Parametric survey of longitudinal prominence oscillation simulations

Q. M. Zhang; P. F. Chen; C. Xia; R. Keppens; H. S. Ji

doi:10.1051/0004-6361/201220705

paper

Parametric survey of longitudinal prominence oscillation simulations

arXiv:1304.3798 · doi:10.1051/0004-6361/201220705

Abstract

It is found that both microflare-sized impulsive heating at one leg of the loop and a suddenly imposed velocity perturbation can propel the prominence to oscillate along the magnetic dip. An extensive parameter survey results in a scaling law, showing that the period of the oscillation, which weakly depends on the length and height of the prominence, and the amplitude of the perturbations, scales with $R / g_{⊙}$ , where $R$ represents the curvature radius of the dip, and $g_{⊙}$ is the gravitational acceleration of the Sun. This is consistent with the linear theory of a pendulum, which implies that the field-aligned component of gravity is the main restoring force for the prominence longitudinal oscillations, as confirmed by the force analysis. However, the gas pressure gradient becomes non-negligible for short prominences. The oscillation damps with time in the presence of non-adiabatic processes. Compared to heat conduction, the radiative cooling is the dominant factor leading to the damping. A scaling law for the damping timescale is derived, i.e., $τ \sim l^{1.63} D^{0.66} w^{- 1.21} v_{0}^{- 0.30}$ , showing strong dependence on the prominence length $l$ , the geometry of the magnetic dip (characterized by the depth $D$ and the width $w$ ), and the velocity perturbation amplitude $v_{0}$ . The larger the amplitude, the faster the oscillation damps. It is also found that mass drainage significantly reduces the damping timescale when the perturbation is too strong.

17 PAGES, 8FIGURES

Parametric survey of longitudinal prominence oscillation simulations

Abstract

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