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

J Kraśkiewicz,A K Srivastava,A Solov’Ev,K Murawski

doi:10.1007/s11207-016-0850-0

J Kraśkiewicz, A K Srivastava + Show 2 more

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https://doi.org/10.1007/s11207-016-0850-0

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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.

Highlights

Prominences are dense and cold solar coronal magnetic structures, which are highly complex, as shown for instance by their long and thin threads (Tandeberg-Hanssen, 1974)
Solar prominences can be classified into two groups: i) active prominences and ii) quiescent prominences (Zirin, 1988)
Quiescent prominences can live for months; they form over a magnetic neutral line that separates the regions of opposite magnetic polarities on the photosphere

Summary

Introduction

Prominences are dense and cold solar coronal magnetic structures, which are highly complex, as shown for instance by their long and thin threads (Tandeberg-Hanssen, 1974). Average prominence temperature is about two hundred times lower and the mass density approximately two hundred times higher than the ambient coronal values. Prominences are linked to the underlying photosphere by several footpoints and lie along the polarity inversion line. Active prominences have life-times of no more than a few days, undergoing dramatic changes in plasma motions and magnetic activity. They are often associated with solar flares. Quiescent prominences can live for months; they form over a magnetic neutral line that separates the regions of opposite magnetic polarities on the photosphere

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