Temperature structures of H ii regions around dwarf stars and supergiants of effective temperatures of 30 000 K, 40 000 K, and 50 000 K at different metallicities (using the same physical conditions for the gas as in Fig. A.7). The influence of the metallicity on the temperature of the gas is primarily a result of the reduced number of metal particles that contribute to the cooling of the gas (metal-poorer H ii regions are thus characterized by considerably higher temperatures than H ii regions with larger metal abundances), but it is also a result of the harder ionization spectra obtained for metal-poorer stars (see Figs. A.1–A.4), which results in a larger energy input by photoionization heating; the temperature of the gas therefore rises with decreasing metallicity of the irradiating stars (see also Fig. A.10).