For the first time, scientists have been able to capture near-daily measurements of the Sun’s global coronal magnetic field, a region that was previously observed irregularly. These observations offer valuable insights into the processes that drive solar storms, which can have significant impacts on technologies and daily life on Earth. The data was collected over eight months using an instrument called the Upgraded Coronal Multi-channel Polarimeter (UCoMP) and the results are published in the journal Science. Solar storms, driven by the magnetic field, can pose threats to power grids, communication systems, and GPS technology, making it crucial to understand the mechanisms behind them.
The solar corona, the upper atmosphere of the Sun, has been a challenging region to study due to the difficulty of observing its magnetic field. Traditional methods of measuring the magnetic field in the corona require large and expensive equipment, limiting the ability to study the entire region. However, by combining coronal seismology with UCoMP observations, researchers were able to create consistent and comprehensive views of the global coronal magnetic field. This approach allows for a whole-Sun view of the magnetic field, filling a crucial gap in our understanding of the Sun and its impact on Earth.
The international research team, comprised of scientists from Northumbria University, NSF NCAR, Peking University, and the University of Michigan, utilized the UCoMP instrument to make these groundbreaking observations. The funding for the research came from grants from the National Natural Science Foundation of China and the National Key R&D Program of China, with support from the U.S. National Science Foundation. The development of the UCoMP instrument was also funded by NSF and operated at the Mauna Loa Solar Observatory, allowing for enhanced observations of the coronal magnetic field.
While scientists have been able to measure the magnetic field on the surface of the Sun, known as the photosphere, the coronal magnetic field has been more difficult to observe due to its dimness. The UCoMP instrument, while smaller than telescopes like the Daniel K. Inouye Solar Telescope (DKIST), is better-suited for capturing global pictures of the coronal magnetic field. By combining a coronagraph with a Stokes polarimeter, UCoMP can provide wide views of the Sun, allowing for detailed studies of the coronal magnetic field in a two-dimensional projection, complementing the data collected by larger telescopes like DKIST.
Using coronal seismology, the research team tracked magnetohydrodynamic (MHD) transverse waves in the UCoMP data, enabling them to create a two-dimensional map of the coronal magnetic field’s strength and direction. The upgraded capabilities of UCoMP allowed for more detailed and routine measurements of the coronal magnetic field, producing 114 magnetic field maps over an eight-month period. This research marks a new era in solar physics research, where routine measurements of the coronal magnetic field are becoming possible, providing crucial insights into solar activity and its impact on Earth.
The observations also yielded the first measurements of the coronal magnetic field in the polar regions, which had not been directly observed before due to viewing limitations from Earth. The improved data quality provided by UCoMP and the Sun’s proximity to solar maximum allowed for stronger emissions from the polar regions, making it easier to obtain measurements. The ultimate goal of this research is to enhance existing coronal models based on photospheric measurements and to capture the full three-dimensional magnetic field of the corona. By combining various techniques, researchers aim to gain a deeper understanding of the magnetic field’s role in solar eruptions and better predict and prepare for solar storms that can disrupt life on Earth.