Scientists have discovered for the first time long fluctuations in the Sun with a period of 27 days.
Scientists have previously found that the Sun has short-period oscillations of about five minutes. They are used to study the internal structure and dynamics of our star – just like seismologists study the internal structure of the Earth.
Long swings with a period of 27 days were predicted over 40 years ago.
After the NASA space observatory was launched to study the dynamics of the Sun, the Solar Dynamics Observatory (SDO), scientists analyzed the obtained images and found long-period oscillations in the Sun, comparable to the 27-day period of the Sun’s rotation. Oscillations appear on the surface of the Sun in the form of vortices moving at a speed of about five kilometers per hour.
Long-period oscillations depend on the rotation of the Sun, they are not acoustic in nature. To detect long-term oscillations of the Sun, measurements of horizontal motions on the Sun’s surface are required for many years. Continuous helioseismic and magnetic observations aboard the SDO are ideal for this purpose.
Laurent Gieson is a fellow at the Max Planck Institute for Solar System Research and the University of Göttingen in Germany.
Researchers have recorded dozens of vibration modes, each with its own period and spatial dependence:
- the first ones have the maximum speed at the poles,
- the second – in middle latitudes,
- still others are at the equator.
The discovery of this type of vibration will help scientists learn more about the inner structure of the sun.