Washington, July 14 (): Two satellites have spotted a plasma “tsunami” wave spreading on the surface of the Sun after a coronal mass ejection or a release of matter into space.
The solar tsunami was observed by NASA’s Solar Dynamics Observatory (SDO) and the Japanese Hinode spacecraft has been used to provide the first accurate estimates of the Sun’s magnetic field.
Solar tsunamis are produced by huge explosions in the atmosphere of the Sun called coronal mass ejections (CME). As the CMEs travel into space, the tsunami travels across the Sun at speeds of up to 1000 kilometres per second.
The magnetic field of the Sun is difficult to measure directly and usually has to be estimated using computer simulations. The Hinode spacecraft has 3 highly sensitive telescopes which use the visible, X-ray and ultraviolet spectrum to examine slow and rapid changes in the magnetic field. Understanding the magnetic field may help predict how CMEs will affect the Earth.
Japanese satellite Hinode is part of a pair of satellites that have been studying the sun. Hinode has been orbiting the star since 2006 and NASA’s Solar Dynamics Observatory (SDO) joined the satellite in 2010. The satellites use ultraviolet light to spot and also track the movement of the “waves” through their powerful telescopes.
Both satellites look at ultraviolet light from the Sun – colours we cannot see but that give hints as to both the chemical makeup and the extreme physical conditions at and near the Sun’s agitating, turbulent surface.
The SDO satellite was capable of capturing the ultraviolet light emitted as the wave spread out. From that, the team was able to determine the wave’s speed – some 400km per second – and its rough temperature, over a million degrees.
Meanwhile, the Hinode satellite sent a high-resolution map of the density of the surface of the Sun for every 45 seconds. Using both data sets, the team was able to determine the strength of the magnetic field in the “quiet corona” – a tricky measurement of the Sun in its typical, inactive state.