In the realm of solar physics, a team of researchers from the University of California, Berkeley, including Forrest Mozer, Oleksiy Agapitov, Kyungeun Choi, and Andrii Voshchepynets, has made a notable discovery during the Parker Solar Probe’s 24th orbit. Their findings, published in the journal Geophysical Research Letters, shed new light on the behavior of plasma near the sun and its potential implications for the energy sector.
The researchers encountered a confined region of enhanced plasma density, approximately 25,000 particles per cubic centimeter, and broadband electrostatic waves near the perihelion of the Parker Solar Probe’s orbit. This region, located at about 10 solar radii from the sun’s surface, exhibited significantly reduced solar wind velocity and ion temperature compared to the ambient solar wind. The plasma conditions were observed on closed magnetic field lines, indicating that the spacecraft had passed through the base of a pseudo-streamer, a structure that extended out to 10 solar radii.
The electric field detected in the plasma frame during the crossing was as large as 400 millivolts per meter, with a current less than one milliampere per square meter, corresponding to a drift velocity less than 2.5 kilometers per second. The plasma in this region was also found to be turbulent, with density fluctuations as large as 30% of the average density. This turbulence suggests that the resistive term in the generalized Ohm’s law was significant. Additionally, the density as a function of time had a non-zero slope when the electric field was non-zero, indicating that the pressure gradient term also played a role.
The researchers noted that the plasma in this pseudo-streamer had a remarkably low flow velocity compared to earlier remote sensing and theoretical results. This discovery challenges existing models and could have implications for understanding solar wind and its interaction with Earth’s magnetosphere, which in turn affects space weather and the performance of satellites and other space-based energy infrastructure.
Understanding the behavior of plasma near the sun is crucial for predicting space weather events, which can impact power grids, communication systems, and other critical infrastructure on Earth. The findings from this study could help improve space weather forecasting models and mitigate potential risks to the energy sector. As the Parker Solar Probe continues its mission, further insights into the sun’s atmosphere and its effects on space weather are expected, providing valuable data for the energy industry and beyond.
This article is based on research available at arXiv.