An innovative solar observing satellite, Hinode, has successfully observed the detailed evolution of an emerging
magnetic field, starting from its appearance at the solar surface, to forming a developed bipolar region. The high
spatial and temporal resolutions provided by the satellite has enabled us to capture prominent dynamic phenomena
caused by the emerging magnetic field, such as a running wave in a chromospheric layer and the rotation of
a magnetic polarity region on the Sun, which is reminiscent of a cyclone on Earth. A possible mechanism for
producing the chromospheric running wave spreading from a solar cyclone has been demonstrated with a threedimensional
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 propagates outwards from the
site of emergence.
Reference
Magara, T. 2012 PASJ, 64, L4
