American scientists, based on data from NASA's Parker Solar Probe, measured the intensity of the flow of electrons - the main component of the solar wind, which for the first time made it possible to accurately calculate the potential of the solar electric field. The results of the study are published in The Astrophysical Journal.
The electric field of the Sun arises as a result of the interaction of protons and electrons, formed when hydrogen atoms separate under the influence of heat generated by thermonuclear fusion deep inside the Sun. Both those and other particles make up the solar wind carried away from the solar surface in the direction of the outer layer of the heliosphere.
Some electrons are held in the stream by positively charged protons, and some, having a mass 1,800 times less than that of protons, are detached from them and return back to the surface of the Sun. This movement of electrons determines the electric field of the Sun.
Physicists at the University of Iowa analyzed new data from the Parker Solar Probe, an automated corona spacecraft that flew just 0.1 AU from a star - closer than any ship before - and gained a new understanding of the Sun's electric field.
"The key point is that you cannot make such measurements far from the Sun. You can only make them when you get close," one of the study's authors, Jasper Halekas, associate professor of physics, quoted in a university press release. and astronomy. "It's like trying to understand a waterfall by looking at a river a mile downstream. The measurements we took at 0.1 AU are like inside the waterfall."
In particular, the researchers estimated the ratio of outgoing and returning electrons and more accurately than ever before calculated the parameters of the solar electric field, its width and configuration.
"The electrons are trying to escape, and the protons are trying to pull them back. This is the electric field," says Halekas. …
Researchers figuratively describe the electric field of the Sun in the form of a huge bowl, and electrons in the form of balls rolling along its inner surface at different speeds. Some electrons, or balls, are mobile enough to cross the edge of the bowl, while others gradually slow down and eventually slide to the bottom of the bowl.
"Basically, there is an energy boundary between those balls that leave the bowl and those that cannot, and it can be measured. Being close enough to the Sun, we can make accurate measurements of the distribution of electrons. First of all, we measure those electrons, which return, and not those that fly away, - explains the scientist. - So we can determine how much of this acceleration is provided by the electric field of the Sun. It seems that this is a very small part. This is not the main thing that gives an impulse to the solar wind, but it indicates to other mechanisms that give more energy."
The authors hope that the results of their study will provide a more accurate idea of the solar wind - a jet of plasma that flies away from the Sun at a speed of millions of kilometers per hour and washes the Earth and other planets of the solar system, and also has a significant impact on the operation of comic devices.