The Dynamics of Funnel Prominences

TL;DR

This paper uses advanced 2.5D MHD simulations to model the formation and dynamics of funnel prominences, revealing their growth, drainage, and potential for eruption through kink instability.

Contribution

It introduces realistic thermodynamic MHD simulations that replicate funnel prominence formation and dynamics, including flux rope formation and eruption mechanisms.

Findings

Prominences form via thermal instability in magnetic dips.

Mass drainage matches observational data.

Flux ropes can become kink-unstable and erupt.

Abstract

We present numerical simulations in 2.5D settings where large scale prominences form in situ out of coronal condensation in magnetic dips, in close agreement with early as well as recent reporting of `funnel prominences'. Our simulation uses full thermodynamic MHD with anisotropic thermal conduction, optically thin radiative losses, and parametrized heating as main ingredients to establish a realistic arcade configuration from chromosphere to corona. The chromospheric evaporation from especially transition region heights ultimately causes thermal instability and we witness the growth of a prominence suspended well above the transition region, continuously gaining mass and cross-sectional area. Several hours later, the condensation has grown into a structure connecting the prominence-corona transition region with the underlying transition region, and a continuous downward motion from the accumulated mass represents a drainage that matches observational findings. A more dynamic phase is found as well, with coronal rain, induced wave trains, and even a reconnection event when the core prominence plasma weighs down the fieldlines until a fluxrope gets formed. The upper part of the prominence is then trapped in a fluxrope structure, and we argue for its violent kink-unstable eruption as soon as the (ignored) length dimension would allow for ideal kink deformations.