麻豆淫院

Sunspots are the most striking phenomenon of the solar magnetic field. After the invention of the telescope early in the 17th century, the Italian astronomer Galileo Galilei was the first to routinely observe sunspots. In the 20th century, with the help of modern techniques such as spectroscopy and later polarimetry, scientists realized that these spots are the locations of strong magnetic fields.

The magnetic field inside sunspots is as strong as the one in an MRI (magnetic resonance imaging) machine typically used in hospitals, but it spreads over an area larger than that of the entire Earth. The number of sunspots on the surface of the sun reaches a maximum every 11 years when the solar activity cycle reaches its peak.

Unstable magnetic configurations in the vicinity of sunspots can cause explosions known as coronal mass ejections and solar flares, especially during sunspot maximum. These explosions can have a serious impact on satellite communications. The strongest explosions can lead to power failures.

Stable sunspots can exist on the sun's surface for periods ranging from a few days to several months and they are the key to understanding the solar activity cycle. While it was assumed in the early 1970s that the reason for the long life of sunspots was the fact that an equilibrium is reached between gas pressure and the magnetic field, this equilibrium has so far been very difficult to explain due to disturbances in the magnetic field.

The journal Astronomy & Astrophysics recently published a on the development of a new method for analyzing the stability of sunspots. As part of this study, an international team鈥攍ed by scientists from Germany in collaboration with colleagues from Sweden, the U.S. and Spain鈥攁pplied this new method to observations with the German GREGOR solar telescope.

During this process, physicists at the Institute of Solar 麻豆淫院ics (KIS) in Freiburg succeeded in extending and improving a technique, developed originally at the G枚ttingen Max Planck Institute for Solar System Research, in such a way that the influence of Earth's atmosphere could be removed from the observations. The magnetic field measurements carried out with the new method at the German GREGOR solar telescope now achieve a quality previously only attained with satellites, but at a much lower cost. A comparison between the measurements before and after the correction is shown in figure 1.

The development of a powerful numerical program, led by Dr. Juan Manuel Borrero at the Institute of Solar 麻豆淫院ics (KIS) in Freiburg, enabled the researchers to analyze the polarized light emitted by the sun. This analysis showed that the magnetic forces inside sunspots are compensated by pressure forces in such a way that equilibrium is strictly maintained (figure 2).

This discovery explains why sunspots can survive for so long on the surface of the sun. In the future, it could be used to detect when sunspots become unstable, making it more likely to trigger the above-mentioned explosions that potentially threaten modern life on Earth.