2.1. The Models
The models are constrained by their physical sizes, so that it
is easy to compare the predictions with compact H II regions
of known sizes and hence of known distance and luminosity.
Paper I, but without the constraint
Three types of exciting stars,
viz., O4, O7 and B0.5 are considered. For each stellar type,
r0, r-1 and r-2, radial density distributions
are considered. For each density distribution, 13 models, with
100 ranging from 0.0045
to 0.34 are considered. For every
model the inner dust radius (Rmin) is determined by the density of
dust, the stellar luminosity and the dust sublimation temperature.
The outer radius is assumed to be 2 pc for every model. For
scheme I the gas and the dust composition and also the ISRF at
the outer boundary are the same as those in
Paper I. For
scheme II, the gas component is assumed to have typical H II
region abundances (an average of
Baldwin et al., 1991,
Osterbrock et al., 1992 &
Rubin et al., 1991,
as computed by
Ferland, 1996).
Only those elements having abundances (relative to hydrogen)
more than 3 x 10-6 are taken into consideration.
Thus in scheme II, the gas consists of H, He, C, N, O, Ne, Mg,
Si, S and Ar and the dust is composed of silicate and graphite
grains in equal quantities. Geometrical details
of these models are presented in Tables 1,
2 and 3 for exciting sources
corresponding to ZAMS stars of types O4, O7 and B0.5 respectively.
The parameters presented in these tables are self-explanatory,
and follow the same naming convention, as in
Paper I.
![]() | r0 | r-1 | r-2 | |||
RHII | nd(Rmin) | RHII | nd(Rmin) | RHII | nd(Rmin) | |
(10-2 pc) | (10-7 cm-3) | (10-3 pc) | (10-4 cm-3) | (10-3 pc) | (10-4 cm-3) | |
0.0045 | 75.5 | 0.781 | 181 | 0.100 | 2.30 | 0.679 |
0.006 | 59.5 | 1.042 | 78.2 | 0.134 | 2.30 | 0.906 |
0.008 | 46.8 | 1.390 | 37.6 | 0.178 | 2.30 | 1.207 |
0.012 | 33.4 | 2.085 | 16.3 | 0.267 | 2.30 | 1.811 |
0.020 | 21.7 | 3.474 | 7.63 | 0.446 | 2.30 | 3.018 |
0.050 | 9.99 | 8.686 | 3.65 | 1.115 | 2.30 | 7.546 |
0.075 | 7.09 | 13.03 | 3.09 | 1.672 | 1.95 | 11.32 |
0.100 | 5.56 | 17.37 | 2.85 | 2.230 | 1.50 | 15.09 |
0.150 | 3.96 | 26.06 | 2.63 | 3.345 | 1.28 | 22.64 |
0.200 | 3.11 | 34.74 | 2.53 | 4.460 | 1.22 | 30.18 |
0.250 | 2.59 | 43.43 | 2.47 | 5.575 | 1.19 | 37.73 |
0.300 | 2.23 | 52.12 | 2.43 | 6.690 | 1.18 | 45.27 |
0.340 | 2.02 | 59.06 | 2.40 | 7.582 | 1.17 | 51.31 |
![]() | r0 | r-1 | r-2 | |||
RHII | nd(Rmin) | RHII | nd(Rmin) | RHII | nd(Rmin) | |
(10-2 pc) | (10-7 cm-3) | (10-4 pc) | (10-4 cm-3) | (10-4 pc) | (10-3 cm-3) | |
0.0045 | 40.5 | 0.781 | 353 | 0.331 | 5.80 | 0.269 |
0.006 | 32.3 | 1.041 | 162 | 0.441 | 5.80 | 0.359 |
0.008 | 25.8 | 1.389 | 81.8 | 0.588 | 5.80 | 0.478 |
0.012 | 18.8 | 2.083 | 37.1 | 0.882 | 5.80 | 0.717 |
0.020 | 12.5 | 3.471 | 18.0 | 1.469 | 5.80 | 1.195 |
0.050 | 5.98 | 8.679 | 8.86 | 3.674 | 3.44 | 2.988 |
0.075 | 4.30 | 13.02 | 7.56 | 5.510 | 3.12 | 4.482 |
0.100 | 3.40 | 17.36 | 6.98 | 7.347 | 3.02 | 5.976 |
0.150 | 2.44 | 26.04 | 6.44 | 11.02 | 2.95 | 8.964 |
0.200 | 1.92 | 34.71 | 6.13 | 14.69 | 2.93 | 11.95 |
0.250 | 1.60 | 43.39 | 4.81 | 18.37 | 2.92 | 14.94 |
0.300 | 1.38 | 52.07 | 3.34 | 22.04 | 2.91 | 17.93 |
0.340 | 1.24 | 59.01 | 2.60 | 24.98 | 2.91 | 20.32 |
![]() | r0 | r-1 | r-2 | |||
RHII | nd(Rmin) | RHII | nd(Rmin) | RHII | nd(Rmin) | |
(10-3 pc) | (10-7 cm-3) | (10-6 pc) | (10-4 cm-3) | (10-5 pc) | (10-3 cm-3) | |
0.0045 | 89.69 | 0.781 | 1595 | 1.035 | 10.74 | 0.974 |
0.006 | 73.37 | 1.041 | 9544 | 1.380 | 9.339 | 1.299 |
0.008 | 59.97 | 1.388 | 615.0 | 1.840 | 8.702 | 1.732 |
0.012 | 45.07 | 2.082 | 374.6 | 2.760 | 8.297 | 2.598 |
0.020 | 31.38 | 3.471 | 237.1 | 4.599 | 8.105 | 4.329 |
0.050 | 16.27 | 8.677 | 58.55 | 11.53 | 8.017 | 10.82 |
0.075 | 12.13 | 13.02 | 26.02 | 17.25 | 8.007 | 16.24 |
0.100 | 9.837 | 17.35 | 14.64 | 23.03 | 8.004 | 21.65 |
0.150 | 7.311 | 26.03 | 6.506 | 34.50 | 8.002 | 32.47 |
0.200 | 5.917 | 34.71 | 3.660 | 45.99 | 8.001 | 43.29 |
0.250 | 5.018 | 43.38 | 2.342 | 57.49 | 8.001 | 54.12 |
0.300 | 4.385 | 52.06 | 1.626 | 68.99 | 8.000 | 64.94 |
0.340 | 3.997 | 59.00 | 1.266 | 78.19 | 8.000 | 73.60 |