Solar tsunami used to measure Sun’s magnetic field
2 Aug 2013 by hddbqtthcb.d hddbqtthcb.d
A solar tsunami has been used to provide the first accurate estimates of the Sun’s magnetic field.
Solar tsunamis are produced by huge explosions in the Sun’s atmosphere called coronal mass ejections (CMEs). When the CME travels out into space, the tsunami can travel across the sun at speeds of up to 1000 kilometres per second.
Dr David Long, from UCL Mallard Space Science Laboratory and lead author of the research soon to be published in Solar Physics said: “We’ve demonstrated that the Sun’s atmosphere has a magnetic field about ten times weaker than a normal fridge magnet.”
The shape of a solar tsunami is changed by the environment through which they move. In the presence of a strong magnetic field, solar tsunamis gain speed. This was the unique feature that allowed Long’s team to go about measuring the Sun’s magnetic field.
The researchers used data obtained using the Extreme ultraviolet Imaging Spectrometer (EIS), a UK-led instrument on the Japanese Hinode spacecraft, to measure the density of the tsunami’s solar atmosphere.
Though visible as loops and other structures in the Sun’s atmosphere, the Sun’s magnetic field is difficult to measure directly and usually has to be estimated using intensive computer simulations.
But the Hinode possesses three highly sensitive telescopes which use visible, X-ray and ultraviolet light to examine magnetic field changes. They act like a microscope to track how the magnetic field around sunspots is generated, shapes itself and then fades away.
The group’s results demonstrate just how sensitive these telescopes can be, measuring magnetic fields that were previously thought too weak to detect.
CMEs can hurtle towards the Earth, which although protected by its own magnetic field, is vulnerable to solar storms that can damage satellites and technological infrastructure.
Long said: “As our dependency on technology increases, understanding how these eruptions occur and travel will greatly assist in protecting against solar activity.”
