The quiet Sun is the area of the solar surface outside of active regions. Dominated by granular convection, it appears to be dull and uninteresting. However, observations with high sensitivity have demonstrated that the quiet Sun harbors ubiquitous magnetic fields. These fields are extremely weak, but may contain most of the magnetic energy of the solar surface, outweighing sunspots and active regions by far. Unfortunately, we do not know much about their properties and evolution due to the lack of sensitive measurements at high spatial resolution.
Recent observations with the Narrowband Filter Imager on the Japanese satellite Hinode have been used to investigate this important aspect of the solar magnetism. Quiet Sun fields emerge on the surface in the form of tiny, low-lying magnetic loops that connect patches of opposite polarity, as shown by the closed colored field lines resulting from a magneto-frictional simulation of the data. Some loops are able to reach the chromosphere. On their way up, they interact with pre-existing fields and other quiet Sun loops. These interactions may release energy on very small spatial scales, perhaps contributing to chromospheric heating. EST will allow us to detect even weaker loops, trace their ascent in the atmosphere, and quantify how much energy they deposit in the chromosphere through interactions with ambient fields.
This image shows a side view of the magnetic field lines derived from the magnetofrictional simulation.
Credit: M. Gosic (IAA-CSIC), M. Cheung (LMSAL), L. Bellot Rubio (IAA-CSIC) Observations: Hinode (ISAS/JAXA, NAOJ, NASA; STFC, ESA), HOP 151
Quiet Sun magnetic fields (1/2)
[MOVIE] Quiet Sun magnetic fields (2/2)
Evolution of internetwork magnetic elements in the quiet Sun
[MOVIE] Evolution of internetwork magnetic elements in the quiet Sun
[MOVIE] Evolution of magnetic elements in the quiet Sun
Tiny magnetic loops in the quiet Sun (1/6)
[MOVIE] Tiny magnetic loops in the quiet Sun (2/6)
Tiny magnetic loops in the quiet Sun (3/6)
[MOVIE] Tiny magnetic loops in the quiet Sun (4/6)
Tiny magnetic loops in the quiet Sun (5/6)
[MOVIE] Tiny magnetic loops in the quiet Sun (6/6)
The smallest dipoles ever observed in a star
[MOVIE] Quiet-sun magnetic field observed with IMaX