The Sun in the radio frequency band
Since the first detection of solar radio emission in 1942, radio observations of the Sun have provided valuable information for understanding solar structure and processes. At centimetre wavelengths, in particular, the radiation detected has its source in the photosphere and corona, namely in the solar atmosphere. The EU-funded project RADIOSUN (Radiophysics of the Sun) worked to lay the ground for the exploitation of new observational facilities. To this end, internationally recognised experts from three EU Member States (Czech Republic, Poland and the United Kingdom) and two eligible states (China and Russia) joined their efforts. Cross-disciplinary training and exchange visits prepared a new generation of scientists for the analysis and interpretation of observations from some of the most powerful radio telescopes. Among these is the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile consisting of 66 radio dishes. RADIOSUN fellows achieved significant advances regarding quasi-periodic pulsations observed during solar flares. They identified physical mechanisms underlying a zebra pattern, a complex and common spectral feature of solar flares, the formation of which was poorly understood. The solar corona is a fertile site of waves, including fast wave trains. The team identified different types of such oscillations and used this information to create new theoretical models describing the evolution of magnetic fields driving space weather-related phenomena. RADIOSUN research led to 49 publications in high-impact international journals. Moreover, its results have been used by the solar and heliophysics working group in the Square Kilometre Array (SKA) being built in Australia and South Africa to survey the entire sky in unprecedented detail and probe Sun-like stars.
Keywords
Sun, radio emission, RADIOSUN, ALMA, solar flares, Square Kilometre Array
