shaping planetary nebulae (PNe; e.g., Morris (1987); Soker (1990); Sahai & Trauger (1998)) has received great attention and support in recent years (e.g., Rechy-García et al (2017); Akashi & Soker (2018); Balick et al (2019); Derlopa et al (2019); Estrella-Trujillo et al (2019); Tafoya et al (2019); Balick et al (2020); Rechy-García et al (2020)). The binary system might launch jets before and/or after the common envelope evolution (CEE; e.g., Tocknell et al (2014)).…”