超大质量恒星的特征：超巨星和它们的宇宙速率
Signatures of very massive stars: supercollapsars and their cosmological rate
摘要：
我们利用宇宙学、N体、水文、化学等结构形成的模拟方法，按照适当的产额（He、C、N、O、Si、S、Fe、Mg、Ca、Ne等），跟踪详细的恒星演化，计算了超巨星的形成率。不同质量和金属丰度的恒星以及不同的恒星星族（星族III和星族II-I）的寿命。我们发现，超级巨星通常与致密的，几乎没有金属污染的塌陷气体和以氧为主的丰度。由此产生的超巨星率约为$10^{-2}\,\rm yr^{-1} sr^{-1}$，在红移$z=0$处，它们对总速率的贡献为$ < 0.1 $ %，这解释了为什么它们迄今为止从未被探测到。在红移$z\simeq 6$处的预期速率是$\sim 10^{-3}\,\rm yr^{-1} sr^{-1}$的量级，并且在更高的$z$处进一步降低。由于大质量短寿命恒星的强烈金属富集，在同一恒星形成区中只可能产生$\sim 1$超巨星。考虑到它们对原始恒星质量函数的高质量端的敏感性，它们是探测原始第三星族恒星形成和低金属丰度下恒星演化的合适候选者。
英文摘要：
We compute the rate of supercollapsars by using cosmological, N-body, hydro, chemistry simulations of structure formation, following detailed stellar evolution according to proper yields (for He, C, N, O, Si, S, Fe, Mg, Ca, Ne, etc.) and lifetimes for stars having different masses and metallicities, and for different stellar populations (population III and population II-I). We find that supercollapsars are usually associated to dense, collapsing gas with little metal pollution and with abundances dominated by oxygen. The resulting supercollapsar rate is about $10^{-2}\,\rm yr^{-1} sr^{-1}$ at redshift $z=0$, and their contribution to the total rate is $ < 0.1 $ per cent, which explains why they have never been detected so far. Expected rates at redshift $z\simeq 6$ are of the order of $\sim 10^{-3}\,\rm yr^{-1} sr^{-1}$ and decrease further at higher $z$. Because of the strong metal enrichment by massive, short-lived stars, only $\sim 1$ supercollapsar generation is possible in the same star forming region. Given their sensitivity to the high-mass end of the primordial stellar mass function, they are suitable candidates to probe pristine population III star formation and stellar evolution at low metallicities.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
