All Figures

$\begin{figure} \par\includegraphics[origin=rb,angle=90,width=12.4cm,clip]{4223fi... ...ncludegraphics[origin=rb,angle=90,width=12.4cm,clip]{4223fig1b.ps} \end{figure}$ Figure 1: Top panels: the position of a star in the HR diagram, and the star's position transformed into a diagram of age as a function of stellar mass, assuming that we know effective temperature ${\pm } 5$ % and luminosity ${\pm } 0.1$ dex. The transformation uses standard evolution tracks for Z = 0.02 (Schaller et al. 1992); several fractional ages (fraction of main sequence life completed) are labelled. Bottom panels: the same transformation as in the top panels, but using tracks of metallicity Z=0.008 (Schaerer et al. 1993).
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{4223fig2.ps} \end{figure}$ Figure 2: $\ensuremath{\langle B_z\rangle}$ measurements of HD 94660 from individual Balmer lines. Each panel refers to a different observing date as specified in the figure. The $\ensuremath{\langle B_z\rangle}$ values measured from H $\beta$ and blueward Balmer lines are plotted with filled circles at the corresponding wavelength. The $\ensuremath{\langle B_z\rangle}$ determination from H $\alpha$ obtained on 2002-02-04 is arbitrarily plotted with an empty circle at $\lambda =4600$ Å. The solid lines correspond to $\ensuremath{\langle B_z\rangle}$ obtained using all Balmer lines from H $\beta$ down to the Balmer jump, and the dotted lines indicate $\ensuremath{\langle B_z\rangle}$ obtained from the metal lines with grism 600 B. The dashed line in the second panel shows the $\ensuremath{\langle B_z\rangle}$ value obtained from the metal lines observed with grism 600 R.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{4223fig3.ps} \end{figure}$ Figure 3: Longitudinal field determinations of HD 94660. The solid line is a fit to the $\ensuremath{\langle B_z\rangle}$ determinations from metal lines. We have used a first-order Fourier expansion. At phase 0.075 we have considered the $\ensuremath{\langle B_z\rangle}$ determination obtained with grism 600 B and not the one obtained with grism 600 R. For the star's rotation period we adopt 2800 d (Landstreet & Mathys 2000), and the zero phase point is at JD = 2446500.0.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{4223fig4.ps} \end{figure}$ Figure 4: $\ensuremath{\langle B_z\rangle}$ determinations from metal lines versus $\ensuremath{\langle B_z\rangle}$ determinations from Balmer lines for the stars of Table A.3. The solid line has slope = 1. For clarity, only stars for which $\ensuremath{\langle B_z\rangle}$ obtained from Balmer lines is such that $\vert\ensuremath{\langle B_z\rangle}\vert / \sigma[\ensuremath{\langle B_z\rangle} ] \ge 1$ have been plotted. The outliers HD 318107 and NGC 2244 334 (see Table A.3) are not plotted.
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In the text

$\begin{figure} \par\includegraphics[angle=90,width=8.5cm,clip]{4223fig5.ps} \end{figure}$ Figure 5: Histograms of the error bars for the $\ensuremath{\langle B_z\rangle}$ measurements of Table A.3 obtained from Balmer lines and from metal lines. The median of the distribution of the error from Balmer lines is 78 G, from metal lines it is 130 G.
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In the text

$\begin{figure} \par\includegraphics[width=8.4cm,clip]{4223fig6.ps} \end{figure}$ Figure 6: Distance modulus versus age of open clusters. The empty circles show all open clusters with known age and $\delta <+10\hbox {$^\circ $ }$ . Filled circles are the clusters observed in this survey (same data as in Table 2). Data have been extracted from WEBDA.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=8.7cm,clip]{4223fig7a.ps}\pa... ...ce*{4mm} \includegraphics[angle=270,width=8.7cm,clip]{4223fig7b.ps} \end{figure}$ Figure 7: Distribution of $\ensuremath{\langle B_z\rangle}$ values normalised to their error bars measured from Balmer lines in the Ap stars (upper panel) and in the normal A and B-type stars (lower panel). Five stars have been omitted from the upper panel (Ap stars) because they are off scale. The dotted lines correspond to the 3- $\sigma$ detection level.
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In the text

$\begin{figure} \par\includegraphics[width=17.1cm,clip]{4223fig8.ps} \end{figure}$ Figure 8: Top panels: Stokes I (thin solid lines, arbitrary units) V/I profiles (thick solid line, in %), and error bar associated to V/I, for three stars observed during the survey. Bottom panels: the corresponding best-fit to the Balmer lines obtained by minimizing the $\chi ^2$ of Eq. (3). The longitudinal field measured in HD 190290 (left panels) is $\ensuremath{\langle B_z\rangle} = +2429 \pm 110$ G; the field measured in HD 87240 (middle panels) is $-257 \pm 58$ G; the field measured in HD 69003 (right panels) is $-48 \pm 53$ G.
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In the text

$\begin{figure} \par\includegraphics[angle=90,width=8.5cm,clip]{4223fig5.ps} \end{figure}$	Figure 5: Histograms of the error bars for the $\ensuremath{\langle B_z\rangle}$ measurements of Table A.3 obtained from Balmer lines and from metal lines. The median of the distribution of the error from Balmer lines is 78 G, from metal lines it is 130 G.
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$\begin{figure} \par\includegraphics[width=8.4cm,clip]{4223fig6.ps} \end{figure}$	Figure 6: Distance modulus versus age of open clusters. The empty circles show all open clusters with known age and $\delta <+10\hbox {$^\circ $ }$ . Filled circles are the clusters observed in this survey (same data as in Table 2). Data have been extracted from WEBDA.
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$\begin{figure} \par\includegraphics[angle=270,width=8.7cm,clip]{4223fig7a.ps}\pa... ...ce*{4mm} \includegraphics[angle=270,width=8.7cm,clip]{4223fig7b.ps} \end{figure}$	Figure 7: Distribution of $\ensuremath{\langle B_z\rangle}$ values normalised to their error bars measured from Balmer lines in the Ap stars (upper panel) and in the normal A and B-type stars (lower panel). Five stars have been omitted from the upper panel (Ap stars) because they are off scale. The dotted lines correspond to the 3- $\sigma$ detection level.
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