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$\begin{figure} \par\includegraphics[width=8.1cm,clip]{6067f1.ps}\end{figure}$ Figure 1: Best fit model SED to the redshift- and extinction-corrected observed spectrum of UM 462c. The model SED is calculated assuming that the H II region is ionisation-bounded. It is seen that the red part of spectrum is fitted quite well whereas the modelled SED underestimates the flux shortward of the Balmer jump. This is likely due to the leakage of ionising photons from the H II region.
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In the text

$\begin{figure} \par\hspace*{0.1cm}\psfig{figure=6067f2a.ps,angle=0,height=9.9cm,... ...hspace*{-0.15cm}\psfig{figure=6067f2c.ps,angle=0,height=9.9cm,clip=}\end{figure}$ Figure 2: a) Example of the parameter space explored with the Monte Carlo technique (2253 solutions out of 10⁵ simulations) to fit the spectrum of the BCD UM 311. The parameters shown are the equivalent width of the H $\beta$ emission line EW(H $\beta$ ), the ages of the old and young stellar populations, t(old) and t(young), the mass ratio b of the old-to-young stellar population, the extinction coefficient for the stellar emission C(H $\beta$ ) $_{\rm stars}$ , the extinction coefficient for the ionised gas C(H $\beta$ ) $_{\rm gas}$ , and the electron temperature $t_{\rm e}$ (H⁺) = 10^-4 $T{_{\rm e}}$ (H⁺) in the H⁺ zone. The parameter $\sigma$ is an estimator of the goodness of the fit. b) and c) are the same as a) except that only the 64 and 10 best Monte Carlo realizations are shown.
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In the text

$\begin{figure} \par\hspace*{-0.05cm}\psfig{figure=6067f4a.ps,angle=0,height=6.3c... ...hspace*{-0.17cm}\psfig{figure=6067f4c.ps,angle=0,height=6.3cm,clip=}\end{figure}$ Figure 4: a) Comparison of the $t_{\rm e}$ (H⁺) derived from fitting the Balmer jump and the SED with the $t_{\rm e}$ (O III) = 10^-4 $T{_{\rm e}}$ (O III) derived from the nebular to auroral line flux ratio [O III] $\lambda$ (4959+5007)/ $\lambda$ 4363. In each panel, the dashed line denotes equal temperatures, the solid line is the linear regression obtained by the likelihood method (Press et al. 1992), dotted lines denote 1 $\sigma$ dispersions of our sample H II regions around the regression line. Error bars are the root mean square temperature deviations from the mean of the 10 best Monte Carlo simulations. 3.6 m data are shown by large filled circles. Two objects, Pox 186 and UM 462c, which could not be fitted by ionisation-bounded model are denoted by squares. For each of these two galaxies we show by open squares the solutions from the ionisation-bounded model and by filled squares the solutions from the model with escaping Lyc photons. The derived $t_{\rm e}$ (H⁺) from the Balmer jump in 23 low-metallicity H II regions (MMT data) and the Paschen jump in 24 low-metallicity H II regions (SDSS data) are shown by large and small open circles, respectively (Guseva et al. 2006). For comparison we have also plotted by dots in a) the data of Liu et al. (2004), Zhang et al. (2004), Wesson et al. (2005) and Krabbe & Copetti (2005) for 58 Galactic PNe. Stars show the data for H II regions from Esteban et al. (1998), García-Rojas et al. (2006,2004), Peimbert & Torres-Peimbert (1992), Peimbert et al. (2000), Peimbert (2003) and González-Delgado et al. (1994). b) This panel is identical to panel a) except that only H II regions with small dispersions for $t_{\rm e}$ (H⁺) ( $\sigma$ [ $t_{\rm e}$ (H⁺)]/ $t_{\rm e}$ (H⁺) < 0.1) for 3.6 m data (present paper) and data from Guseva et al. (2006) (MMT and SDSS data) are shown. c) The same as in a) but only H II regions with large equivalent widths and small errors for $t_{\rm e}$ (H⁺) and $t_{\rm e}$ (O III) are included ( $\sigma$ [ $t_{\rm e}$ (H⁺)]/ $t_{\rm e}$ (H⁺) < 0.1; $\sigma$ [ $t_{\rm e}$ (O III)]/ $t_{\rm e}$ (O III) < 0.013; EW(H $\beta$ ) > 80 Å).
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In the text

$\begin{figure} \par\hspace*{1.0cm}\psfig{figure=6067f3a.ps,angle=0,width=16.cm,clip=}\end{figure}$ Figure 3: Best fit model SEDs (thick solid lines) superposed by the redshift- and extinction-corrected 3.6 m spectra of 69 H II regions in 45 blue compact dwarf galaxies. The separate contributions from the stellar and ionised gas components are shown by thin solid lines (see the labels in the upper left panel of each page). Names of the SDSS objects are given in short form without seconds.
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In the text

$\begin{figure} \par\hspace*{1.0cm}\psfig{figure=6067f3b.ps,angle=0,width=16.cm,clip=}\end{figure}$ Figure 3: continued.
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In the text

$\begin{figure} \par\hspace*{1.0cm}\psfig{figure=6067f3c.ps,angle=0,width=16.cm,clip=}\end{figure}$ Figure 3: continued.
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In the text

$\begin{figure} \par\hspace*{1.0cm}\psfig{figure=6067f3d.ps,angle=0,width=16.cm,clip=}\end{figure}$ Figure 3: continued.
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In the text

$\begin{figure} \par\hspace*{1.0cm}\psfig{figure=6067f3e.ps,angle=0,width=16.cm,clip=}\end{figure}$ Figure 3: continued.
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In the text

$\begin{figure} \par\hspace*{1.0cm}\psfig{figure=6067f3f.ps,angle=0,width=16.cm,clip=}\end{figure}$ Figure 3: continued.
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In the text

$\begin{figure} \par\hspace*{1.0cm}\psfig{figure=6067f3a.ps,angle=0,width=16.cm,clip=}\end{figure}$	Figure 3: Best fit model SEDs (thick solid lines) superposed by the redshift- and extinction-corrected 3.6 m spectra of 69 H II regions in 45 blue compact dwarf galaxies. The separate contributions from the stellar and ionised gas components are shown by thin solid lines (see the labels in the upper left panel of each page). Names of the SDSS objects are given in short form without seconds.
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$\begin{figure} \par\hspace*{1.0cm}\psfig{figure=6067f3b.ps,angle=0,width=16.cm,clip=}\end{figure}$	Figure 3: continued.
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