The Hydromagnetic Interior of a Solar Quiescent Prominence. I. Coupling Between Force Balance and Steady Energy Transport

Abstract

This series of papers investigates the dynamic interior of a quiescent prominence revealed by recent Hinode and SDO/AIA high-resolution observations. This first paper is a study of the static equilibrium of the Kippenhahn-Schlüter diffuse plasma slab, suspended vertically in a bowed magnetic field, under the frozenin condition and subject to a theoretical thermal balance among an opticallythin radiation, heating, and field-aligned thermal conduction. The everywhereanalytical solutions to this nonlinear problem are an extremely restricted subset of the physically admissible states of the system. For most values of the total mass frozen into a given bowed field, force-balance and steady energy-transport cannot both be met without a finite fraction of the total mass having collapsed into a cold sheet of zero thickness, within which the frozen-in condition must break down. An exact, resistive hydromagnetic extension of the Kippenhahn-Schlüter slab is also presented, resolving the mass-sheet singularity into a finite-thickness layer of steadily-falling dense fluid. Our hydromagnetic result suggests that the narrow, vertical prominence H α threads may be falling across magnetic fields, with optically-thick cores much denser and ionized to much lower degrees than conventionally considered. This implication is discussed in relation to (i) the recent SDO/AIA observations of quiescent prominences that are massive and yet draining mass everywhere in their interiors, (ii) the canonical range of 5 − 60 G determined from spectral-polarimetric observations of prominence magnetic fields over the years and (iii) the need for a more realistic multi-fluid treatment.

Mass Flows in a Prominence Spine as Observed in Euv

“…Alternative models include dynamic processes such as injection (e.g., Wang 1999;Chae et al 2001), levitation (e.g., Galsgaard & Longbottom 1999;Litvinenko & Wheatland 2005), and magnetothermal convection (e.g., Berger et al 2011;Low et al 2012aLow et al , 2012b. However, substantial work is needed to produce comparable, quantitative, timedependent predictions for other models of prominence plasma and magnetic structure (see Mackay et al 2010).…”

Thermal Signatures of Tether-Cutting Reconnections in Pre-Eruption Coronal Flux Ropes: Hot Central Voids in Coronal Cavities

“…Although our numerical simulation does not include radiative cooling and thus cannot model the process of prominence formation, it is likely that the prominence plasma is co-spatial with the dense current layer (e.g., van Ballegooijen & Cranmer 2010; Low et al 2012). Our MHD simulation also does not model explicitly the background coronal heating but instead simply assumes a high temperature coronal plasma with an adiabatic index of γ = 1.1, without explicitly incorporating the coronal heating and radiative cooling processes.…”

Differences between Doppler velocities of ions and neutral atoms in a solar prominence

“…Because of their low temperature, prominences are made of partially-ionized plasma, with the ionization fraction of hydrogen characteristically 0.2 (Ruzdjak & Tandberg-Hanssen 1989;Engvold et al 1990;Labrosse et al 2010) in the centre of the dense prominence material. In prominences, it has been suggested that plasma is supported against gravity by the Lorentz force (Kippenhahn & Schlüter 1957;Kuperus & Raadu 1974), and neutral atoms are supported by the frictional force between them and the plasma (Low et al 2012). Prominences are dynamic structures, displaying motions of various kinds, such as turbulence (e.g.…”