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Table 8

CO depletion, HNC/HCN ratio, lower limit of ionization, and velocity asymmetric degree of H13CO+ in four IRDCs.

Source l b DGC a I0.87 mm Tg NH2 DCO b c x(e) e δ VH13CO+ f
(o) (o) (kpc) (Jy/beam) (K) 1022 (cm-2) C18O 13CO C17O (10-7)
G28.34 S 28.324 0.067 4.6 0.77 ± 0.10 12 13.23 ± 0.17 15.22 ± 2.19 13.71 ± 6.51 14.54 ± 2.55 1.56 ± 0.77 1.10 −0.51 ± 0.01
IRDC 18530 35.431 0.137 4.5 0.56 ± 0.07 9 17.12 ± 0.21 36.47 ± 5.24 19.54 ± 6.83 − 0.64 ± 0.22 3.66 −0.19 ± 0.002
IRDC 18306 23.296 0.056 3.6 0.48 ± 0.12 8 19.10 ± 0.48 49.81 ± 13.46 21.52 ± 6.51 41.20 ± 11.87 − d 6.89 0.30 ± 0.02
IRDC 18308 23.251 0.017 4.4 0.36 ± 0.07 12 6.12 ± 1.20 19.45 ± 4.31 12.16 ± 4.69 24.04 ± 7.03 − d 0.51 0.0009 ± 0.005

Notes.

(a)

Assuming the galactocentric distance of the Sun is 8 kpc.

(b)

Estimated from C18O and optical depth corrected 13CO with Eqs. (B.2)–(B.4).

(c)

Measured with the optical depth corrected HNC and hyperfine fitted HCN at the same gas temperature Tex,CO.

(d)

The value is not given because of large uncertainties in HCN abundance, see Table A.4.

(e)

Lower limit is measured from Eq. (17), with hyperfine fitted N2H+, the optical depth corrected 13CO, and H13CO+ at the same gas temperature Tex,CO.

(f)

δVH13CO+ = (VHCO+−VH13CO+)/ΔυH13CO+, Mardones et al. (1997).

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