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Table 2

Statistics of IRDC sample.

IRDC parametera Mean Min. Median Max.

Trot [K] 15 8 14 29
Tkin [K] 18 8 16 41
NNH3 [1014 cm-2] 7.0 0.9 5.1 32.0
[1022 cm-2] 3.5 0.1 2.9 27.3
χNH3 [10-8] 3.8 0.6 1.9 45.9
Δ   v1 [km s-1] 1.7 0.7 1.6 4.0
d [kpc] 3.2 0.4 3.2 5.9

Mvirb [M] 325 6 264 1099
α OH c 6.1 0.3 2.3 155.2
α MRN 4 1.9 0.1 0.7 49.4

Notes.The statistics have been built up by the 109 IRDCs with detected ammonia transitions.


Note that Trot represents the rotation temperature, Tkin the kinetic temperature, NNH3 the column density of ammonia, the column density of molecular hydrogen, χNH3 the abundance of ammonia, Δv1 the line width FWHM of the ammonia (1,1)-inversion line, d the distance between source and sun, Mvir the virial mass and αi the virial parameters for the used models (cf. Sect. 4.5).


The here given virial mass Mvir is the mean value of the virial masses for the individual density profiles. Cf. Sect. 4.5.1 for more details.


These are the sources’ virial parameters, giving the ratio between kinetic and gravitational energy and, thus, an estimation for the stability of the sources. These Parameters will be discussed in more detail in Sect. 4.5.3.

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