Fine Magnetic Characteristics of a Light Bridge by Hinode

Abstract

Light bridge (LB) is bright structure crossing the umbra of sunspots and associated to the breakup or assembly of sunspots. In this paper, a LB is presented and studied using the observatory data obtained by {\it Hinode} satellites. Force-free factor ($\alpha$) and the z-component of current ($J_z$) and tension force ($T_z$) are calculated basing on the vector magnetograms observed by Spectro-Polarimeter (SP) of the Solar Optical Telescope (SOT) on board {\it Hinode}. It is found that the amplitudes of $\alpha$ and $J_z$ of LB are generally larger than those of umbra. It is found that there are two signs of $J_z$ along LB, which are divided at near the middle position of LB. It is found that the amplitudes of $T_z$ of LB are smaller than those of umbra and there are changes of sign of $T_z$ between the boundary of LB and umbra. Through comparisons and investigations, it suggest that LB and umbra maybe two different magnetic systems, which is a necessary condition for interaction magnetic reconnection.

arXiv comment22 pages, 6 Figures,

References in corpus (8)

• The Solar Optical Telescope for the Hinode Mission: An Overview
• Plasma Ejections from a Light Bridge in a Sunspot Umbra
• Formation Process of a Light Bridge Revealed with the Hinode Solar Optical Telescope
• Global Twist of Sunspot Magnetic Fields Obtained from High Resolution Vector Magnetograms
• Evolution of Currents of Opposite Signs in the Flare Productive Solar Active Region NOAA 10930
• Detection of opposite polarities in a sunspot light bridge: evidence of low-altitude magnetic reconnection
• A Statistical Study on Force-Freeness of Solar Magnetic Fields in the Photosphere
• Magnetic Tension of Sunspot Fine Structures

Cited by in corpus (1)

• Signatures of magnetic reconnection at the footpoints of fan shape jets on a light bridge driven by photospheric convective motions