More than 40 years of data have made it possible to reveal theinner life‘ of the Sun, i.e. i subtle changes that occur in his internal structure between one solar cycle and another. The result, online on the arXiv platform and being published in the journal Monthly Notices of the Royal Astronomical Society, is due to the group led by the British University of Birmingham, which analyzed the observations made by Birmingham Solar Oscillations Network (Bison)the network of 6 solar observatories in California, Chile, the Canary Islands, South Africa and Australia. The large amount of data collected in 40 years of activity is important because the internal behavior of our star influences its activity and, therefore, better understand these mechanisms will allow to do more accurate forecasts within the scope of space weather.
Every 11 years the Sun passes through a cycle who sees his activity vary from a minimum to a maximum level. The researchers coordinated by Sarbani Basu did concentrate sui four quieter periods recorded over the last 40 years, analyzing the tiny vibrations produced inside the Sun by trapped sound waves.
They thus discovered that the period of minimum activity registered between 2008 and 2009known to be one of the quietest and longest ever recordedha left a very different internal signature compared to the other three. The where sound characteristics of theelio they turned out significantly largerwhich indicates a structural difference. Furthermore, the outer layers they were characterized by higher speed of sound, which suggests higher gas pressures and temperatures e stronger magnetic fields.
“With future missions, such as the European Space Agency’s Plato, the techniques used in this study could be applied to other stars similar to the Sun – says one of the authors of the research, William Chaplin – helping us to better understand how they influence the surrounding environment, including any planets”.
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