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 (R_min) 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.

Table 1. Parameters for O4 type exciting star (R_min = 2.30 x 10^-3 pc)

100	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

Table 2. Parameters for O7 type exciting star (R_min = 5.80 x 10^-4 pc)

100	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

Table 3. Parameters for B0.5 type exciting star (R_min = 1.60 x 10^-4 pc)

100	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