The Sun is a magnetized star, and its magnetic field plays a crucial role in the formation of the Sun
The magnetic field penetrates the various layersthe atmosphere of the Sun, which means that information about the magnetic field of the entire atmosphere is necessary to understand the interaction between the solar plasma and the magnetic field. Until now, however, conventional measurements of the Sun's magnetic field have only been carried out on the surface of our star - a region of the Sun known as the photosphere.
Corona magnetic field map superimposed on the corona image taken by the AIA instrument at the Solar Dynamics Observatory. Credit: Yang et al. 2020, Science
Although more than 100 years have passed since the first measurement of the solar magnetic field, we still do not have accurate information about the magnetic field in the upper layers of the sun's atmosphere, especially about the corona.
More than 20 years ago, the magnetoseismology method wasproposed as a method for measuring the magnetic field in the corona. This method uses Alfven magnetic waves, transverse magnetohydrodynamic plasma waves, propagating along the lines of force of the magnetic field.
Coronal magnetic field lines obtained from the PFSS model. Credit: Courtesy: Yang et al. 2020, Science
It is important to note that the speed of propagation of waves is dependent on the strength of the magnetic field, which means that being able to measure how fast they propagate allows you to estimate the magnetic field.
Dr. Richard Morton, Future Research FellowUKRI, based at the University of Northumbria, is a global expert in observing and analyzing waves in the Sun's corona and was part of the team that produced these exciting results. He has long used the CoMP instrument and advocated increasing the frequency of such measurements to study the solar magnetic field.
CoMP data shows that the Sun's corona is full of these Alfvén waves and gives us the best view of them available.
Dr Richard Morton, UKRI Future Research Fellow based at Northumbria University
Current research is based on earlierthe works of Dr. Morton, which demonstrated the possibility of using magnetic waves as a tool. He also stated that his research is an excellent demonstration of how scientists can use Alfvén waves to study the properties of the Sun. The process is similar to how seismologists use earthquakes to figure out what is inside the earth.
This is the first time that a global mapThe coronal magnetic field was obtained through real coronal observations, which marks a step towards solving the problem of measuring the coronal magnetic field.
In principle, with this technique it is now possible to routinely obtain maps of the global coronal magnetic field, filling in the missing part of the measurements of the Sun's global magnetism.
In addition, synoptic corona magnetogramscan provide important information for a deeper understanding of how the magnetic field binds different layers of the sun's atmosphere, as well as the physical mechanisms responsible for solar eruptions and the solar cycle.
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