Joint operations between a solar observation satellite and a sounding rocket telescope have allowed scientists to measure the magnetic field strength in the photosphere and chromosphere. The research is published in Science Advances.

Despite being the brightest object in the sky, the Sun still holds many mysteries for astronomers. It is generally accepted that magnetic fields play an important role in heating the solar corona, but the details of this process are still unclear. To solve this mystery, it is important to understand the magnetic field in the chromosphere, which is sandwiched between the corona and the photosphere – the visible surface of the Sun.

An international team led by Ryhko Ishikawa, Associate Professor at the National Astronomical Observatory of Japan, and Javier Trujillo Bueno, Professor at the Institute of Astrophysics of the Canary Islands, analyzed the data collected from the CLASP2 probe rocket experiment over six and a half minutes on April 11, 2019. They determined the longitudinal component of the magnetic field above the active region layer and its surroundings. To do this, the scientists analyzed the signature that the magnetic field left on the ultraviolet light from the chromosphere.

The unique high-precision CLASP2 data allowed researchers to determine the magnetic field strength in the lower, middle and upper regions of the chromosphere. At the same time, data obtained from the Japanese satellite for observing the Sun Hinode provided information about the magnetic field in the photosphere itself. So scientists discovered that the magnetic field of the layer in the photosphere is highly structured, but expands, rapidly merging and spreading horizontally in the chromosphere. The results of the study are bringing scientists closer to understanding how magnetic fields transfer energy to the corona from the lower layers of the Sun.