2.2. The Models

The constraints on the family of models presented here are such that they are useful to explain emissions from compact H II regions, for which both total luminosity and mass (gas+dust) are available from observations. All models are constrained by a total mass, M_T, of 2.7 x 10⁴ M and the luminosity is constrained by the type of ZAMS star embedded at the centre. The outer boundary condition is provided by the ISRF taken from Mathis et al., 1983. Three types of ZAMS stars, viz., O4, O7 and B0.5, with luminosity covering a range of two orders of magnitude, are considered. The stellar type also determines the flux of photons with < 912 Å and hence has a direct bearing on the radio continuum calculations. In this study, stellar parameters like luminosity, effective temperature and number of Lyman continuum photons emitted per sec, have been taken from Thompson (1984) and the stellar luminosity for < 912 Å has been obtained from Panagia (1973). The stellar characteristics used here, are presented in Table 1. For each stellar type, both r⁰ and r^-1 density distributions are considered. Again, for each density distribution, a family of 12 models with the total radial optical depth (defined at the wavelength of 100 µm, hereafter ₁₀₀) ranging from 0.005 to 0.260 are considered. The r^-2 density distribution has not been considered here, since for the M_T and range of ₁₀₀ explored, the cloud sizes become too large and unphysical.

Table 1. Details of the central stars used for this study

Spectral type	Luminosity	Teff	NLyc
	L	K	sec-1
O4	1.260 x 106	50000	5.811 x 1049
O7	1.000 x 105	38500	3.630 x 1048
B0.5	1.064 x 104	26200	1.318 x 1046

The geometrical details of the models are determined as follows: R_min is determined by the sublimation temperature of dust and the stellar luminosity, hence it remains the same for each stellar type; R_max for each model is determined from the total mass, ₁₀₀, and the radial density distribution; the extent of the H II region (R_HII) is determined by the embedded stellar type and the radial density profiles of the interstellar material of the cloud. All these parameters are presented in Tables 2, 3 and 4 for embedded stellar types O4, O7 and B0.5 respectively.

Table 2. Parameters for models with O4 as exciting star

100	r0				r-1
	Rmin	Rmax	RHII	nd(Rmin)	Rmin	Rmax	RHII	nd(Rmin)
	(10-4)	(pc)	(10-2 pc)	(10-7 cm-3)	(10-4)	(pc)	(10-2 pc)	(10-7 cm-3)
0.005	2.10	14.21	341	0.122	2.40	35.99	410	0.752
0.0075	2.10	11.60	209	0.224	2.40	29.05	108	1.153
0.010	2.20	10.05	148	0.345	2.40	24.96	48.1	1.563
0.015	2.20	8.20	89.6	0.635	2.40	20.14	19.0	2.399
0.020	2.20	7.10	62.7	0.977	2.40	17.29	11.4	3.254
0.040	2.30	5.02	26.3	2.765	2.20	12.04	4.71	7.328
0.060	2.30	4.10	15.7	5.080	2.10	9.73	3.42	11.74
0.080	2.30	3.55	10.9	7.822	2.00	8.38	2.85	16.64
0.100	2.30	3.18	8.22	10.93	1.80	7.49	2.38	23.13
0.150	2.30	2.59	4.92	20.09	1.70	6.06	2.02	37.43
0.200	2.40	2.25	3.44	30.94	1.50	5.24	1.70	56.69
0.260	2.40	1.97	2.49	45.87	1.30	4.60	1.43	84.91

Table 3. Parameters for models with O7 as exciting star

100	r0				r-1
	Rmin	Rmax	RHII	nd(Rmin)	Rmin	Rmax	RHII	nd(Rmin)
	(10-4)	(pc)	(10-2 pc)	(10-7 cm-3)	(10-4)	(pc)	(10-2 pc)	(10-7 cm-3)
0.005	5.00	14.21	165	0.122	6.20	38.56	654	0.268
0.0075	5.40	11.60	105	0.224	6.20	31.18	198	0.411
0.010	5.40	10.05	75.7	0.345	6.20	26.81	95.2	0.564
0.015	5.60	8.20	47.5	0.635	6.20	21.67	40.9	0.877
0.020	5.60	7.11	34.0	0.977	6.20	18.63	25.6	1.226
0.040	5.80	5.02	15.0	2.763	5.80	12.99	11.5	2.772
0.060	5.80	4.10	9.22	5.077	5.60	10.51	8.61	4.583
0.080	5.80	3.55	6.50	7.817	5.20	9.07	7.10	6.743
0.100	5.80	3.18	4.96	10.92	4.80	8.10	6.11	9.128
0.150	5.80	2.59	3.01	20.07	4.40	6.57	5.09	16.31
0.200	5.90	2.25	2.12	30.90	3.80	5.69	4.21	24.88
0.260	5.90	1.97	1.53	45.81	3.50	4.98	3.75	36.30

Table 4. Parameters for models with B0.5 as exciting star

100	r0				r-1
	Rmin	Rmax	RHII	nd(Rmin)	Rmin	Rmax	RHII	nd(Rmin)
	(10-4)	(pc)	(10-2 pc)	(10-7 cm-3)	(10-4)	(pc)	(10-2 pc)	(10-7 cm-3)
0.005	1.40	14.21	323	0.122	1.80	40.75	2320	0.781
0.0075	1.40	11.60	213	0.224	1.80	32.99	1070	1.192
0.010	1.40	10.05	158	0.345	1.80	28.39	675	1.609
0.015	1.40	8.20	104	0.635	1.80	22.97	405	2.457
0.020	1.50	7.11	76.7	0.977	1.80	19.77	305	3.319
0.040	1.50	5.02	36.8	2.763	1.70	13.79	132	7.217
0.060	1.50	4.10	23.9	5.076	1.60	11.19	57.0	11.66
0.080	1.50	3.55	17.5	7.815	1.50	9.65	31.6	16.70
0.100	1.50	3.18	13.8	10.92	1.50	8.59	19.8	21.10
0.150	1.60	2.59	8.85	20.07	1.30	6.99	8.69	36.73
0.200	1.60	2.25	6.45	30.89	1.20	6.04	4.83	53.38
0.260	1.60	1.97	4.82	45.79	1.10	5.28	2.83	76.03