JWST Spectroscopy of 3I/ATLAS: Isotopic Evidence for a Cold and Distant Origin
2026/03/06 by Martin Cordiner, Nathan Roth, Nathan X. Roth +23 · 15 voices · 3 citations
Physics and Astronomy · #Astrophysics and Star Formation Studies #Astro and Planetary Science #Astronomy and Astrophysical Research
paper · pdf · doi:10.21203/rs.3.rs-8930056/v1
Abstract
Interstellar objects provide the only directly observable samples of icy planetesimals formed around other stars, and can therefore provide insight into the diversity of physical and chemical conditions occurring during exoplanet formation. Here we report isotopic measurements of the interstellar comet 3I/ATLAS, which reveal an elemental composition unlike any Solar System body. The water in 3I/ATLAS is enriched in deuterium, at a level of D/H = (0.95 +- 0.06)%, which is more than an order of magnitude higher than in known comets, while its range of 12C/13C ratios (141-191 for CO2 and 123-172 for CO) exceeds typical values found in the Solar System, as well as nearby interstellar clouds and protoplanetary disks. Such extreme isotopic signatures indicate formation at temperatures \lesssim30 K in a relatively metal-poor environment, early in the history of the Galaxy. When interpreted with respect to models for Galactic chemical evolution, the carbon isotopic composition implies that 3I/ATLAS accreted roughly 10-12 billion years ago, following an early period of intense star formation. 3I/ATLAS thus represents a preserved fragment of an ancient planetary system, and provides direct evidence for active ice chemistry and volatile-rich planetesimal formation in the young Milky Way.
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- JWST 🔭 reports deuterium galore in 3I/ATLAS in new paper by @drcordiner.bsky.social et al. arxiv.org/pdf/2603.06911 [bsky, 38 points, 2 comments]
- Wow - according to this paper 3I/ATLAS is more than twice as old as our solar system - a messenger from the distant past doi.org/10.48550/arX... 🧪🔭 [bsky, 25 points, 0 comments]
- Isotopic Evidence for a Cold and Distant Origin of Interstellar Object 3I/Atlas [hn, 22 points, 1 comments]
- Several papers on the isotopic composition of 3I/ATLAS on the arxiv today, with, e.g., 12C/13C being ca. 50% higher than measured in all solar system materials (D/H, 14N/15N too). Before, these kind o [bsky, 16 points, 1 comments]
- The Cordiner et al paper. arxiv.org/pdf/2603.06911 [bsky, 5 points, 0 comments]
- Today on the #arXiv: @drcordiner.bsky.social et al. 2026, "Isotopic Evidence for a Cold and Distant Origin of the Interstellar Object 3I/ATLAS" arxiv.org/abs/2603.06911 One of a set of studies showing [bsky, 4 points, 1 comments]
- Here's a paper reporting on the isotopic makeup of 3I/ATLAS, which claims it is consistent with having formed ten to twelve billion years ago. A long, lonely time. ⚛️🔭 [bsky, 2 points, 1 comments]
- Isotopic Evidence for a Cold and Distant Origin of the Interstellar Object 3I/ATLAS: arxiv.org/abs/2603.06911 (some numbers have changed slightly) -> Webb finds clues to ancient origin of Comet 3I/ATL [bsky, 2 points, 0 comments]
- Two new papers on 3I/ATLAS Isotopic Evidence for a Cold and Distant Origin of the Interstellar Object 3I/ATLAS arxiv.org/abs/2603.06911 A Direct View of the Chemical Properties of Water from Another P [bsky, 0 points, 0 comments]
- 2603.06911] Isotopic Evidence for a Cold and Distant Origin of the Interstellar Object 3I/ATLAS [https://arxiv.org/abs/2603.06911 [bsky, 0 points, 0 comments]
- [2603.06911] Isotopic Evidence for a Cold and Distant Origin of the Interstellar Object 3I/ATLAS arxiv.org/abs/2603.06911 [bsky, 0 points, 0 comments]
- Isotopic Evidence for a Cold and Distant Origin of Interstellar Object 3I/Atlas https://arxiv.org/abs/2603.06911 [bsky, 0 points, 0 comments]
- Isotopic Evidence for a Cold and Distant Origin of the Interstellar Object 3I/ATLAS Cordiner et al. arXiv arxiv.org/abs/2603.06911 [bsky, 0 points, 0 comments]
- Today on the # arXiv : Cordiner et al. 2026, "Isotopic Evidence for a Cold and Distant Origin of the Interstellar Object 3I/ATLAS" https:// arxiv.org/abs/2603.06911 One of a set of studies showing tha [mastodon, 0 points, 1 comments]
- Isotopic Evidence for a Cold and Distant Origin of Interstellar Object 3I/Atlas https:// arxiv.org/abs/2603.06911 # arxiv [mastodon, 0 points, 0 comments]
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