N/O增强的化学增丰：大质量恒星中光学厚风与旋转的相互作用
N/O-enhanced chemical enrichment by massive stars: the interplay of optically-thick winds and rotation
- Universität Heidelberg（海德堡大学）
- INFN-Padova（意大利国家核物理研究所帕多瓦分部）
- Università di Padova（帕多瓦大学）
- University of Cambridge（剑桥大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究通过MESA模型计算，发现旋转大质量恒星的光学厚风可解释高红移星系的N/O增强，并再现三个星系的丰度模式，揭示了星暴后数Myr内的演化序列。
AI中文摘要：
近期詹姆斯·韦布空间望远镜（JWST）的观测揭示了一批高红移星系样本，其N/O丰度比显著增强，$\log\rm (N/O)\gtrsim -1.1$。经历沃尔夫-拉耶（WR）相的旋转大质量恒星所驱动的强光学厚风，为这种N/O增强提供了一种可行的解释，这一解释得到了在少数星系中直接探测到的WR光谱特征的支持。这种强风也是再现小麦哲伦云（SMC）中单一WR恒星所必需的。在此，我们利用两组\textsc{mesa}单恒星演化模型（一组包含光学厚风，另一组不包含），在致密的金属丰度网格（$Z_\star\sim 0.001-0.0045$）和初始自转速度网格（$ω\equivΩ/Ω_{\rm crit}\sim 0-0.7$）上，计算了质量约为$\sim 20-100\\ \rm M_\odot$的贫金属大质量恒星的金属产额。考虑到基于SMC中O型星观测的初始自转速度分布，我们发现两组模型在星暴后数百万年内均能产生高达$\rm \log(N/O)\sim 0.1$的强N/O增强。包含光学厚风的模型在$t\sim 3-4$~Myr时，由富C/O风驱动，从高N/O状态快速过渡到$\rm \log(N/O)\sim -1.5$的“正常”状态，而不包含光学厚风的模型过渡则较慢且较弱。光学厚风情景能够再现三个代表性高红移星系（RXCJ2248-ID、Sunburst Arc和MARTA 4327）的星云C、N、O和He丰度模式，这些星系的恒星金属丰度和年龄与通过光谱能量分布拟合（SED-fitting）推断的结果相似。这可以解释为在过渡前（$t\lesssim 3$~Myr）、过渡中（$t\sim 3-4$~Myr）和过渡后（$t\gtrsim 5$~Myr）捕获的一个连贯演化序列。相比之下，仅光学薄风情景通过风抛出的C和O要少得多，无法再现Sunburst Arc和MARTA 4327。产额数据可在https://zenodo.org/records/22897057获取。
英文摘要：
Recent JWST observations have revealed a sample of high-$z$ galaxies with highly enhanced N/O abundance ratios, $\log\rm (N/O)\gtrsim -1.1$. Strong optically-thick winds of rotating massive stars going through the Wolf-Rayet (WR) phase provide a viable explanation for such N/O enhancements, supported by the direct spectroscopic WR signatures discovered in a few galaxies. Such strong winds are also needed to reproduce the single WR stars in the Small Magellanic Cloud (SMC). Here, we compute the metal yields of massive ($\sim 20-100\ \rm M_\odot$), metal-poor stars using two sets of MESA single stellar evolution models with and without optically-thick winds in a dense grid of metallicities ($Z_\star\sim 0.001-0.0045$) and initial spins ($ω\equivΩ/Ω_{\rm crit}\sim 0-0.7$). Considering an initial spin distribution based on observations of O-type stars in the SMC, we find that both sets produce strong N/O enhancements up to $\rm \log(N/O)\sim 0.1$ within a few Myr after a starburst. The models with optically-thick winds undergo a rapid transition from high N/O to the `normal' state of $\rm \log(N/O)\sim -1.5$ at $t\sim 3-4$ Myr driven by C/O-rich winds, while the transition is slower and weaker without optically-thick winds. The optically-thick-wind scenario can reproduce the nebular C, N, O, and He abundance patterns of three representative high-$z$ galaxies showing direct WR signatures: RXCJ2248-ID, Sunburst Arc, and MARTA 4327, with stellar metallicities and ages similar to those inferred from SED-fitting. This can be interpreted as a coherent evolution sequence captured before ($t\lesssim 3$ Myr), during ($t\sim 3-4$ Myr), and after ($t\gtrsim 5$ Myr) the transition. In contrast, the optically-thin-wind-only scenario ejects much less C and O via winds and cannot reproduce Sunburst Arc and MARTA 4327. The yields are available at https://zenodo.org/records/22897057.
