Pre-perihelion Emergence of the CN Gas Coma in 3I/ATLAS Temporally and Spatially Resolved by the 7-Dimensional Telescope
Institute for Astronomy, University of Hawai‘i（夏威夷大学天体物理研究所）；Astronomy Program, Department of Physics and Astronomy, Seoul National University（首尔大学物理与天文学系天文项目）；SNU Astronomy Research Center, Seoul National University（首尔大学天文研究中心）；Korea Astronomy and Space Science Institute (KASI)（韩国天体宇宙科学研究所）
Gregory S. H. Paek, Myungshin Im, Mankeun Jeong, Hyeonho Choi, Yoonsoo P. Bach, Masateru Ishiguro, Bumhoo Lim, Seo-Won Chang, Ji Hoon Kim, Jooyeon Geem, Willem B. Hoogendam
We present time-series medium-band (R~20-40) observations of the third interstellar object 3I/ATLAS (C/2025 N1) obtained with the 7-Dimensional Telescope (7DT), enabling spatially resolved monitoring of its gas and dust activity from 2025 July to September. The m400-band image (lambda_c = 400 nm, Delta lambda approx 25 nm) reveals the emergence of pronounced and spatially extended CN emission at heliocentric distances r_h < 3 au. This onset is consistently identified across multiple diagnostics, including a break in the light-curve evolution, excess reflectance, inward expansion of annular excess beyond 10,000-20,000 km, growth of the coma half-light radius from ~11,000 to ~19,000 km, and a rapid rise in the CN production rate Q_CN relative to Af rho. We further separate the CN-emitting and dust-scattered components through two-dimensional surface-brightness fitting into inner (dust) and outer (gas) components. The outer component preserves a nearly constant profile shape, varying only in normalization, implying relatively fast expansion of CN-bearing molecules. Together, these results reveal a transition in the optical from dust-dominated scattering at large heliocentric distances to volatile-driven, gas-dominated activity as 3I/ATLAS enters the inner Solar System. The timing and characteristics of the CN activation resemble the volatile enhancement observed in 2I/Borisov, suggesting that both known active interstellar objects exhibit comparable activation behavior at heliocentric distances of ~2-3 au.
SPHEREx Re-Observation of Interstellar Object 3I/ATLAS in December 2025: Detection of Increased Post-Perihelion Activity, Refractory Coma Dust, and New Coma Gas Species
Johns Hopkins University Applied Physics Laboratory（约翰斯·霍普金斯大学应用物理实验室）；Korea Astronomy and Space Science Institute（韩国天体宇宙科学研究所）；Arizona State University（亚利桑那州立大学）；California Institute of Technology（加州理工学院）；Jet Propulsion Lab（喷气推进实验室）；University of California Irvine（加州大学尔湾分校）；Infrared Processing and Analysis Center, Caltech（加州理工学院红外处理与分析中心）；Center for Astrophysics, Harvard & Smithsonian（哈佛-史密森尼天体物理中心）
Post-perihelion Coma Composition of the Interstellar Comet 3I/ATLAS from Optical Spectroscopy
CAS Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台光学天文重点实验室）；Yunnan Observatories, Chinese Academy of Sciences (CAS)（中国科学院云南天文台）；School of Astronomy and Space Sciences, University of Chinese Academy of Sciences（中国科学院大学天文学与空间科学学院）；Instituto de Estudios Astrofísicos, Facultad de Ingeniería y Ciencias, Universidad Diego Portales（迭戈帕托莱斯大学工程与科学学院天体物理研究所）；Planetary Science Institute（行星科学研究所）
Origin and evolution of NiI and FeI in the coma of the interstellar comet 3I/ATLAS throughout its trajectory
Université de Liège（列日大学）；University of Edinburgh（爱丁堡大学）；Université Catholique de Louvain（天主教鲁汶大学）；University of Canterbury（坎特伯雷大学）；Auburn University（奥本大学）；University of Helsinki（赫尔辛基大学）；University of Padova（帕多瓦大学）
研究揭示了镍和铁在星际彗星3I/ATLAS彗核 coma 中的起源与演化，发现其金属产量显著高于太阳系彗星，并提出羰基假说解释其形成机制。
Perihelion observations of interstellar comet 3I/ATLAS with the IRAM 30-m telescope
LIRA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Université, Université de Paris（巴黎天文台）；IRAM（红外毫米波天文台）；NASA Goddard Space Flight Center（美国宇航局戈达德太空飞行中心）；Department of Physics, Catholic University of America（美利坚天主教大学物理系）；Department of Physics, American University（美利坚大学物理系）
Pre-perihelion evolution of the NiI/FeI abundance ratio in the coma of the interstellar comet 3I/ATLAS. From extreme to normal
Université de Liège（列日大学）；University of Edinburgh（爱丁堡大学）；Pontificia Universidad Católica de Chile（智利天主教 Pontificia 大学）；University of Canterbury（坎特伯雷大学）；University of Helsinki（赫尔辛基大学）
Dust Activity Evolution and Constraints on Icy Grains in the Interstellar Comet 3I/ATLAS
State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology（澳门科技大学月球与行星科学国家重点实验室）；School of Aeronautics and Astronautics, Shenzhen Campus of Sun Yat-sen University（中山大学深圳校区航空航天学院）；Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）
Dynamically New Comet C/2025 D1 (Groeller) with Record Perihelion Distance
Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）；The University of Western Ontario（韦仕敦大学）；ESA NEO Coordination Centre, Planetary Defence Office（欧洲空间局近地天体协调中心行星防御办公室）
Water Production of Interstellar Comet 3I/ATLAS from SOHO/SWAN Observations after Perihelion
University of Michigan（密歇根大学）；Finnish Meteorological Institute（芬兰气象局）；LATMOS/IPSL UVSQ Université Paris-Saclay, Sorbonne Université, CNRS（巴黎萨克雷大学、索邦大学、法国国家科学研究中心LATMOS/IPSL联合实验室）；ACRI-st；LIRA, Observatoire de Paris（巴黎天文台LIRA）
利用SOHO/SWAN观测，研究星际彗星3I/ATLAS水生产率，发现其在近日点后9天的水生产率为3.17 x 10^29 s^-1，随后逐渐下降。
Multi-Wavelength Post-Perihelion Polarimetry of Interstellar Comet 3I/ATLAS
University of Helsinki（赫尔辛基大学）；Institute of Astronomy and National Astronomical Observatory, Bulgarian Academy of Sciences（保加利亚科学院天文研究所与国家天文台）；Armagh Observatory & Planetarium（阿马天文台与天文馆）；University of Maryland（马里兰大学）；TU Braunschweig（布伦瑞克工业大学）；INAF – Osservatorio Astrofisico di Torino（意大利国家天体物理研究所都灵天文台）；Finnish Centre for Astronomy with ESO, University of Turku（图卢大学ESO芬兰天文学中心）；Luleå University of Technology（吕勒奥理工大学）
Contemporaneous Optical and Near-Infrared Observations of the Interstellar Comet 3I/ATLAS Pre- and Post-Perihelion
NSF Graduate Research Fellow（美国国家科学基金会研究生研究员）；Instituto de Estudios Astrofísicos, Facultad de Ingeniería y Ciencias, Universidad Diego Portales（迭戈帕托莱斯大学工程与科学学院天文研究所）；School of Earth and Atmospheric Sciences, Georgia Institute of Technology（佐治亚理工学院地球与大气科学学院）；Center for Cosmology and Astroparticle Physics, The Ohio State University（俄亥俄州立大学宇宙学与高能物理中心）
High-resolution optical spectroscopy reveals the distinctive volatile composition of the interstellar comet 3I/ATLAS
STAR Institute, Université de Liège（列日大学STAR研究所）；Institute for Astronomy, University of Edinburgh, Royal Observatory（爱丁堡大学天文研究所皇家天文台）；Physics Department, Edmund C. Leach Science Center, Auburn University（奥本大学艾德蒙·C·利奇科学中心物理系）；School of Physical and Chemical Sciences – Te Kura Matū, University of Canterbury（坎特伯雷大学物理与化学科学学院）；Faculty of Science and Engineering, Northumbria University（诺森比亚大学科学与工程学部）；Koyama Space Science Institute, Kyoto Sangyo University（京都产业大学小山宇宙科学研究所）；INAF – Osservatorio Astrofisico di Arcetri（意大利国家天体物理研究所阿切特里天文台）
Very Large Telescope observations of interstellar comet 3I/ATLAS III: High-resolution monitoring of CN and forbidden oxygen emission across the perihelion passage with ESPRESSO
SPHEREx Pre-Perihelion Mapping of $\mathrm{H_2O}$, $\mathrm{CO_2}$, and $\mathrm{CO}$ in Interstellar Object 3I/ATLAS
Johns Hopkins University（约翰斯·霍普金斯大学）；Johns Hopkins University Applied Physics Laboratory（约翰斯·霍普金斯大学应用物理实验室）；Korea Astronomy and Space Science Institute (KASI)（韩国天文学与空间科学研究院）；Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）；Department of Physics, California Institute of Technology（加州理工学院物理系）；School of Earth and Space Exploration, Arizona State University（亚利桑那州立大学地球与空间探索学院）；Department of Physics & Astronomy, University of California Irvine（加州大学欧文分校物理与天文系）
Near-perihelion activity and composition of 3I/ATLAS from JUICE/MAJIS observations
LIRA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris（巴黎天文台，巴黎文理研究大学，法国国家科学研究中心，索邦大学，巴黎大学）；Institut d’Astrophysique Spatiale, CNRS/Université Paris-Saclay（宇宙物理学研究所，法国国家科学研究中心/巴黎萨克雷大学）；Observatoire des Sciences de l’Univers Nantes Atlantique (Osuna/UARO), CNRS UAR-3281, Nantes Université（南大西洋宇宙科学观测站，法国国家科学研究中心，南特大学）；Istituto Nazionale di Astrofisica – Istituto di Astrofisica e Planetologia Spaziali (INAF-IAPS)（意大利国家天体物理研究所 - 空间天体物理和行星学研究所）；Université Paris Cité, Institut de physique du globe de Paris (IPGP), CNRS（巴黎西岱大学，巴黎地球物理研究所，法国国家科学研究中心）；LAB, CNRS/Université de Bordeaux（实验室，法国国家科学研究中心/波尔多大学）；INAF - Astronomical Observatory of Padova（意大利国家天体物理研究所 - 帕多瓦天文台）；Université Grenoble Alpes, CNRS, IPAG（格勒诺布尔阿尔卑斯大学，法国国家科学研究中心，地球与行星物理学研究所）；Royal Belgian Institute for Space Aeronomy（比利时皇家空间气动力学研究所）
