The Parker Solar Probe, which has been unraveling the secrets of the Sun, has flown close enough to see the structure of the solar wind close to where it is generated. This is a crucial discovery. Solar winds are energized particles flowing from the Sun’s corona, its outer atmosphere, toward Earth. They are the source of space weather, which can disrupt power grids, telecommunications systems, and GPS signals.
The probe’s latest findings, published Tuesday in the journal Nature, show that portions of the solar wind originate near funnel-shaped regions on the Sun known as coronal holes. These structures, which appear as jets on the Sun’s surface, are created when magnetic fields emerge from the photosphere — the Sun’s visible layer of gas sits just below its corona. They then collide, reconnect and send charged particles flying into the solar system. The solar wind, which can reach more than 1.7 million miles per hour, results from these phenomena.
But the particles don’t just surf along on magnetic waves; they also gain energy as they are accelerated in the corona by robust magnetic reconnection processes. The scientists analyzed the speed of a small sample of these particles and discovered that some were up to 10 times faster than the average for solar wind. This speed is a telltale sign that they are surfing on plasma — the hot, magnetized fluid that makes up the outer layers of the corona.
When the researchers analyzed data from the probe’s most recent flyby on December 20, they found that the speed of these particles matches patterns of up-and-down hydrogen flows within the Sun. These flows are packed together like thunderstorms in a process known as supergranulation. The spacecraft also spotted events that accelerated the particles in these plasma flows, which the team believes are the origin of the solar winds.
In the future, the researchers hope to discover how much solar wind is produced in these regions by observing how the particles are accelerated. They also want to understand the exact structure of these funnels and the physics behind their formation.
To make these observations, the Parker probe uses its spectrometers to take an inventory of the elements that comprise the solar wind. Its magnetometers measure the speed and direction of the solar wind, while its plasma spectrometer looks at the electrical properties of its constituents.
The Parker Solar Probe is named after University of Chicago astrophysicist Eugene Newman Parker, who, in the 1950s, proposed several concepts that helped us understand how stars — including our own — release energy. The mission was renamed in 2017 to honor the late scientist’s 90th birthday and his contributions to our understanding of how stars give off energy. The probe is set to swoop even closer to the Sun, reaching about 4 million miles from its surface when it reentered the atmosphere in January 2022.
