Plasma on 'dark spots'

Extreme Ultraviolet Imaging Spectrometer (EIS), the 'solar speed camera' on Hinode shows plasma moving on the giant dark spots associated with solar flares.

Solar flares, massive energetic explosions that rise up from the Sun, can damage manmade satellites and pose a radiation hazard to astronauts. Despite decades of study, many aspects of this phenomenon are not well-understood. Hinode’s observations are now shedding light on possible mechanisms that accelerate solar particles in flares.

It was known that solar flares can impact a vast area on the Sun, sometimes leaving behind mysterious ‘dark patches’. Using Hinode, for the first time, a speed camera has been trained on the material in these dark areas – which can be twenty times the diameter of the Earth. The material flowing from the dark patch in the wake of the flare has been seen, feeding the particle flow that can be hazardous for anything in its path as it hurtles through space at 2000 times the speed of a fighter plane.

Using EIS, it is now possible to pinpoint the source of eruptions during solar flares and to find new clues about the heating processes of the corona. The speed camera is a spectrometer, an instrument that splits the light coming from solar plasma, a tenuous and highly variable gas, into its distinct colours (or spectral lines), providing detailed information about the plasma. The velocity of the gases in a solar feature is measured by the Doppler effect - the same effect that is used by police radars to detect speeding motorists.