Solar Wind’s Potential Source Discovered by Solar Orbiter: Plasma Jets

The Solar Orbiter, a joint project by ESA and NASA, has made a significant discovery regarding the sun’s outer layer. It has observed a sequence of short bursts of material jets, lasting between 20 to 100 seconds, which expel plasma at a speed of 100 km/s. These jets could potentially be the long-sought origin of the solar wind.

The solar wind, a stream of charged particles, is constantly escaping from the sun and interacting with celestial bodies. When it collides with the Earth’s magnetic field, it produces the aurora borealis.

Understanding the origin of the solar wind near the Sun has long been a challenge. However, Solar Orbiter’s advanced instruments have made significant progress. Data from the spacecraft’s Extreme Ultraviolet Imager (EUI) camera reveal faint, transient features at the sun’s south pole associated with tiny jets of plasma.

Lakshmi Pradeep Chitta of the Max Planck Institute points out that the EUI’s high-resolution images were crucial in detecting these jets. In particular, the extreme ultraviolet channel of the EUI images captured the million-degree solar plasma at a wavelength of 17.4 nanometers.

The analysis confirms that these features are indeed caused by the escape of plasma from the solar atmosphere.

Previous knowledge linked some of the solar wind to magnetic structures called coronal holes, where the sun’s magnetic field extends outward. Plasma travels along these “open” magnetic lines, forming the solar wind. The origin of this plasma removal remained unclear.

Traditionally, it was assumed that due to the heat of the corona, it naturally expands, causing the plasma to escape along the magnetic field lines. However, Solar Orbiter’s focus on the coronal hole challenges this idea. The isolated jets found suggest that solar wind production may be more intermittent than previously thought.

Andrei Zhukov of the Royal Observatory of Belgium emphasizes the non-uniform nature of this flow and suggests that the coronal hole-based solar wind may arise from a highly random outflow.

Although the energy of each jet is modest, together they contribute significantly to the production of the solar wind. These findings also suggest possible smaller, more frequent events.

The ongoing Solar Orbiter mission

The ongoing mission of the Solar Orbiter, which is gradually tilting its orbit toward the polar regions, is providing new perspectives on these jets. Since holes in the corona appear at different latitudes throughout the solar cycle, new insights are expected.

These discoveries extend beyond our solar system. Although the Sun is the only star with observable detailed atmospheres, this process is likely to occur in other stars, making these revelations essential to astrophysics.

Essentially, these fleeting jets of plasma discovered by the Solar Orbiter bring us closer to solving the riddle of the origin of the solar wind.