Table 1
Isotopologue ratios [CH2DOH]/[CH3OD] in low-, intermediate- and high-mass protostars, luminosities and distances of the sources, column densities ( × 1015 cm-2) and rotational temperatures of CH3OH.
| Source | Luminosity (L⊙) | Distance (pc) | Ntot(CH3OH) | Trot(CH3OH) (K) | [CH2DOH]/[CH3OD] | ⟨[CH2DOH]⟩/⟨[CH3OD]⟩ | |
|
|
|||||||
| IRAS 4Aa | 6 | 2.2 × 102 | 0.7 ± 0.1 | 38 ± 3 | 14 |
||
| IRAS 4Ba | 6 | 2.2 × 102 | 0.8 ± 0.3 | 85 ± 17 | 26 |
||
| IRAS 2a | 16 | 2.2 × 102 | 1.1 ± 0.4 | 207 ± 48 | >5.5 | ||
| IRAS 16293a | 27 | 1.6 × 102 | 3.5 ± 0.4 | 85 ± 6 | 21 |
||
| Cepheus Eb | 1 × 102 | 7.3 × 102 | 0.5 |
44 ± 31 | 20 ± 5 | 18 ± 5 | |
| OMC2FIR4b | 1 × 103 | 4.4 × 102 | 1.4 |
48 ± 24 | 9 ± 3 | 8 ± 7 | |
| Orion IRc2c | 5 × 103 | 4.5 × 102 | 84 ± 8.0 | 112 ± 11 | 1.1−1.5 | ||
| W3(H2O)d | 2 × 104 | 2 × 103 | 13 |
133 ± 17 | <0.9 | ||
| G24.78+0.08e | ≤7 × 104 | 7.7 × 103 | 9.3 |
113 ± 44 | <1.4* | ||
Notes. The column [CH2DOH]/[CH3OD] contains abundance ratios derived from the line pair 134.0655 GHz (for CH2DOH) and 133.9254 GHz (for CH3OD), which shows similar Eup (ΔEup ~ 4.2 K); the column ⟨[CH2DOH]⟩/⟨[CH3OD]⟩) contains ratios derived from averaged column densities (see text). Data for low-mass protostars (IRAS 16293, IRAS 4a, IRAS 4b and IRAS 2) and Orion IRc2 were taken respectively from Parise et al. (2002, 2006) and Jacq et al. (1993), and references therein. The asterisk refers the uncertain identification of the CH3OD line (133.9254 GHz) in G24.78+0.08.
References. For luminosities and distances:
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