Coronae of nondegenerate single and binary stars: A survey of our present understanding and problems ripe for solution

Information about the coronae of stars in different portions of the HR diagram, and how the characteristics of such coronae compare with what is known about the solar corona are reviewed. For each type of star, some unanswered questions and the generic type of X-ray instrument required to answer these questions are listed. The survey points out the critical need for a sensitive X-ray instrument with both moderate spectra resolution and imaging capability that can monitor selected targets for long periods of time. There is also a need for high spectral resolution, provided sensitivities can be improved greatly over Einstein, and near simultaneous ultraviolet spectroscopy.