Chromospheric Running Wave Produced through the Emergence of a Twisted Magnetic Flux Tube

We report the detailed evolution of emerging magnetic field that starts from the appearance of magnetic field at the solar surface to the formation of a developed bipolar region. The high spatial and temporal resolution provided by a solar observing satellite Hinode enables to capture the prominent dynamic phenomena caused by the emerging magnetic field; a running wave in a chromospheric layer that spreads ahead of a rotating magnetic polarity region which is reminiscent of a cyclone on the Earth. A possible mechanism for producing the running wave accompanied with a solar cyclone is demonstrated with a three-dimensional magnetohydrodynamic simulation for the emergence of a twisted flux tube. The simulation shows that as the emergence proceeds, an arc-shaped region with enhanced plasma density appears in a chromospheric layer and propagates outwards from the site of emergence.