Table 1
Main I Zw 18 properties used in this study.
| Parameter | Value | Reference |
|
|
||
| Coordinates (J2000) | 09h34m02.2s, + 55d14m28.0s | |
| Distance | 18.2 Mpc | (1) |
| M(H0) (main body) | 108 M⊙ | (2,3) |
| M(H0) (NW) | ≈2 × 107 M⊙ | (this study) |
| M(H+) (NW) | 3.4 × 106 M⊙ | (4) |
| M ∗ | 1−20 × 106 M⊙ | (5, 6) |
| M∗ (NW) | ~3 × 105 M⊙ | (7) |
| M dust a |  M⊙,  M⊙ |
(6) |
| D/Gb |
|
(6) |
| L FIR | 2.88 ± 0.13 × 107 L⊙ | (6) |
| L UV | 1.06 × 108 L⊙ | (8) |
| SFR | ≈0.1 M⊙ yr-1 | (9) |
|
|
||
| Abundances | 12 + log (C/H) = 6.59 | (4) |
| 12 + log (N/H) = 5.57 | (4) | |
| 12 + log (O/H) = 7.22 | (4) | |
| 12 + log (Ne/H) = 6.41 | (4) | |
| 12 + log (Si/H) = 6.00 | (4) | |
| 12 + log (S/H) = 5.63 | (4) | |
| 12 + log (Fe/H) = 5.79 | (4) | |
| 12 + log (Ar/H) = 5.79 | (4) | |
Notes.
The dust mass is given for two dust compositions (Galliano et al. 2011, “standard” and “AC”) with different emissivities (Rémy-Ruyer et al. 2015).
Reference. (1) Aloisi et al. (2006); see also Sect. 2.1; (2) Lelli et al. (2012); (3) van Zee et al. (1998); (4) Péquignot (2008); see also Sect. 2.4; (5) Schneider et al. (2016); (6) Rémy-Ruyer et al. (2015); (7) Stasinska & Schaerer (1999); (8) Heckman et al. (1998); (9) Cannon et al. (2005); see also Sect. 2.3.
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