论文标题
R-Process Alliance：J1521-3538，非常贫穷的，非常r-process增强的恒星，具有[eu/fe] =+2.2，R-III恒星等级
The R-Process Alliance: J1521-3538, a very metal-poor, extremely r-process-enhanced star with [Eu/Fe]=+2.2, and the class of r-III stars
论文作者
论文摘要
我们报告了J1521-3538，明亮的（v = 12.2），非常金属贫困（[Fe/h] = -2.8）的发现，基于高分辨率高分辨率，高信号到噪声麦芽岩/Mike Spectrum。 J1521-3538显示了任何已知的R-Process增强恒星中最大的R-过程元素过度，具有[EU/FE] =+2.2，并且其22个中子捕获元件的化学丰度与缩放的太阳能Rocess模式非常匹配。 J1521-3538也是少数已知的具有R-Process增强型碳增强金属贫困星（CEMP-R星），如校正了恒星进化状态的测得的C丰度后发现的那样。 We propose to extend the existing classification of moderately enhanced (+0.3<=[Eu/Fe]<=+1.0) r-I and strongly r-process enhanced ([Eu/Fe]>+1.0) r-II stars to include an r-III class, for r-process stars such as J1521-3538, with [Eu/Fe]>+2.0 and [Ba/Eu]<-0.5, or >欧洲与铁的太阳比的100倍。使用CosmochRonometry，我们使用两组不同的初始生产比例估计J1521-3538为12.5+-5 GYR和8.9+-5 GYR。这些年龄基于在4019 A和其他R-Process元素丰度的TH线的测量值。这与低质量金属贫困场红色水平分支星的老年大致一致。 J1521-3538可能起源于低质量矮人的星系，后来由银河系吸收，其高度偏心轨道证明了这一点。
We report the discovery of J1521-3538, a bright (V=12.2), very metal-poor ([Fe/H]=-2.8) strongly r-process enhanced field horizontal branch star, based on a high-resolution, high signal-to-noise Magellan/MIKE spectrum. J1521-3538 shows the largest r-process element over-abundance in any known r-process-enhanced star, with [Eu/Fe]=+2.2, and its chemical abundances of 22 neutron-capture elements closely match the scaled solar r-process pattern. J1521-3538 is also one of few known carbon-enhanced metal-poor stars with r-process enhancement (CEMP-r stars), as found after correcting the measured C abundance for the star's evolutionary status. We propose to extend the existing classification of moderately enhanced (+0.3<=[Eu/Fe]<=+1.0) r-I and strongly r-process enhanced ([Eu/Fe]>+1.0) r-II stars to include an r-III class, for r-process stars such as J1521-3538, with [Eu/Fe]>+2.0 and [Ba/Eu]<-0.5, or >100 times the solar ratio of europium to iron. Using cosmochronometry, we estimate J1521-3538 to be 12.5+-5 Gyr and 8.9+-5 Gyr old, using two different sets of initial production ratios. These ages are based on measurements of the Th line at 4019 A and other r-process element abundances. This is broadly consistent with the old age of a low-mass metal-poor field red horizontal branch star. J1521-3538 likely originated in a low-mass dwarf galaxy that was later accreted by the Milky Way, as evidenced by its highly eccentric orbit.
