Small-scale convection signatures associated with strong plage solar magnetic field

TL;DR

This study investigates small-scale magnetoconvection in strong plage regions, revealing granular patterns with reduced velocities, asymmetric profiles, and bright downflows, supported by observations and simulations.

Contribution

It provides the first direct observations of small-scale magnetoconvection within strong magnetic fields, comparing observed properties with MHD simulations.

Findings

Detected small-scale granular magneto-convection patterns.

Observed RMS velocities are 70% of field-free granulation.

Found bright downflows along flux concentration boundaries.

Abstract

In this work, we study and quantify properties of strong-field small-scale convection and compare observed properties with those predicted by numerical simulations. We analyze spectropolarimetric 630.25 nm data from a unipolar ephemeral region near sun center. We use line-of-sight velocities and magnetic field measurements obtained with Milne-Eddington inversion techniques along with measured continuum intensities and Stokes V amplitude asymmetry at a spatial resolution of 0.15 arcseconds to establish statistical relations between the measured quantities. We also study these properties for different types of distinct magnetic features, such as micropores, bright points, ribbons, flowers and strings. We present the first direct observations of a small-scale granular magneto-convection pattern within extended regions of strong (more than 600 G average) magnetic field. Along the boundaries of the flux concentrations we see mostly downflows and asymmetric Stokes V profiles, consistent with synthetic line profiles calculated from MHD simulations. We note the frequent occurrence of bright downflows along these boundaries. In the interior of the flux concentrations, we observe an up/down flow pattern that we identify as small-scale magnetoconvection, appearing similar to that of field-free granulation but with scales 4 times smaller. Measured RMS velocities are 70% of those of nearby field-free granulation, even though the average radiative flux is not reduced. The interiors of these flux concentrations are dominated by upflows.