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Title: New 26 P(p, γ) 27 S Thermonuclear Reaction Rate and Its Astrophysical Implications in the rp-process
Abstract

Accurate nuclear reaction rates for26P(p,γ)27S are pivotal for a comprehensive understanding of therp-process nucleosynthesis path in the region of proton-rich sulfur and phosphorus isotopes. However, large uncertainties still exist in the current rate of26P(p,γ)27S because of the lack of nuclear mass and energy level structure information for27S. We reevaluate this reaction rate using the experimentally constrained27S mass, together with the shell model predicted level structure. It is found that the26P(p,γ)27S reaction rate is dominated by a direct capture reaction mechanism despite the presence of three resonances atE= 1.104, 1.597, and 1.777 MeV above the proton threshold in27S. The new rate is overall smaller than the other previous rates from the Hauser–Feshbach statistical model by at least 1 order of magnitude in the temperature range of X-ray burst interest. In addition, we consistently update the photodisintegration rate using the new27S mass. The influence of new rates of forward and reverse reaction in the abundances of isotopes produced in therp-process is explored by postprocessing nucleosynthesis calculations. The final abundance ratio of27S/26P obtained using the new rates is only 10% of that from the old rate. The abundance flow calculations show that the reaction path26P(p,γ)27S(β+,ν)27P is not as important as previously thought for producing27P. The adoption of the new reaction rates for26P(p,γ)27S only reduces the final production of aluminum by 7.1% and has no discernible impact on the yield of other elements.

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Award ID(s):
1927130
NSF-PAR ID:
10423112
Author(s) / Creator(s):
; ; ; ; ; ;
Publisher / Repository:
DOI PREFIX: 10.3847
Date Published:
Journal Name:
The Astrophysical Journal
Volume:
950
Issue:
2
ISSN:
0004-637X
Format(s):
Medium: X Size: Article No. 133
Size(s):
["Article No. 133"]
Sponsoring Org:
National Science Foundation
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