Superbursts: A New Probe of the rp-Process

Long term monitoring of X-ray burst sources has discovered a new class of thermonuclear X-ray bursts from accreting neutron stars in low mass X-ray binaries. These “superbursts” have durations and energies 1000 times larger than usual Type I X-ray bursts. They are believed to be due to thermally unstable carbon burning in the neutron star ocean, providing a new opportunity to study the ashes of rp-process hydrogen/helium burning. I summarize the current theory of superbursts, giving analytic formulae where possible, and compare with observations. I review recent work on carbon production by the rp-process, the detection of superbursts from the rapid accretor GX 17+2, and models of superburst lightcurves.