Title: Fluorine abundances in CEMP stars at the lowest metallicity: Hints on the nature of the first stars Show Chinese title

Title: 碳增强贫金属星中氟的丰度：关于第一代恒星性质的线索

Abstract: In the last decade, the available measurements of fluorine abundance have increased significantly, providing additional information on the chemical evolution of our Galaxy and details on complex stellar nucleosynthesis processes. However, the observational challenges to obtain stellar F abundances favor samples with higher metallicities, resulting in a scarcity of measurements at low-metallicity ([Fe/H] $<-2.0$). We present F abundances and upper limits in 7 carbon enhanced metal-poor (CEMP) stars observed with the Immersion Grating Infrared Spectrometer (IGRINS), at the Gemini-South telescope. These new observations delivered high-resolution, high signal-to-noise ratio, infrared spectra allowing us to probe significantly deeper into the metal-poor regime and the cosmic origin of F. This work presents the results of our observations, including two 2-sigma detections and five upper limits in a variety of CEMP stars. Arguably the most important result is for CS 29498-0043, a CEMP-no star at [Fe/H] = $-3.87$ with a F detection of [F/Fe] = $+2.0\pm 0.4$, the lowest metallicity star (more than a factor of 10 lower in metallicity than the next detection) with observed F abundance to date. This measurement allowed us to differentiate between two zero metallicity Population III (Pop III) progenitors: one involving He-burning with primary N in Wolf-Rayet stars, and the other suggesting H-burning during hypernova explosions. Our measured value is in better agreement with the latter scenario. This detection represents a pilot, and pioneering study demonstrating the power of F to explore the nature and properties of the first chemical enrichment from Pop III stars. Show Chinese abstract

Abstract: 在过去十年中，氟丰度的可用测量值显著增加，为银河系的化学演化和复杂恒星核合成过程提供了额外的信息。然而，获得恒星氟丰度的观测挑战使得样本更倾向于高金属丰度，导致低金属丰度([Fe/H] $<-2.0$)的测量稀缺。我们展示了使用Gemini-South望远镜上的Immersion Grating Infrared Spectrometer (IGRINS)观测的7颗碳增强贫金属(CEMP)星的氟丰度和上限。这些新观测提供了高分辨率、高信噪比的红外光谱，使我们能够更深入地探究贫金属区域和氟的宇宙起源。这项工作呈现了我们的观测结果，包括在多种CEMP星中的两个2倍标准差检测和五个上限。可以说，最重要的结果是CS 29498-0043，这是一颗[Fe/H] = $-3.87$的CEMP-no星，其氟检测值为[F/Fe] = $+2.0\pm 0.4$，这是目前观测到的金属丰度最低的恒星（比下一个检测的金属丰度低超过一个数量级）。这一测量使我们能够区分两种零金属丰度的第三星族（Pop III）前体：一种涉及沃尔夫-拉叶星中的氦燃烧和主要氮，另一种则表明在超新星爆炸期间的氢燃烧。我们测量的数值与后一种情景更为一致。这一检测代表了一项试点研究，开创性地展示了氟在探索第三星族恒星首次化学富集性质方面的潜力。