By Will Dunham
WASHINGTON (Reuters) – The solar wind is a ubiquitous feature of our solar system. An endless stream of high-speed charged particles from the sun fills interplanetary space. On Earth, this triggers geomagnetic storms that can disrupt satellites and cause dazzling aurorae – northern and southern lights – at high latitudes.
But exactly how the sun generates solar wind is still unclear. New observations made by the Solar Orbiter spacecraft may provide the answer.
Researchers on Thursday said the spacecraft had detected a series of relatively small jets of charged particles ejected periodically from the corona – the sun’s outer atmosphere – at supersonic speeds for 20 to 100 seconds.
The emission originates from structures in the corona called coronal holes, where the sun’s magnetic field stretches out into space, not back into the star. They are called “picoflalar jets” because of their relatively small size. They emerge from an area several hundred miles wide – minuscule when compared to the sun’s massive scale, which has a diameter of 865,000 miles (1.4 million km).
“We argue that these jets could actually be a major source of mass and energy to sustain the solar wind,” said solar physicist Lakshmi Pradeep Chitta of the Max Planck Institute for Solar System Research in Germany, lead author of the research published in the journal. Science.
The solar wind is composed of plasma ionized gas, or gas in which atoms have lost electrons – and most of it is ionized hydrogen.
Unlike the winds on Earth that circulate around the Earth, solar wind is blown out into interplanetary space, Chitta said.
“Earth and other planets in the solar system move via the solar wind as they orbit around the sun. Earth’s magnetic field and atmosphere act as a shield and protect life by blocking harmful particles and radiation from the sun. But the solar wind continued to creep outward. from the sun and expands the bubble of plasma called the heliosphere which envelops the planets,” Chitta added.
The heliosphere extends about 100 to 120 times farther than Earth’s distance from the Sun.
The data for the study was obtained last year by one of three telescopes on an instrument called the Extreme Ultraviolet Imager aboard the Solar Orbiter, a solar observation probe built by the European Space Agency and the US space agency NASA which launched in 2020. The Solar Orbiter is located at approx. 31 million miles (50 million km) from the sun at the time – about a third the distance between the sun and the earth.
“This finding is important because it sheds more light on the physical mechanism of solar wind generation,” said solar physicist and study co-author Andrei Zhukov of the Royal Observatory of Belgium.
The existence of the solar wind was predicted by American physicist Eugene Parker in the 1950s and verified in the 1960s.
“However, the origin of the solar wind is still a puzzle in astrophysics,” said Chitta. “The main challenge is identifying the dominant physical processes that drive the solar wind.”
Solar Orbiter discovered new details about the solar wind and hopes to get better data in the coming years by using additional instruments and looking at the sun from other angles.
Zhukov said stellar winds are a common phenomenon for most, if not all, stars, although the physical mechanisms may differ among different types of stars.
“Our understanding of the sun is far more detailed than that of other stars, because its proximity allows for more detailed observations,” added Zhukov.
(Reporting by Will Dunham, Editing by Rosalba O’Brien)
2023-08-24 20:20:21
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