SDO/AIA and Hinode/EIS Observations of Interaction between EUV wave with nearby Active Region Loops

Yang Liheng, Key Laboratory of Solar Activity, National Astronomical Observatories
Zhang Jun, Key Laboratory of Solar Activity, National Astronomical Observatories
Li Ting, Key Laboratory of Solar Activity, National Astronomical Observatories

Abstract
We present observations of a coronal EUV wave on 2011 August 4 by using the Solar Dynamics Observatory/Atmospheric Imaging Assembly (AIA) and the Hinode/EUV Imaging Spectrometer (EIS). The EUV wave was associated with an M9.3 class flare, a fast halo CME and a slow filament eruption. The interactions between the EUV wave with nearby active region loops and the spectroscopic characteristics of the EUV wave were examined. The interactions contained three course: (1) The wave propagated along the loops. (2) When the wave arrived at the top of the loops, part of the wave was damped. The damped wave drove the loops forward. The driven loops had velocities from 40 to 60 km/s and a maximum displacement of about 36 Mm. (3) The damped wave flowed into the nearby active region with velocities from 110 to 290 km/s. Reflected waves from several coronal structures were observed, and they also finally injected into the above active region along open magnetic filed lines. The EUV wave were observed to pass through an active region on its path with an increased velocity, and cross over a filament channel with a invariable velocity. The EUV wave had velocities from 460 to 830 km/s at different directions, and show an weak deceleration. EIS data of the wave reveal that when the EUV wave passed through the EIS slit, the corresponding red shifted feature enhanced whereas the blue shifted features weakened. While after the EUV wave passed, the red shifted feature weakened whereas the blue shifted features increased. Such variations resembled oscillation signals, and repeat three times. These findings can be well explained by the fast mode magnetoacoustic interpretations of EUV waves, in which the observed waves generated by the expanding CME.