Monday

How mass is loaded into the upper chromosphere and transition region is an important unclosed matter. The standard fibrilar mass loading scenario is of feeding of material up relatively static fieldlines by the guiding magnetic field, resulting from initial impulses made by p-mode oscillations (Hansteen et al 2006, De Pontieu et al 2007). Rutten et al. (2018) suggest that some fibrils are the cooling aftermaths of transient heating events. The new era of high resolution telescopes with updated instrumentation such as DKIST and EST will provide an excellent opportunity to address this issue.

We use passive tracer particles (corks) to examine the movements of mass elements within dense fibrils in 3D RMHD Bifrost simulations in order to understand fibril creation and destruction methods. The most common “lift and drain” mass loading scenario found are markedly different to previous suggestions. Box oscillations, the simulation equivalent of the p-modes initiate the formation. Rather than loading material up the footpoints of static fieldlines, the fieldlines themselves rise dramatically, firstly near the footpoints where the plasma velocity is well aligned with vertical fieldlines. Material is then caught above the flattened apexes of rising fieldlines and lifted by the Lorentz force along the central lengths of the fibrils as the fieldline untwists and becomes more parabolic. Subsequently, the material drains into one or both footpoints under gravity. Instances are found of material with horizontal velocities that are simultaneously elevated in rising fieldlines, creating the illusion of parabolic motion up a static fieldline.

The mechanisms observed in Bifrost simulations are not implausible additional solar scenarios for fibrilar mass loading. Criteria for discerning between this new and standard mass loading mechanisms are described and experimental parameters required to achieve great standard model fibrilar mass loading are discussed.