Astronomy & Astrophysics

All Figures

$\begin{figure} \par\includegraphics[width=5.5cm,clip]{0568fg1.eps} \end{figure}$ Figure 1: Average clusters Ca ${\rm II}$ K line spectra. The synthetic photospheric-solar model is super-imposed. In the bottom panel we plot the real solar spectrum, also super-imposed on its model. The effect of the back heating of the chromosphere is also evident outside the core.
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In the text

$\begin{figure} \par\includegraphics[width=14cm,clip]{0568fg2.eps}\end{figure}$ Figure 2: HIRES spectra of the Hyades stars of our sample.
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In the text

$\begin{figure} \par { \begin{tabular}{c c} &{\includegraphics[width=10.7cm,heigh... ...aphics[width=10.8cm,height=3.7cm]{0568fg3f.eps} }\\ \end{tabular}} \end{figure}$ Figure 3: UVES spectra of the stars of our sample. For the stars in IC 4651, NGC 3680 and M 67, in each panel, the spectrum non corrected for IS line is plotted over the corrected one.
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In the text

$\begin{figure} \par\includegraphics[width=12.3cm]{0568fg4.eps}\end{figure}$ Figure 4: Template spectra used to detect the IS-line feature. The original spectra (one for each of the 3 distant clusters) are over plotted on the supposed non contaminated profile on the 3 upper panels. In the lower panels the resulting IS features are shown.
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In the text

$\begin{figure} \par\begin{tabular}{c c} {\includegraphics[width=6.8cm]{0568fg5a.eps} }&{\includegraphics[width=6.8cm]{0568fg5b.eps} } \end{tabular}\end{figure}$ Figure 5: The trend of $F_K^{\rm\prime }$ with the colour. In the right panel the chromospheric activity is not corrected for the IS absorption, in the left one chromospheric-activity indices regarding IC 4651, NGC 3680 and M 67 stars are measured on IS absorption corrected spectra. There is no remarkable difference between the two diagrams. A decreasing trend with colour for chromospheric-activity index can only be seen for Praesepe stars, since the range of colours involved is narrow.
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In the text

$\begin{figure} \par\includegraphics[width=7.3cm,clip]{0568fg6.eps}\end{figure}$ Figure 6: Calibration of $v \sin i$ with the FWHM of the cross correlation profiles of UVES spectra.
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In the text

$\begin{figure} \par\includegraphics[width=7.3cm,clip]{0568fg7.eps}\end{figure}$ Figure 7: $v \sin i$ vs. FWHM diagram for Hyades stars, and the fit to the data points: $v \sin i=0.82 \cdot\left( FWHM^2- 10.75^2 \right) ^{1/2}$ . Also equatorial velocities from periods of rotation are plotted. The latter are indicated as square symbols with the downward arrow (they are in fact upper limits for $v \sin i$ ), while $v \sin i$ data points from Paulson et al. (2003) are indicated as triangles.
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In the text

$\begin{figure} \par\includegraphics[width=15cm]{0568fg8.eps}\end{figure}$ Figure 8: X-ray luminosities vs. chromospheric activity and rotation diagrams. In neither of those can a trend be clearly seen.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{0568fg9.eps}\end{figure}$ Figure 9: The evolution of chromospheric activity (measured by $F_K^{\rm\prime }$ corrected for IS absorption, upper panel) and rotation ( lower panel) with age. Here the vertical bars represent the whole spread of the ordinate data within the cluster. The points are the mean values. For both quantities the surprising result is that the intermediate age clusters show the same level of chromospheric activity and mean rotational velocity of M 67 and the Sun. Since, as remarked, the bars are not error bars but peak to peak spreads, their position attests that the activity distribution of the 7 intermediate age stars and that of the 7 M 67 stars are virtually equal. For both diagrams we tried to fit three power laws, as indicated in the figure. -2/3 and -1/2 are the exponent values suggested respectively by Barry et al. (1987) and Skumanich (1972). As can be seen, they do not fit our data. By minimizing the $\chi ^2$ we find, for the free parameters: $a_1=-0.38,~ b_1=1.79,~ a_2=-0.79,~ b_2=2.24,~ a_3=0.47,~ b_3=0.43,~ \exp=2.79,~ c_1=0.71,~ d_1=4.20,~ c_2=-0.05,~ d_2=5.00,~ c_3=2.23,~ d_3=2.35,~ \exp1=1.47$ .
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In the text

$\begin{figure} \par\includegraphics[width=8cm]{0568fg10.eps}\end{figure}$ Figure 10: Histogram of the chromospheric-activity levels in the sample of stars from Pasquini (1992).
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In the text

$\begin{figure} \par\includegraphics[width=5.5cm,clip]{0568fg1.eps} \end{figure}$	Figure 1: Average clusters Ca ${\rm II}$ K line spectra. The synthetic photospheric-solar model is super-imposed. In the bottom panel we plot the real solar spectrum, also super-imposed on its model. The effect of the back heating of the chromosphere is also evident outside the core.
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$\begin{figure} \par\includegraphics[width=14cm,clip]{0568fg2.eps}\end{figure}$	Figure 2: HIRES spectra of the Hyades stars of our sample.
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$\begin{figure} \par { \begin{tabular}{c c} &{\includegraphics[width=10.7cm,heigh... ...aphics[width=10.8cm,height=3.7cm]{0568fg3f.eps} }\\ \end{tabular}} \end{figure}$	Figure 3: UVES spectra of the stars of our sample. For the stars in IC 4651, NGC 3680 and M 67, in each panel, the spectrum non corrected for IS line is plotted over the corrected one.
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$\begin{figure} \par\includegraphics[width=12.3cm]{0568fg4.eps}\end{figure}$	Figure 4: Template spectra used to detect the IS-line feature. The original spectra (one for each of the 3 distant clusters) are over plotted on the supposed non contaminated profile on the 3 upper panels. In the lower panels the resulting IS features are shown.
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$\begin{figure} \par\includegraphics[width=7.3cm,clip]{0568fg6.eps}\end{figure}$	Figure 6: Calibration of $v \sin i$ with the FWHM of the cross correlation profiles of UVES spectra.
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$\begin{figure} \par\includegraphics[width=15cm]{0568fg8.eps}\end{figure}$	Figure 8: X-ray luminosities vs. chromospheric activity and rotation diagrams. In neither of those can a trend be clearly seen.
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$\begin{figure} \par\includegraphics[width=8cm]{0568fg10.eps}\end{figure}$	Figure 10: Histogram of the chromospheric-activity levels in the sample of stars from Pasquini (1992).
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