Dynamics of a solar prominence tornado observed by SDO/AIA on 2012 November 7-8

TL;DR

This study analyzes the dynamics of a solar prominence tornado over 30 hours, revealing quasi-periodic transverse displacements, possible MHD wave activity, and its role as a CME precursor, using multi-wavelength SDO/AIA observations.

Contribution

It provides detailed observational insights into the tornado's evolution, displacements, and potential instability mechanisms leading to CME, highlighting the tornado's role as a CME precursor.

Findings

Tornado persisted for over 30 hours with a mean rising speed of ~1.5 km/s.

Detected quasi-periodic transverse displacements with periods of 40 and 50 minutes.

Tornado eruption was associated with a coronal mass ejection, supporting the magnetic breakout or kink instability models.

Abstract

We study the detailed dynamics of a solar prominence tornado using time series of 171, 304, 193 and 211 {\AA} spectral lines obtained by Solar Dynamics Observatory/ Atmospheric Imaging Assembly during 2012 November 7-8. The tornado first appeared at 08:00 UT, November 07, near the surface, gradually rose upwards with the mean speed of $\sim$ 1.5 km s$^{-1}$ and persisted over 30 hr. Time-distance plots show two patterns of quasi-periodic transverse displacements of the tornado axis with periods of 40 and 50 minute at different phases of the tornado evolution. The first pattern occurred during the rising phase and can be explained by the upward motion of the twisted tornado. The second pattern occurred during the later stage of evolution when the tornado already stopped rising and could be caused either by MHD kink waves in the tornado or by the rotation of two tornado threads around a common axis. The later hypothesis is supported by the fact that the tornado sometimes showed a double structure during the quasi-periodic phase. 211 and 193 {\AA} spectral lines show a coronal cavity above the prominence/tornado, which started expansion at $\sim$ 13:00 UT and continuously rose above the solar limb. The tornado finally became unstable and erupted together with the corresponding prominence as coronal mass ejection (CME) at 15:00 UT, November 08. The final stage of the evolution of the cavity and the tornado-related prominence resembles the magnetic breakout model. On the other hand, the kink instability may destabilize the twisted tornado, and consequently prominence tornadoes can be used as precursors for CMEs.