Coexisting fast and slow propagating waves of the extreme-UV intensity in solar coronal plasma structures

Abstract

Context. From 06:15 UT to 08:15 UT on 2011 June 2, a toroidal filament located at the joint of two active regions, 11226 and 11227, appeared to perform two eruptions. During this phenomenon, fast and slow magnetoacoustic waves were detected to propagate simultaneously along a funnel coronal loop system of AR 11227. Aims. We aim to understand the relationship between fast and slow magnetoacoustic waves during their propagations and measure their properties, such as the propagating speed, path, amplitude, and period observed in the extreme ultraviolet (EUV) wavebands. Methods. We analyse time sequences of EUV images acquired by the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory. By creating time-distance maps along selected directions, we measure the speeds and localisation of EUV intensity waves in different EUV wavebands. We determine the periods of the waves with wavelet analysis. Results. The fast and slow magnetoacoustic waves, apparently propagating along the same path, are found to have different properties. Their apparent propagation speeds, travel distances, and periods are about 900 km s −1 and 100 km s −1 , 145 Mm and 36 Mm, and 2 min and 3 min, respectively.

Spatially resolved observation of the fundamental and second harmonic standing kink modes using SDO/AIA

“…Rather, it is based on the relationship to other periodicities and comparison with those expected for known wave modes when realistic loop and plasma properties are assumed. Zhang et al (2015) reported an observation of a coronal funnel with SDO/AIA which demonstrates fast and slow waves propagating along the same field-aligned path, consistent with numerical simulations of Pascoe et al (2013b; Nisticò et al (2014). Measurement of the propagation speeds allowed the plasma-β to be estimated as approximately 0.01.…”

Nonlinear oscillations of coalescing magnetic flux ropes

“…Thus, for low values of β, which are also observed in solar coronal plasma structures (e.g. β ≈ 0.01 [22]), for the electron plasma frequencies of about 0.4 GHz, typical periods of current sheet oscillations are a few microseconds. …”

Coronal loop seismology using damping of standing kink oscillations by mode coupling

“…Andries et al 2005;Srivastava et al 2013) or wave modes (e.g. Zhang et al 2015), spatial seismology using time series from different locations (e.g. Verth et al 2007;Pascoe et al 2009b), temperature data from multiple bandpasses (e.g.…”