Table 7
Cooling efficiency and estimated physical parameters to compute γ in Fig. 22.
| Region | L[C II] ∕LFIR | G0 (a) | n (b) | T (c) | |
|---|---|---|---|---|---|
| (cm−3) | (K) | ||||
| M42 | all | 3.6 × 10−3 | 1 × 103 | 1 × 104 | 200 |
| OMC1(d) | 6.5 × 10−4 | 2 × 104 | 1 × 105 | 300 | |
| Eastern Rim | 3.5 × 10−3 | 500 | 1 × 104 | 100 | |
| OMC4 | 2.8 × 10−3 | 500 | 1 × 104 | 100 | |
| Veil Shell | 4.3 × 10−3 | 200 | 3 × 103 | 100 | |
| M43 | all | 2.7 × 10−3 | 1 × 103 | 1 × 104 | 120 |
| background, H II | 2.8 × 10−3 | 1.5 × 103 | 1 × 104 | 120 | |
| faint CO, faint [C II] | 4.7 × 10−3 | 300 | 1 × 103 | 100 | |
| bright CO, faint [C II] | 3.0 × 10−3 | 300 | 1 × 104 | 100 | |
| shell | 2.3 × 10−3 | 1 × 103 | 1 × 104 | 120 | |
| NGC | all | 8.9 × 10−3 | 100 | 5 × 103 | 90 |
| 1977 | H II | 7.9 × 10−3 | 200 | 5 × 103 | 90 |
| OMC3 | 5.9 × 10−3 | 200 | 2 × 104 | 100 | |
| faint Hα | 9.7 × 10−3 | 100 | 1 × 103 | 50 | |
| shell | 1.3 × 10−2 | 100 | 5 × 103 | 70 |
Notes. (a) Estimated from average distance to respective central star with systematic uncertainty of ± 50%. (b) Estimated from [C II]-CO separation in Eastern Rim and M43 shell, otherwise τ160, with systematic uncertainty of ±50%. (c) Estimated from [C II] excitation temperature (cf. Appendix A in Paper I). PDR models predict up to twice as large temperature for the [C II]-emitting layers. (d)[O I] 63 μm cooling contributes significantly in OMC1. We find L[O I] ≃ 320 L⊙ (Higgins et al., in prep.), hence (L[C II] + L[O I])∕LFIR ≃ 4.5 × 10−3. The Bright Ridge with BN/KL and Orion S accounts for L[O I] ≃ 90 L⊙, hence including this area yields a cooling efficiency of (L[C II] + L[O I])∕LFIR ≃ 5.1 × 10−3 for the PDR.
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