Solar activity (III)

1989/06/01 Arregi Bengoa, Jesus Iturria: Elhuyar aldizkaria

• Astronomia

The type of activity of the Sun that most influences the Earth are the eruptions. This was, for example, what took place last March 6, related to some large dwellings that could be seen on the surface of the Sun. Minutes later, and until the situation recovered, many of the radio communications could not be carried out. Later we will also see the exact reason for this phenomenon, but first we will have to make a brief analysis of the eruptions.

As discussed in previous articles, the solar magnetic field evolves locally. Although it is not easy, and due to the movement of matter, sometimes magnetic lines are stacked forming tubes. In this situation, due to the forces between them, some are deformed by going up the surface of the Sun creating a structure in the shape of a ring (see figure 1). The high intensity of the magnetic field stops the convection currents of the base of the structure, creating black spots in the two regions where the tube cuts the surface. Therefore, the polarities of the elements of the pair of created blackheads are contrary. This particularity that we have not mentioned so far has its importance.

The phenomenon was known thanks to measurements made by magnetometers located on Earth. In addition, the following occurs: If the direction of the positive and negative polarity of the tanning pairs of one of the two solar hemispheres is from east to west, the other occurs backwards and, in addition, the direction of each hemisphere varies in a cycle of eleven years. Some therefore speak of a period of twenty years to consider this investment.

But we have not yet talked about anything that tells us about the eruptions. What is the origin of these violent phenomena? The release of energy occurs in the aforementioned rings. Although different models have been developed to explain the origin of instability, there is no consensus regarding this problem. However, being one of the observations that best suits the experience, highlights the approach of the rings of different polarity. According to its main lines, the interaction of magnetic fields would occur in centimeters or meters when approaching a newly created ring to another previous one (see figure 2).

Then, between the tubes would produce very strong electric currents and their materials, electrons and protons, above all, would be expelled at high speed, as two attractive magnetic plates inside a liquid would eject the intermediate skirt. The release of energy is enormous and occurs differently (Figure 3 outlines what is shown below). As mentioned above, in the beginning protons and electrons are launched with acceleration caused by the electric field of thousands of volts. Most of these fractions are exposed to the magnetic ring and move depending on them, making circular tours around the magnetic lines. On their journey they emit violent x-rays and microwave. The latter are a consequence of the synchrotron effect, that is, of the radiation emitted by the fractions charged by a spiral movement.

The rest is due to the process called “bremsstrahlung”. This occurs when lots of fractions are very narrow. Thus, the magnetic field increases greatly and synchrotron radiation represents a very high loss of energy. Fractions are therefore subjected to a braking process and in turn emit energy radiation.

As the fractions approach the feet of the hoop, higher density maternal regions undergo two effects: on the one hand, the warming of matter that sometimes reaches 10 million degrees of temperature and on the other, the nuclear reactions that the protons cause when colliding with the nuclei of atoms. The first makes it emits gases, x-rays, ultraviolet radiation and light from the H-alpha line of the hydrogen spectrum, and also elevates the hot gas to the ring, at a speed of a few hundred kilometers per second. As for the second, protons provoke nuclear reactions with atoms they find in their path, emitting high-energy neutrons and gamma procedures. This interpretation therefore requires stronger initial accelerations of protons than previous ones, with fields that should be 1,000 million volts.

Therefore, we have described the eruptions as a great accelerator of fractions. Although this vision seems quite coherent, it lacks gaps. Perhaps the most important thing is what derives from the observation made at the end of the previous paragraph, since we have assumed without great explanations that the accelerations that occupy the fractions are obtained by interaction of magnetic fields. We must recognize, without a doubt, that obtaining a solar energy of 10 million billion (1019) kilowatt hours is a very difficult task in the short time that the observations last. It is more difficult if we have to give way to all that energy through accelerated fractions. According to some scientists studying the sun, the accumulation of energy in the eruptions would begin with the warming of a gaseous environment of large volume. This gas could emit x-rays and give a lot of energy to the atmosphere. Eruptions can be hybrid complexes of these and other processes.

Finally, we have analyzed all the phenomena necessary to understand the consequences of solar activity on Earth. In the next issue we will begin to directly analyze these conclusions, such as polar fossils, conditioning radiocommunications or climate change.