Table 3
Properties of I Zw 18.
| Parameter | I Zw 18 A | I Zw 18 C |
|
|
||
| α (B1950) |
|
|
| δ (B1950) | 55°27′47′′ ± 1′′ | 55°28′06′′ ± 2′′ |
| Vsys (km s-1) | 767 ± 4 | 751 ± 5 |
| Position angle (°) | 145 ± 5 | – |
| Inclination angle (°) | 70 ± 4 | – |
| Vrot (km s-1) | 38 ± 4.4 | – |
| LB (107L⊙) | 13.9 | 1.1 |
| LR (107L⊙) | 5.8 | 0.4 |
| MH I (108 M⊙) | 1.0 | ≲ 1.2 |
| Mdyn (108 M⊙) | 3 ± 1 | – |
Notes. Optical luminosities were calculated using the apparent magnitudes from Papaderos et al. (2002), the distance from Aloisi et al. (2007) and the solar absolute magnitudes from Binney & Merrifield (1998). The H i mass of I Zw 18 C refers to the extended emission described in Sect. 5, although only part of this gas may be physically associated with the C-component. The southern “tail” accounts for ~0.5 × 108 M⊙.
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