星际彗星3I/ATLAS甲烷重氢比例达3.18%：韦布望远镜测量为太阳系记录的13倍
一项刊于《自然天文学》（Nature Astronomy）的研究说，星际彗星 3I/ATLAS 的甲烷中，重氢（氘）所占比例达到3.18%，误差为0.30个百分点，是太阳系内所测同类数值的13倍。研究团队说，这一比例显示该彗星形成于一个极其寒冷的未知恒星系统。
这颗彗星由位于智利 Río Hurtado 的 ATLAS 巡天望远镜于2025年7月1日报告发现，被确认时已知不到六个月。韦布空间望远镜于2025年12月22日在总观测者计划5094下对其观测；在此之前，英国 Upminster、Bridgend，西班牙 Alcarràs 与克罗地亚 Zagreb 等地的学校团体通过 Comet Chasers 计划提供了位置测量，帮助天文学家修正其预报位置。
论文由 NASA 戈达德太空飞行中心的 Nathan X. Roth 领衔，共18位作者。观测时该彗星距太阳约3.6亿公里，距韦布望远镜约2.69亿公里。研究团队未指认该彗星来自哪颗恒星。
Interstellar comet 3I/ATLAS methane shows 3.18 percent heavy hydrogen, 13 times the solar system record measured by Webb
A study published in Nature Astronomy reports that methane in the interstellar comet 3I/ATLAS contains heavy hydrogen at a ratio of 3.18 percent, with an uncertainty of 0.30 points, 13 times the level measured in the solar system. The team said the ratio shows the comet was born in an incredibly cold, unknown star system.
The comet was reported on July 1, 2025, by the ATLAS survey telescope in Río Hurtado, Chile, and had been known for less than six months. The James Webb Space Telescope observed it on December 22, 2025, under General Observer program 5094. Before that, school groups in Upminster and Bridgend in Britain, Alcarràs in Spain and Zagreb in Croatia sent in position measurements through the Comet Chasers program, helping astronomers refine the comet's predicted location.
The paper is led by Nathan X. Roth of NASA's Goddard Space Flight Center, with 17 co-authors. At the time of observation the comet was about 360 million kilometres from the Sun and 269 million kilometres from Webb. The paper does not name a home star for 3I/ATLAS.
来源：自然天文学
发布：GSM·美国（发布链接）
图片来源：图中是詹姆斯韦布空间望远镜的艺术想象图，该望远镜对星际彗星3I/ATLAS作了光谱观测。ESA, CC BY 4.0, via Wikimedia Commons
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