Fig. 1
From: Transient rotation of photospheric vector magnetic fields associated with a solar flare
Azimuth angle changes in association with Flare emission. All of the four images (first and second rows) were taken simultaneously at the flare peak time (18:00 UT) in a common FOV of 40ʺ by 40ʺ. a SDO/HMI white light map. Running difference image in Hα blue wing (−1.0 Å), showing the eastern flare ribbon in (b). The bright part is the leading front and the dark component is the following component. c The GST/NIRIS LOS magnetogram, scaled in a range of −2500 (blue) to 2500 G (yellow). Running difference map of azimuth angle generated by subtracting the map taken at 17:58:45 UT from the one taken at 18:00:12 UT in (d). The dark signal pointed to by the pink arrow represents the sudden, transient increase of azimuth angle at 18:00:12 UT. The white contours outline 60% of the maximum emission of the Hα ribbon front. e Time–distance diagram of Hα difference maps. The slit position is shown in (b). The time period is from 17:50 UT to 18:05 UT. f Time–distance diagram of azimuth difference maps. The slit position is shown in (d). The time period is from 17:50 UT to 18:05 UT. The white contours outline 15% of the maximum emission of the Hα ribbon front in (e)
