An imager with added value for the Solar Orbiter mission Original Research Article

Our current ways of observing the Sun with spectrometers and imagers are limited. With a slit spectrometer, we require time to build up a 2-D image which results in temporal blurring. When we use a traditional imager, we have no ability to measure and detect line-of-sight flows or to discriminate contributions from gas at different temperatures in the imager passband, causing spectral confusion of the images. For Solar Orbiter, the combination of an exciting new viewpoint of the Sun, and the best resolution of the corona ever seen, means that we require the best time cadence and velocity information that we can get. The spatial resolution expected from the imager on Solar Orbiter will reach approximately 70 km. At such a resolution in the corona, we expect to see the fundamental magnetic flux tubes, which are predicted to have high velocities. This is also the scale at which we will be able to search for evidence basic physical processes such as magnetic reconnection. We will describe the design of an imager that gives not only high quality images, but also provides simultaneous information about plasma flows and temperature. A prototype instrument is being flown on a NASA sounding rocket next year. The concept will be described, along with some methods of extracting the spectroscopic information.