Magnetic Fields and Velocity Structures around a Cancellation Site

TL;DR

This study uses Hinode satellite data to analyze magnetic and velocity structures around a solar magnetic cancellation, providing evidence that Omega-loop submergence is the dominant process in this event.

Contribution

It offers observational evidence supporting the Omega-loop submergence model over the U-loop emergence in magnetic cancellation.

Findings

Transverse magnetic fields connect canceling features.

Long-lasting Doppler red-shifts are observed.

Red-shift delays by 20 minutes after cancellation.

Abstract

A cancellation is thought to be a basic process of the photospheric magnetic field and plays an important role in magnetic flux budget and in various solar activities. There are two major theoretical scenarios for this phenomena, i.e. the "U-loop emergence" and the Omega-loop submergence models. It is important to clarify which is the dominant process during the cancellation for the estimation of the solar magnetic flux transport through the surface. We study the vector magnetic field and velocity structures around a quiet Sun cancellation by using the Solar Optical Telescope on board Hinode satellite. Transverse magnetic field connecting the canceling magnetic features and strong long-lasting Doppler red-shift signal are found. The transverse field is observed in the first spectropolarimetric observation after the occurrence of the cancellation while the red-shift clearly delayed to the cancellation by 20 minutes. These results indicate that the observed cancellation is an Omega-loop submergence.