On the Asymmetric Longitudinal Oscillations of a Pikelner's Model Prominence

TL;DR

This paper develops analytical and numerical models of a quiescent prominence based on Pikelner's model, revealing how pressure perturbations induce asymmetric oscillations and plasma growth in magnetic dips, explaining observed prominence oscillations.

Contribution

It provides the first combined analytical and numerical study of asymmetric oscillations in Pikelner's prominence model, linking pressure perturbations to observed oscillation phenomena.

Findings

Pressure perturbations cause antisymmetric magnetoacoustic-gravity oscillations.

Magnetic dip depth influences plasma condensation and oscillation amplitude.

Long-period oscillations are likely due to internal pressure perturbations.

Abstract

We present analytical and numerical models of a normal-polarity quiescent prominence that are based on the model of Pikelner (Solar Phys. 1971, 17, 44 ). We derive the general analytical expressions for the two-dimensional equilibrium plasma quantities such as the mass density and a gas pressure, and we specify magnetic-field components for the prominence, which corresponds to a dense and cold plasma residing in the dip of curved magnetic-field lines. With the adaptation of these expressions, we solve numerically the 2D, nonlinear, ideal MHD equations for a Pikelner's model of a prominence that is initially perturbed by reducing the gas pressure at the dip of magnetic-field lines. Our findings reveal that as a result of pressure perturbations the prominence plasma starts evolving in time and this leads to the antisymmetric magnetoacoustic--gravity oscillations as well as to the mass-density growth at the magnetic dip, and the magnetic-field lines subside there. This growth depends on the depth of magnetic dip. For a shallower dip, less plasma is condensed and vice-versa. We conjecture that the observed long-period magnetoacoustic-gravity oscillations in various prominence systems are in general the consequence of the internal pressure perturbations of the plasma residing in equilibrium at the prominence dip.