标题： 银河系薄盘中锂的演化来自主序星和早期红巨星分支恒星 显示英文标题

标题： Lithium evolution in the Galactic thin disc from Main-Sequence and early Red-Giant-Branch stars

摘要： 作为银河系锂生产者的新星作用自20世纪70年代以来就被提出，最近由于在它们的爆发中检测到$^7$Be 而被重新考虑。 与此同时，恒星模型正在向前发展，以理解标准大爆炸核合成理论预测的原始锂丰度与古老矮星测量值之间的差异。 在本工作中，我们从原始值 A(Li)=2.69 dex 开始，研究银河系薄盘中$^7$Li 的演化，并将具有对流超射的恒星模型的$^7$Li 损耗修正应用到我们的化学演化模型中。 我们使用观测数据的上限来约束模型。 除了矮星主序星（MS）之外，我们的分析首次包括了早期红巨星分支（RGB）星。 除了众所周知的低金属丰度下主序星的 Spite 平台外，我们还确认了早期 RGB 星存在第二个 A(Li) 平台，这可以通过考虑恒星模型修正的模型来解释。 我们的最佳拟合模型是在新星整个生命周期中获得的有效平均$^7$Li 产出量$^{Li}Y_\mathrm{Nova}=2.34\times 10^{-5} M_\odot$。 这加强了新星可能是银河系主要$^7$Li 源的可能性，同时结合恒星模型在此背景下理解“宇宙学锂问题”的能力。 显示英文摘要

摘要： The role of novae as producers of galactic lithium has been suggested since the 1970s, and it has been reconsidered recently with the detection of $^7$Be in their outbursts. At the same time, stellar models are moving forward to comprehend the discrepancy between the primordial lithium abundance predicted by the standard Big Bang Nucleosynthesis theory and the measured value of old dwarf stars. In this work, we follow the evolution of $^7$Li in the galactic thin disc starting from a primordial value of A(Li)=2.69 dex and applying $^7$Li depletion corrections of the stellar model with overshooting to our chemical evolution models. We use the upper envelope of the observational data to constrain the models. In addition to the dwarf main sequence (MS) stars, our analysis includes, for the first time, the early red-giant-branch (RGB) stars. Besides the renowned Spite plateau of the MS stars at low metallicities, we also confirm the existence of a second A(Li) plateau of the early RGB stars, which can be explained by our model with the corrections from stellar models. Our best-fit model is obtained with an effective averaged $^7$Li yield $^{Li}Y_\mathrm{Nova}=2.34\times 10^{-5} M_\odot$ during the whole lifetime of a nova. This reinforces the possibility that novae are the main galactic $^7$Li source, together with the stellar models' ability to comprehend the "cosmological lithium problem" in this context.