银心附近缺少冷演化恒星的原因是什么？
What is the reason for the lack of cool evolved stars near the center of the Galaxy?
浏览论文内容
中文总结 AI 辅助
该研究通过三维流体动力学模拟，探究红巨星穿过Sgr A*喷流的效应，发现喷流剥蚀红巨星包层并提升其表面温度，或可解释银心附近冷巨星缺失、热恒星过剩的现象。
中文摘要 AI 辅助
观测发现，银河系中心秒差距范围内明亮的晚型巨星存在缺失，这仍是一个未解决的问题。本研究探究红巨星（RGs）多次穿过人马座A*（Sgr A*）过去产生的喷流，是否会改变其包层和表观光谱型。三维流体动力学模拟追踪了一颗1倍太阳质量（1 M☉）、半径100倍太阳半径（100 R☉）的红巨星，在10^5年的活跃阶段内，以10^-3秒差距的距离穿过喷流达10次，喷流动能光度分别取10^42、10^44和10^48 erg/s。每次穿过都会产生激波、包层剥蚀和不对称的下游尾迹。对于光度不超过10^44 erg/s的喷流，累积剥蚀质量近似按ΔM∝t^(1/2)演化，在10^5年活跃阶段内约达到10^-4 M☉。反复加热还会使表面温度在头10次穿过中从约3600K升至8500K，可能使M型巨星表现为A型源。因此，喷流反馈可能是银核（GN）中冷巨星表观缺失、热恒星过剩的原因之一。
英文摘要
The observed deficit of bright late-type giants in the central parsec of the Milky Way remains an open problem. We investigate whether repeated passages of red giants (RGs) through a past jet from Sgr$~$A$^*$ can modify their envelopes and apparent spectral types. Three-dimensional hydrodynamical simulations follow a $1\,M_\odot$, $100\,R_\odot$ RG through up to ten jet crossings at $10^{-3}\,\text{pc}$, using jet kinetic luminosities of $10^{42}$, $10^{44}$, and $10^{48}\,\text{erg}\,\text{s}^{-1}$. Each passage produces shocks, envelope ablation, and an asymmetric downstream tail. For jet luminosities up to $10^{44}\,\text{erg}\,\text{s}^{-1}$, the cumulative ablated mass evolves approximately as $ΔM\propto t^{1/2}$ and reaches about $10^{-4}\,M_\odot$ over a $10^5\,\text{yr}$ active phase. Repeated heating also raises the surface temperature from about $3600$ to $8500\,\text{K}$ during the first ten passages, potentially making an M-type giant appear as an A-type source. Jet feedback may therefore contribute to the apparent depletion of cool giants and the excess of hot stars in galactic nuclei (GN).
