Sunrise-III detects magnetic threads above quiet regions of the Sun — ScienceDaily

An international research team led by the National Astronomical Observatory of Japan has discovered a complex network of thin magnetic structures above regions of the Sun considered relatively quiet. The observations were carried out by the Sunrise-III solar observatory, which was lifted into the stratosphere aboard a high-altitude balloon in 2024. ScienceDaily reports on the results.

A magnetic canopy of thin threads

The SCIP instrument aboard Sunrise-III recorded numerous narrow elongated magnetic structures in the chromosphere, the layer of the solar atmosphere above the star's visible surface. They are part of the so-called magnetic canopy: magnetic fields concentrated in the photosphere expand and curve upward into the chromosphere.

New measurements showed that this canopy is not a smooth structure that spreads uniformly through the atmosphere. Instead, it contains a large number of thin thread-like elements. Computer modeling reproduced the structures recorded by the observatory. According to the model, motions on the Sun's surface may twist magnetic field lines, forming such structures at greater heights.

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Observations near the edge of the solar disk

Sunrise-III also studied another quiet region near the visible edge of the Sun. There, scientists measured magnetic fields in spicules, narrow jets of solar material extending upward from the surface. The observations made it possible to trace how the distribution of magnetic fields changes with increasing height above the star's visible edge.

Relatively quiet regions occupy most of the solar surface, although their magnetic fields are usually weaker than in active regions with sunspots. They are difficult to study with ground-based telescopes because of Earth's atmospheric turbulence. During the 2024 mission, Sunrise-III operated at an altitude of approximately 35 kilometers, where atmospheric interference is significantly lower.

SCIP is an infrared spectropolarimeter developed under the leadership of the National Astronomical Observatory of Japan. It is capable of continuously measuring magnetic fields in different layers of the solar atmosphere, from the photosphere to the chromosphere. The study authors note that such measurements may help determine how energy from motions near the solar surface is transferred to higher atmospheric layers and contributes to their heating.