Long-period oscillations of the Sun discovered

Photo: MPS/Liang Ten years of data from NASA's Solar Dynamics Observatory combined with numerical models reveal the deep low musical notes of the Sun   (mps) A team of solar physicists led by Professor Laurent Gizon of the Max Planck Institute for Solar System Research (MPS) and the University of Göttingen in Germany has reported the discovery of global oscillations of the Sun with very long periods, comparable to the 27-day solar rotation period. The oscillations manifest themselves at the solar surface as swirling motions with speeds on the order of five kilometers per hour. These motions were measured by analyzing ten years of observations from NASA's Solar Dynamics Observatory (SDO). Using computer models, the scientists have shown that the newly discovered oscillations are resonant modes and owe their existence to the Sun's differential rotation. The oscillations will help establish novel ways to probe the Sun's interior and obtain information about our star's inner structure and dynamics. The scientists describe their findings in a letter to appear today in the journal Astronomy & Astrophysics. In the 1960's the Sun's high musical notes were discovered: The Sun rings like a bell.