太阳物理研究组知识库

The rotational motions of the photospheric magnetic flux play a role in magnetic twist transportation between the corona and the solar interior. Using observations from the Helioseismic and Magnetic Imager on board the Solar Dynamic Observatory (SDO), we found one counterclockwise and two clockwise vortex flows on the photosphere in the NOAA active region 12371 during the flare SOL2015-06-22T18:23 (M6.5). The counterclockwise vortex was located on the footpoint of the erupting hot channels observed by the Atmospheric Imaging Assembly (AIA) Telescope on board SDO. The two clockwise vortices resided on either side of the polarity inversion line. At these vortices, the impulsive and irreversible change in the photospheric vector magnetic field were detected. The resulting change in the photospheric Lorentz force provides a torque in each vortex, which has the same direction with each vortex. A magnetic field extrapolation model shows that the coronal field starting from the two clockwise vortices suffered significant shrinkage during the changeover period of the photospheric field. Moreover, some of the modeled field rooted in the counterclockwise vortex displays a pronounced expansion during the flare. These results suggest that the clockwise vortices could result from the contraction of the magnetic field lines during the flare, while the counterclockwise vortex may be attributed to the expansion of the eruptive flux rope as observed in the AIA images.