Tuesday, May 19, 2009

Wanpeng Tan: Measurement of alpha-induced nuclear reactions for X-ray bursts

Wanpeng told us about three reactions, alpha captures on waiting points, that are important for type I X-ray bursts: 14O(a,p), 15O(a,g), and 26Si(a,p); such reactions are some of the first that occur at ignition.

15O(a,g) is particularly crucial for burst ignition. Tan's analysis of the measurements result in a rate that is sufficiently precise to constrain the critical accretion rate above which burning is thermally stable to within 10%; the critical rate is roughly the Eddington limit.

However, several workshop participants called the accuracy of his analysis into question. Barry Davids asserted that "it's not a detection at the two sigma level."

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