2020/10/21 by Eun-Kyung Lim, Eun‐Kyung Lim, Heesu Yang +5 · 10 citations
Biochemistry, Genetics and Molecular Biology · Medicine · Physics and Astronomy · #Anatomy #Association (psychology) #Astronomy #Astrophysics #Bridge (graph theory) #Genetics #Geomagnetism and Paleomagnetism Studies #Ionosphere and magnetosphere dynamics #Medicine #Physics #Polarity (international relations) #Solar and Space Plasma Dynamics #astro-ph.SR
paper · pdf · doi:10.3847/1538-4357/abc1e0
published in The Astrophysical Journal 904(2), 84 (IOP Publishing) · 24pages, 11figures, accepted by the ApJ
arxiv created 2020/10/21 · openalex publication_date 2020/11/24 · arxiv updated 2020/12/02 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Abstract Light bridges (LBs) are relatively bright structures that divide sunspot umbrae into two or more parts. Chromospheric LBs are known to be associated with various activities including fan-shaped jet-like ejections and brightenings. Although magnetic reconnection is frequently suggested to be responsible for such activities, not many studies present firm evidence to support the scenario. We carry out magnetic field measurements and imaging spectroscopy of an LB where fan-shaped jet-like ejections occur with co-spatial brightenings at their footpoints. We study LB fine structure and magnetic field changes using TiO images, Near-InfraRed Imaging Spectropolarimeter, and H α data taken by the 1.6 m Goode Solar Telescope. We detect magnetic flux emergence in the LB that is of opposite polarity to that of the sunspot. The new magnetic flux cancels with the pre-existing flux at a rate of 5.6 × 10 18 Mx hr −1 . Both the recurrent jet-like ejections and their base brightenings are initiated at the vicinity of the magnetic flux cancellation, and show apparent horizontal extension along the LB at a projected speed of up to km s −1 to form a fan-shaped appearance. Based on these observations, we suggest that the fan-shaped ejections may have resulted from slipping reconnection between the new flux emerging in the LB and the ambient sunspot field.