Table 4
Parameters of the emerging H ii regions deduced from line and continuum radiative transfer modeling (Sect. 5).
| Parameter | CRL 618 | M2-9 |
|
|
||
| Distance (d) | 900 pc | 650 pc |
| LSR systemic velocity (Vsys) | − 19 km s-1 | +75 km s-1 |
| Geometry | cylindrical † | cylindrical † |
| Inner radius (Rin) | 45 au | 0.05 au (≲2 au) |
| Outer radius (Rout) | 95 au | 160 au |
| Electron density (ne) | 2.4 × 107( )-2.0 cm-3 |
6.4 × 105 cm-3 |
| Electron temperature (Te) | 16500 K | 7500 K |
| Kinematics | radial expansion | radial expansion |
| Velocity (V) |  km s-1 |
22 km s-1 |
| Kinematic age (tk) | ≈15–20 yr | ≲15 yr |
| Inclination (i) | 24° | 17° |
| Mass-loss rate (Ṁ) | 8.4 × 10-6 M⊙ yr-1 |
3.9 × 10-7 M⊙ yr-1 |
| Ionized mass (Mion) | 2.0 × 10-4 M⊙ | 5.5 × 10-6M⊙ |
| Parameter | MWC 922 |
|
|
|
| Distance (d) | 1700 pc |
| LSR systemic velocity (Vsys) | +33 km s-1 |
| Geometry | double-cone ‡ |
| Double-cone’s semi-opening angle (θa) | 25° |
| Inclination (i) | 0° |
| Inner radius (Rin) | 0.05 au (≲35 au) |
| Electron density (ne) | 9 × 107 exp(− (θa − θ) / 2°) cm-3 |
| Electron temperature (Te) | 6700 K |
| Opening angle of the ionized disk (θd) | 6.5° |
| Ionized disk’s outer radius (rd) | 50 au |
| Ionized outflow’s outer radius (Rout) | ~150 au |
| Ionized outflow’s velocity (Vexp) | 5 km s-1 (radial expansion) |
| Keplerian rotation velocity (Vrot) | 32.6/ km s-1 |
| Mass-loss rate (Ṁ) | 2 × 10-6 M⊙ yr-1 |
| Ionized mass (Mion) | 3.6 × 10-5M⊙ |
Notes. In all cases, r is the radial distance to the center; the mass-loss rate (Ṁ) is the equivalent isotropic mass-loss rate for a constant expansion velocity and ne∝ r-2; and the departure coefficients bn used are from Storey & Hummer (1995).
For CRL 618 and M 2-9, we assume a cylindrical H ii region with an outer radius Rout at the base (i.e., along the nebula equator) and a central spherical cavity with inner radius Rin. The cylinder extends to infinity along the major axis, where ~90% of the mm-continuum is produced within ~110 au and ~50 au along the axis, respectively.
Double-cone geometry as described in Sect. 5.3 and depicted in Fig. 3 of Báez-Rubio et al. (2013).
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