Dead calm areas in the very quiet Sun

TL;DR

This study reveals that the very quiet Sun contains filamentary, dead calm areas with very low magnetic activity, indicating an intrinsic, intermittent magnetic field generation mechanism in these regions.

Contribution

It provides high-resolution observations showing non-uniform magnetic field distribution and identifies intrinsic calm areas, advancing understanding of quiet Sun magnetism.

Findings

497 small-scale magnetic loops identified

Dead calm areas characterized by low magnetic signals

Magnetic field generation is recurrent and intermittent in quiet Sun regions

Abstract

We analyze two regions of the quiet Sun (35.6 x 35.6 Mm^2) observed at high spatial resolution (~100 km) in polarized light by the IMaX spectropolarimeter onboard the Sunrise balloon. We identify 497 small-scale (~400 km) magnetic loops, appearing at an effective rate of 0.25 loop h^{-1} arcsec^{-2}; further, we argue that this number and rate are underestimated by ~30%. However, we find that these small dipoles do not appear uniformly on the solar surface: their spatial distribution is rather filamentary and clumpy, creating dead calm areas, characterized by a very low magnetic signal and a lack of organized loop-like structures at the detection level of our instruments, that cannot be explained as just statistical fluctuations of a Poisson spatial process. We argue that this is an intrinsic characteristic of the mechanism that generates the magnetic fields in the very quiet Sun. The spatio-temporal coherences and the clumpy structure of the phenomenon suggest a recurrent, intermittent mechanism for the generation of magnetic fields in the quietest areas of the Sun.