Simultaneous longitudinal and transverse oscillation in an active filament

TL;DR

This paper reports the observation of simultaneous longitudinal and transverse oscillations in an active solar filament triggered by a shock wave from a nearby CME, and estimates related physical parameters.

Contribution

It presents the first detailed observation of co-existing longitudinal and transverse filament oscillations triggered by a shock wave, and provides estimates of magnetic field strength and filament parameters.

Findings

Observed co-existing oscillations in a solar filament.

Estimated magnetic field strength and radius of curvature.

Analyzed damping due to mass accretion.

Abstract

We report on the co-existence of longitudinal and transverse oscillations in an active filament. On March 15$^{th}$ 2013, a M1.1 class flare was observed in the active region AR 11692. A CME was found to be associated with the flare. {The CME generated a shock wave that triggered the oscillations in a nearby filament}, situated at the south-west of the active region as observed from National Solar Observatory (NSO)\textit{Global Oscillation Network Group}(GONG) H$\alpha$ images. In this work we report the longitudinal oscillations in the two ends of the filament, co-existing with the transverse oscillations. We propose a scenario in which {an} incoming shock wave hits the filament obliquely and triggers both longitudinal and transverse oscillations. Using the observed parameters, we estimate the lower limit of the magnetic field strength. We use simple pendulum model with gravity as the restoring force to estimate the radius of curvature. We also calculate the mass accretion rate which causes the filament motions to damp quite fast.