中等金属贫的银核球状星团NGC 6539与NGC 6569中的磷元素
Phosphorous in the moderately metal-poor bulge globular clusters NGC 6539 and NGC 6569
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中文总结 AI 辅助
本研究利用APOGEE光谱分析NGC 6539、NGC 6569等银核球状星团的Na、Al及P丰度，发现NGC 6539有1颗富磷星，为银核早期组成与化学演化提供了新约束。
中文摘要 AI 辅助
银河系银核的不同恒星族群可通过详细分析其化学丰度与运动学性质来区分。近期研究表明，银核中金属丰度约为[Fe/H]≈-0.7的球状星团，可能代表银河系中最古老的系统之一，或可追溯到早期的椭球星核。场星与球状星团中均存在[Fe/H]≈-0.7的金属丰度峰，同时富磷（P-rich）恒星的存在，可能为银河系第一代恒星的性质提供重要线索。本研究利用APOGEE光谱，对银核球状星团NGC 6539（[Fe/H]≈-0.75）与NGC 6569（[Fe/H]≈-0.85）中的奇Z元素钠（Na）、铝（Al），尤其是磷（P）进行研究，还分析了存在磷增强证据的星团Tonantzintla-1与NGC 6316。分析证实NGC 6539是值得关注的星团，拥有1颗明确的富磷恒星，而NGC 6569的磷增强水平较低。这进一步表明，可能存在一个金属丰度约为[Fe/H]≈-0.75的早期银核组成部分，NGC 6539便属于该组成部分。观测到的丰度模式显示，钠与铝的产生与大质量恒星的核合成一致，但磷增强的起源仍不确定，表明需额外的核合成通道来解释观测到的丰度。这些发现为银核的化学演化及其最早恒星族群的性质提供了新的约束。
英文摘要
The distinct stellar populations of the Galactic bulge can be disentangled through detailed analysis of their chemical abundances and kinematical properties. Recent studies have suggested that globular clusters located in the Galactic bulge with metallicities around $\rm [Fe/H] \approx -0.7$, may represent some of the oldest systems in the Milky Way, potentially tracing the early spheroidal bulge. The coincidence of a metallicity peak at $\rm [Fe/H] \approx -0.7$ in both field stars and globular clusters, together with the presence of phosphorus-rich (P-rich) stars, may provide important clues to the nature of the first generations of stars formed in the Galaxy. In this work, we investigate the odd-Z elements Na, Al and particularly P in the bulge globular clusters NGC~6539 ($\rm[Fe/H] \sim -0.75$) and NGC~6569 ($\rm [Fe/H] \sim -0.85$) using APOGEE spectra. We also examine the clusters Tonantzintla-1 and NGC~6316, which exhibit evidence of phosphorus enhancement. Our analysis confirms that NGC~6539 is a cluster of interest, with one clearly P-rich star, whereas NGC~6569 shows a lower level of P-enhancement. This again suggests that there might have been an early bulge building block with the metallicity of $\rm[Fe/H] \sim-0.75$, of which NGC~6539 would be part of. The observed abundance patterns indicate that the production of Na and Al is consistent with nucleosynthesis in massive stars. However, the origin of the phosphorus enrichment remains uncertain, suggesting that additional nucleosynthetic channels may be required to explain the observed abundances. These findings provide new constraints on the chemical evolution of the Galactic bulge and the nature of its earliest stellar populations.
