Table 1.
Production rates and abundances in comet 3I/ATLAS on November 1–3, 2025.
| Molecule | Prod. Ratea | Abundance relative to water | Abundance relative to HCN | ||
|---|---|---|---|---|---|
| (1025 molec.s−1) | 3I/ATLASb | Comets | 3I/ATLAS | Comets | |
| HCN | 4.1 ± 0.2 | 0.062 ± 0.003% | 0.08–0.25% | 1 | 1 |
| HNC | 0.5 ± 0.2c | < 0.009% | 0.0015–0.035%d | < 0.13 | 0.01–0.29d |
| CH3CN | 1.5 ± 0.4 | 0.023 ± 0.006% | 0.008–0.054% | 0.36 ± 0.09 | 0.07–0.52 |
| CH3OH | 338 ± 5 | 5.1 ± 0.1% | 0.4–6.1% | 83 ± 4 | 4–64e |
| H2CO | 35 ± 4c | 0.53 ± 0.06% | 0.13–1.4% | 8.6 ± 1.0 | 1.3–13 |
| CO | 680 ± 11 | 10.3 ± 1.7% | 0.4–35% | 167 ± 8 | 8–270e |
| H2S | < 39 | < 0.59% | 0.09–1.5% | < 9 | 1.5–9 |
| CS | 1.7 ± 0.4c | 0.024 ± 0.006% | 0.05–0.20%d | 0.34 ± 0.11 | 0.2–3.2d |
| HC3N | < 2.1 | < 0.031% | 0.002–0.068% | < 0.52 | 0.016–0.42 |
| OCS | < 50 | < 0.75% | 0.05–0.40% | < 12 | 0.43–3.5 |
| CH3CHO | 14 ± 7 | < 0.32% | 0.04–0.08% | < 5.1 | 0.1–0.8 |
| (CH2OH)2 | 33 ± 13 | < 0.59% | 0.07–0.35% | < 9.5 | 0.8–2.9 |
| SO | < 27c | < 0.41% | < 0.03–0.30% | < 7 | 0.3–4.6 |
| HNCO | 25 ± 11 | < 0.52% | < 0.01–0.62% | < 8 | 0.2–4.8 |
| HCOOH | < 109 | < 1.7% | < 0.04–0.68% | < 27 | 0.6–7.2 |
| NH2CHO | < 4.8 | < 0.08% | 0.015–0.022% | < 1.2 | 0.09–0.3 |
| HDO | < 121 | < 1.83% | 0.028–0.12% | – | – |
| CH3OD | < 17.9 | < 0.27% | < 0.02% | – | – |
Notes.
Uncertainties correspond to propagated 1σ uncertainties on the line areas, and do not include an estimated additional uncertainty of 7% related to model parameters.
Assuming the water production rate QH2O = 6.58 × 1028 molec. s−1 measured from MAJIS/JUICE (Bockelée-Morvan et al. 2026). Uncertainties in QH2O are not taken into account.
Daughter distributions with Lp = 0–1600, 1700, 2000, and 3000 km are assumed for HNC, CS, H2CO and SO, respectively. Due the large beam size (15 000–26 000 km), distributed sources with Lp ≤ 3000 km provide similar results.
Decreasing abundance with increasing rh.
Excluding values in C/2016 R2 (PanSTARRS): 280, 2.6 × 104 for CH3OH/HCN and CO/HCN, respectively.
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