Damping of prominence longitudinal oscillations due to mass accretion

TL;DR

This paper models how mass accretion causes damping of prominence longitudinal oscillations, showing that the process can explain observed rapid damping and can help estimate accretion rates and coronal heating.

Contribution

It introduces a new model linking mass accretion to oscillation damping in prominences, providing analytical equations and insights into the damping mechanism.

Findings

Damping time is inversely proportional to the accretion rate.

Oscillation periods decrease by up to 20% during damping.

Nonlinear effects slightly reduce damping time.

Abstract

We study the damping of longitudinal oscillations of a prominence thread caused by the mass accretion. In this model we considered a thin curved magnetic tube filled with the plasma. The parts of the tube at the two sides of the thread are filled with hot rarefied plasma. We assume that there are flows of rarefied plasma toward the thread caused by the plasma evaporation at the magnetic tube footpoints. Our main assumption is that the hot plasma is instantaneously accommodated by the thread when it arrives at the thread, and its temperature and density become equal to those of the thread. Then we derive the system of ordinary differential equations describing the thread dynamics. We consider linear and nonlinear oscillation. The nonlinearity reduces the damping time, however this reduction is small. The damping time is inversely proportional to the accretion rate. We also obtain that the oscillation periods decrease with time. However even for the largest initial oscillation amplitude considered in our article the period reduction does not exceed 20%. We conclude that the mass accretion can damp the motion of the threads rapidly. Thus, this mechanism can explain the observed strong damping of large-amplitude longitudinal oscillations. In addition, the damping time can be used to determine the mass accretion rate and indirectly the coronal heating.