Gourier, D. et al. Extreme deuterium enrichment of organic radicals in the Orgueil meteorite: revisiting the interstellar interpretation? Geochim. Cosmochim. Acta 72, 1914–1923 (2008).

Article 
ADS 

Google Scholar
 

Duprat, J. et al. Extreme deuterium excesses in ultracarbonaceous micrometeorites from central Antarctic snow. Science 328, 742–745 (2010).

Article 
ADS 

Google Scholar
 

Levison, H. F., Morbidelli, A., Tsiganis, K., Nesvorny, D. & Gomes, R. Late orbital instabilities in the outer planets induced by interaction with a self-gravitating planetesimal disk. Astrophys. J. 142, 152 (2011).


Google Scholar
 

Ito, M. et al. A pristine record of outer Solar System materials from asteroid Ryugu’s returned sample. Nat. Astron. 6, 1163–1171 (2022).

Article 
ADS 

Google Scholar
 

Miguel, Y. & Vazan, A. Interior and evolution of the giant planets. Remote Sens. 15, 681 (2023).

Article 
ADS 

Google Scholar
 

Biver, N., Dello Russo, N., Opitom, C. & Rubin, M. Chemistry of comet atmospheres. In Comets III (eds Meech, K. J. et al.) 459–498 (Univ. Arizona Press, 2024).

Willacy, K. et al. Comets in context: comparing comet compositions with protosolar nebula models. Astrophys. J. 931, 164 (2022).

Article 
ADS 

Google Scholar
 

Bailer-Jones, C. A. L., Farnocchia, D., Ye, Q., Meech, K. J. & Micheli, M. A search for the origin of the interstellar comet 2I/Borisov. Astron. Astrophys. 634, A14 (2020).

Article 
ADS 

Google Scholar
 

Seligman, D. Z. et al. Discovery and preliminary characterization of a third interstellar object: 3I/ATLAS. Astrophys. J. Lett. 989, L36 (2025).

Article 
ADS 

Google Scholar
 

Guo, Y. et al. Search for past stellar encounters and the origin of 3I/ATLAS. Astron. J. 170, 362 (2025).

Article 
ADS 

Google Scholar
 

Taylor, A. G. & Seligman, D. Z. The kinematic age of 3I/ATLAS and its implications for early planet formation. Astrophys. J. Lett. 990, L14 (2025).

Article 
ADS 

Google Scholar
 

Hopkins, M. J. et al. From a different star: 3I/ATLAS in the context of the Ōtautahi–Oxford Interstellar Object Population Model. Astrophys. J. Lett. 990, L30 (2025).

Article 
ADS 

Google Scholar
 

Cordiner, M. A. et al. JWST detection of a carbon-dioxide-dominated gas coma surrounding interstellar object 3I/ATLAS. Astrophys. J. Lett. 991, L43 (2025).

Article 
ADS 

Google Scholar
 

Hutsemékers, D. et al. Pre-perihelion evolution of the NiI/FeI abundance ratio in the coma of the interstellar comet 3I/ATLAS: from extreme to normal. Astron. Astrophys. 706, A43 (2026).

Article 

Google Scholar
 

Roth, N. X. et al. CH3OH and HCN in interstellar comet 3I/ATLAS mapped with the ALMA Atacama Compact Array: distinct outgassing behaviors and a remarkably high CH3OH/HCN production rate ratio. Astrophys. J. Lett. 999, L99 (2026).


Google Scholar
 

Salazar Manzano, L. E. et al. Water D/H in 3I/ATLAS as a probe of formation conditions in another planetary system. Nat. Astron. 10, 988–1000 (2026).

Article 

Google Scholar
 

Cordiner, M. et al. Isotopic evidence for a cold and distant origin of the interstellar object 3I/ATLAS. Nature 655, 870–874 (2026).

Article 

Google Scholar
 

Opitom, C. et al. High nitrogen and carbon isotopic ratios in the interstellar comet 3I/ATLAS. Nat. Astron. https://doi.org/10.1038/s41550-026-02921-7 (2026).

Article 

Google Scholar
 

Botelho, R. B. et al. Carbon, isotopic ratio 12C/13C, and nitrogen in solar twins: constraints for the chemical evolution of the local disc. Mon. Not. R. Astron. Soc. 499, 2196–2213 (2020).

Article 
ADS 

Google Scholar
 

Romano, D. The evolution of CNO elements in galaxies. Astron. Astrophys. Rev. 30, 7 (2022).

Article 
ADS 

Google Scholar
 

Millar, T. J., Bennett, A. & Herbst, E. Deuterium fractionation in dense interstellar clouds. Astrophys. J. 340, 906 (1989).

Article 
ADS 

Google Scholar
 

Pagani, L., Roueff, E. & Lesaffre, P. Ortho-H2 and the age of interstellar dark clouds. Astrophys. J. Lett. 739, L35 (2011).

Article 
ADS 

Google Scholar
 

Jensen, S. S., Jørgensen, J. K., Furuya, K., Haugbølle, T. & Aikawa, Y. Modeling chemistry during star formation: water deuteration in dynamic star-forming regions. Astron. Astrophys. 649, A66 (2021).

Article 
ADS 

Google Scholar
 

Cazaux, S., Caselli, P. & Spaans, M. Interstellar ices as witnesses of star formation: selective deuteration of water and organic molecules unveiled. Astrophys. J. Lett. 741, L34 (2011).

Article 
ADS 

Google Scholar
 

Taquet, V. et al. Interferometric observations of warm deuterated methanol in the inner regions of low-mass protostars. Astron. Astrophys. 632, A19 (2019).

Article 

Google Scholar
 

Riaz, B. & Thi, W.-F. First CH3D detection in class 0/I proto-brown dwarfs: constraints on CH4 abundances. Mon. Not. R. Astron. Soc. 511, L50–L54 (2022).

Article 
ADS 

Google Scholar
 

Müller, D. R. et al. High D/H ratios in water and alkanes in comet 67P/Churyumov-Gerasimenko measured with Rosetta/ROSINA DFMS. Astron. Astrophys. 662, A69 (2022).

Article 

Google Scholar
 

Villanueva, G. L., Smith, M. D., Protopapa, S., Faggi, S. & Mandell, A. M. Planetary Spectrum Generator: an accurate online radiative transfer suite for atmospheres, comets, small bodies and exoplanets. J. Quant. Spectrosc. Radiat. Transf. 217, 86–104 (2018).

Article 
ADS 

Google Scholar
 

Villanueva, G. et al. Non-LTE modeling in cometary atmospheres. In Fundamentals of the Planetary Spectrum Generator (ed. Villanueva, G.) 65–78 (NASA, 2025).

Bonev, B. P. et al. A comprehensive study of infrared OH prompt emission in two comets. I. Observations and effective g-factors. Astron. J. 653, 774–787 (2006).

Article 

Google Scholar
 

Dello Russo, N., Kawakita, H., Vervack, R. J. J. & Weaver, H. A. Emerging trends and a comet taxonomy based on the volatile chemistry measured in thirty comets with high-resolution infrared spectroscopy between 1997 and 2013. Icarus 278, 301–332 (2016).

Article 
ADS 

Google Scholar
 

Belyakov, M. et al. The volatile inventory of 3I/ATLAS as seen with JWST/MIRI. Astrophys. J. Lett. 1001, L11 (2026).

Article 
ADS 

Google Scholar
 

Biver, N. et al. Perihelion observations of interstellar comet 3I/ATLAS with the IRAM 30-m telescope. Astron. Astrophys. 708, L16 (2026).

Article 
ADS 

Google Scholar
 

Gibb, E. L. et al. Chemical composition of comet C/2007 N3 (Lulin): another ‘atypical’ comet. Astrophys. J. 750, 102 (2012).

Article 
ADS 

Google Scholar
 

Bonev, B. P. et al. Comet C/2004 Q2 (Machholz): parent volatiles, a search for deuterated methane, and constraint on the CH4 spin temperature. Astrophys. J. 699, 1563–1572 (2009).

Article 
ADS 

Google Scholar
 

Kawakita, H., Watanabe, J., Furusho, R., Fuse, T. & Boice, D. C. Nuclear spin temperature and deuterium-to-hydrogen ratio of methane in comet C/2001 Q4 (NEAT). Astrophys. J. Lett. 623, L49 (2005).

Article 
ADS 

Google Scholar
 

Mandt, K. E. et al. A nearly terrestrial D/H for comet 67P/Churyumov-Gerasimenko. Sci. Adv. 10, eadp2191 (2024).

Article 

Google Scholar
 

Ceccarelli, C. et al. Deuterium fractionation: the Ariadne’s thread from the precollapse phase to meteorites and comets today. In Protostars & Planets VI (eds H. Beuther et al.) 859–882 (Univ. of Arizona Press, 2014).

Cleeves, L. I. et al. Exploring the origins of deuterium enrichments in solar nebular organics. Astrophys. J. 819, 13 (2016).

Article 
ADS 

Google Scholar
 

Furuya, K. et al. High water D/H ratio of the interstellar object 3I/ATLAS is consistent with a low-metallicity origin. Astrophys. J. Lett. 1009, L25 https://doi.org/10.3847/2041-8213/aea221 (2026).

Article 

Google Scholar
 

Roberts, H., Herbst, E. & Millar, T. J. Enhanced deuterium fractionation in dense interstellar cores resulting from multiply deuterated \({{\rm{H}}}_{3}^{+}\). Astrophys. J. Lett. 591, L41–L44 (2003).

Article 
ADS 

Google Scholar
 

Hugo, E., Asvany, O. & Schlemmer, S. \({{\rm{H}}}_{3}^{+}\) + H2 isotopic system at low temperatures: microcanonical model and experimental study. J. Chem. Phys. 130, 164302 (2009).

Article 
ADS 

Google Scholar
 

Sipilä, O. et al. Modelling line emission of deuterated \({{\rm{H}}}_{3}^{+}\) from prestellar cores. Astron. Astrophys. 509, A98 (2010).

Article 

Google Scholar
 

Taquet, V., Charnley, S. B. & Sipilä, O. Multilayer formation and evaporation of deuterated ices in prestellar and protostellar cores. Astrophys. J. https://doi.org/10.1088/0004-637X/791/1/1 (2014).

Article 

Google Scholar
 

Furuya, K., van Dishoeck, E. F. & Aikawa, Y. Reconstructing the history of water ice formation from HDO/H2O and D2O/HDO ratios in protostellar cores. Astron. Astrophys. 586, A127 (2016).

Article 

Google Scholar
 

Aikawa, Y., Wakelam, V., Hersant, F., Garrod, R. T. & Herbst, E. From prestellar to protostellar cores. II. Time dependence and deuterium fractionation. Astrophys. J. 760, 40 (2012).

Article 
ADS 

Google Scholar
 

Albertsson, T., Semenov, D. A., Vasyunin, A. I., Henning, T. & Herbst, E. New extended deuterium fractionation model: assessment at dense ISM conditions and sensitivity analysis. Astrophys. J. Suppl. Ser. 207, 27 (2013).

Article 
ADS 

Google Scholar
 

Jørgensen, J. K. et al. The ALMA-PILS survey: isotopic composition of oxygen-containing complex organic molecules toward IRAS 16293-2422B. Astron. Astrophys. 620, A170 (2018).

Article 

Google Scholar
 

Taquet, V., Ceccarelli, C. & Kahane, C. Formaldehyde and methanol deuteration in protostars: fossils from a past fast high-density pre-collapse phase. Astrophys. J. Lett. 748, L3 (2012).

Article 
ADS 

Google Scholar
 

Qasim, D. et al. An experimental study of the surface formation of methane in interstellar molecular clouds. Nat. Astron. 4, 781–785 (2020).

Article 
ADS 

Google Scholar
 

Aikawa, Y. & Herbst, E. Deuterium fractionation in protoplanetary disks. Astrophys. J. 526, 314 (1999).

Article 
ADS 

Google Scholar
 

Böker, T. et al. The near-infrared spectrograph (NIRSpec) on the James Webb Space Telescope. III. Integral-field spectroscopy. Astron. Astrophys. 661, A82 (2022).

Article 

Google Scholar
 

Bushouse, H. et al. JWST calibration pipeline. Zenodo https://doi.org/10.5281/zenodo.16280965 (2025).

Roth, N. X. apertureSynthesis/jwstComet: jwstComet. Zenodo https://doi.org/10.5281/zenodo.18700806 (2026).

DiSanti, M. A., Mumma, M. J., Dello Russo, N., Magee-Sauer, K. & Griep, D. M. Evidence for a dominant native source of carbon monoxide in comet C/1996 B2 (Hyakutake). J. Geophys. Res.: Planets 108, 5061 (2003).

ADS 

Google Scholar
 

Bonev, B. P. et al. The inner coma of comet C/2012 S1 (ISON) at 0.53 AU and 0.35 AU from the Sun. Astrophys. J. Lett. 796, L6 (2014).

Article 
ADS 

Google Scholar
 

DiSanti, M. A. et al. Hypervolatiles in a Jupiter-family comet: observations of 45P/Honda-Mrkos-Pajdušáková using iSHELL at the NASA-IRTF. Astron. J. 154, 246 (2017).

Article 
ADS 

Google Scholar
 

Faggi, S., Mumma, M. J., Villanueva, G. L., Paganini, L. & Lippi, M. Quantifying the evolution of molecular production rates of comet 21P/Giacobini-Zinner with iSHELL/NASA-IRTF. Astron. J. 158, 254 (2019).

Article 
ADS 

Google Scholar
 

Ejeta, C. et al. Coma abundances of volatiles at small heliocentric distances: compositional measurements of long-period comet C/2020 S3 (Erasmus). Astron. J. 167, 32 (2024).

Article 
ADS 

Google Scholar
 

Woodward, C. E. et al. A JWST study of the remarkable Oort cloud comet C/2017 K2 (PanSTARRS). Planet. Sci. J. 6, 139 (2025).

Article 

Google Scholar
 

Furuya, K. et al. Water delivery from cores to disks: deuteration as a probe of the prestellar inheritance of H2O. Astron. Astrophys. 599, A40 (2017).

Article 

Google Scholar
 

Tobin, J. J. et al. Deuterium-enriched water ties planet-forming disks to comets and protostars. Nature 615, 227–230 (2023).

Article 
ADS 

Google Scholar
 

Altwegg, K. et al. D2O and HDS in the coma of 67P/Churyumov–Gerasimenko. Philos. Trans. R. Soc. A 375, 20160253 (2017).

Article 
ADS 

Google Scholar
 

Dolginov, A. Z. & Stepinski, T. F. Are cosmic rays effective for ionization of protoplanetary disks? Astrophys. J. 427, 377 (1994).

Article 
ADS 

Google Scholar
 

Cleeves, L. I., Adams, F. C. & Bergin, E. A. Exclusion of cosmic rays in protoplanetary disks: stellar and magnetic effects. Astrophys. J. 772, 5 (2013).

Article 
ADS 

Google Scholar
 

Cleeves, L. I. et al. The ancient heritage of water ice in the Solar System. Science 345, 1590–1593 (2014).

Article 
ADS 

Google Scholar
 

Nomura, H. et al. The isotopic links from planet forming regions to the Solar System. In Protostars and Planets VII, Vol. 534 (eds Inutsuka, S. et al.) 1075 (ASP, 2023).

Sakai, N. et al. Tentative detection of deuterated methane toward the low-mass protostar IRAS 04368+2557 in L1527. Astrophys. J. Lett. 758, L4 (2012).

Article 
ADS 

Google Scholar
 

Sakai, N. & Yamamoto, S. Warm carbon-chain chemistry. Chem. Rev. 113, 8981–9015 (2013).

Article 

Google Scholar
 

Devaraj, R. et al. JOYS: JWST MIRI/MRS spectra of the inner 500 au region of the L1527 IRS bipolar outflow. Astron. Astrophys. 708, A29 (2026).

Article 

Google Scholar
 

Millar, T. J., Walsh, C., Van de Sande, M. & Markwick, A. J. The UMIST Database for Astrochemistry 2022. Astron. Astrophys. 682, A109 (2024).

Article 

Google Scholar
 

Rodgers, S. D. & Millar, T. J. The chemistry of deuterium in hot molecular cores. Mon. Not. R. Astron. Soc. 280, 1046–1054 (1996).

Article 
ADS 

Google Scholar
 

Sakai, N., Sakai, T., Hirota, T. & Yamamoto, S. Deuterated molecules in warm carbon chain chemistry: the L1527 case. Astrophys. J. 702, 1025–1035 (2009).

Article 
ADS 

Google Scholar
 

Lis, D. C. et al. An 18–25 GHz spectroscopic survey of dense cores in the Chamaeleon I molecular cloud. Astron. Astrophys. 696, A61 (2025).

Article 

Google Scholar
 

Ferrer Asensio, J. et al. c-C3H2 deuteration towards prestellar and starless cores in the Perseus molecular cloud. Astron. Astrophys. 707, A28 (2026).

Article 

Google Scholar
 

Brown, P. D. & Charnley, S. B. Chemical models of interstellar gas-grain processes. II. The effect of grain-catalysed methane on gas phase evolution. Mon. Not. R. Astron. Soc. 249, 69 (1991).

Article 
ADS 

Google Scholar
 

Cuppen, H. M., Linnartz, H. & Ioppolo, S. Laboratory and computational studies of interstellar ices. Annu. Rev. Astron. Astrophys. 62, 243–286 (2024).

Article 
ADS 

Google Scholar
 

Chantzos, J. et al. A study of the c-C3HD/c-C3H2 ratio in low-mass star-forming regions. Astrophys. J. 863, 126 (2018).

Article 
ADS 

Google Scholar
 

Gratier, P. et al. A new reference chemical composition for TMC-1. Astrophys. J. Suppl. Ser. 225, 25 (2016).

Article 
ADS 

Google Scholar
 

Roth, N. X. An enriched methane D/H ratio in the interstellar object 3I/ATLAS: spectra and PSG scripts. Zenodo https://doi.org/10.5281/zenodo.23246274 (2026).

Astropy Collaboration Astropy: a community Python package for astronomy. Astron. Astrophys. 558, A33 (2013).

Article 

Google Scholar
 

Astropy Collaboration The Astropy project: building an open-science project and status of the v2.0 core package. Astron. J. 156, 123 (2018).

Article 
ADS 

Google Scholar
 

Astropy Collaboration The Astropy project: sustaining and growing a community-oriented open-source project and the latest major release (v5.0) of the core package. Astrophys. J. 935, 167 (2022).

Article 
ADS 

Google Scholar
 

Bradley, L. et al. astropy/photutils: 2.2.0. Zenodo https://doi.org/10.5281/zenodo.14889440 (2025).

Ginsburg, A. et al. Astroquery: an astronomical web-querying package in Python. Astron. J. 157, 98 (2019).

Article 
ADS 

Google Scholar
 

Prodanović, T., Steigman, G. & Fields, B. D. The deuterium abundance in the local interstellar medium. Mon. Not. R. Astron. Soc. 406, 1108–1115 (2010).

ADS 

Google Scholar
 

Geiss, J. & Gloeckler, G. Abundances of deuterium and helium-3 in the protosolar cloud. Space Sci. Rev. 84, 239–250 (1998).

Article 
ADS 

Google Scholar
 

Lellouch, E. et al. The deuterium abundance in Jupiter and Saturn from ISO-SWS observations. Astron. Astrophys. 370, 610–622 (2001).

Article 
ADS 

Google Scholar
 

Blake, J. S. D. et al. Refining Saturn’s deuterium-hydrogen ratio via IRTF/TEXES spectroscopy. Astron. Astrophys. 653, A66 (2021).

Article 

Google Scholar
 

Marty, B. The origins and concentrations of water, carbon, nitrogen and noble gases on Earth. Earth Planet. Sci. Lett. 313, 56–66 (2012).

Article 
ADS 

Google Scholar
 

Nixon, C. A. et al. Isotopic ratios in Titan’s methane: measurements and modeling. Astrophys. J. 749, 159 (2012).

Article 
ADS 

Google Scholar
 

Irwin, P. G. J. et al. The application of new methane line absorption data to Gemini-N/NIFS and KPNO/FTS observations of Uranus’ near-infrared spectrum. Icarus 220, 369–382 (2012).

Article 
ADS 

Google Scholar
 

Irwin, P. G. J. et al. Line-by-line analysis of Neptune’s near-IR spectrum observed with Gemini/NIFS and VLT/CRIRES. Icarus 227, 37–48 (2014).

Article 
ADS 

Google Scholar
 

Grundy, W. M. et al. Measurement of D/H and 13C/12C ratios in methane ice on Eris and Makemake: evidence for internal activity. Icarus 411, 115923 (2024).

Article 

Google Scholar
 

Donahue, T. M. & Hodges, R. R. Venus methane and water. Geophys. Res. Lett. 20, 591–594 (1993).

Article 
ADS 

Google Scholar
 

Messenger, S. Identification of molecular-cloud material in interplanetary dust particles. Nature 404, 968–971 (2000).

Article 
ADS 

Google Scholar
 

Öberg, K. I., Qi, C., Wilner, D. J. & Hogerheijde, M. R. Evidence for multiple pathways to deuterium enhancements in protoplanetary disks. Astrophys. J. 749, 162 (2012).

Article 
ADS 

Google Scholar
 

Huang, J. et al. An ALMA survey of DCN/H13CN and DCO+/H13CO+ in protoplanetary disks. Astrophys. J. 835, 231 (2017).

Article 
ADS 

Google Scholar
 

Persson, M. V. et al. The ALMA-PILS Survey: formaldehyde deuteration in warm gas on small scales toward IRAS 16293-2422 B. Astron. Astrophys. 610, A54 (2018).

Article 

Google Scholar
 

Ilyushin, V. V. et al. Rotational spectroscopy of CH3OD with a reanalysis of CH3OD toward IRAS 16293-2422. Astron. Astrophys. 687, A220 (2024).

Article 

Google Scholar
 

Zeng, S. et al. Determining the methanol deuteration in the disk around V883 Orionis with laboratory measured spectroscopy. Astron. J. 170, 33 (2025).

Article 
ADS 

Google Scholar
 

Lee, J.-E. et al. Complex organic molecules in a very young hot corino, HOPS 373SW. Astrophys. J. 956, 43 (2023).

Article 
ADS 

Google Scholar