Spectro-Polarimetric Observation of an Emerging Flux Region: Triggering Mechanism of Ellerman Bombs

TL;DR

This study uses high-resolution spectro-polarimetric observations to investigate the magnetic field configurations associated with Ellerman bombs in an emerging flux region, revealing their triggering mechanisms and magnetic topologies.

Contribution

First report of undulatory magnetic field patterns in horizontal components, linking emerging flux tubes to Ellerman bombs through detailed spectro-polarimetric analysis.

Findings

Ellerman bombs are associated with regions of large magnetic field gradients.

Undulatory magnetic fields in both vertical and horizontal components were observed.

Ellerman bombs occur at flux tube footpoints, tops, and unipolar regions, consistent with magnetic reconnection.

Abstract

High spatial resolution observation of an emerging flux region (EFR) was done using a vector magnetograph and a H-alpha Lyot filtergraph with Domeless Solar Telescope at Hida Observatory on October 22, 2006. In H-alpha wing images, we could see many Ellerman bombs (EBs) in the EFR. Two observation modes, slit scan and slit fixed, were performed with the vector magnetograph, along with H-alpha filtergraph. Using H-alpha wing images, we detected 12 EBs during slit scan observation period and 9 EBs during slit fixed observation period. With slit scan observation, we found that all the EBs were distributed in the area where the spatial gradient of vertical field intensity was large, which indicates the possibility of rapid topological change in magnetic field in the area of EBs. With slit fixed observation, we found that EBs were distributed in the areas of undulatory magnetic fields, both in vertical and horizontal components. This paper is the first to report the undulatory pattern in horizontal components of magnetic field, which is also evidence for emerging magnetic flux by Parker instability. These results allow us to confirm the association between EBs and emerging flux tubes. Three triggering mechanism of EBs is discussed with respect to emerging flux tubes: 9 out of 21 EBs occurred at the footpoints of emerging flux tubes, 8 out of 21 EBs occurred at the top of emerging flux tubes, and 4 out of 21 EBs occurred at unipolar region. Each case can be explained by magnetic reconnection in the low chromosphere.