使用Hobby-Eberly望远镜搭载的VIRUS仪器对3I/ATLAS = C/2025 N1 (ATLAS)彗星的IFU观测
IFU Observations of Comet 3I/ATLAS = C/2025 N1 (ATLAS) using the Hobby-Eberly Telescope with the VIRUS Instrument
- McDonald Observatory, University of Texas at Austin（德克萨斯大学奥斯汀分校麦克唐纳天文台）
- Hobby Eberly Telescope, University of Texas at Austin（德克萨斯大学奥斯汀分校霍比-埃伯利望远镜）
- STAR Institute, University of Liège（列日大学STAR研究所）
- Koyama Space Science Institute, Kyoto Sangyo University（京都产业大学小山宇宙科学研究所）
- Department of Physics and Astronomy, Appalachian State University（阿巴拉契亚州立大学物理与天文学系）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究利用Hobby-Eberly望远镜的VIRUS仪器观测3I/ATLAS彗星，采用Haser模型分析其光谱，发现其气体外流速度为同距离太阳系彗星的一半，详细探测了该彗星的彗发。
AI中文摘要：
我们于2025年12月9日世界时，使用Hobby-Eberly望远镜搭载的VIRUS光谱仪对星际天体3I/ATLAS = C/2025 N1 (ATLAS)进行了观测。VIRUS是一款低光谱分辨率的多积分视场单元（IFU）光学光谱仪。我们使用单个IFU开展观测，成功获取了从光心向太阳方向延伸至约85000公里处、每1角秒（对应1327公里）间隔的光谱。这些光谱包含太阳系彗星光学光谱中常见的分子特征，同时还存在许多极强的FeI和NiI谱线。我们采用Haser（1957）模型框架对观测结果进行建模，发现只有假设气体外流速度为相同日心距离下观测到的太阳系彗星的一半时，才能拟合数据。我们推导了三条NiI和四条FeI谱线的Haser模型标长，并探讨了该天体与普通太阳系彗星之间异同的意义。VIRUS出色的空间分辨率、50×50角秒的视场以及1.83天文单位的地心距离，使我们能够详细探测3I的彗发。
英文摘要：
We observed interstellar object 3I/ATLAS = C/2025 N1 (ATLAS) on 9 December 2025 UT with the VIRUS spectrograph on the Hobby-Eberly Telescope. VIRUS is a low spectral resolving power, multi-IFU, optical spectrograph. We used a single IFU for the observations and were able to obtain spectra spaced every one arcsec (1327 km) from the optocenter out to about 85,000 km in the sunward direction. The spectra include molecular features normally seen in the optical for spectra of Solar System comets, with the addition of many very strong lines of FeI and NiI. We modeled these observations using the Haser (1957) model framework and find that the data can only be fit if we assume that the outflow velocity of the gas is half that of comets in our Solar System observed at the same heliocentric distance. We derived Haser model scale lengths for three NiI and four FeI lines. We discuss the implication of the similarities and differences between this object and normal Solar System comets. The excellent spatial resolution of VIRUS, coupled with a FOV of 50X50 arcsecs and a geocentric distance of 1.83 au, allowed us to probe the coma of 3I in great detail.
