标题： 富磷星中的重元素丰度：s-过程的一个新场所？ 显示英文标题

标题： Heavy element abundances in P-rich stars: A new site for the s-process?

摘要： 近期发现的富磷星对恒星演化和核合成理论提出了挑战，因为现有的任何模型都无法解释它们极为特殊的化学丰度模式。除了显著的磷增强外，这类恒星还显示出其他轻元素（如氧、镁、硅、铝）和重元素（如铈）的增强。 我们获得了两颗光学明亮的富磷星（包括一颗新的富磷星）的高分辨率光学光谱，并确定了更多的元素丰度（从碳到铅）。我们确认了异常的轻元素丰度模式，其中镁、硅、铝和磷有非常大的增强，且可能存在铜的增强，但新富磷星的光谱是唯一显示出碳（与氮）增强的。与其他合适的贫金属和中子俘获增强的恒星相比，这两颗富磷星显示出了类似于低中子密度s-过程核合成的重元素过量，具有第一峰值（锶、钇、锆）和第二峰值（钡、镧、铈、钕）元素的显著增强（其中一颗恒星甚至存在铅的增强），并且具有负的[Rb/Sr]比值。然而，这种s-过程与发生在渐近巨星分支（AGB）恒星中的不同。显著的区别包括较大的[Ba/La]比值以及较低的Eu和Pb含量，低于其AGB对应物。 我们的观测应该引导恒星核合成理论家和观测者识别富磷星的前身，这代表了一个新的s-过程核合成场所，对银河系的化学演化具有重要意义。 显示英文摘要

摘要： The recently discovered phosphorus-rich stars pose a challenge to stellar evolution and nucleosynthesis theory, as none of the existing models can explain their extremely peculiar chemical abundances pattern. Apart from the large phosphorus enhancement, such stars also show enhancement in other light (O, Mg, Si, Al) and heavy (e.g., Ce) elements. We have obtained high-resolution optical spectra of two optically bright phosphorus-rich stars (including a new P-rich star), for which we have deter-mined a larger number of elemental abundances (from C to Pb). We confirm the unusual light-element abundance pattern with very large enhancements of Mg, Si, Al, and P, and possibly some Cu enhancement, but the spectra of the new P-rich star is the only one to reveal some C(+N) enhancement.When compared to other appropriate metal-poor and neutron-capture enhanced stars, the two P-rich stars show heavy-element overabundances similar to low neutron density s-process nucleosynthesis,with high first- (Sr, Y, Zr) and second-peak (Ba, La, Ce, Nd) element enhancements (even some Pb enhancement in one star) and a negative [Rb/Sr] ratio. However, this s-process is distinct from the one occurring in asymptotic giant branch (AGB) stars. The notable distinctions encompass larger[Ba/La] and lower Eu and Pb than their AGB counterparts. Our observations should guide stellar nucleosynthesis theoreticians and observers to identify the P-rich star progenitor, which represents anew site for s-process nucleosynthesis, with important implications for the chemical evolution of our Galaxy.