Physicists at the University of Iowa analyzed new data from the Parker Solar Probe, an automated corona spacecraft, and measured the Sun’s electric field.
The electric field of a star arises from the interaction of protons and electrons, formed when hydrogen atoms separate under the influence of heat generated by thermonuclear fusion deep inside the star.
Both types of particles create the solar wind: it flies away from the solar surface towards the outer layer of the heliosphere.
Some of the electrons are in the flow with the help of positively charged protons, and some, having a mass 1800 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.
During the new work, the authors estimated the ratio of outgoing and returning electrons and, with unprecedented accuracy, calculated the parameters of the solar electric field, its width and configuration.
The key point is that you cannot take such measurements away from the Sun. You can only do them when you get close. It’s like trying to understand a waterfall by looking at a river a mile downstream. The measurements that we made at a distance of 0.1 astronomical units are like inside a waterfall.
Jasper Halekas, Associate Professor, Department of Physics and Astronomy
Halekas notes that there is an energy boundary between those electrons that leave the energy field and those that cannot: it can be measured.
First of all, the authors measured those electrons that are returning, and not those that fly away, so it is possible to determine how much of this acceleration is provided by the electric field of the Sun.
The authors believe that their work will help scientists to supplement their understanding of the features of solar wind.