All Figures

$\begin{figure} \par\includegraphics[angle=-90,width=16cm,clip]{7205fig1.eps} \end{figure}$ Figure 1: Abundances of C, N, Na, Mg, Al and Mg isotopes in stars of NGC 6752, as a function of the corresponding oxygen abundance. Observations (filled symbols) in the left column (plotted as a function of [O/Fe]) are from Carretta et al. (2005), and in the other two columns (plotted as a function of O/H) from Yong et al. (2003). In all the figures, the estimated initial abundances of the gas from which the cluster was formed are indicated by an open circle (i.e., it is assumed that they have the same composition as field halo stars of the same metallicity ${\rm [Fe/H]}=-1.5$ , with e.g. ${\rm [O/Fe]}=0.5$ , ${\rm [C/Fe]}=0$ , etc.). The most extreme abundances observed at present in NGC 6752 are indicated by open squares. Arrows indicate the magnitude and direction of the abundance spread, which is also given by $\Delta y$ (in dex, where $y={\rm log}$ (abundance)) in each panel; $\Delta y_{\rm O}$ in the bottom panels indicates the corresponding variation of oxygen abundance, larger in the case of Carretta et al. (2005, a factor of $\sim$ 8), than in the case of Yong et al. (2003, a factor of 5).
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=15cm,clip]{7205fig2.eps} \end{figure}$ Figure 2: Evolution of the composition during H-burning at constant temperature. Adopted temperatures are given on top of each column. Results are plotted as a function of the consumed H fraction $\Delta X/X_0$ (where X₀=0.75), i.e. time increases to the right of each panel. Abundances are mass fractions in the first three rows, while in the bottom row the quantity (A/B)/(A/B)₀ is given (where A and B are abundances by number and 0 stands for abundances in the original mixture).
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In the text

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{7205fig3.eps} \end{figure}$ Figure 3: Evolution of mass fractions ( left column) and abundance ratios by number ( right column) of elements in the Na-Al region, during H-burning at constant temperature; they are plotted as a function of the consumed H fraction (see Fig. 2) for six values of the temperature in the 70-80 MK range (see top left panel). The abundance of ²⁶Al is always counted in the one of ²⁶Mg and of total Mg. All theoretical values are corrected for mixing with original material with a factor f=0.31, such as to ensure that the abundance in the mixture will be equal to $X_{\rm E,OBS}$ for oxygen (see text). Horizontal solid lines in all panels represent the observed extreme values of each element or abundance ratio ( $X_{\rm E}$ in Table 1). The vertical dotted lines in all panels indicate a consumed H fraction of $\Delta X/X=0.025$ , where calculations at T=74-76 MK agree with observational requirements for all elements.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=15.5cm,clip]{7205fig4.eps} \end{figure}$ Figure 4: Abundances of C, N, Na, Mg, Al and Mg isotopes as a function of O abundance. The O abundance scale is expanded in the upper row, to accomodate the range of values (i.e. down to the O equilibrium value) obtained in the calculation at $T={\rm const.}=74$ MK; results of calculations are shown by the solid and dotted curves in each panel, with O reaching its equilibrium value in the extreme left. Abundances corresponding to a consumed H fraction of $\Delta X/X_0=0.025$ are shown with open circles and squares in each panel in the upper row. Observations (filled points in all panels) are from references given in Fig. 1. Open symbols in the lower row panels denote abundances obtained after mixing the calculated abundances at $\Delta X/X_0=0.025$ of the corresponding upper panels with various amounts of material having the original composition. The corresponding dilution factors appear on top of the lower row panels; smaller dilution factors result in abundances closer to the processed ones (e.g. higher Na, Al etc.). The abundances of Mg $_{\rm TOT}$ and ²⁶Mg $_{\rm TOT}$ include those of ²⁶Al.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{7205fig5.eps} \end{figure}$ Figure 5: Mg isotopic ratios vs. O/H. Theoretical results (open symbols) are obtained for T=74 MK and at $\Delta X/X=0.025$ , as in Fig. 4; they are mixed to various degrees with material of original composition (mixing factors f=0.3, 0.8, 5 and 40, from left to right). Observations (filled points) are as in Fig. 1.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{7205fig6.eps} \end{figure}$ Figure 6: Li in the globular cluster NGC 6752. Observations (filled symbols with error bars) are from Pasquini et al. (2005) derived for the Alonso et al. (1996) temperature scale. Open symbols indicate H-burned material ( $\Delta X\sim 0.025$ of H consumed and no Li present), mixed to various degrees with material of original composition (containing Big Bang Li, at the level of WMAP); dilution factors are 0.1, 0.6, 5, 40 and 250, from left to right. Filled symbols indicate uniform depletion of 0.4 dex in all theoretical mixtures, to account for the difference between the WMAP constraint on primordial Li and observations of the "Spite plateau'' (Charbonnel & Primas 2005).
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In the text

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{7205fig7.eps} \end{figure}$ Figure 7: Fluorine in the globular cluster M4. Observations are from Smith et al. (2005). Open symbols indicate H-burned material at T=74 MK ( $\Delta X\sim 0.025$ of H consumed and no F present), mixed to various degrees with material of original composition; dilution factors are 0.1, 0.6, 5, 40 and 250, from left to right.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{7205fig8.eps} \end{figure}$ Figure 8: H-burning temperatures at various phases of a star's life, as a function of initial stellar mass. The correspondence between symbols and evolutionary phases is displayed in the bottom right part of the figure. Vertical straight lines (for central H-burning) start at the ZAMS and end at central H-exhaustion. For the other phases we show only the maximum temperature reached in the H-burning zones of interest (see details in the text). The two horizontal dotted lines enclose the temperature range of our one-zone models reproducing the extreme abundances that are observed in NGC 6752, after the analysis of Sect. 3. The shaded aerea encloses our rough estimates for the corresponding maximal temperature range in the case of convective H-burning regions (in the bottom of AGB envelopes or in the center of massive star cores), as discussed in Sect. 5.1.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{7205fig5.eps} \end{figure}$	Figure 5: Mg isotopic ratios vs. O/H. Theoretical results (open symbols) are obtained for T=74 MK and at $\Delta X/X=0.025$ , as in Fig. 4; they are mixed to various degrees with material of original composition (mixing factors f=0.3, 0.8, 5 and 40, from left to right). Observations (filled points) are as in Fig. 1.
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$\begin{figure} \par\includegraphics[width=7.8cm,clip]{7205fig7.eps} \end{figure}$	Figure 7: Fluorine in the globular cluster M4. Observations are from Smith et al. (2005). Open symbols indicate H-burned material at T=74 MK ( $\Delta X\sim 0.025$ of H consumed and no F present), mixed to various degrees with material of original composition; dilution factors are 0.1, 0.6, 5, 40 and 250, from left to right.
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