X-ray bursters form a class of Low Mass X-Ray Binaries where accreted material froma donor star undergoes rapid thermonuclear burning in the surface layers of a neutron star. Theflux released can temporarily exceed the Eddington limit and drive the photosphere to large radii.Such photospheric radius expansion bursts likely eject nuclear burning ashes into the interstellarmedium, and may make possible the detection of photoionization edges. Indeed, theoretical modelspredict that absorption edges from "Fe at 9.2 keV, ~(60)Zn and ~(62)at 12.2 keV should be detectableby the future missions Simbol-X and NuSTAR. A positive detection would thus probe the nuclearburning as well as the gravitational redshift from the neutron star. Moreover, likely observations ofatomic X-ray spectral components reflected from the inner accretion disk have been reported. Thehigh spectral resolution capabilities of the focusing X-ray telescopes may therefore make possibleto differentiate between the potential interpretations of the X-ray bursts spectral features.
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