The first generation of stars, often called Population III (or Pop III), form from metal-free primordial gas at redshifts z ∼ 30 and below. They dominate the cosmic star-formation history until z ∼ 15–20, at which point the formation of metal-enriched Population II stars takes over. We review current theoretical models for the formation, properties, and impact of Pop III stars and discuss existing and future observational constraints. Key takeaways from this review include the following: ▪ Primordial gas is highly susceptible to fragmentation and Pop III stars form as members of small clusters with a logarithmically flat mass function. ▪ Feedback from massive Pop III stars plays a central role in regulating subsequent star formation, but major uncertainties remain regarding its immediate impact. ▪ In extreme conditions, supermassive Pop III stars can form, reaching masses of several 105M⊙. Their remnants may be the seeds of the supermassive black holes observed in high-redshift quasars. ▪ Direct observations of Pop III stars in the early Universe remain extremely challenging. Indirect constraints from the global 21-cm signal or gravitational waves are more promising. ▪ Stellar archeological surveys allow us to constrain both the low-mass and the high-mass ends of the Pop III mass distribution. Observations suggest that most massive Pop III stars end their lives as core-collapse supernovae rather than as pair-instability supernovae.

中文翻译：

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第一批恒星：形成、特性和影响

第一代恒星，通常称为星族 III（或 Pop III），由红移 z ∼ 30 及以下的无金属原始气体形成。它们在宇宙恒星形成历史中占据主导地位，直到 z ∼ 15-20，此时富含金属的第二星族恒星的形成占据了主导地位。我们回顾了当前关于 Pop III 恒星的形成、性质和影响的理论模型，并讨论了现有和未来的观测限制。本次审查的主要结论如下： ▪ 原始气体极易发生碎裂，而 Pop III 恒星作为具有对数平坦质量函数的小星团成员形成。 ▪ 来自大质量 Pop III 恒星的反馈在调节后续恒星形成方面发挥着核心作用，但其直接影响仍存在重大不确定性。 ▪ 在极端条件下，可以形成超大质量 Pop III 恒星，质量可达数十倍5中号⊙。它们的残余物可能是在高红移类星体中观察到的超大质量黑洞的种子。 ▪ 直接观测早期宇宙中的 Pop III 恒星仍然极具挑战性。来自全球 21 厘米信号或引力波的间接约束更有希望。 ▪ 恒星考古调查使我们能够限制Pop III 质量分布的低质量端和高质量端。观测结果表明，大多数大质量 Pop III 恒星以核心塌缩超新星而非不稳定对超新星的形式结束生命。