The contribution of the solar internetwork to the network magnetic flux
The weakest magnetic elements on the solar surface determine the maintenance of the network flux patches
At any one time, most of the solar surface is devoid of sunspots and active regions. This "quiet" Sun is however far from being unmagnetized, and harbors a significant fraction of the solar magnetic flux. The quiet Sun (QS) consists of network (NE) and internetwork (IN) regions. The former outlines the borders of supergranular cells, while the latter represents the cell interiors. Most of the total QS flux observed on the solar surface is organized in form of NE. However, the origin and maintenance of NE fields are not well known. The current paradigm is that ephemeral regions provide the flux needed to maintain the NE in the QS. In this paper, we investigate for the first time the contribution of small and weak IN flux patches to the NE flux. To do this, we use long-duration sequences of Hinode magnetograms at the unprecedented sensitivity, spatial resolutions and cadence. We find that IN elements frequently interact with NE patches and modify the flux budget of the NE either by adding flux or by removing it. The observed rate of the flux transfer from the IN to the NE reveals that IN supplies as much flux as is present in the NE in only 9–13 hr. This result promotes the IN as the most important contributor to the NE and seeks for a change of the above mentioned paradigm that ephemeral regions are the main source of flux in the QS.
Figure caption: This is a snapshot from an animation of data set 2 showing IN flux patches that eventually supply flux to the NE. Red contours mark IN elements contributing to the NE through merging processes while those undergoing cancellations are outlined with green contours. Blue contours represent NE patches. The borders of supergranular cells are marked with pink contours.
Reference: Gosic et al. (2014), ApJ 797 49
The Solar Internetwork. I. Contribution to the Network Magnetic Flux