Table 2
Parameters employed or derived for the Orion Bar.
| Parameter | Value | Reference |
|---|---|---|
| Distance | 414 ± 7 pc(a) 1″ = 0.002 pc | Menten et al. (2007) |
| Projected distance, dproj, between θ1 Ori C and the IF(b) | 0.228 pc | Sect. 5.1 |
| Physical distance, dphys, between θ1 Ori C and the IF | ~0.27 pc | Sect. 6.3.2 |
Transverse size  |
~0.10 pc | Sect. 6.3.2 |
| Line-of-sight distance, dlos, between θ1 Ori C and the IF | Sect. 6.3.2 | |
| Average | ~0.15 pc | |
| Minimum | ~0.05 pc | |
| Maximum | ~0.20 pc | |
| Projected distance between He-IF and H-IF (c) | 0.5 × 10−2 pc; 2.5″ | Sect. 6.2 |
| Projected distance between IF and DF dIF−DF (c,d) | (2.2, 2.9, 4.0) × 10−2 pc 11.0″, 14.5″, 19.8″ | Sect. 5.1 |
| G0 at IF | ~(2.2−7.1) × 104 | Sect. 6.3.2, Appendix F |
| Width IF at peak G0 | (0.22−0.34) × 10−2 pc 1.1″ − 1.7″ | Sects. 5.1, 6.3 |
| Condition for face-on PDR to dominate G0 | dproj ≥ 0.24 pc | Sect. 6.3.1 |
| FUV dust cross-section σH | 6.5 × 10−22 cm2 / H | Cardelli et al. (1989); Blagrave et al. (2007) Schirmer et al. (2022) |
| RV = AV/E(B − V) | 5.5 | Cardelli et al. (1989); Blagrave et al. (2007) |
| AV /NH | 3.5 × 10−22 mag/cm−2 | Cardelli et al. (1989); Blagrave et al. (2007) |
| Total IR emission LIR | 9.5 × 103 L⊙ | Salgado et al. (2016) |
| Foreground extinction AV | 0.9–1.9 mag | Sect. 6.1 |
| Emission measure EM (Brγ) | (0.84−4.15) × 106 pc cm−6 | Sect. 6.1 |
| Rms electron density ne,rms near IF (Brγ) | ~9000 cm−3 | Sect. 6.1 |
| Density at the IF ne (d) | 2−3 × 103 cm−3 | Weilbacher et al. (2015) |
| Temperature at the IF Te (d) | ~9 × 103 K | Weilbacher et al. (2015) |
| Density in atomic PDR nH (AIB emission)(d) | (5−10) × 104 cm−3 | Habart et al. (2024, Sect. 5.1) |
| Density from NIR H2 nH | (3.5) × 104 to 105 cm−3 | Sect. 6.4 |
| Temperature at the DF T | ~400−700 K | Van De Putte et al. (2024) Allers et al. (2005) |
| Emission measure EM ([C I] 0.984 µm) | (1.1−2.8) × 105 pc cm−6 | Sect. 6.5 |
Notes. (a) See Habart et al. (2024) for a discussion on the adopted distance. (b) IF is defined by the peak emission of the [O I] 6300 Å and [Fe II] 1.644 µm emission.(c) Projected distance along the NIRSpec cut. As the cut is not perpendicular to the IF, a correction factor of cos(19.58°)=0.942 needs to be applied to obtain a perpendicular distance from the IF. (d) Given the complexity of the PDR surface, parameters given are specific for the NIRSpec FOV. For average values across the entire Bar, see Habart et al. (2024).
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