How Tiny Jets on the Sun Fuel the Solar Wind: Latest Orbiter Findings

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main causes of the solar wind, representing progress in deciphering the incomprehensible actions of our star and in perfecting forecasts of its tempests.

The term "solar wind" denotes bursts of high-energy particles emitted from the sun. At times, these particles are aimed at Earth, as happened last summer when a rare series of such storms affected our planet and ignited stunning auroras worldwide — probably the most intense auroras in hundreds of years. Nevertheless, the solar wind can adversely impact Earth, for instance by disrupting GPS signals and other technologies dependent on satellite and radio communications; It may also jeopardize the safety of astronauts in Earth orbit.

Nevertheless, identifying the exact origins of the solar wind has proven challenging. This is partly due to the fact that the "footprints" carried by the charged particles in the wind — characteristics that scientists believe would show unique signatures of the solar regions responsible for the solar wind — are often distorted by the time they arrive on Earth.

It has been found in earlier studies that the fastest solar wind particles are propelled by tiny jets that emerge from large, dark gaps in the sun's corona, even though these jets are a trillion times weaker than the sun's most intense flares and last only up to a minute. These so-called "picoflares" are everywhere and are fueled by magnetic field lines that extend into space instead of looping back to the sun's surface, acting as cosmic highways that enable superheated plasma particles to break free from the sun's magnetic grip and shoot outward at hypersonic speeds.

Lakshmi Pradeep Chitta of the Max Planck Institute for Solar System Research in Germany previously told Space.com that "the energy content of a single picoflare jet that lasts about one minute is equivalent to the average power consumption of approximately 10,000 households in the U.K. over the course of a year."

Scientists have discovered, though, that it is harder to identify the source of the solar wind's slower component. Chitta and his team conducted a new analysis using detailed data from the European Space Agency's Solar Orbiter spacecraft, revealing strong evidence that these picoflares contribute energy to the slower solar wind.

Chitta remarked in a recent statement, "We were quite astonished to observe that the same minuscule plasma jets seem to be propelling both the rapid and the sluggish solar wind." We had previously assumed that various processes were involved.

Chitta and his colleagues based their conclusions on an analysis of data gathered by Solar Orbiter during its planned close encounters with the sun in late 2022 and early 2023. 

On these passes, the probe reached a distance of about 31 million miles (50 million kilometers) from our star, enabling its onboard cameras to take high-resolution images of jets in coronal holes and allowing direct measurements of the solar wind.

ESA stated that by merging these observations, “the researchers could directly link the solar wind measured at the spacecraft to those exact same jets.”

“For the first time, we can state with certainty that at least a portion of the slow solar wind originates from small jets in coronal holes,” the agency added. The source of the solar wind had remained elusive until now.

According to the statement, Solar Orbiter’s upcoming close passes of the sun, which happen about biannually, might provide further insight into the mechanism by which picoflares initiate the solar wind.

The findings of this research are detailed in a paper that appeared on February 5 in the journal Astronomy & Astrophysics.