Evolution of magnetic field corresponding to X-ray brightening events in coronal holes and quiet Sun regions

Huang Zhenghua, zhu@arm.ac.uk, Armagh Observatory, United Kingdom
Madjarska Maria, Armagh Observatory
Doyle Gerry, Armagh Observatory
Lamb Derek, Southwest Research Institute


Abstract
By using observations from Hinode/XRT and Hinode/SOT, we study the magnetic field structure and evolution for tens of X-ray brightening events in coronal holes and quiet Sun regions, including bright points and jets. With both visual analysis and feature tracking methods, we found that all the brightening events were associated with bipolar regions. By investigating the correspondence between the evolution of the magnetic field and X-ray emission, we found that magnetic cancellation is directly responsible for the brightenings. Oscillations of X-ray emission in some events was also strongly related to the evolution of the cancellation. The relationship between magnetic flux emergence and the events was also investigated. In coronal holes, flux emergence is important in forming the cancellation sites. Comparing coronal holes and the quiet Sun, we do not find differences in their corresponding magnetic field behavior.