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Table 7

Column densities for the targeted species from the RTD analysis, Weeds or CASSIS (CH3OH) models and those derived from 13C-isotopologues.

IRAS 20126+4104 IRAS 18089-1732 G31.41+0.31
Species RTD Model N(12C)a RTD Model N(12C)a RTD Model N(12C)a
H2COb 8.4E+15 6.0E+15 <4.7E+16 1.9E+16 1.5E+16 6.3E+16 6.5E+16 6.0E+16 9.6E+16
CH3OH 2.9E+16 1.1E+17 <4.0E+17c 2.2E+17 2.0E+17 2.0E+18c 1.2E+18 1.0E+18 2.7E+18d
C2H5OH – <0.3E+16 – 3.9E+16 2.5E+16 – 1.5E+17 1.0E+17 –
HNCO – 1.0E+15 <7.0E+15 2.5E+15 0.4E+16 <3.8E+16 3.6E+15 0.6E+16 <8.2E+16
NH2CHO – 0.3E+15 – 8.4E+14 0.5E+15 – 2.1E+15 0.4E+16 –
CH3CN 1.5E+15 1.3E+15 <1.4E+15 >4.7E+15 >3.5E+15 2.2E+16 >1.6E+16 >2.0E+16 1.6E+17
C2H5CN – <0.5E+15 – 3.1E+15 0.4E+16 – 2.0E+16 2.0E+16 –
HCOOCH3 – <0.2E+16 – 2.8E+16 3.0E+16 – 1.7E+17* 1.0E+18 –
CH3OCH3 – <0.1E+17 – 1.3E+17 1.0E+17 – 5.4E+17 5.0E+17 –
CH2CO – <2.5E+13 – 7.9E+13 7.5E+13 – – 3.3E+14 –
CH3CHO – <0.5E+14 – – <0.5E+14 – – 5.0E+14 –
HCOOH – <2.5E+13 – – <2.5E+13 – 3.2E+15 1.0E+15 –
CH3CCH 2.7E+14 3.5E+14 – 5.2E+14 0.9E+15 – 1.0E+15 1.4E+15 –

Notes.Column densities for the warm molecules are source-averaged, while those for cold molecules are beam-averaged. Column densities where optical depth has a significant effect are labeled as lower limits.

(*)

Rotation diagram fit on HCOOCH3 on all lines, while Weeds model on the 230 GHz lines only.

(a)

N(12C) obtained from the N(13C) adopting a 12C/13C ratio equal to 70, 54 and 41 for IRAS 20126, IRAS 18089 and G31.41, respectively.

(b)

Column density from 13C-isotopologue from ortho-H213CO, corrected using the statistical ortho to para ratio of 3:1.

(c)

Calculated from the line intensity of transition 22,0,+0–31,3,+0 at 345.084 GHz with Eup = 44.6 K, assuming a Trot of 300 K.

(d)

Calculated from the line intensity of transition 131,12,−0–130,13,+0 at 341.132 GHz with Eup = 206 K, assuming a Trot of 300 K.

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