Propagating wave in active region-loops, located over the solar disk observed by the Interface Region Imaging Spectrograph^★

¹ CAS Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, PR China
e-mail: yijunhou@nao.cas.cn, zjun@nao.cas.cn
² School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing 100049, PR China

Received: 25 April 2017
Accepted: 4 January 2018

Abstract

Aims. We aim to ascertain the physical parameters of a propagating wave over the solar disk detected by the Interface Region Imaging Spectrograph (IRIS).

Methods. Using imaging data from the IRIS and the Solar Dynamic Observatory (SDO), we tracked bright spots to determine the parameters of a propagating transverse wave in active region (AR) loops triggered by activation of a filament. Deriving the Doppler velocity of Si IV line from spectral observations of IRIS, we have determined the rotating directions of active region loops which are relevant to the wave.

Results. On 2015 December 19, a filament was located on the polarity inversion line of the NOAA AR 12470. The filament was activated and then caused a C1.1 two-ribbon flare. Between the flare ribbons, two rotation motions of a set of bright loops were observed to appear in turn with opposite directions. Following the end of the second rotation, a propagating wave and an associated transverse oscillation were detected in these bright loops. In 1400 Å channel, there was bright material flowing along the loops in a wave-like manner, with a period of ~128 s and a mean amplitude of ~880 km. For the transverse oscillation, we tracked a given loop and determine the transverse positions of the tracking loop in a limited longitudinal range. In both of 1400 Å and 171 Å channels, approximately four periods are distinguished during the transverse oscillation. The mean period of the oscillation is estimated as ~143 s and the displacement amplitude as between ~1370 km and ~690 km. We interpret these oscillations as a propagating kink wave and obtain its speed of ~1400 km s⁻¹.

Conclusions. Our observations reveal that a flare associated with filament activation could trigger a kink propagating wave in active region loops over the solar disk.