Statistical investigation on the formation of sunspot light bridges

Abstract Light bridges (LBs) are bright lanes that divide one sunspot umbra into two or more parts. Though frequently observed in sunspots, their formation mechanisms have rarely been studied and thus not well understood. Here we present results from the first statistical investigation on of LBs. Using observations with Helioseismic Magnetic Imager board Solar Dynamics Observatory, identified 144 LBs within 71 active regions (ARs) over whole year 2014. The processes these can be categorized three groups: penumbral intrusion (type-A), merging (type-B) umbral-dot emergence (type-C). numbers events categories 74, 57 13, respectively. duration LB process is mostly less than 40 hours, an average ∼20 hours. Most a maximum length 20″. For type-A LBs, found positive correlation between process, suggesting similar speed different sunspots.