Transient horizontal magnetic fields in solar plage regions

TL;DR

This paper reports the discovery of widespread, transient horizontal magnetic fields in solar plage regions, revealing their dynamic behavior and potential magnetic buoyancy-driven emergence, with implications for understanding solar magnetic activity.

Contribution

The study provides the first detailed observations of small-scale, transient horizontal magnetic fields in plage regions, highlighting their frequent occurrence and dynamic nature.

Findings

Horizontal magnetic fields are widespread and transient in plage regions.

Granular convection influences the horizontal magnetic fields' dynamics.

An event driven by magnetic buoyancy instability was observed.

Abstract

We report the discovery of isolated, small-scale emerging magnetic fields in a plage region with the Solar Optical Telescope aboard Hinode. Spectro-polarimetric observations were carried out with a cadence of 34 seconds for the plage region located near disc center. The vector magnetic fields are inferred by Milne-Eddington inversion. The observations reveal widespread occurrence of transient, spatially isolated horizontal magnetic fields. The lateral extent of the horizontal magnetic fields is comparable to the size of photospheric granules. These horizontal magnetic fields seem to be tossed about by upflows and downflows of the granular convection. We also report an event that appears to be driven by the magnetic buoyancy instability. We refer to buoyancy-driven emergence as type1 and convection-driven emergence as type2. Although both events have magnetic field strengths of about 600 G, the filling factor of type1 is a factor of two larger than that of type2. Our finding suggests that the granular convection in the plage regions is characterized by a high rate of occurrence of granular-sized transient horizontal fields.