Strong Transverse Photosphere Magnetic Fields and Twist in Light Bridge Dividing Delta Sunspot of Active Region 12673

TL;DR

This study investigates the strong magnetic fields and apparent twist in the light bridge of the highly flare-productive active region 12673, revealing key magnetic features associated with its flare activity.

Contribution

It provides detailed observations of intense magnetic fields and twist in the light bridge of AR 12673, enhancing understanding of magnetic configurations leading to solar flares.

Findings

Magnetic fields in the light bridge exceed 5500 G.

Presence of apparent photospheric twist in the light bridge.

Correlation between magnetic features and flare activity.

Abstract

Solar Active Region (AR) 12673 is the most flare productive AR in the solar cycle 24. It produced four X-class flares including the X9.3 flare on 06 September 2017 and the X8.2 limb event on 10 September. Sun and Norton (2017) reported that this region had an unusual high rate of flux emergence, while Huang et al. (2018) reported that the X9.3 flare had extremely strong white-light flare emissions. Yang at al. (2017) described the detailed morphological evolution of this AR. In this report, we focus on usual behaviors of the light bridge (LB) dividing the delta configuration of this AR, namely the strong magnetic fields (above 5500 G) in the LB and apparent photospheric twist as shown in observations with a 0.1 arcsec spatial resolution obtained by the 1.6m telescope at Big Bear Solar Observatory.