Solar Orbiter has revealed that tiny, hair-like jets in the Sun’s coronal holes are responsible for both fast and slow solar wind. Scientists have now confirmed that these fleeting bursts of energy propel charged particles into space, finally shedding light on a long-standing mystery about the Sun’s power.
In 2023, scientists using the Solar Orbiter spacecraft discovered tiny jets near the Sun’s south pole that appeared to contribute to the solar wind. Now, with additional data from the European Space Agency’s ongoing solar mission, researchers have confirmed that these jets are widespread across dark patches in the Sun’s atmosphere and play a role in generating both fast and slow solar wind.
These newly identified jets appear in high-speed footage as thin, fleeting wisps of energy, particularly in the highlighted areas of the Sun’s surface. Although they seem brief in the video, they actually last about a minute, launching charged particles into space at speeds of around 100 km/s (224,000 mph).
This surprising breakthrough, published on February 5 in Astronomy & Astrophysics, showcases how Solar Orbiter’s advanced instruments are helping to unravel the mysteries of our Sun.
Solar Wind’s Mysterious Origins
The solar wind — a continuous stream of charged particles flowing from the Sun—extends throughout the Solar System, influencing everything from planetary atmospheres to space weather on Earth. Despite decades of research, its exact origins remained elusive. Until now.
The solar wind comes in two main forms: fast and slow. We have known for decades that the fast solar wind comes from the direction of dark patches in the Sun’s atmosphere called coronal holes – regions where the Sun’s magnetic field does not turn back down into the Sun but rather stretches deep into the Solar System.
Charged particles can flow along these ‘open’ magnetic field lines, heading away from the Sun, and creating the solar wind. But a big question remained: how do these particles get launched from the Sun in the first place?
A Breakthrough in Solar Wind Research
Building upon their previous discovery, the research team (led by Lakshmi Pradeep Chitta at the Max Planck Institute for Solar System Research, Germany) used Solar Orbiter’s onboard ‘cameras’ to spot more tiny jets within coronal holes close to the Sun’s equator.
By combining these high-resolution images with direct measurements of solar wind particles and the Sun’s magnetic field around Solar Orbiter, the researchers could directly connect the solar wind measured at the spacecraft back to those exact same jets.
Fast and Slow: A Surprising Discovery
What’s more, the team was surprised to find not just fast solar wind coming from these jets, but also slow solar wind. This is the first time that we can say for sure that at least some of the slow solar wind also comes from tiny jets in coronal holes – until now, the origin of the solar wind had been elusive.
The fact that the same underlying process drives both fast and slow solar wind comes as a surprise. The discovery is only possible thanks to Solar Orbiter’s unique combination of advanced imaging systems, as well as its instruments that can directly detect particles and magnetic fields.
Looking Ahead: Future Solar Investigations
The measurements were taken when Solar Orbiter made close approaches to the Sun in October 2022 and April 2023. These close approaches happen roughly twice a year; during the next ones, the researchers hope to collect more data to better understand how these tiny jets ‘launch’ the solar wind.
Reference: “Coronal hole picoflare jets are progenitors of both fast and Alfvénic slow solar wind” by L. P. Chitta, Z. Huang, R. D’Amicis, D. Calchetti, A. N. Zhukov, E. Kraaikamp, C. Verbeeck, R. Aznar Cuadrado, J. Hirzberger, D. Berghmans, T. S. Horbury, S. K. Solanki, C. J. Owen, L. Harra, H. Peter, U. Schühle, L. Teriaca, P. Louarn, S. Livi, A. S. Giunta, D. M. Hassler and Y.-M. Wang, 5 February 2025, Astronomy & Astrophysics.
DOI: 10.1051/0004-6361/202452737
Solar Orbiter is a collaborative space mission between the European Space Agency (ESA) and NASA, designed to study the Sun up close and in unprecedented detail. Operated by ESA, the spacecraft carries a suite of advanced instruments to observe the Sun’s outer layers, track solar wind, and analyze the Sun’s magnetic fields.
Among its key tools are the Extreme Ultraviolet Imager (EUI), which captures high-resolution images of the Sun’s corona, and the Polarimetric and Helioseismic Imager (PHI), which maps magnetic activity on the Sun’s surface. The Solar Wind Plasma Analyser (SWA) measures particles streaming from the Sun, while the Magnetometer (MAG) monitors changes in the Sun’s magnetic field.
By combining these powerful instruments, Solar Orbiter is providing groundbreaking insights into the Sun’s behavior, including the origins of the solar wind and the mechanisms driving space weather across the Solar System.
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1 Comment
Nice find! It is the correlation between fast and slow wind to the cornoal hole size that suggests that picoflare jets ar not only a wind component but the dominant component:
“However, by employing SO/PHI-HRI and HRIEUV observations acquired at nearly the same high spatial resolution, we are now able to trace individual faint jet features to the narrow magnetic network lanes in the interiors of coronal holes. Granular-scale emerging bipoles in the solar photosphere (Moore et al. 2011) facilitate continuous interactions between the parasitic polarity magnetic field patches and the network magnetic field (Gošić et al. 2014; Wang et al. 2022; Chitta et al. 2023b), leading to magnetic reconnection (Tu et al. 2005; Yang et al. 2013; Panesar et al. 2019; Pontin et al. 2024) and the launching of these picoflare jets from network lanes.
These tenuous jets form the most common and widespread background activity within the darker interiors of coronal holes. Their existence thus signifies the operation of magnetic reconnection at the base of the solar wind (Tu et al. 2005). The intermittency of the jets highlights the fleeting nature of the magnetic reconnection. While the observed picoflare jets at the coronal base have not yet evolved into a fully developed supersonic solar wind themselves, they do propagate along the direction of the large-scale open magnetic field of coronal holes. Based on this we suggest that they are the dominant progenitors of the solar wind flow from those open field regions. In this scenario, as these jets reach higher altitudes and begin to merge, their transition to the solar wind outflow will be regulated by the degree of coronal hole expansion. Consequently, different types of the solar wind arise, as our MAG and SWA in situ observations reveal.”