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Title: HD 222925: A New Opportunity to Explore the Astrophysical and Nuclear Conditions of r-process Sites
Abstract

With the most trans-iron elements detected of any star outside the solar system, HD 222925 represents the most complete chemical inventory among metal-poor stars enhanced with elements made by the rapid neutron capture (“r”) process. As such, HD 222925 may be a new “template” for the observationalr-process, where before the (much higher-metallicity) solarr-process residuals were used. In this work, we test under which conditions a single site accounts for the entire elementalr-process abundance pattern of HD 222925. We found that several of our tests—with the single exception of the black hole–neutron star merger case—challenge the single-site assumption by producing an ejecta distribution that is highly constrained, in disagreement with simulation predictions. However, we found that ejecta distributions that are more in line with simulations can be obtained under the condition that the nuclear data near the secondr-process peak are changed. Therefore, for HD 222925 to be a canonicalr-process template likely as a product of a single astrophysical source, the nuclear data need to be reevaluated. The new elemental abundance pattern of HD 222925—including the abundances obtained from space-based, ultraviolet (UV) data—call for a deeper understanding of both astrophysicalr-process sites and nuclear data. Similar UV observations of additionalr-process–enhanced stars will be required to determine whether the elemental abundance pattern of HD 222925 is indeed a canonical template (or an outlier) for ther-process at low metallicity.

 
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Award ID(s):
2020275 2205847 1815403
NSF-PAR ID:
10427265
Author(s) / Creator(s):
; ; ; ;
Publisher / Repository:
DOI PREFIX: 10.3847
Date Published:
Journal Name:
The Astrophysical Journal
Volume:
951
Issue:
1
ISSN:
0004-637X
Format(s):
Medium: X Size: Article No. 30
Size(s):
Article No. 30
Sponsoring Org:
National Science Foundation
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