抚仙湖太阳观测和研究基地知识库

With the launch of the Solar Dynamic Observatory, many extreme ultraviolet (EUV) waves have been observed during solar eruptions. However, joint observations of Moreton and EUV waves are still relatively rare. We present an event in active region NOAA 12740 wherein a small-scale filament eruption simultaneously results in a Moreton wave, an EUV wave, and a coronal mass ejection. First, we find that some dark elongated lanes or filamentary structures in the photosphere that exist under the small-scale filament drift downward; this manifests as the small-scale filament emerging and lifting up from the subsurface. Second, combining simultaneous observations in different EUV and H alpha passbands, we study the kinematic characteristics of Moreton and EUV waves. Comparable propagation velocities and similar morphologies of the Moreton and different-passband EUV wave fronts were obtained. We deduce that Moreton and different-passband EUV waves are the perturbations in different temperature-associated layers induced by a coronal magnetohydrodynamic shock wave. We also find refracted, reflected, and diffracted phenomena during the propagation of the EUV wave. By using power-law fittings, the kinematic characteristics of unaffected, refracted, and diffracted waves were obtained. The extrapolation field derived by the potential field source surface model manifests as an interface between different magnetic systems (magnetic separatrix), resulting in the refraction, reflection, and deviation of the EUV wave.