Exploring the interface between the Sun's surface and corona

Abstract

We present the science case for a broadband X­ray imager with high­resolution spectroscopy, including simulations of X­ray spectral diagnostics of both active regions and solar flares. This is part of a trilogy of white papers discussing science, instrument (Bandler et al. 2010), and missions (Bookbinder et al. 2010) to exploit major advances recently made in transition­edge sensor (TES) detector technology that enable resolution better than 2 eV in an array that can handle high count rates. Combined with a modest X­ray mirror, this instrument would combine arcsecondscale imaging with high­resolution spectra over a field of view sufficiently large for the study of active regions and flares, enabling a wide range of studies such as the detection of microheating in active regions, ion­resolved velocity flows, and the presence of nonthermal electrons in hot plasmas. It would also enable more direct comparisons between solar and stellar soft X­ray spectra, a waveband in which (unusually) we currently have much better stellar data than we do of the Sun.