Table 3
Inferred abundances and deuterium fractionation (from interferometric and single-dish data, respectively) for different organic molecules.
| (D/H) ratios | ||||||
|---|---|---|---|---|---|---|
| Species | [X/CH3OH] | Single-dish | Interferometric | Model (Taquet et al. 2014) | ||
| (~1000 AU) | (~50 AU) | 1.1 × 105 yr | 2.0 × 105 yr | |||
| Formaldehyde | H2CO | 19% | 7.5%a | 3%f | 2.1% | 0.21% |
| Methanol | CH3OH | – | 1.8–5.9%a,b | 2%g | 3.5–1.8% | 0.28–0.17% |
| Ethanol | CH3CH2OH | 2.3% | – | 5%g | 0.63–9.7%k | 0.090%–0.12%k |
| Dimethyl ether | CH3OCH3 | 2.4% | 3%c | 4%g | 3.7% | 0.10% |
| Glycolaldehyde | CH2OHCHO | 0.34% | – | 5%h | 6.5–13% | 0.22–0.38% |
| Methyl formate | CH3OCHO | 2.6% | 6%d | 6%g | 7–9% | 0.25–0.22% |
| Acetaldehyde | CH3CHO | 1.2% | – | 8%g | 9.2%l | 0.068%l |
| Ketene | CH2CO | 0.48% | – | 2%g | 0.25% | 0.015% |
| Formic acid | HCOOH | 0.56% | – | 2%g | 2.3–1.0%m | 0.58–0.66%m |
| Isocyanic acid | HNCO | 0.27% | – | 1%i | – | – |
| Formamide | NH2CHO | 0.10% | – | 2%i | – | – |
| Water | H2O | – | 0.25%e | 0.046%j | 1.2% | 0.33% |
Notes. For the deuterium fractionation, the numbers refer to the inherent D/H ratio (i.e. taking into account the statistical ratios for the functional groups with multiple H-atoms) for the singly deuterated species. As noted in the text the uncertainties on the relative abundances from the ALMA data are about 30% – or 0.6 or 1.5 percentage points for D/H ratios of 2 or 5%, respectively. (a) Parise et al. (2006). (b) Parise et al. (2006) infers a different deuterium fractionation for CH3OD (lower value) and CH2DOH (higher value). In the models of Taquet et al. (2014), the D/H ratio for CH3 OD is higher than that of CH2 DOH when corrected for the statistics (last two columns). We note that according to Belloche et al. (2016), issues were identified with the spectroscopic predictions for CH2 DOH causing the column densities for CH2 DOH to be overpredicted by a factor 2.1 ± 0.4. We have corrected for this factor in the number quoted here. (c)From Richard et al. (2013). (d)From Demyk et al. (2010) inferred for CH3OCDO: in the paper a D/H ratio of 15% is quoted but according to the actual numbers for the column densities given in the paper, the fraction is in fact 6%. (e)From Coutens et al. (2012) for cold water in the outer envelope based on detailed radiative transfer modeling of the water abundance profiles. (f) Persson et al. (2018). (g) This paper. (h) Jørgensen et al. (2016). (i) Coutens et al. (2016). (j) Persson et al. (2013) referring to IRAS16293A. (k)Taquet et al. (2014) predict D/H ratios of 0.63, 4.6 and 9.7% for CH2 DCH2OH, CH3 CHDOH and CH3 CH2OD, respectively, in the early model and 0.090, 0.095 and 0.12% in the late model. (l) For CH3 CDO detected in PILS. For CH2DCHO, Taquet et al. (2014) predict D/H ratios of 0.90 and 0.040% for the early and late models, respectively. (m) Taquet et al. (2014) predict different D/H ratios for DCOOH and HCOOD of 2.3 and 1%, respectively, for the early model and 0.58 and 0.66%, respectively, for the late model.
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