Table 1
Parameters of the continuum models.
| Source | Ca | Diameter | T d | τ d | N H b | M c | L d | τ 25,fgr e | L att f |
| (pc) | (K) | at 200 μm | (cm-2) | (108 M⊙) | (L⊙) | (L⊙) | |||
|
|
|||||||||
| NGC 4418 | C hot | 5.2 | 350 | 0.007 | 3.5 × 1022 | 8 × 10-5 | 8.5 × 1010 | 1.3 | 9.0 × 109 |
| C core | 20 | 140−150 | 1−2 | (0.5−1) × 1025 | 0.16−0.33 | (6−8) × 1010 | 1.5 | 3.1 × 1010 | |
| C warm | 31 | 110 | 0.5 | 2.4 × 1024 | 0.2 | 6 × 1010 | 1.2 | 2.9 × 1010 | |
| C extended | 200 | 90−30 | 0.03 | (1.0−1.3) × 1023 | 0.18 | 2.4 × 1010 | 0 | 2.4 × 1010 | |
| Arp 220 | C hot | 5.2 | 400 | 0.007 | 3.4 × 1022 | 8 × 10-5 | 1.4 × 1011 | 1.1 | 2.0 × 1010 |
| C west | 150−80 | 90−130 | 6−12 | (3−6) × 1025g | 55−30g | (6.5−8.2) × 1011 | 1.4 | 3.7 × 1011 | |
| C east | 108 | 87 | 2.7 | 1.3 × 1025 | 13 | 3 × 1011 | 1.0 | 2.1 × 1011 | |
| C extended | 650 | 90−40 | 0.17 | 8 × 1023 | 30 | 6.9 × 1011 | 0 | 6.9 × 1011 | |
Notes.
Column density of H nuclei, calculated assuming a mass-absorption coefficient of 12.3 cm2/g at 200 μm and a gas-to-dust mass ratio of 100.
The estimated mass of Cwest , based on the flux density at 860 μm reported by Sakamoto et al. (2008) and on an emissivity index of β = 2 in the submillimeter (κ860 ≈ 0.7 cm2 g-1 of dust), is higher than the dynamical mass of ~109 M⊙ estimated by several authors (Downes & Solomon 1998; Sakamoto et al. 2008). This probably indicates that β = 1 is a better approach in the submillimeter (yielding κ860 ~ 3 cm2 g-1 of dust), as estimated for some Galactic massive star-forming regions (e.g. Zhang et al. 2007).
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