Tstreams of charged particles are continuously blasted from the solar atmosphere and radiated outward at millions of kilometers per hour, creating a solar wind so powerful that its limit defines the outer edge of our solar system.

Despite the enormous distribution of this wind, its formation has long remained a mystery. Now, a new analysis claims that the solar wind is fed by a collective set of discontinuous small-scale jet eruptions in the solar corona, or outer layer. “The idea is similar to how the individual sounds of applause in the audience turn into a continuous roar when the audience applauds,” he said. Craig DeForestsolar physicist at the Southwestern Research Institute in Boulder, Colorado, and co-author of the study.

Although scientists already knew that the corona is home to small plumes that typically last a few minutes, they had previously found only a small number of them, mostly at the base of plumes emerging from cooler, less dense regions of the corona known as coronal holes. .

A new study shows they are ubiquitous. “Once you know how to find them, you will see that they are constantly present in almost every structure of the crown,” said the co-author. Dan Seatona solar physicist who also works at the Southwestern Research Institute.

The team found that the jets, each 1,000 to 3,000 kilometers wide, are present even during solar minimum, the least active phase of the Sun’s 11-year cycle – a result that is consistent with the pervasive nature of the solar wind. “You can randomly select any day and the jets will be there like solar wind,” he said. Nur Rawafisolar physicist at the Johns Hopkins University Applied Physics Laboratory and lead author of the study.

In an article presenting new findings, published earlier this year in the journal Astrophysical JournalThe team provides evidence that the jets are ignited by a process called magnetic reconnection, which heats and accelerates the plasma of charged particles. The researchers speculate that the jets then produce waves that heat up the corona and allow the plasma to escape the Sun’s gravity and coalesce to form the solar wind.

“The numbers look promising and show that it is indeed quite possible that jets could deliver the mass lost by the sun to the solar wind,” he said. Charles Kankelborga solar physicist at Montana State University who was not involved in the study.

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The idea that small-scale discontinuous events can collectively drive the solar wind goes back to the work of Eugene Parker, a solar physics pioneer who died last year. In 1988, he suggested that a “nanoflare swarm” propelled by tiny flashes of magnetic reconnection could heat the corona to the point of propelling the wind.

However, finding evidence for this small-scale reconnection has proven difficult due to the low resolution of magnetic measurements.

For the new study, the researchers examined high-resolution images from a variety of sources, including those from NASA’s Solar Dynamics Observatory. GOES-R satellites— best known as meteorological satellites — and the Goode Solar Telescope at the Big Bear Solar Observatory. They found that regions of the corona that previously appeared to be devoid of magnetic flux were in fact filled with complex magnetic fields. The team was also able to link several aircraft to specific reunion events. The researchers expect that magnetic field data, even at a finer scale, could reveal higher reconnection and jet rates.

The team went on to suggest that the jets create a special type of wave called Alfvén waves that heat up the corona. Alfvén waves were seen as a competing mechanism that could explain the solar wind. But there is a growing consensus that these processes can work together. “The global presence of these reunion-induced jets provides a natural explanation for both the reunion and the Alfvén waves powering the solar wind,” he said. Judith Karpensolar physicist at NASA Goddard Space Flight Center.

The researchers expect upcoming efforts to uncover coronal processes in unprecedented detail. They are looking forward to newer telescopes such as the Daniel K. Inouye Solar Telescope at the National Solar Observatory, as well as solar orbitera joint project between NASA and the European Space Agency launched in 2020.

“It could turn out that the emission spectrum goes from relatively large events to Parker nanoflares on the smallest scales,” Rawafi said.

And jets can be associated with large-scale events on the Sun, such as flares and coronal mass ejections. Ji Zhang, solar physicist at George Mason University. “Small-scale eruptions may play a role in transforming magnetic configurations into more coherent large-scale structures that can store large amounts of energy before an eruption,” he said.

So far, new aircraft finds have confirmed the legacy of Parker and his contemporaries. “Here are some observations 30 years later that they were probably correct,” Kankelborg said.

This article has been originally published on Quantum abstractions blog.

Featured image: NASA’s Solar Dynamics Observatory took an ultraviolet image of the erupting flare. Credit: NASA

• Theo Nikotopoulos

  Published May 5, 2023

  Theo Nikitopoulos is a science writer covering earth and space science news. His work has been published in various publications, including Scientific American, Wired, astronomy another hakai magazine. He is pursuing a master’s degree in science writing from Johns Hopkins University.

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