3I/ATLAS等离子体尾中的离子丰度表明其富含N₂
Ion abundances in the plasma tail of 3I/ATLAS show that it is N2-rich
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中文总结 AI 辅助
本研究通过WHT/WEAVE-LIFU观测3I/ATLAS的等离子体尾，发现其N₂/CO下限为0.023±0.001，相比太阳系彗星富含N₂，或与其寒冷形成条件相关。
中文摘要 AI 辅助
星际天体可让我们对比太阳系与其他恒星周围的早期行星形成过程。第二和第三个星际天体2I/Borisov与3I/ATLAS均呈现出可见的活动迹象，使我们能够通过对其气体彗发的光谱分析评估其组成。彗星周围的中性挥发物易于用普通摄谱仪探测，而离子发射大多来自彗尾，更便于用积分视场单元检测。我们展示了2025年11月30日及12月02日近日点后用WHT/WEAVE-LIFU对3I/ATLAS的观测结果，在反太阳彗尾中同时检测到离子N₂⁺、CO⁺、CO₂⁺、H₂O⁺和CH⁺。利用常见的荧光因子，我们确定了这些物种在彗尾中的丰度比，其中N₂⁺/CO⁺比值使我们能限定N₂/CO的下限为0.023±0.001，表明3I/ATLAS相比太阳系彗星富含N₂，该特性或与其寒冷的形成条件相关。其他离子间的丰度比虽无法直接限定中性粒子丰度，但似乎与3I/ATLAS富含超挥发物的事实一致。我们还研究了这些比值是否沿彗尾变化，仅检测到CH⁺随彗星中心距离呈微弱下降。
英文摘要
Interstellar objects allow us to compare the early planetary formation process in the Solar System and around other stars. The second and third interstellar objects, 2I/Borisov and 3I/ATLAS, showed visible signs of activity, making it possible to assess their composition via spectroscopic analysis of their gas coma. While neutral volatiles surrounding comets are easily probed by common spectrographs, ion emissions emanate mostly from the tail, making them easier to detect with integral-field units. We present WHT/WEAVE-LIFU observations of 3I/ATLAS, performed post-perihelion on 2025 November 30 and 2025 December 02. We simultaneously detect the ions N2+, CO+, CO2+, H2O+ and CH+ located in an anti-solar tail. Using common fluorescence factors, we determine abundance ratios of these species in the tail. In particular, the N2+/CO+ ratio allows us to constrain the lower-limit N2/CO>0.023+/-0.001, indicating that 3I/ATLAS is N2-rich compared to Solar System comets, a property which can be linked to cold formation conditions. Abundance ratios between other ions cannot directly be used to constrain abundances of neutrals but seem consistent with the fact that 3I/ATLAS is enriched in hypervolatiles. We also investigate whether these ratios vary along the tail, and only detect a marginal decrease of CH+ with cometocentric distance.
发表机构
- Northumbria University（诺森比亚大学）
- University of Edinburgh（爱丁堡大学）
机构由 AI 辅助整理，请以论文原文为准。
