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Accueil > In the headlines > Star bursts pinned down

Star bursts pinned down

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Direct Mass Measurements of Short-Lived A=2Z-1 Nuclides 63Ge, 65As, 67Se, and 71Kr and Their Impact on Nucleosynthesis in the rp Process.

Pathways of nucleosynthesis processes in stars are determined by masses of unstable nuclei. However, these nuclei are difficult to address in laboratory due to their short lifetimes and extremely small production rates. In a recent paper published in Physical Review Letters, on a base of just a few produced particles, masses of four nuclei have been measured in a storage ring by comparing tiny differences in their revolution times. The experiment has been conducted at the cooler-storage ring CSRe at IMP in Lanzhou, China.

The measured nuclei lie along the so-called rp-process path, the process which is believed to power energetic X-ray bursts observed in space. Such explosive events occur on the surface of neutron stars accreting matter from a companion star in a stellar binary system. One of yet unsolved questions is why the bursts can last for extended periods of time of up to a few 100 seconds. With the new results, it could be shown, that one from the three suggested ‘waiting point’ nuclei, the nuclei that delay the nuclear burning and lead to the extended bursts, namely Ge-64 is not a major ‘waiting point’ nucleus.

This is an important result since the reaction flow effects the opacity of the atmosphere and therefore distance estimates and attempts to extract properties of the underlying neutron stars. This work has been done by an international team of scientists from China, France, Germany, Japan and USA.

IMP, Lanzhou/China