With the Large Angle and Spectrometric Coronagraph (LASCO) mounted on the NASA and European Space Agency Solar and Heliospheric Observatory (SOHO) spacecraft, the U.S. National Oceanic and Atmospheric Administration (NOAA) has been observing the Sun’s corona since 1995 to track space weather that may have an impact on Earth. However, LASCO has an observational gap that prevents scientists from seeing the middle solar corona, where the solar wind is generated.
A team of scientists from Southwest Research Institute (SwRI), NASA, and the Max Planck Institute for Solar System Research (MPS) has discovered web-like plasma structures in the Sun’s middle corona. The researchers describe their innovative new observation method, imaging the middle corona in ultraviolet (U.V.) wavelength.
The findings could lead to a better understanding of the solar wind‘s origins and interactions with the rest of the solar system.
Scientists proposed pointing a different instrument, the Solar Ultraviolet Imager (SUVI) on NOAA’s Geostationary Operational Environmental Satellites (GOES), at either side of the Sun instead of directly at it and making U.V. observations for a month to discover new ways to observe the Sun’s corona. In the central corona of the Sun, scientists observed extended, web-like plasma formations. Particles are propelled into space by interactions within these structures, which release stored magnetic energy.
SwRI Principal Scientist Dr. Dan Seaton, one of the study’s authors, said, “No one had monitored what the Sun’s corona was doing in U.V. at this height for that amount of time. We had no idea if it would work or what we would see. The results were very exciting. For the first time, we have high-quality observations that unite our observations of the Sun and the heliosphere as a single system.”
“Our observations could lead to more comprehensive insights and even more exciting discoveries from missions like PUNCH (Polarimeter to Unify the Corona and Heliosphere), a SwRI-led NASA mission that will imagine how the Sun’s outer corona becomes the solar wind.”
“Now that we can image the Sun’s middle corona, we can connect what PUNCH sees back to its origins and have a complete view of how the solar wind interacts with the rest of the solar system. Before these observations, very few people believed you could observe the middle corona to these distances in U.V. These studies have opened up a whole new approach to observing the corona on a large scale.”
- Chitta, L.P., Seaton, D.B., Downs, C., et al. Direct observations of a complex coronal web driving highly structured slow solar wind. Nat Astron (2022). DOI: 10.1038/s41550-022-01834-5