3I/ATLAS has an extreme taste for heavy water

More and more details about 3I/ATLAS are filtering through the scientific process as time goes on. Our third known interstellar visitor attracted the attention of some of the world's most powerful observatories when it was discovered in July 2025, and some of those telescopes found something peculiar—the isotopes it contained appeared different. A new paper submitted to The Astrophysical Journal Letters (and available as a preprint on arXiv) by Kenji Furuya of the RIKEN Pioneering Research Institute in Japan and his co-authors shows that the isotopic discrepancy is likely due to the "low metallicity" of the stellar nursery in which 3I/ATLAS was born.