All Figures

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{3046f1a.eps}\par\vspace*{3mm} \includegraphics[width=7.8cm,clip]{3046f1b.eps} \end{figure}$ Figure 1: Comparison of $T_{\rm eff}$ ( upper panel) and [Fe/H] ( lower panel) between our study and Santos et al. (2004, open diamonds) and Edvardsson et al. (1993, filled diamonds). The errorbars represent the individual 1 $\sigma$ errors for our study and for Santos et al. Edvardsson et al. do not list individual error estimates and we adopt their typical errors of 50 K for $T_{\rm eff}$ and 0.05 dex for [Fe/H]. The over-plotted lines represent an identity relation, not a fit to the data.
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In the text

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{3046f2a.eps}\hspace*{3mm} \includegraphics[width=7.7cm,clip]{3046f2b.eps} \end{figure}$ Figure 2: Left panel: color-magnitude diagram V-K vs. M_K. The filled circles correspond to our metallicity determinations and the open circles to those from WW05. The symbol size is proportional to the metallicity. The dashed lines represent isometallicity contours for the polynomial relation of Eq. (1), spaced by 0.25 dex from -1.50 dex ( left) to +0.25 dex ( right). The right-hand axis shows masses from the DFS00 K-band Mass-luminosity, which has very low dispersion and allows to interpret the figure as a Mass-Colour-Metallicity diagram. Gl 876 and Gl 436, the two known M-dwarf planet-host stars, are indicated to illustrate their solar metallicity. Right panels: residuals from the calibration as a function of both M_K and V-K photometry.
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In the text

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{3046f3.eps} \end{figure}$ Figure 3: V band M/L relation, with masses derived from the K-band M/L relation of DFS00 and 2MASS photometry. The filled circles represent our metallicity determinations and the open circles those from WW05. The symbol size is proportional to the metallicity, and the dashed contours represent isometallicity for the Eq. (1) calibration, spaced by 0.25 dex from +0.25 ( left) to -1.5 dex ( right). The solid lines represents the V-band empirical M/L relation of DFS00.
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In the text

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{3046f4.eps} \end{figure}$ Figure 4: Metallicity of M and K dwarfs (filled circles for our measurements, and open circles for WW05 data) as a function of the difference ( $\Delta$ M) between masses calculated from the V- and K-band M/L relations of DFS00.
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In the text

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{3046f5.eps} \end{figure}$ Figure 5: Upper panel: M-dwarf metallicity distribution derived from Eq. (1) and, over-plotted in dashed line, the metallicity distribution of 1000 non-variable stars of our CORALIE radial-velocity planet-search programme. Bottom panel: cumulative distributions of the same samples.
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In the text

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{3046f4.eps} \end{figure}$	Figure 4: Metallicity of M and K dwarfs (filled circles for our measurements, and open circles for WW05 data) as a function of the difference ( $\Delta$ M) between masses calculated from the V- and K-band M/L relations of DFS00.
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$\begin{figure} \par\includegraphics[width=7.8cm,clip]{3046f5.eps} \end{figure}$	Figure 5: Upper panel: M-dwarf metallicity distribution derived from Eq. (1) and, over-plotted in dashed line, the metallicity distribution of 1000 non-variable stars of our CORALIE radial-velocity planet-search programme. Bottom panel: cumulative distributions of the same samples.
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