A Model for Solar Polar Jets

We propose a model for the jetting activity that is commonly observed in the Sun’s corona, especially in the open-field regions of polar coronal holes. Magnetic reconnection is the process driving the jets and a relevant magnetic configuration is the well known null-point and fan-separatrix topology. The primary challenge in explaining the observations is that reconnection must occur in a short-duration energetic burst, rather than quasi-continuously as is implied by the observations of long-lived structures in coronal holes, such as polar plumes. The key idea underlying our model for jets is that reconnection is forbidden for an axisym-metric null-point topology. Consequently, by imposing a twisting motion that maintains the axisymmetry, magnetic stress can be built up to high levels un-til an ideal instability breaks the symmetry and leads to an explosive release of energy via reconnection. Using three-dimensional magnetohydrodynamic simu-lations, we demonstrate that this mechanism does produce massive, high-speed jets driven by nonlinear Alfvén waves. We discuss the implications of our results for observations of the solar corona. Subject headings: Sun: corona—Sun: magnetic fields 1