Scientists have developed a new theory to explain the formation of magnetic switchbacks around the sun. These switchbacks are reversals of the radial magnetic field in the solar wind, the stream of charged particles emanating from the sun’s surface. While sporadically observed since the 1970s, the Parker Solar Probe mission has recently identified magnetic switchbacks as a typical component of solar wind fluctuations in the inner heliosphere.

The research team, led by Dr. Gabor Toth from the University of Michigan, worked alongside Dr. Bart van der Holst and Dr. Marco Velli to publish their study in The Astrophysical Journal. The study proposes a simple and predictive theory for forming these magnetic reversals. It suggests that the switchbacks are created when circularly polarized Alfvén waves, which are waves perpendicular to the magnetic field, become distorted and start oscillating in different directions due to variations in the wave speed.

The team analyzed data the Parker Solar Probe sent back after its flyby in 2018 and found that the magnetic field and plasma velocity oscillates in the switchbacks. This discovery challenged previous assumptions and provided valuable insights into the heating and acceleration of the solar wind. The findings have implications for predicting space weather and understanding the impact of space weather events on spacecraft, communication systems, GPS, and the electric power grid.

The research also contributes to developing the Space Weather Modeling Framework, a collaborative effort to improve forecasting for space weather events. The Alfvén Wave Solar-atmosphere Model (AWSoM) is one of the models within this framework and aims to unravel the mysteries of Alfvén waves and their role in coronal heating. The new theory on magnetic switchbacks aligns well with this framework and enhances our understanding of turbulence in the solar wind and heating in the inner heliosphere.

Moving forward, the research team plans to conduct three-dimensional numerical modeling of switchbacks, incorporating turbulence, and investigate how the formation of switchbacks affects the theory of Alfvén wave heating. These advancements will contribute to better space weather models and a deeper understanding of our sun’s atmosphere dynamics.

References

• Priebe, M. & University of Michigan College of Engineering. (2023, November 30). New theory explains how magnetic switchbacks form in the solar wind. Phys.Org; University of Michigan. https://phys.org/news/2023-11-theory-magnetic-switchbacks-solar.html
• Toth, G., Velli, M., & Van Der Holst, B. (2023). Theory of Magnetic Switchbacks Fully Supported by Parker Solar Probe Observations. The Astrophysical Journal, 957(2), 95. https://doi.org/10.3847/1538-4357/acfd91