All Figures

$\begin{figure} \par\includegraphics[width=6.7cm,clip]{0507fg1.eps}\end{figure}$ Figure 1: Two-branches diagram. Filled circles and asterisks represent population IIa and IIb stars, respectively. Open circles represent two peculiar population IIa stars (see text for details).
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In the text

$\begin{figure} \par\includegraphics[width=14.05cm,clip]{0507fg2.eps}\end{figure}$ Figure 2: Part of HD 76932 spectrum around the CH lines analyzed.
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In the text

$\begin{figure} \par\includegraphics[width=6.5cm,clip]{0507fg3a.eps}\hspace*{1.6cm} \includegraphics[width=6.7cm,clip]{0507fg3b.eps}\end{figure}$ Figure 3: Correlation diagrams for [O/Fe] versus [Mg/Fe] for the stars from which abundances have been deduced from the forbidden line ( left panel) and from the triplet ( right panel). Symbols are the same as in Fig. 1.
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In the text

$\begin{figure} \par\includegraphics[width=5.5cm,clip]{0507fg4a.eps}\hspace*{1cm} \includegraphics[width=5.5cm,clip]{0507fg4b.eps}\end{figure}$ Figure 4: Abundances of C and O relative to Fe versus [Fe/H]. Symbols are the same as in Fig. 1.
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In the text

$\begin{figure} \par\mbox{\includegraphics[width=5.5cm,clip]{0507fg5a.eps}\hspace{1cm} \includegraphics[width=5.5cm,clip]{0507fg5b.eps} } \end{figure}$ Figure 5: Abundances of Na and Al relative to Fe versus [Fe/H]. Symbols are the same as in Fig. 1.
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In the text

$\begin{figure} \par\includegraphics[width=5.5cm,clip]{0507fg6a.eps}\hspace*{1cm}... ...c.eps}\hspace*{1cm} \includegraphics[width=5.5cm,clip]{0507fg6d.eps}\end{figure}$ Figure 6: Abundances of O, Mg, Si and Ca relative to Fe versus [Ti/Fe] ( top left, top right, bottom left and bottom right, respectively). Symbols are the same as in Fig. 1. Solid lines represent the fits.
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In the text

$\begin{figure} \par\includegraphics[width=7.2cm,clip]{0507fg7.eps} % \end{figure}$ Figure 7: [Ca/Fe] versus [Ti/Fe] from different analyses: present paper (solid circles), Nissen & Schuster (1997, solid triangles), Bensby et al. (2003, open triangles), and Gratton et al. (2003, open circles).
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In the text

$\begin{figure} \par\includegraphics[width=8.7cm,clip]{0507fg8.eps}\end{figure}$ Figure 8: [Ca/Fe] versus [Fe/H]. Results from this study and from Nissen & Schuster (1997) are plotted. Filled and open triangles represent disk and halo stars, respectively, the separation between the two populations having been set at a velocity of 150 km s^-1 with respect to the Local Standard of Rest.
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In the text

$\begin{figure} \par\includegraphics[width=5.95cm,clip]{0507fg9.eps}\end{figure}$ Figure 9: Upper mass cutoff for a Salpeter IMF as a function of the total number of first generation stars in the cloud (upper abscissa) and of the total number of SNeII (lower abscissa). $M_{\rm max}$ is the mass above which the integrated IMF drops below 0.5, which means that the majority of the clouds will contain no star with mass $> M_{\rm max}$ .
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In the text

$\begin{figure} \par\includegraphics[width=8.6cm,clip]{0507fg10.eps}\end{figure}$ Figure 10: Ratio of the yields of oxygen and silicon versus the upper mass cutoff for SNeII. These yields are integrated using the results of Umeda & Nomoto (2002), from $8~M_\odot$ up to $M_{\rm max}$ . The dotted lines correspond to the maximum range of $M_{\rm O} / M_{\rm Si}$ obtained from our data, and thus correspond to an $M_{\rm max}$ varying between 21 and 36 $M_\odot$ .
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In the text

$\begin{figure} \par\includegraphics[width=8.65cm,clip]{0507fg11.eps}\end{figure}$ Figure 11: [Ca/Fe] versus the modulus of the velocity with respect to the Local Standard of Rest (LSR). Results from this study and from Nissen & Schuster (1997) are plotted. Filled and open triangles represent disk and halo stars, respectively.
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In the text

$\begin{figure} \par\includegraphics[width=6.7cm,clip]{0507fg12.eps}\end{figure}$ Figure 12: Correlation diagrams for [C/Fe] versus [Y/Fe]. Symbols are the same as in Fig. 1. Also shown is the straight line fit through Pop IIb stars.
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In the text

$\begin{figure} \par\includegraphics[width=6.5cm,clip]{0507fg13.eps}\end{figure}$ Figure 13: Correlation diagrams for [O/Fe] versus [Y/Fe]. Symbols are the same as in Fig. 1.
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In the text

$\begin{figure} \par\includegraphics[width=6.7cm,clip]{0507fg14.eps}\end{figure}$ Figure 14: Correlation diagrams for [Na/Fe] versus [Y/Fe]. Symbols are the same as in Fig. 1. Also shown is the straight line fit through Pop IIb stars.
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In the text

$\begin{figure} \par\includegraphics[width=6.7cm,clip]{0507fg1.eps}\end{figure}$	Figure 1: Two-branches diagram. Filled circles and asterisks represent population IIa and IIb stars, respectively. Open circles represent two peculiar population IIa stars (see text for details).
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$\begin{figure} \par\includegraphics[width=14.05cm,clip]{0507fg2.eps}\end{figure}$	Figure 2: Part of HD 76932 spectrum around the CH lines analyzed.
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$\begin{figure} \par\includegraphics[width=6.5cm,clip]{0507fg3a.eps}\hspace*{1.6cm} \includegraphics[width=6.7cm,clip]{0507fg3b.eps}\end{figure}$	Figure 3: Correlation diagrams for [O/Fe] versus [Mg/Fe] for the stars from which abundances have been deduced from the forbidden line ( left panel) and from the triplet ( right panel). Symbols are the same as in Fig. 1.
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$\begin{figure} \par\includegraphics[width=5.5cm,clip]{0507fg4a.eps}\hspace*{1cm} \includegraphics[width=5.5cm,clip]{0507fg4b.eps}\end{figure}$	Figure 4: Abundances of C and O relative to Fe versus [Fe/H]. Symbols are the same as in Fig. 1.
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$\begin{figure} \par\mbox{\includegraphics[width=5.5cm,clip]{0507fg5a.eps}\hspace{1cm} \includegraphics[width=5.5cm,clip]{0507fg5b.eps} } \end{figure}$	Figure 5: Abundances of Na and Al relative to Fe versus [Fe/H]. Symbols are the same as in Fig. 1.
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$\begin{figure} \par\includegraphics[width=5.5cm,clip]{0507fg6a.eps}\hspace{1cm}... ...c.eps}\hspace{1cm} \includegraphics[width=5.5cm,clip]{0507fg6d.eps}\end{figure}$	Figure 6: Abundances of O, Mg, Si and Ca relative to Fe versus [Ti/Fe] ( top left, top right, bottom left and bottom right, respectively). Symbols are the same as in Fig. 1. Solid lines represent the fits.
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$\begin{figure} \par\includegraphics[width=7.2cm,clip]{0507fg7.eps} % \end{figure}$	Figure 7: [Ca/Fe] versus [Ti/Fe] from different analyses: present paper (solid circles), Nissen & Schuster (1997, solid triangles), Bensby et al. (2003, open triangles), and Gratton et al. (2003, open circles).
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$\begin{figure} \par\includegraphics[width=8.7cm,clip]{0507fg8.eps}\end{figure}$	Figure 8: [Ca/Fe] versus [Fe/H]. Results from this study and from Nissen & Schuster (1997) are plotted. Filled and open triangles represent disk and halo stars, respectively, the separation between the two populations having been set at a velocity of 150 km s^-1 with respect to the Local Standard of Rest.
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$\begin{figure} \par\includegraphics[width=5.95cm,clip]{0507fg9.eps}\end{figure}$	Figure 9: Upper mass cutoff for a Salpeter IMF as a function of the total number of first generation stars in the cloud (upper abscissa) and of the total number of SNeII (lower abscissa). $M_{\rm max}$ is the mass above which the integrated IMF drops below 0.5, which means that the majority of the clouds will contain no star with mass $> M_{\rm max}$ .
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$\begin{figure} \par\includegraphics[width=8.6cm,clip]{0507fg10.eps}\end{figure}$	Figure 10: Ratio of the yields of oxygen and silicon versus the upper mass cutoff for SNeII. These yields are integrated using the results of Umeda & Nomoto (2002), from $8~M_\odot$ up to $M_{\rm max}$ . The dotted lines correspond to the maximum range of $M_{\rm O} / M_{\rm Si}$ obtained from our data, and thus correspond to an $M_{\rm max}$ varying between 21 and 36 $M_\odot$ .
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$\begin{figure} \par\includegraphics[width=8.65cm,clip]{0507fg11.eps}\end{figure}$	Figure 11: [Ca/Fe] versus the modulus of the velocity with respect to the Local Standard of Rest (LSR). Results from this study and from Nissen & Schuster (1997) are plotted. Filled and open triangles represent disk and halo stars, respectively.
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$\begin{figure} \par\includegraphics[width=6.7cm,clip]{0507fg12.eps}\end{figure}$	Figure 12: Correlation diagrams for [C/Fe] versus [Y/Fe]. Symbols are the same as in Fig. 1. Also shown is the straight line fit through Pop IIb stars.
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$\begin{figure} \par\includegraphics[width=6.5cm,clip]{0507fg13.eps}\end{figure}$	Figure 13: Correlation diagrams for [O/Fe] versus [Y/Fe]. Symbols are the same as in Fig. 1.
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$\begin{figure} \par\includegraphics[width=6.7cm,clip]{0507fg14.eps}\end{figure}$	Figure 14: Correlation diagrams for [Na/Fe] versus [Y/Fe]. Symbols are the same as in Fig. 1. Also shown is the straight line fit through Pop IIb stars.
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