With the Large Angle and Spectrometric Coronagraph (LASCO) mounted on the NASA and European Space Agency Solar and Heliospheric Observatory (SOHO) spacecraft, the US National Oceanic and Atmospheric Administration (NOAA) has been observing the sun’s corona since 1995 to track space weather that can have an impact on the earth. However, LASCO has an observing hole that prevents scientists from seeing the solar center corona, where the solar wind is generated.
A team of scientists from the 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, in which they image the center corona in ultraviolet (UV) wavelength.
The findings could lead to a better understanding of the origin of the solar wind and its interactions with the rest of the solar system.
Scientists proposed pointing another instrument, the Solar Ultraviolet Imager (SUVI) on NOAA’s Geostationary Operational Environmental Satellites (GOES), on either side of the sun instead of directly at it, and taking UV observations for a month to discover new ways to observe the sun. corona. In the sun’s central corona, scientists observed vast, 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 followed what the sun’s corona was doing in UV at this altitude during that 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 one system.”
“Our observations could lead to more comprehensive insights and even more exciting discoveries from missions such as PUNCH (Polarimeter to Unify the Corona and Heliosphere), a SwRI-led NASA mission that will envision how the sun’s outer corona becomes the solar wind.”
“Now that we can image the sun’s middle corona, we can link what PUNCH sees back to its origin and have a complete picture of how the solar wind interacts with the rest of the solar system. Before these observations, very few people believed that you could observe the center corona in UV at these distances. These studies have opened up an entirely new approach to observing the corona on a large scale.
- Chitta, LP, Seaton, DB, Downs, C., et al. Direct observations of a complex coronal web driving a highly structured slow solar wind. Wet Astron (2022). DOI: 10.1038/s41550-022-01834-5