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Table 2.

Summary of the formation and evolution of the LBs.

Light bridge Formation and evolution
LB1 Strong and broad penumbral intrusion that breaks the umbra into two parts

LB2 Weak and thin penumbral intrusion, which, after splitting the umbra, retreats until its disappearance

LB3 Close approach of two umbra until the LB disappears from the northern part and finally from the south

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