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Table 4

Molecular column densities and abundances with respect to H2.

IRAS 4A2 IRAS 4A1a
Molecule T rot b N b X A2 N(50 K) N(100 K) X A1 X A2 / X A1
(K) (cm-2) (cm-2) (cm-2)
t-HCOOH 100–200 (4.6 − 8.3) × 1015 (0.6–2.9) ×10-9 < 1.0 × 1014 < 1.3 × 1014 <9.7 ×10-12 >62
CH3CHO 100–200 (1.0 − 1.9) × 1016 (1.1–7.4) ×10-9 < 1.5 × 1014 < 1.7 × 1014 <1.3×10-11 >85
HCOOCH3 196 3.5×1016 1.1×10-8 <1.4×1015 <1.1×1015 <8.2×10-11 >120
CH3OCH3 129 4.5×1016 1.0×10-8 < 6.5 × 1015 < 5.6 × 1015 <4.3×10-10 >21
(CH3)2COc 100–200 (4.2 − 5.9) × 1015 (0.5–2.2) ×10-9 < 6.4 × 1014 < 3.8 × 1014 <2.9×10-11 >17
cis-CH2OHCHO 100–200 (5.8 − 6.8) × 1015 (0.7–2.4) ×10-9 < 5.4 × 1014 < 2.8 × 1014 <2.1×10-11 >33
C2H5OH 100–200 (3.3–4.9) ×1016 (0.4–1.9) ×10-8 < 2.1 × 1015 < 1.6 × 1015 <1.2×10-10 >33
C2H5CN 100–200 (1.4 − 1.5) × 1015 (1.7–5.6) × 10-10 < 2.8 × 1014 < 1.1 × 1014 <1.0×10-11 >17
NH2CHO 100–200 (1.0 − 2.0) × 1015 (1.2–6.7) ×10-10 < 2.1 × 1013 < 2.8 × 1013 <2.1×10-12 >57
HNCO 100–200 (2.3 − 4.0) × 1015 (0.3−1.4) ×10-9 < 4.5 × 1013 < 5.5 × 1013 <4.2 ×10-12 >71
CH3CNd 100–200 (1.9–4.8) ×1016 (0.4–2.1) ×10-8 <6.4 ×1014 <4.8 ×1014 <2.7 ×10-11 >150

Notes.

(a)

3σ upper limits, where σ is the RMS measured after smoothing the spectra to a channel width of 1 km s-1.

(b)

For HCOOCH3 and CH3OCH3, Trot and N correspond to the best fit results from the rotational diagram analysis. For the other molecules, they correspond to the indicated range of excitation temperatures (see text).

(c)

Derived from 241,23 − 232,22 AA transition.

(d)

Derived from the K = 4 transition.

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