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

¹ Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, 100012 Beijing, PR China
e-mail: yuzong@nao.cas.cn; zjun@nao.cas.cn; wangjx@nao.cas.cn
² Physics Department, University of Warwick, Coventry CV4 7AL, UK
e-mail: V.Nakariakov@warwick.ac.uk
³ Central Astronomical Observatory of the Russian Academy of Sciences at Pulkovo, 196140 St Petersburg, Russia

Received: 7 January 2015
Accepted: 12 July 2015

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.