Sunspots rotation and magnetic transients associated with flares in NOAA AR 11429

Abstract

We analyze sunspots rotation and magnetic transients in NOAA AR 11429 during two X-class (X5.4 and X1.3) flares using the data from the Helioseismic and Magnetic Imager on board the \emph{Solar Dynamics Observatory}. A large leading sunspot with positive magnetic polarity rotated counterclockwise. As expected, the rotation was significantly affected by the two flares. The magnetic transients induced by the flares were clearly evident in the sunspots with negative polarity. They were moving across the sunspots with speed of order $3-7\ \rm km \ s^{-1}$. Furthermore, the trend of magnetic flux evolution of these sunspots exhibited changes associated with the flares. These results may shed light on the understanding of the evolution of sunspots.