Creating an X-ray photoionized nebula in the laboratory
Accretion onto compact objects leads to photoionization-dominated X-ray spectra
The circumstellar gas near the source of hard x-rays is highly ionized--overionized for its temperature compared to coronal equilibrium--and produces an x-ray spectrum dominated by radiative recombination continua and recombination cascades.
Artist’s conception of an accretion-powered X-ray binary.
A new generation of X-ray telescopes (Chandra pictured here) is producing high-resolution X-ray spectra for the first time.