New research may help scientists unravel the physics of the solar wind

January 15 2022

(Nanwerk NewsA new study led by researchers from the University of Minnesota Twin Cities, using data from NASA’s Parker Solar Probe, provides insight into what generates and accelerates the solar wind, a stream of charged particles emitted by the sun’s corona.

Understanding how the solar wind works can help scientists predict “space weather” or respond to solar activity – such as solar flares – that can affect astronauts in space and much of the technology people rely on on Earth.

The paper was published in Astrophysical Journal Letters (“Parker Solar Probe Evidence for No Sirens Close to the Sun for Strahl Dispersal and for Regulating Heat Flow”). Parker Solar Probe A new study led by researchers from the University of Minnesota Twin Cities, using data from NASA’s Parker Solar Probe, provides insight into how the solar wind is generated and accelerated. (Photo: NASA/Johns Hopkins APL/Steve Gribben)

Scientists used data collected from the Parker Solar Probe, which was launched in 2018 with the goal of helping scientists understand what heats the sun’s corona (the sun’s outer atmosphere) and generates the solar wind. To answer these questions, scientists need to understand the ways energy flows from the sun. The latest round of data was obtained in August 2021 at a distance of 4.8 million miles from the sun – the closest spacecraft ever to the star.

Previous research indicated that in the solar wind, at distances from about 35 solar radii (one solar radius just over 432,000 miles) to Earth’s orbit at about 215 solar radii, electromagnetic waves called “Whistler” waves help regulate heat flow. , a form of energy flow. In this new study, a research team led by the University of Minnesota discovered that in a region closer to the sun, within about 28 solar radii, there are no whistling waves.

Instead, the researchers saw a different kind of wave that was electrostatic rather than electromagnetic. And in that same region, they noticed something else: the electrons showed the effect of an electric field created in part by the Sun’s gravitational pull, similar to what happens at Earth’s poles where “polar winds” accelerate.

“What we found is that when we go within 28 solar radii, we lose the whistles. That means the whistles can’t do anything to control the whistles,” said Cynthia Cattell, lead author on the paper and a professor in the School of Physics and Astronomy at the University of Minnesota Twin Cities. heat flow in that area.” This finding was very surprising to people. It has implications not only for understanding the solar wind and the winds of other stars, but it’s also important for understanding the heat flow of many other astrophysical systems that we can’t send satellites into — things like how star systems form. ”

Learning about the solar wind is also important to scientists for other reasons. First, it can disturb the Earth’s magnetic field, generate “space weather” events that can disrupt satellites, affect communications and GPS signals, and cause blackouts on Earth at northern latitudes such as Minnesota. . Energetic particles spread through the solar wind can also be harmful to astronauts traveling in space.

“Scientists want to be able to predict space weather,” Cattell explained. “And if you don’t understand the details of the energy flow near the sun, you can’t predict how fast or intense the solar wind will move when it reaches Earth. These are some of the characteristics that determine how solar activity affects us.”

In late 2024, the Parker Solar Probe will fly closer to 3.8 million miles from the Sun. From now on, Cattell and her colleagues are excited to see the next round of data from the spacecraft. Their next goal will be to find out why there is such an absence of whistle waves near the sun, how electrons accelerated by the electric field associated with gravity can excite other waves, and how this affects the solar wind.

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