论文标题
Spinstars的喷射样超新星中的强烈中子爆发
A strong neutron burst in jet-like supernovae of spinstars
论文作者
论文摘要
一些金属贫困的星星具有丰富的模式，它们在慢速（S）和快速（R）中子捕获过程之间。我们表明，经历喷气样爆炸的快速旋转巨星的氦壳经历了两个有效的中子捕获过程：一个在恒星演化期间，一个在爆炸期间。它最终提供了一种材料，其化学成分位于S-和R过程之间。低金属性40〜 $ m _ {\ odot} $模型，其初始旋转速度为$ \ sim 700 $ 〜km〜S $^{ - 1} $是从出生到较慢的中子捕获过程之后带有核网络的核网络的前核网络。 2D流体动力学代码用于模拟A $ e = 10^{52} $ 〜ERG相对论喷射样爆炸，击中了恒星的壁炉。用1812核网络进行后处理，计算出喷射诱导的核合成。在恒星一生中，由于有效的S-Process而产生了$ 30 \ Lessim Z \ Lessim 82 $的沉重元素，该元素通过旋转而增强。在进化结束时，氦外壳在很大程度上充满了反铁元素和（未燃烧的）$^{22} $ ne，其丰度为$ \ sim 20 $ 20 $倍于非旋转模型。在爆炸期间，喷气机将氦气壳加热至$ \ sim 1.5 $ gk。它有效地激活（$α，n $）反应，例如$^{22} $ ne（$α，n $），并导致强烈的N-过程，中子密度为$ \ sim 10^{19} - 10^{20} {20} $ 〜cm $ $ $ $ $ $^{ - 3} $在0.1 $ $ 〜secon中。这具有将S过程模式转移到较重元素（例如EU）的效果。所得的化学模式与碳增强金属贫困R/S星CS29528-028的丰度一致，前提是喷射模型的弹出不是均匀混合的。这是一个新的天体物理遗址，可以至少解释一些金属贫困的恒星，显示S-和R过程之间的丰度模式。
Some metal-poor stars have abundance patterns which are midway between the slow (s) and rapid (r) neutron capture processes. We show that the helium shell of a fast rotating massive star experiencing a jet-like explosion undergoes two efficient neutron capture processes: one during stellar evolution and one during the explosion. It eventually provides a material whose chemical composition is midway between the s- and r-process. A low metallicity 40~$M_{\odot}$ model with an initial rotational velocity of $\sim 700$~km~s$^{-1}$ was computed from birth to pre-supernova with a nuclear network following the slow neutron capture process. A 2D hydrodynamic relativistic code was used to model a $E = 10^{52}$~erg relativistic jet-like explosion hitting the stellar mantle. The jet-induced nucleosynthesis was calculated in post-processing with a network of 1812 nuclei. During the star's life, heavy elements from $30 \lesssim Z \lesssim 82$ are produced thanks to an efficient s-process, which is boosted by rotation. At the end of evolution, the helium shell is largely enriched in trans-iron elements and in (unburnt) $^{22}$Ne, whose abundance is $\sim 20$ times higher than in a non-rotating model. During the explosion, the jet heats the helium shell up to $\sim 1.5$ GK. It efficiently activates ($α,n$) reactions, such as $^{22}$Ne($α,n$), and leads to a strong n-process with neutron densities of $\sim 10^{19} - 10^{20}$~cm$^{-3}$ during $0.1$~second. This has the effect of shifting the s-process pattern towards heavier elements (e.g. Eu). The resulting chemical pattern is consistent with the abundances of the carbon-enhanced metal-poor r/s star CS29528-028, provided the ejecta of the jet model is not homogeneously mixed. This is a new astrophysical site which can explain at least some of the metal-poor stars showing abundance patterns midway between the s- and r-process.
