  During the lifetime of AR 12673, its magnetic field evolved drastically and
produced numerous large flares. In this study, using full maps of the Sun
observed by the Solar Dynamics Observatory and the Solar Terrestrial Relations
Observatory, we identified that AR 12673 emerged in decayed AR 12665, which had
survived for two solar rotations. Although both ARs emerged at the same
location, they possessed different characteristics and different flare
productivities. Therefore, it is important to study the long-term magnetic
evolution of both ARs to identify the distinguishing characteristics of an AR
that can produce large solar flares. We used the Spaceweather Helioseismic and
Magnetic Imager Active Region Patch data to investigate the evolution of the
photospheric magnetic field and other physical properties of the recurring ARs
during five Carrington rotations. All these investigated parameters dynamically
evolved through a series of solar rotations. We compared the long-term
evolution of AR 12665 and AR 12673 to understand the differences in their
flare-producing properties. We also studied the relation of the long-term
evolution of these ARs with the presence of active longitude. We found that the
magnetic flux and complexity of AR 12673 developed much faster than those of AR
12665. Our results confirmed that a strong emerging flux that emerged in the
pre-existing AR near the active longitude created a very strong and complex AR
that produced large flares.
