Understanding the solar wind could help scientists predict how it will affect Earth’s satellites and astronauts in space.
A new study by scientists at the University of Minnesota using data from NASA’s Parker Solar Probe provides insight into what generates and accelerates the solar wind, a stream of charged particles emitted from the solar corona.
Understanding how the solar wind works could help scientists predict “space weather” or the response to solar activity such as solar flares.
Scientists used data from the Parker, launched in 2018, to help scientists understand what heats up the solar corona (the Sun’s outer atmosphere) and generates solar wind. The latest data was obtained in August 2021 at a distance of 7.7 million km from the Sun – this is the closest distance that the spacecraft has ever been to a star.
Previous research has shown that in the solar wind, from about 35 solar radii (one solar radius is just over 695,236 km) to Earth’s orbit of about 215 solar radii, electromagnetic waves called “whistles” help regulate heat flow. In a new study, a research team led by the University of Minnesota found that a region closer to the Sun, about 28 solar radii, does not have whistling waves.
Instead, the researchers saw a different type of wave that was electrostatic rather than electromagnetic. There they noticed something else: the electrons showed an electric field effect, created in part by the Sun’s gravity, similar to what happens at the Earth’s poles, where the “polar wind” speeds up.
“We found that when we get inside 28 solar radii, we lose whistlers. This means that whistlers cannot do anything to control the flow of heat in this region, ”said Cynthia Cattell, lead author of the paper and professor in the School of Physics and Astronomy at the University of Minnesota.
“This result was very unexpected for us. This not only affects the understanding of the solar wind and the winds of other stars, but is also important for understanding the heat flow of many other astrophysical systems that we cannot send satellites to, such as how star systems form,” Cattell explained.
Studying the solar wind is important to scientists for other reasons as well. The solar wind can disrupt the Earth’s magnetic field, creating “space weather” events that can cause satellites to malfunction, affect GPS communications and signals, and cause power outages on Earth at northern latitudes. Energy particles that are propagated by the solar wind can also be harmful to astronauts.
“Scientists want to be able to predict space weather. And if you don’t understand the details of energy flow near the Sun, then you can’t predict how fast the solar wind will move or what its density will be when it hits the Earth. These are some of the properties that determine how solar activity affects us, ”the scientist noted.