揭示富磷星的化学指纹 II. 来自UVES/VLT光谱的重元素丰度
Unveiling the chemical fingerprint of phosphorus-rich stars II. Heavy-element abundances from UVES/VLT spectra
AI总结：
本研究通过分析四颗富磷星的UVES光谱获取了广泛的重元素丰度，发现其s-过程峰值元素过丰且Ba极高，比较三种核合成情景后指出s-与i-过程组合模型差异最少但因缺乏模拟仍具高度不确定性。
摘要：
富磷星大气中P的含量已被证明比我们的太阳高出10到100倍。鉴于P作为生命必需元素的关键作用，揭示富磷星的起源尤为必要，这有助于我们深入了解银河系中目前仍属未知的P核合成形成路径。我们的目标是获取四颗富磷星覆盖大范围重元素的广泛化学丰度清单。这一表征将作为核天体物理学界揭示形成富磷星独特化学指纹过程的里程碑。我们对四颗富磷星的光学UVES光谱进行了详细的1D局部热力学平衡丰度分析。我们的重点在于中子俘获元素，特别是Sr和Ba之间的元素以及Pb，因为它们为核合成计算提供了有价值的约束。我们将获得的丰度与三种不同的核合成情景进行了比较：单一i-过程、双重i-过程以及s-过程和i-过程的组合。我们进行了迄今为止最广泛的富磷星丰度分析，包括Sr和Ba之间的元素（如Ag），这些元素在任何类型的恒星中都很少被测量。我们发现在s-过程峰值元素中相对于太阳存在过丰度，伴随着极高的Ba丰度以及Rb和Sn之间某些元素的轻微增强。对于该模式的核合成起源，未能找到能解释全部四颗恒星的全局解决方案。在四颗恒星中的三颗里产生最少差异的模型是s-过程和i-过程的组合，但目前缺乏广泛的多元流体动力学模拟来追踪不同类型恒星中i-过程的发生，这使得该情景具有高度不确定性。
英文摘要：
The atmospheres of phosphorus-rich stars have been shown to contain between 10 and 100 times more P than our Sun. Given its crucial role as an essential element for life, it is especially necessary to uncover the origin of P-rich stars to gain insights into the still unknown nucleosynthetic formation pathways of P in our Galaxy. Our objective is to obtain the extensive chemical abundance inventory of four P-rich stars, covering a large range of heavy elements. This characterization will serve as a milestone for the nuclear astrophysics community to uncover the processes that form the unique chemical fingerprint of P-rich stars. We performed a detailed 1D local thermodynamic equilibrium abundance analysis on the optical UVES spectra of four P-rich stars. Our focus lay on the neutron-capture elements, in particular, on the elements between Sr and Ba, as well as on Pb, as they provide valuable constraints to nucleosynthesis calculations. We compare the obtained abundances with three different nucleosynthetic scenarios: a single i-process, a double i-process, and a combination of s- and i-processes. We have performed the most extensive abundance analysis of P-rich stars to date, including the elements between Sr and Ba, such as Ag, which are rarely measured in any type of stars. We found overabundances with respect to solar in the s-process peak elements, accompanied by an extremely high Ba abundance and slight enhancements in some elements between Rb and Sn. No global solution explaining all four stars could be found for the nucleosynthetic origin of the pattern. The model that produces the least number of discrepancies in three of the four stars is a combination of s- and i-processes, but the current lack of extensive multidimensional hydrodynamic simulations to follow the occurrence of the i-process in different types of stars makes this scenario highly uncertain.
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