Simulations of Solar Jets Confined by Coronal Loops

TL;DR

This paper uses simulations to study how the size and shape of coronal loops influence the behavior and energy of solar jets confined within them, revealing that loop geometry critically affects jet dynamics.

Contribution

The study introduces a detailed simulation model showing how the ratio of loop length to source width determines jet characteristics and reconnection extent in closed coronal loops.

Findings

Longer loops with larger L/N ratios produce more energetic, longer-lasting jets.

Jet behavior transitions from reflection-affected to open-like as L/N increases.

Reconnection flux can match or exceed the flux beneath the jet source dome.

Abstract

Coronal jets are collimated, dynamic events that occur over a broad range of spatial scales in the solar corona. In the open magnetic field of coronal holes, jets form quasi-radial spires that can extend far out into the heliosphere, while in closed-field regions the jet outflows are confined to the corona. We explore the application of the embedded-bipole model to jets occurring in closed coronal loops. In this model, magnetic free energy is injected slowly by footpoint motions that introduce twist within the closed dome of the jet source region, and is released rapidly by the onset of an ideal kink-like instability. Two length scales characterize the system: the width (N) of the jet source region and the footpoint separation (L) of the coronal loop that envelops the jet source. We find that the jet characteristics are highly sensitive to the ratio L/N, in both the conditions for initiation and the subsequent dynamics. The longest-lasting and most energetic jets occur along long coronal loops with large L/N ratios, and share many features of open-field jets, while smaller L/N ratios produce shorter-duration, less energetic jets that are affected by reflections from the far-loop footpoint. We quantify the transition between these behaviours and show that our model replicates key qualitative and quantitative aspects of both quiet-Sun and active-region loop jets. We also find that the reconnection between the closed dome and surrounding coronal loop is very extensive: the cumulative reconnected flux at least matches the total flux beneath the dome for small L/N, and is more than double that value for large L/N.