Fully resolved quiet-Sun magnetic flux tube observed with the Sunrise IMaX instrument

TL;DR

This study uses high-resolution IMaX observations to directly resolve a quiet-Sun magnetic flux tube, revealing a fully magnetized, kilogauss-strength magnetic structure with enhanced mid- to upper photospheric temperature, consistent with flux tube models.

Contribution

It demonstrates that IMaX data can resolve quiet-Sun flux tubes without relying on indirect inference methods, using a one-component, fully magnetized atmospheric model.

Findings

Magnetic field strength exceeds 1 kG in the flux tube.

The flux tube shows increased temperature in the mid- to upper photosphere.

Observations are consistent with semi-empirical flux tube models.

Abstract

Until today, the small size of magnetic elements in quiet Sun areas has required the application of indirect methods, such as the line-ratio technique or multi-component inversions, to infer their physical properties. A consistent match to the observed Stokes profiles could only be obtained by introducing a magnetic filling factor that specifies the fraction of the observed pixel filled with magnetic field. Here, we investigate the properties of a small magnetic patch in the quiet Sun observed with the IMaX magnetograph on board the balloon-borne telescope Sunrise with unprecedented spatial resolution and low instrumental stray light. We apply an inversion technique based on the numerical solution of the radiative transfer equation to retrieve the temperature stratification and the field strength in the magnetic patch. The observations can be well reproduced with a one-component, fully magnetized atmosphere with a field strength exceeding 1 kG and a significantly enhanced temperature in the mid- to upper photosphere with respect to its surroundings, consistent with semi-empirical flux tube models for plage regions. We therefore conclude that, within the framework of a simple atmospheric model, the IMaX measurements resolve the observed quiet-Sun flux tube.