Magnetic field emergence in mesogranular-sized exploding granules observed with SUNRISE/IMaX data

TL;DR

This study investigates magnetic field emergence in exploding granules on the solar surface using high-resolution SUNRISE/IMaX data, revealing flux emergence patterns, velocities, and magnetic structures linked to granular dynamics.

Contribution

It provides detailed observations and analysis of magnetic flux emergence in mesogranular-sized exploding granules, including the first evidence of loop-like structures and flux intensification mechanisms.

Findings

Magnetic flux of ~10^18 Mx emerges in exploding granules.

Granule expansion velocity is around 1 km/s, magnetic patches expand at 0.65 km/s.

Emerging magnetic structures are influenced by convective motions and downflows.

Abstract

We report on magnetic field emergences covering significant areas of exploding granules. The balloon-borne mission SUNRISE provided high spatial and temporal resolution images of the solar photosphere. Continuum images, longitudinal and transverse magnetic field maps and Dopplergrams obtained by IMaX onboard SUNRISE are analyzed by Local Correlation Traking (LCT), divergence calculation and time slices, Stokes inversions and numerical simulations are also employed. We characterize two mesogranular-scale exploding granules where $\sim$ 10$^{18}$ Mx of magnetic flux emerges. The emergence of weak unipolar longitudinal fields ($\sim$100 G) start with a single visible magnetic polarity, occupying their respective granules' top and following the granular splitting. After a while, mixed polarities start appearing, concentrated in downflow lanes. The events last around 20 min. LCT analyses confirm mesogranular scale expansion, displaying a similar pattern for all the physical properties, and divergence centers match between all of them. We found a similar behaviour with the emergence events in a numerical MHD simulation. Granule expansion velocities are around 1 \kms while magnetic patches expand at 0.65 \kms. One of the analyzed events evidences the emergence of a loop-like structure. Advection of the emerging magnetic flux features is dominated by convective motion resulting from the exploding granule due to the magnetic field frozen in the granular plasma. Intensification of the magnetic field occurs in the intergranular lanes, probably because of being directed by the downflowing plasma.