Table 8
Column density ratios between the 3 isomers of C2H4O2 and abundances from star-forming regions in this work and in literature.
| Source | AA/GA | MF/GA | Diameter | X(MF) | X(AA) | X(GA) | N(H2) | References | |
|---|---|---|---|---|---|---|---|---|---|
| [au] | [cm−2] | ||||||||
| High-mass sources | |||||||||
| G31 | 9–17 | 40 ± 16 | 4400 | (2.0 ± 0.6) × 10−7 | (4.3−8) × 10−8 | (5.0 ± 1.4) × 10−9 | 1.0 × 1025 | This work | |
| SgrB2(N)-LMH | 2.9 ± 0.7 | 7.5 ± 0.7 | 17 000 | (1.2 ± 0.3) × 10−9 | (4.6 ± 1.4) × 10−10 | (1.6 ± 0.4) × 10−10 | 1.0 × 1026 (a) | (1) | |
| NGC 6334I MM1 | I | 0.7 ± 0.3 | 15 ± 5 | 350 | – | – | – | – | (2) |
| II | 0.4 ± 0.2 | 16 ± 7 | – | – | – | – | |||
| III | 1.4 ± 0.8 | 17 ± 13 | – | – | – | – | |||
| IV | 0.42 ± 0.19 | 38 ± 13 | – | – | – | – | |||
| V | 7.4 ± 1.2 | 45 ± 6 | – | – | – | – | |||
| VI | 1.0 ± 0.4 | 13 ± 8 | – | – | – | – | |||
| VII | 1.4 ± 0.7 | 25 ± 11 | – | – | – | – | |||
| VIII | 0.9 ± 0.3 | 30 ± 12 | – | – | – | – | |||
| IX | 0.6 ± 0.3 | 35 ± 15 | – | – | – | – | |||
| NGC 6334I MM2 | I | >5(*) | >158(*) | 350 | – | – | – | – | (2) |
| II | >7(*) | >110(*) | – | – | – | – | |||
| III | >14(*) | >373(*) | – | – | – | – | |||
| W51e1/e2 | >15(*) | >550(*) | 13 000 | – | – | – | – | (3),(4) | |
| G34.3+0.2 | >5(*) | >200(*) | 29 000 | – | – | – | – | (3),(5) | |
| Low-mass sources | |||||||||
| IRAS 16293-2422B | 0.09 ± 0.04 | 6 ± 3 | 60 | <3.3 × 10−8 | <5.0 × 10−10 | <5.8 × 10−9 | >1.2 × 1025 (b) | (6),(7) | |
| IRAS 16293-2422A | 3.5 ± 1.5 | 210 ± 90 | 60 | – | – | – | – | (8) | |
| NGC 1333 IRAS 4A | <1.1(**) | 6 ± 4(**) | 120 | (1.4 ± 1.0) × 10−9 | <2.6 × 10−10 | (2.4 ± 1.1) × 10−10 | 3.7 × 1025 (c) | (5),(9) | |
Notes. Sources in literature where all three isomers have been detected, or only one isomer not detected with an estimate on the upper limit of the column density; column density ratio AA/GA; column density ratio MF/GA; linear scale to which the ratio refers; abundance of MF; abundance of AA; abundance of GA; N(H2) used to derive the abundances; references for the column density values of the 3 isomers of C2 H4 O2. The high-mass sources are listed in the upper part of the table, while the low-mass sources are listed in the lower part. (*) The column density of GA is an upper limit, so the ratio with MF and AA are lower limits; (**) estimate of MF and GA inside 0.′′5 from Taquet et al. (2015) and upper limit of AA rescaled to the same source size (0′′.5) from the value in Remijan et al. (2003). Since the column density of AA is an upper limit, the ratio AA/GA is an upper limit too. Abundances have been calculated only for sources for which an estimate of N(H2) is available within an angular diameter close to the one of the derived column densities of the 3 isomers.
References. References to the works on the 3 isormers: (1) Xue et al. (2019); (2) El-Abd et al. (2019); (3) Lykke et al. (2015); (4) Remijan et al. (2002); (5) Remijan et al. (2003); (6) Jørgensen et al. (2012); (7) Jørgensen et al. (2016); (8) Manigand et al. (2020); (9) Taquet et al. (2015). Reference to the N(H2) values: (a) mean value for position AN01 from Sánchez-Monge et al. (2017); (b)lower limit from (7); (c)derived from emission at 145 GHz from (9).
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