When the upper layer of an accreting neutron star experiences a thermonuclear runaway of helium and hydrogen, it exhibits an X-ray burst with a cool-down phase of typically 1 minute. Analysis of light curves of 1254 X-ray bursts observed by the Rossi X-ray Timing Explorer shows that the decay is described as a power-law with index in the range 1.3—2.1, with a Gaussian component also required for half of the bursts. The Gaussian appears consistent with being due to the rp process, which consists of rapid proton captures and slow beta-decays of proton-rich isotopes, and is expected to be prominent in bursts with a significant fraction of hydrogen in the fuel. The Gaussian fluence fraction suggests that the layer where the rp process is active is underabundant in H by a factor of at least five with respect to cosmic abundances. Jean's paper reporting the analysis is now accepted by A&A.

Read the paper arXiv:1708.08644

Labels: 2017, thermonuclear bursts