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Table 2
Observed median column densities (N) and the standard deviation (SD) for IRDCs, HMPOs, HMCs, and UCHii regions as a(x) = a × 10x.
| IRDC | HMPO | HMC | UCHii | |||||
| N | SD | N | SD | N | SD | N | SD | |
| cm-2 | cm-2 | cm-2 | cm-2 | cm-2 | cm-2 | cm-2 | cm-2 | |
|
|
||||||||
| HCO+ | 7.9(13) | 6.8(13) | 3.7(14) | 1.7(14) | 7.6(14) | 4.3(14) | 3.8(14) | 5.9(14) |
| HCN | 7.2(13) | 5.7(13) | 1.3(14) | 1.7(14) | 3.5(14) | 3.4(15) | 3.4(14) | 3.7(14) |
| HNC | 9.7(13) | 8.4(13) | 2.9(14) | 1.6(14) | 5.5(14) | 3.5(14) | 2.0(14) | 7.7(14) |
| N2H+ | 2.2(13) | 1.5(13) | 4.6(13) | 3.2(13) | 5.5(13) | 4.6(13) | 3.7(13) | 6.4(13) |
| DCO+ | ≤3.1(11) | 1.1(12) | 6.7(11) | 6.5(11) | 2.0(12) | 7.6(12) | 4.6(11) | 3.4(11) |
| DCN | ≤6.1(11) | 7.3(11) | 2.0(12) | 2.2(12) | 8.0(12) | 3.6(13) | 1.9(12) | 6.0(12) |
| DNC | ≤6.1(11) | 9.2(11) | 1.0(12) | 1.2(12) | 8.7(11) | 7.1(11) | ≤3.0(11) | 1.9(12) |
| N2D+ | ≤6.8(11) | 4.3(11) | ≤3.8(11) | 4.0(11) | ≤2.2(11) | 6.6(10) | ≤3.3(11) | 4.6(10) |
Notes. The median includes detections and upper limits of non-detections. Species detected in less than 50% of the sources are indicated by an upper limit.
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