Jet Power in Pre-Planetary Nebulae: Observations vs. Theory

TL;DR

This paper compares theoretical models of jet formation in pre-planetary nebulae with observations, providing insights into the physical mechanisms and ruling out some scenarios based on empirical data.

Contribution

It offers a systematic comparison of jet formation theories with observational data, highlighting key diagnostics and testing model plausibility.

Findings

Certain jet powering scenarios are ruled out by observations.

Correlations between parameters help test model features.

The energetics of equatorial mass-loss are crucial diagnostics.

Abstract

High velocity jets are among the most prominent features of a wide class of planetary nebulae, but their origins are not understood. Several different types of physical model have been suggested to power the jets, but there is no consensus or preferred scenario. We compare current theoretical ideas on jet formation with observations, using the best studied pre-planetary nebulae in millimeter CO, where the dynamical properties are best defined. In addition to the mass, velocity, momentum, and energy of the jets, the mass and energetics of the equatorial mass-loss that typically accompanies jet formation prove to be important diagnostics. Our integrated approach provides estimates for some key physical quantities - such as the binding energy of the envelope when the jets are launched - and allows testing of model features using correlations between parameters. Even with a relatively small sample of well-observed objects, we find that some specific scenarios for powering jets can be ruled out or rendered implausible, and others are promising at a quantitative level.