As for the source of sunspot activity? So far, there is no very complete theory that can perfectly explain the formation of sunspots, but it can be found that there is a large and relatively simplified model to explain it slightly, and from it, it can lead to the old theory and the subsequent new theory. Establish.
It is generally believed that sunspots and other activities are caused by thermal convection and different rotation speeds of various parts.
It can be imagined that there were originally two magnetic poles in the north and south on the sun, forming a meridional magnetic field in the troposphere. Different parts of the solar material move at different speeds (this is called poor rotation), with faster rotation near the equator and slower rotation near the equator. As a result, the magnetic field lines "frozen" in the solar material will gradually be elongated and surround the sun, with a zonal component. After multiple windings, the weft component becomes stronger and stronger. The strength of the magnetic field is proportional to the density of magnetic field lines. After multiple entanglements, the magnetic field in the solar material basically becomes zonal and its intensity increases greatly. There is a repulsive force between the magnetic field lines, and the repulsive force becomes stronger and stronger when the magnetic field is strengthened. Since the magnetic field is "frozen" in the solar material, the repulsive force of the magnetic field lines adds an expansion pressure to the solar material, often called magnetic pressure. In the convective layer inside the sun, due to inhomogeneity, the gas pressure is not exactly the same everywhere. If the magnetic pressure exceeds the air pressure somewhere, the mass of material will expand, and as a result, it will be affected by the buoyancy force like bubbles in water. Rising toward the surface, eventually even the magnetic field lines and material emerged from the sun's surface. Sunspots form where magnetic field lines converge across the top of the troposphere and into the photosphere. The sunspots formed at the locations where magnetic field lines concentrate and penetrate are N-polar and S-polar respectively. And the magnetic field lines on both sides of the equator have opposite directions, so the polarities of sunspot pairs formed in the southern and northern hemispheres are also opposite.
From left to right, you can see the entanglement of magnetic field lines and the opposite polarity of sunspots in the northern and southern hemispheres.
So far, we have found that the information we have found has little difference in the above explanations, and they all use the same theory as the point of view. But later, when discussing why magnetic field lines affect temperature, two very different theories, the old and the new, emerged.
According to the old theory, due to the large concentration of magnetic field lines in the sunspots, the strong magnetic field hinders the convection from the interior of the sun to the solar surface. That is to say, the plasma cannot move freely under the strong magnetic field in the sunspot area. A plug-like effect is formed, preventing energy from continuing to flow from the interior to the surface. When the material above the plug cools, it flows back to the sun's surface at a speed of nearly 5,000 kilometers per hour. The surrounding plasma further cools and settles toward the magnetic field at the center of the sunspot. The cooling effect can continue to maintain the sunspot before the strength of the magnetic field weakens. Structural stability.
Because the magnetic plug prevents heat from flowing to the sun, the temperature of the lower layer of the sunspot gradually increases. Observations by astronomers in June 1998 found that sunspots are actually very shallow. The speed of sound at 5,000 kilometers below the surface is significantly higher, indicating that the temperature there is also higher than the surrounding area, which is exactly the same phenomenon that sunspots present on the surface. on the contrary. The new theory is also based on a strong magnetic field, but it believes that instead of suppressing it, the magnetic field greatly accelerates the transmission of energy.
The strong magnetic field of sunspots turns most of the heat flow into magnetic fluid waves, which quickly propagate along the magnetic field lines. The energy is then turned into waves, thus cooling down.