Magnetic Field Properties of Flux Cancellation Sites

Abstract

It has been frequently observed in longitudinal magnetograms that magnetic elements disappear when a magnetic polarity element approaches and collides with another polarity element. We examine 12 collision events observed with the Advanced Stokes Polarimeter. We find formation of new magnetic connection between the colliding opposite polarity elements both in the photosphere and in the corona. In some cases, the opposite polarity elements to be collided appear at different times and at widely separated positions. Magnetic fields horizontal to the solar surface are spontaneously formed on the polarity inversion line (PIL) between such colliding elements, and transient bright X-ray loops connecting the opposite polarity elements appear. We suggest that formation of the coronal loops and the photospheric horizontal fields are due to magnetic reconnection between the colliding field lines, possibly at multiple locations with different heights. We also find that a global change in the direction of the photospheric horizontal fields between the colliding elements occurs in association with formation and disappearance of Hα dark filaments. Initial horizontal fields perpendicular to the PIL become parallel to the PIL, when dark filaments are observed along the PIL. They return to being perpendicular to the PIL at around the time of the disappearance of the dark filament. This work was completed while the author was affiliated with the National Astronomical Observatory of Japan and University of Tokyo.