Astronomical observations with normal incidence multilayer optics: recent results and future prospects

Abstract

We have obtained high resolution (~1 arcsec) X-ray and EUV images of the solar corona with two rocket-borne normal incidence Cassegrain multilayer telescopes. The Cassegrain images correspond to material at ~1 000 000 K (λ ~ 173 Å) and ~ 80 000 K (λ ~ 256 Å). Other images, at somewhat lower resolution, were obtained with Herschelian multilayer telescopes and Wolter-Schwarzschild hybrid grazing incidence/multilayer optical systems. We discuss the Cassegrain and Herschelian images, emphasizing the analysis of polar plumes observed at the limb of the Sun. Polar plumes are thought to represent structures that contribute significantly to the flow of coronal material into the solar wind. We will also comment briefly on other coronal features observed, including coronal holes, the chromospheric network, active region loops, and prominence cavities. Multilayer technology represents a major breakthrough in astronomical X-ray and EUV imaging; we will discuss the application of specific multilayer techniques to astronomical observations, emphasizing observations of the sun. We will also report on current efforts in our laboratories to develop a comprehensive Multi-Spectral Solar Telescope Array rocket instrument for the study of a wide variety of problems related to the solar atmosphere.