化学特殊恒星近红外光谱及其在千新星光谱中的应用
Near-infrared spectra of chemically peculiar stars and applications to kilonova spectra
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中文总结 AI 辅助
本研究利用14颗化学特殊恒星的高分辨率近红外光谱，确认了Sr II和Ce III等强跃迁的重要性，并发现Eu II和Nd III在重元素富集条件下可能对千新星光谱有显著贡献。
中文摘要 AI 辅助
千新星光谱提供了中子星合并中快速中子俘获核合成过程的信息。然而，在千新星光谱中识别单个元素仍然具有挑战性，这主要是由于重元素在近红外波段的原子数据不完整。近期研究表明，化学特殊恒星的光谱为研究千新星光谱提供了极佳的实验室。在本文中，为加深我们对重元素在近红外波段强跃迁的理解，我们展示了利用Subaru/IRD获得的14颗化学特殊恒星的高分辨率近红外光谱，这些恒星覆盖了不同的有效温度、表面重力及丰度模式。先前被认为是最强跃迁之一的Sr II、Ce III和Gd III谱线在我们的多数目标恒星光谱中被探测到，证实了它们内在的重要性。此外，在若干恒星中探测到了Eu II和Nd III谱线。通过比较观测到的等值宽度和丰度比，我们表明在高度重元素富集的丰度模式下，Eu II和Nd III谱线对千新星光谱特征的贡献可能与Sr II相当。重要的是，尽管恒星样本更大，我们未发现系统性强于这些跃迁的未识别谱线。这些结果进一步支持了Sr II和Ce III跃迁的首要重要性，并为Eu II和Nd III的潜在贡献提供了新见解。
英文摘要
Kilonova spectra provide information on rapid neutron-capture nucleosynthesis in neutron star mergers. However, it remains challenging to identify individual elements in kilonova spectra, primarily due to incomplete atomic data for heavy elements at near-infrared wavelengths. Recent work demonstrated that spectra of chemically peculiar stars offer excellent laboratory for studying kilonova spectra. In this paper, to expand our understanding of strong transitions of heavy elements at near-infrared wavelengths, we present high-resolution near-infrared spectra of 14 chemically peculiar stars covering a range of effective temperatures, surface gravities, and abundance patterns, obtained with Subaru/IRD. The Sr II, Ce III, and Gd III lines, previously suggested to be among the strongest transitions, are detected in the spectra of most of our targets, confirming their intrinsic importance. In addition, Eu II and Nd III lines are detected in several stars. By comparing observed equivalent widths and abundance ratios, we show that under a highly heavy-element-enriched abundance pattern, Eu II and Nd III lines may contribute to kilonova spectral features comparably to Sr II. Importantly, we find no unidentified lines systematically stronger than these transitions despite the larger stellar sample. These results further support the primary importance of the Sr II and Ce III transitions and provide new insights into the potential contribution of Eu II and Nd III.
发表机构
- The University of Tokyo（东京大学）
- Tohoku University（东北大学）
- National Astronomical Observatory of Japan（日本国立天文台）
- The Graduate University for Advanced Studies, SOKENDAI（综合研究大学院大学）
- Subaru Telescope, National Astronomical Observatory of Japan（日本国立天文台昴星团望远镜）
- National Museum of Nature and Science（国立自然科学博物馆）
- Astrobiology Center（天体生物学中心）
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