Soft X-ray Images of the Solar Corona with a Normal-Incidence Cassegrain Multilayer Telescope
ARTHUR B. C. WALKER JR. 1,
JOAKIM F. LINDBLOM 1,
TROY W. BARBEE JR. 2, and
RICHARD B. HOOVER 3
1 Center for Space Science and Astrophysics, Stanford University, Stanford, CA 94305.
2 Lawrence Livermore National Laboratory, Livermore, CA 94550.
3 Space Science Laboratory, National Aeronautics and Space Administration, Marshall Space Flight Center, Huntsville, AL 35812.
High-resolution images of the sun in the soft x-ray to extreme ultraviolet(EUV) regime have been obtained with normal-incidence Cassegrain multilayer telescopes operated from a sounding rocket in space. The inherent energy-selective property of multilayer-coated optics allowed distinct groups of emission lines to be isolated in the solar corona and the transition region. The Cassegrain telescopes provided images in bands centered at 173 and 256 angstroms. The bandpass centered at 173 angstroms is dominated by emission from the ions Fe IX Fe X. This emission is from coronal plasma in the temperature range 0.8 x 106 to 1.4 x 106K. The images have angular resolution of about 1.0 to 1.5 arc seconds, and show no degradation because of x-ray scattering. Many features of coronal structure, including magnetically confined loops of hot plasma, coronal plumes, polar coronal holes, faint structures on the size scale of supergranulation and smaller, and features due to overlying cool prominences are visible in the images. The density structure of polar plumes, which are thought to contribute to the solar wind, has been derived from the observations out to 1.7 solar radii.
Submitted on July 13, 1988
Accepted on August 12, 1988
