论文标题
原始铁贫困矮星的极端CNO增强组成J0815+4729
The extreme CNO-enhanced composition of the primitive iron-poor dwarf star J0815+4729
论文作者
论文摘要
我们介绍了J0815+4729的高分辨率Keck/Hires光谱观察的分析，这是一种极其碳碳较高的铁矮矮星。这些高质量的数据使我们能够从[Fe/H] $ = -5.49 {\ pm} 0.14 $中得出金属性，从三个最强的\ ion {fe} {1}线中得出了高度[ca/fe]〜$ = 0.75 {\ pm} 0.14 $。 A（c）〜$ = 7.43 {\ pm} 0.17 $（或[c/fe]〜$ \ sim 4.49 {\ pm} 0.11 $）的大碳丰富度将这颗星星放置在A（c） - [fe/h] Dia的低碳频带的上边界处。我们在超级贫穷的恒星中首次以777nm的形式检测氧气三重，表明[O/Fe]〜$ = 4.03 {\ pm} 0.12 $（A（a（o）〜$ = 7.23 {\ pm} 0.14 $），与以前更高的氧氧气丰度比为[o/fe]〜$ = 4.03 {\ pm} 0.12 $（a（o）〜$ = 7.23 {\ pm = 7.14 $）。使用[o/fe]〜$ \ sim2.2 $ 〜DEX at [fe/h]〜$ \ sim -3.9 $检测氧气三重态检测。 （a（n）〜$ = 6.75 {\ pm} 0.08 $）和丰度比[n/fe]〜$ \ sim 4.41 {\ pm} 0.08 $也可以显着增强氮。我们还检测到CA，NA和MG，同时为其他八个元素提供了上限。 J0815+4729的丰度模式类似于He〜1327-2326的模式，表明两者都是第二代星星，被$ \ sim 21-27 $〜\ msun〜单一，零金属性低增强超级诺沃污染，具有很少的混合和实质性的后卫。锂的缺失意味着上限的丰度A（li）〜$ <1.3 $ 〜DEX，低于j0023+0307的Li丰度低于0.7〜DEX，该li含量具有相似的金属性，加剧了宇宙学锂问题。
We present an analysis of high-resolution Keck/HIRES spectroscopic observations of J0815+4729, an extremely carbon-enhanced, iron-poor dwarf star. These high-quality data allow us to derive a metallicity of [Fe/H]$=-5.49{\pm}0.14$ from the three strongest \ion{Fe}{1} lines and to measure a high [Ca/Fe]~$=0.75{\pm}0.14$. The large carbon abundance of A(C)~$=7.43{\pm}0.17$ (or [C/Fe]~$\sim 4.49{\pm}0.11$) places this star in the upper boundary of the low-carbon band in the A(C)-[Fe/H] diagram, suggesting no contamination from a binary AGB companion. We detect the oxygen triplet at 777nm for the first time in an ultra-metal poor star, indicating a large oxygen-to-iron abundance ratio of [O/Fe]~$=4.03{\pm}0.12$ (A(O)~$=7.23{\pm}0.14$), significantly higher than the previously most metal-poor dwarf J2209-0028 with an oxygen triplet detection with [O/Fe]~$\sim2.2$~dex at [Fe/H]~$\sim -3.9$. Nitrogen is also dramatically enhanced with (A(N)~$=6.75{\pm}0.08$) and an abundance ratio [N/Fe]~$\sim 4.41{\pm}0.08$. We also detect Ca, Na and Mg, while provide upper limits for eight other elements. The abundance pattern of J0815+4729 resembles that of HE~1327-2326, indicating that both are second-generation stars contaminated by a $\sim 21-27$~\msun~single, zero-metallicity low-energy supernova with very little mixing and substantial fallback. The absence of lithium implies an upper-limit abundance A(Li)~$<1.3$~dex, about 0.7~dex below the detected Li abundance in J0023+0307 which has a similar metallicity, exacerbating the cosmological lithium problem.
