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Table 2

Results of the excitation analysis toward the center of W49A.

I. Rotation diagrams
SO2 CH3OH H2CO
Trot[K] 156 ± 11 83 ± 7 182 ± 84
Ntota [1015 cm-2] 14.56 ± 2.99 6.58 ± 1.38 0.78 ± 0.17
Source size [′′] 3.1 12.5 2.4
Tex[K] 115 138.2
Ntot,1b [1015 cm-2] 1400.0 9.5
II. Non-LTE calculation
Tkin[K]c 300
N[H2CO] [cm-2] 3.2–4.5 × 1014
N[HCN] [cm-2] 7.3 × 1015
n[cm-3]d 1.8 × 106

Notes. 

(a)

Total beam-averaged column density calculated using the assumption that the lines are optically thin, the level populations can be characterized by a single excitation temperature and the emission fills the telescope beam.

(b)

Total source-averaged column density given by the χ2 minimization, including a correction for the optical depth and a beam dilution factor. The errors show the 1-σ upper and lower limits of the best fit.

(c)

The uncertainty of the kinetic temperatures is ~ 30%.

(d)

The uncertainty of the density estimates is a factor of 2.

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