Hinode EUV spectroscopic observations of coronal oscillations

Abstract

Context: Waves offer a unique opportunity to understand and diagnose the properties of the solar coronal plasma.
Aims: Hinode/EIS observations are analysed to detect wave and oscillatory motions in the solar corona.
Methods: The EIS observations were carried out using a selection of EUV lines. Hinode/XRT images are taken concurrently.
Results: Two examples of oscillations in active regions are presented. We analysed the evolution of the intensities and Doppler shifts. The Hinode/XRT images suggest that both events occurred along loop-like structures. The first event is interpreted as a slow sausage (acoustic) type wave with a period of 1.2 mHz. The second example is associated with a transverse, most likely kink type, wave with a period of 3 mHz. The EUV line ratios were then used to determine the value of the coronal magnetic field.