发表机构
Pontificia Universidad Católica de Chile（智利天主教大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究利用甚大望远镜对星际彗星3I/ATLAS III进行高分辨率光谱观测，通过特定方法得出CN产生率等数据，揭示了彗发成分变化及G/R不对称，公开相关软件和数据，为星际天体监测提供了参考和框架。
AI 中文摘要
3I/ATLAS是已知的第三颗穿越太阳系的星际天体。我们使用VLT/ESPRESSO在23个夜晚对3I/ATLAS进行了高分辨率（$R\simeq 140000$）光谱观测（$r_{h}=1.67 - 2.45$au）。通过CometSpec拟合$B^2\Sigma^+-X^2\Sigma^+$波段得出CN产生率。对三条禁线[OI]进行建模得到绿红（G/R）通量比和一个CO₂/H₂O代理值。拟合$Q_{CN}=a(r_{h}/1\text{au})^b$得到产生率与日心距离关系。近日点前CN幂律指数为$b_{pre}=-4.62^{+1.25}_{-1.22}$。CN残差有较大散射。G/R比从$r_{h}\simeq 2.4$au时的$\sim 0.42\pm 0.14$降至近日点附近的$\sim 0.114 \pm 0.004$。非对称分段氧拟合更优。CO₂/H₂O代理值在$\sim 0.06 - 1.06$之间。还识别出NiI和FeI并报告了近日点后C₂和CH的产生率。此次高分辨率监测揭示了一个富含CO₂的彗发在近日点附近逐渐以H₂O为主，G/R不对称与热惯性模型预测相符。同时公开CometSpec和简化数据，为下一代星际天体监测活动提供了经验参考和方法框架。
英文摘要
We characterize in 3I/ATLAS the heliocentric evolution of the CN production rate and the forbidden [OI] emission, describe the broader emission line inventory, and release the analysis tools and reduced data products to the community. We obtained high-resolution spectroscopy of 3I/ATLAS with VLT/ESPRESSO ($r_{\rm h}\!=\!1.67\!-\!2.45$ au). The CN production rates were derived by fitting the $B^2Σ^+\!-\!X^2Σ^+$ band using CometSpec, a publicly released Python package for flexible fluorescence modeling. The three forbidden [OI] lines were modeled to derive the green-to-red (G/R) flux ratio and a $\rm CO_2 / H_2O$ proxy. We fit $\text{Q}_{\rm CN}=a\,(r_{\rm h}/1\text{ au})^{\,b}$ to the production rate versus heliocentric distance relation. The pre-perihelion CN power-law index is $b_{\rm pre}\!=\!-4.62^{+1.25}_{-1.22}$, which is within the range observed for Solar System comets. The CN residuals about the smooth model show substantial scatter that we attribute to a combination of systematics and possible physical drivers that the current cadence cannot disentangle. The G/R ratio decreases from $\sim\!0.42\!\pm\!0.14$ at $r_{\rm h}\!\simeq\!2.4$ au to $\sim\!0.114\!\pm\!0.004$ near perihelion. The $\rm CO_2 / H_2O$ proxy spans $\sim 0.06 - 1.06$ and is comparable to the values reported by Subaru/HDS and SPHEREx and to those measured for 2I/Borisov. We additionally identify NiI and FeI and report post-perihelion production rates for $\rm C_2$ and CH. Our high-resolution monitoring of 3I/ATLAS reveals a $\rm CO_2$-rich coma that becomes progressively $\rm H_2O$-dominated near perihelion. Together with the public release of CometSpec and the reduced data, these results provide an empirical reference and a methodological framework for the next generation of interstellar object monitoring campaigns.
Comments19 pages, 11 figures. v2: published in A&A
Journal refA&A, 713, A251 (2026)
DOI：10.1051/0004-6361/202660647
