Flare-prolific active region NOAA 12673 produced consecutive X2.2 and X9.3
flares on 06/09/2017. To scrutinize the morphological, magnetic, and horizontal
flow properties associated with these flares, a 7-hour time-series was used
consisting of continuum images, line-of-sight/vector magnetograms, and 1600
{\AA} UV images. These data were acquired with the SDO HMI and AIA. The
white-light flare emission differed for both flares, while the X2.2 flare
displayed localized, confined flare kernels, the X9.3 flare exhibited a
two-ribbon structure. In contrast, the excess UV emission exhibited a similar
structure for both flares, but with larger areal extent for the X9.3 flare.
These two flares represented a scenario, where the first confined flare acted
as precursor, setting up the stage for the more extended flare. Difference maps
for continuum and magnetograms revealed locations of significant changes, i.e.,
penumbral decay and umbral strengthening. The curved magnetic polarity
inversion line in the {\delta}-spot was the fulcrum of most changes. Horizontal
proper motions were computed using the DAVE4VM. Persistent flow features
included (1) strong shear flows along the polarity inversion line, where the
negative, parasitic polarity tried to bypass the majority, positive-polarity
part of the {\delta}-spot in the north, (2) a group of positive-polarity spots,
which moved around the {\delta}-spot in the south, moving away from the
{\delta}-spot with significant horizontal flow speeds, and (3) intense moat
flows partially surrounding the penumbra of several sunspots, which became
weaker in regions with penumbral decay. The enhanced flare activity has its
origin in the head-on collision of newly emerging flux with an already existing
regular, {\alpha}-spot.Comment: 7 pages, 6 Figures, Accepted to be published in Astronomy and
Astrophysic
