Solar Intranetwork Magnetic Elements: bipolar flux appearance

TL;DR

This study characterizes the bipolar flux appearance of solar intranetwork magnetic elements using Hinode/SOT data, revealing their emergence, evolution, and dynamic behaviors, which provide insights into sub-photospheric magneto-convection.

Contribution

It provides detailed observational analysis of bipolar flux emergence and evolution of solar intranetwork magnetic elements, highlighting their dynamic behaviors and magnetic axis rotation.

Findings

IN ERs have flux of 10^{16}-10^{17} Mx and lifetimes of 5-15 minutes.

Most IN ERs show magnetic axis rotation over 10 degrees during emergence.

Bipolar flux appearance includes shrinkage and growth cycles, indicating complex magneto-convection.

Abstract

The current study aims to quantify characteristic features of bipolar flux appearance of solar intranetwork (IN) magnetic elements. To attack such a problem, we use the Narrow-band Filter Imager (NFI) magnetograms from the Solar Optical Telescope (SOT) on board \emph{Hinode}; these data are from quiet and an enhanced network areas. Cluster emergence of mixed polarities and IN ephemeral regions (ERs) are the most conspicuous forms of bipolar flux appearance within the network. Each of the clusters is characterized by a few well-developed ERs that are partially or fully co-aligned in magnetic axis orientation. On average, the sampled IN ERs have total maximum unsigned flux of several 10^{17} Mx, separation of 3-4 arcsec, and a lifetime of 10-15 minutes. The smallest IN ERs have a maximum unsigned flux of several 10^{16} Mx, separations less than 1 arcsec, and lifetimes as short as 5 minutes. Most IN ERs exhibit a rotation of their magnetic axis of more than 10 degrees during flux emergence. Peculiar flux appearance, e.g., bipole shrinkage followed by growth or the reverse, is not unusual. A few examples show repeated shrinkage-growth or growth-shrinkage, like magnetic floats in the dynamic photosphere. The observed bipolar behavior seems to carry rich information on magneto-convection in the sub-photospheric layer.