The solar wind is a ubiquitous feature in the solar system. A relentless, high-speed stream of charged particles from the sun fills interplanetary space. On Earth, it can cause geomagnetic storms that can disrupt satellites and, at high latitudes, the dazzling aurora borealis — the northern and southern lights.
But exactly how the sun generates the solar wind remains unclear. New observations from Solar Orbiter may provide answers.
The spacecraft has detected numerous relatively small jets of charged particles intermittently ejected at supersonic speeds from the corona, the sun’s outer atmosphere, for 20 to 100 seconds, researchers said Thursday.
These jets emerge from structures in the corona called coronal holes, where the sun’s magnetic field extends out into space instead of returning to the star. Due to their relatively small size, they are called “skin flare jets”. They arise over an area a few hundred miles wide — tiny compared to the giant sun, which is 8,65,000 miles (1.4 million kilometers) across.
“We think that these jets may actually be responsible for maintaining the mass and energy of the solar wind,” said solar physicist Lakshmi Pradeep Chitta of the Max Planck Institute for Solar System Research in Germany. Primary source.” He is the lead author of the study published in the journal. science.
The solar wind consists of plasma (ionized gas, or a gas in which atoms have lost electrons), and is mostly ionized hydrogen.
“Unlike the wind that circles the Earth on Earth, the solar wind is ejected outward into interplanetary space,” Chita said.
“As the Earth and other planets in the solar system orbit the sun, they whiz by in the solar wind. Earth’s magnetic field and atmosphere act as a shield, protecting life by blocking harmful particles and radiation from the sun. But the solar wind is constantly traveling outward from the sun. and inflate a bubble of plasma called the heliosphere that surrounds the planet,” Chita added.
The heliosphere extends about 100 to 120 times the distance from the Earth to the Sun.
Data for the study were acquired last year by one of three telescopes on an instrument called the Extreme Ultraviolet Imager aboard Solar Orbiter, a solar orbiter built by the European Space Agency and NASA. The observing probe, Solar Orbiter, launched in 2020, was about 31 million miles (50 million kilometers) from the sun, about one-third the distance from the sun to Earth.
“This discovery is important because it sheds further light on the physics of solar wind power generation,” said study co-author Andrei Zhukov, a solar physicist at the Royal Astronomical Observatory of Belgium.
The existence of the solar wind was predicted by American physicist Eugene Parker in the 1950s and confirmed in the 1960s.
“Nevertheless, the origin of the solar wind remains a long-standing mystery in astrophysics,” Chita said. “A key challenge is to identify the main physical processes that power the solar wind.”
Solar Orbiter is discovering new details about the solar wind and is expected to get even better data in the coming years using additional instruments and observing the Sun from other angles.
Stellar winds are common to most, if not all, stars, Zhukov said, although the physical mechanisms may differ for different types of stars.
Zhukov added: “We know the sun in much more detail than other stars because it is so close to the sun that it is possible to make more detailed observations.”
© Thomson Reuters 2023
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