All Figures

$\begin{figure} \par\includegraphics[width=90mm]{9233f1.eps} \end{figure}$ Figure 1: Composite colour image of Sh2-212 in the optical. North is up and east is left. The size of the field is $7\hbox {$.\mkern -4mu^\prime $ }0$ (E-W) $\times$ $6\hbox {$.\mkern -4mu^\prime $ }6$ (N-S). Pink corresponds to the H $\alpha$ 6563 Å emission, and turquoise to the [S II] 6717 Å + 6731 Å emission, enhanced near the ionization front. The arrow points to the reflection nebulosity, associated with star No. 228, discussed in the text.
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In the text

$\begin{figure} \par\includegraphics[width=90mm]{9233f2.eps} \end{figure}$ Figure 2: Composite colour image of Sh2-212 in the optical and the mid-IR. Red corresponds to the MSX emission at 8.3 $\mu$ m, and turquoise to the optical emission of the ionized gas. The arrow points to the MSX point source associated with star No. 228 and the UC H II region discussed in the text.
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In the text

$\begin{figure} \par\includegraphics[width=90mm]{9233f3.eps} \end{figure}$ Figure 3: Sh2-212. Composite colour image of Sh2-212 in the near-IR (J is blue, H is green, K is red). The colours of the stars are mainly determined by extinction. North is up and east is left. The size of the field is $4\hbox {$.\mkern -4mu^\prime $ }4$ (E-W) $\times$ $5\hbox {$.\mkern -4mu^\prime $ }2$ (N-S). The red nebulosity at the centre of the field corresponds to the optical reflection nebula associated with the MSX point source and star No. 228.
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In the text

$\begin{figure} \par\includegraphics[width=90mm]{9233f4.eps} \end{figure}$ Figure 4: K versus J-K diagram. The main sequence is drawn for a visual extinction of zero (full line) and 3 mag (dotted line). The reddening lines, corresponding to a visual extinction of 30 mag, are issued from O3V and B2V stars. A few stars are identified, according to Fig. 6. Moffat et al.'s (1979) stars are identified by their number according to these authors. The asterisks are for 2MASS measurements. The connected full circles are for the star No. 228 (the YSO) and its associated nebulosity.
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In the text

$\begin{figure} \par\includegraphics[width=90mm]{9233f5.eps} \end{figure}$ Figure 5: J-H versus H-K diagram for stars with $K\leq 17$ mag. The main sequence (full line) is drawn for a visual extinction of zero. The reddening lines, starting at the positions of B0V and M0V stars, have lengths corresponding to a visual extinction of 20 mag. The symbols are the same as in Fig. 4.
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In the text

$\begin{figure} \par\includegraphics[width=90mm]{9233f6.eps} \end{figure}$ Figure 6: Identification of a few objects discussed in the text. The underlying image is a colour composite of the [S II] frame (blue) and of the K frame (orange). The lines indicate the limits of our ${\it JHK}$ frames.
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In the text

$\begin{figure} \par\includegraphics[width=180mm]{9233f7.eps} \end{figure}$ Figure 7: Channel maps of the ¹²CO $J=2\rightarrow 1$ emission as observed with HERA and integrated over velocity intervals of $1\hbox {\kern 0.20em km\kern 0.20em s$^{-1}$ }$ ; the central velocity of each bin is marked in the upper left corner of each panel. The first contour is at 1 K km s^-1 and the contour interval is 2 K km s^-1. The coloured background is the MSX emission at 8.3 $\mu$ m. The 0, 0 position is that of the MSX point source (Table 1).
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In the text

$\begin{figure} \par\includegraphics[width=180mm]{9233f8.eps} \end{figure}$ Figure 8: Top left: condensation C1, showing the ¹³CO(2-1) emission integrated between $-36.1\hbox {\kern 0.20em km\kern 0.20em s$^{-1}$ }$ and $-35.1\hbox {\kern 0.20em km\kern 0.20em s$^{-1}$ }$ . The first contour and the step correspond respectively to 20% and 15% of the peak brightness ( $9.6\hbox {\kern 0.20em K}\hbox {\kern 0.20em km\kern 0.20em s$^{-1}$ }$ ). Bottom Left: condensations C2, C3, and C4, showing the ¹³CO(2-1) emission integrated between $-34.0\hbox {\kern 0.20em km\kern 0.20em s$^{-1}$ }$ and $-32.7\hbox {\kern 0.20em km\kern 0.20em s$^{-1}$ }$ . The first contour and the step are respectively 20% and 15% of the peak brightness ( $15.7\hbox {\kern 0.20em K}\hbox {\kern 0.20em km\kern 0.20em s$^{-1}$ }$ ). Top right: condensation C5, showing the ¹³CO(2-1) emission integrated between $-38.4\hbox {\kern 0.20em km\kern 0.20em s$^{-1}$ }$ and $-36.6\hbox {\kern 0.20em km\kern 0.20em s$^{-1}$ }$ . The first contour and the step are respectively 35% and 15% of the peak brightness ( $3.8\hbox {\kern 0.20em K}\hbox {\kern 0.20em km\kern 0.20em s$^{-1}$ }$ ). Bottom right: filament, with the ¹³CO(2-1) emission integrated between $-36.8\hbox {\kern 0.20em km\kern 0.20em s$^{-1}$ }$ and $-35.9\hbox {\kern 0.20em km\kern 0.20em s$^{-1}$ }$ . The peak is at 6.6 K km s^-1. The first contour and the step are respectively 20% and 20% of the peak brightness.
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In the text

$\begin{figure} \par\includegraphics[width=90mm]{9233f9.eps} \end{figure}$ Figure 9: Molecular lines observed towards the molecular fragments C1 to C4.
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In the text

$\begin{figure} \par\includegraphics[width=90mm]{9233f10.eps} \end{figure}$ Figure 10: Radio continuum emission (contours) superimposed on the H image (grey scale). Star No. 228 is indicated by an arrow. The contours show 1.3 cm continuum emission from the UC H II region coinciding in direction with the MSX point source and the star. The angular resolution of the radio image is $3\hbox{$.\!\!^{\prime\prime}$ }3$ (indicated in the lower left corner) and the contour levels are -15, 15, 20, 25, 30, 40, 45 mJy beam^-1.
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In the text

$\begin{figure} \par\includegraphics[width=90mm]{9233f11.eps} \end{figure}$ Figure 11: H I emission associated with Sh2-212, integrated between -40 km s^-1 and -48 km s^-1. The radio angular resolution ( $50'' \times 41''$ ) is indicated in the upper left corner. Contour levels are -15, 15, 20, 25, ... 50 mJy beam^-1 km s^-1. The H I contours are superimposed on the [S II] image.
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In the text

$\begin{figure} \par\includegraphics[width=90mm]{9233f12.eps} \end{figure}$ Figure 12: Spectral energy distribution of star No. 228, a massive YSO. Filled circles are the fluxes listed in Table 6. The five best fitting models obtained using the web-based tool of Robitaille et al. (2007) are presented.
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In the text

$\begin{figure} \par\includegraphics[width=90mm]{9233f13.eps} \end{figure}$ Figure 13: Morphology of the Sh2-212 complex.
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In the text

$\begin{figure} \par\includegraphics[width=180mm]{9233f14.eps} \end{figure}$ Figure 14: Confrontation of observations and simulations. Left: ¹²CO emission, integrated over the velocity. Right: simulation of a turbulent cloud illuminated by the UV radiation of a massive star (Dale et al. 2005, their Fig. 16).
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In the text

$\begin{figure} \par\includegraphics[width=90mm]{9233f2.eps} \end{figure}$	Figure 2: Composite colour image of Sh2-212 in the optical and the mid-IR. Red corresponds to the MSX emission at 8.3 $\mu$ m, and turquoise to the optical emission of the ionized gas. The arrow points to the MSX point source associated with star No. 228 and the UC H II region discussed in the text.
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$\begin{figure} \par\includegraphics[width=90mm]{9233f5.eps} \end{figure}$	Figure 5: J-H versus H-K diagram for stars with $K\leq 17$ mag. The main sequence (full line) is drawn for a visual extinction of zero. The reddening lines, starting at the positions of B0V and M0V stars, have lengths corresponding to a visual extinction of 20 mag. The symbols are the same as in Fig. 4.
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$\begin{figure} \par\includegraphics[width=90mm]{9233f6.eps} \end{figure}$	Figure 6: Identification of a few objects discussed in the text. The underlying image is a colour composite of the [S II] frame (blue) and of the K frame (orange). The lines indicate the limits of our ${\it JHK}$ frames.
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$\begin{figure} \par\includegraphics[width=90mm]{9233f9.eps} \end{figure}$	Figure 9: Molecular lines observed towards the molecular fragments C1 to C4.
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$\begin{figure} \par\includegraphics[width=90mm]{9233f11.eps} \end{figure}$	Figure 11: H I emission associated with Sh2-212, integrated between -40 km s^-1 and -48 km s^-1. The radio angular resolution ( $50'' \times 41''$ ) is indicated in the upper left corner. Contour levels are -15, 15, 20, 25, ... 50 mJy beam^-1 km s^-1. The H I contours are superimposed on the [S II] image.
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$\begin{figure} \par\includegraphics[width=90mm]{9233f12.eps} \end{figure}$	Figure 12: Spectral energy distribution of star No. 228, a massive YSO. Filled circles are the fluxes listed in Table 6. The five best fitting models obtained using the web-based tool of Robitaille et al. (2007) are presented.
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$\begin{figure} \par\includegraphics[width=90mm]{9233f13.eps} \end{figure}$	Figure 13: Morphology of the Sh2-212 complex.
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$\begin{figure} \par\includegraphics[width=180mm]{9233f14.eps} \end{figure}$	Figure 14: Confrontation of observations and simulations. Left: ¹²CO emission, integrated over the velocity. Right: simulation of a turbulent cloud illuminated by the UV radiation of a massive star (Dale et al. 2005, their Fig. 16).
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