Table 2.

The average bulk H and N isotopic compositions of analysed CI, CM, CR and Tagish Lake samples, along with the bulk solar compositions, the average H isotopic compositions of H₂O and N isotopic compositions of HCN/NH₃ in Oort Cloud (OCC) and Jupiter family (JFC) comets, and the range of isotopic compositions in the envelopes of forming protostars (PS). For the averages, the uncertainties are the 1σ standard deviations of the samples.

	D/H × 10−4	δD (‰)	15N/14N × 10−3	δ15N (‰)
CI [23–25]	1.68 ± 0.01	78 ± 7	3.83 ± 0.02	42 ± 5
CM [23–25]	1.59 ± 0.20	−53 ± 130	3.84 ± 0.24	44 ± 66
CR [23–25]	2.57 ± 0.21	652 ± 134	4.32 ± 0.03	175 ± 8
Tagish Lake [23–25]	2.32 ± 0.13	495 ± 83	3.91 ± 0.03	61 ± 7
Bulk solar [26,27]	0.21 ± 0.05	−865 ± 32	2.27 ± 0.03	−382 ± 8
OCCs [28–36]	2.88 ± 0.71	851 ± 161	6.81 ± 0.41	853 ± 32
JFCs [32,35,37,38]	3.64 ± 2.61	1218 ± 1675	6.97 ± 0.25a	896 ± 19a
PS [39–41]	10–100	5500–63 000	3.44–6.25	−64 to 700

^aThe average JFC N isotopic composition does not include the outlier comet 73P whose ¹⁵N/¹⁴N = 4.65 ± 0.69 × 10⁻³.