论文标题
在视觉二进制组件的锂丰度上
On the lithium abundance of the visual binary components $ξ$ Boo A (G8V) and $ξ$ Boo B (K5V)
论文作者
论文摘要
就丰度和同位素比，对锂共振双线和$ξ$ boo b的光谱调查进行了调查。我们使用1180万lbt和百事可乐获得了新的$ r $ $ = 130 \，000光谱，每个像素的信噪比（s/n）高达3200。根据基于一维MARCS模型大气和3D-NLTE校正的合成线轮廓的拟合，我们确定了这两种同位素的丰度。对于$ξ$ boo a，我们发现a（li）= 2.40 $ \ pm $ 0.03 \，dex和$^6 $ li/$^7 $ li <1.5 $ \ pm $ \ pm $ 1.0 \，\％\，\％\，\％\ in 1d-lte，这增加到$ \ $ \ $ \ $ \ $ 2.45 $ 2.45 $ 2.45。对于$ξ$ boo b，我们获得A（li）= 0.37 $ \ pm $ 0.09 \，dex in 1d-lte，带有未指定的$^6 $ li/$^7 $ li级别。因此，在两颗恒星中的任何一个中都没有$^6 $ li。我们考虑$ξ$ boo b的Li Fit的现场模型，并找到A（li）= 0.45 $ \ pm $ 0.09 \，dex。 $^7 $ li的丰度对于$ξ$ boo a比太阳高23倍，但对于$ξ$ boo b，$ξ$ boo a比太阳低3倍，而两者都符合类似年龄的M35开放式群集中单星的趋势。从TIO带头强度重新确定了有效的温度。我们注意到，最合适的全球金属性是-0.13 $ \ pm $ 0.01 \，dex for $ξ$ boo a，但 +0.13 $ \ pm $ 0.02 \，dex for $ξ$ boo B. boo b。至$ \ $ \ $ 0.15 \，dex，没有现场模型。
A spectroscopic investigation of the lithium resonance doublet in $ξ$ Boo A and $ξ$ Boo B in terms of both abundance and isotopic ratio is presented. We obtained new $R$=130\,000 spectra with a signal-to-noise ratio (S/N) per pixel of up to 3200 using the 11.8m LBT and PEPSI. From fits with synthetic line profiles based on 1D-LTE MARCS model atmospheres and 3D-NLTE corrections, we determine the abundances of both isotopes. For $ξ$ Boo A, we find A(Li) = 2.40$\pm$0.03\,dex and $^6$Li/$^7$Li < 1.5$\pm$1.0\,\%\ in 1D-LTE, which increases to $\approx$2.45 for the 3D-NLTE case. For $ξ$ Boo B we obtain A(Li) = 0.37$\pm$0.09\,dex in 1D-LTE with an unspecified $^6$Li/$^7$Li level. Therefore, no $^6$Li is seen on any of the two stars. We consider a spot model for the Li fit for $ξ$ Boo B and find A(Li) = 0.45$\pm$0.09\,dex. The $^7$Li abundance is 23 times higher for $ξ$ Boo A than the Sun's, but three times lower than the Sun's for $ξ$ Boo B while both fit the trend of single stars in the similar-aged M35 open cluster. Effective temperatures are redetermined from the TiO band head strength. We note that the best-fit global metallicities are --0.13$\pm$0.01\,dex for $ξ$ Boo A but +0.13$\pm$0.02\,dex for $ξ$ Boo B. Lithium abundance for the K5V benchmark star 61\,Cyg\,A was obtained to A(Li)$\approx$0.53\,dex when including a spot model but to $\approx$0.15\,dex without a spot model.
