All Figures

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{7068fig1.ps} \end{figure}$ Figure 1: Emission reversal in the Ca II H line of GJ 674 ( top) and GJ 581 ( bottom). Within our sample, GJ 581 has one of the weakest Ca II emissions and illustrates a very quiet M dwarf. GJ 674 has much stronger emission and is moderately active.
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In the text

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{7068fig2.eps} \end{figure}$ Figure 2: Upper panel: radial-velocity measurements of GJ 674 as a function of time. The high dispersion ( $\sigma = 7.35 \mbox{${\rm m~s^{-1}}$ }$ ) and chi-square value ( $\bar{\chi}^2 = 132$ ) betray a (coherent or incoherent) signal in the data. Bottom panel: the Lomb-Scargle periodogram of the velocities has prominent power excess around P = 4.69 days (downward arrow), which indicates that much of the excess dispersion reflects a coherent signal with a period close to that value. The second-highest peak, at 1.27 day, is a one-day alias of the 4.69 day period ( $1.27 \simeq 1+1/4.69$ ).
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In the text

$\begin{figure} \par\includegraphics[width=7.3cm,clip]{7068fig3.eps} \end{figure}$ Figure 3: Upper panel: radial velocities of GJ 674 (red filled circles) phase-folded to the 4.6940 days period of the best 1-planet fit (curve). The dispersion around the fit ( $\sigma = 3.27 \mbox{${\rm m~s^{-1}}$ }$ ) and its reduced chi-square ( $\bar{\chi}^2 = 30.6$ per degree of freedom) indicate that a single planet does not describe the data very well. Middle panel: radial-velocity residuals of the 1-planet fit Bottom panel: the Lomb-Scargle periodogram of the residuals shows a broad peak centered around 35 days.
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In the text

$\begin{figure} \par\includegraphics[width=8cm]{7068fig4.eps} \end{figure}$ Figure 4: Top two panels: radial velocity measurements phased to each of the two periods, after subtraction of the other component of our best 2-planet Keplerian model. Third panel: residuals of the best 2-planet fit as a function of time (O-C, Observed minus Computed). Bottom panel: lomb-Scargle periodogram of these residuals.
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In the text

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{7068fig5.eps} \end{figure}$ Figure 5: Upper panel: differential photometry of GJ 674 as a function of time. The star clearly varies with a 1.3% amplitude. Bottom panel: the periodogram of the GJ 674 photometry exhibits significant power excess peaking at 35 days (small black arrow).
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In the text

$\begin{figure} \par\includegraphics[width=15cm,clip]{7068fig6.eps} \end{figure}$ Figure 6: Upper panel: differential radial velocity of GJ 674, corrected for the signature of the 4.69 days planet in our 2-planet Keplerian fit, as a function of the H $\alpha$ (red filled circles) and Ca II H&K (green filled squares) spectral indices defined in the text. Bottom right panels: the Ca II H+K and H $\alpha$ indexes phased to the longer period of the 2-planet keplerian model. Bottom left panels: Power density spectra of the spectroscopic indexes. A clear power excess peaks at 34.8 days (vertical dashed lines).
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In the text

$\begin{figure} \par\includegraphics[width=8cm]{7068fig7.ps} \end{figure}$ Figure 7: Upper panel: metallicity distributions of 44 M dwarfs without known planets (gray shading) and of the 5 M dwarfs known to host planets (black shading). Bottom panel: corresponding cumulative distributions (solid and dashed lines, respectively).
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{7068fig8.eps} \end{figure}$ Figure A.1: Bisector analysis for GJ 674 measurements.

In the text

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{7068fig1.ps} \end{figure}$	Figure 1: Emission reversal in the Ca II H line of GJ 674 ( top) and GJ 581 ( bottom). Within our sample, GJ 581 has one of the weakest Ca II emissions and illustrates a very quiet M dwarf. GJ 674 has much stronger emission and is moderately active.
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$\begin{figure} \par\includegraphics[width=8cm]{7068fig4.eps} \end{figure}$	Figure 4: Top two panels: radial velocity measurements phased to each of the two periods, after subtraction of the other component of our best 2-planet Keplerian model. Third panel: residuals of the best 2-planet fit as a function of time (O-C, Observed minus Computed). Bottom panel: lomb-Scargle periodogram of these residuals.
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$\begin{figure} \par\includegraphics[width=7.7cm,clip]{7068fig5.eps} \end{figure}$	Figure 5: Upper panel: differential photometry of GJ 674 as a function of time. The star clearly varies with a 1.3% amplitude. Bottom panel: the periodogram of the GJ 674 photometry exhibits significant power excess peaking at 35 days (small black arrow).
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$\begin{figure} \par\includegraphics[width=8cm]{7068fig7.ps} \end{figure}$	Figure 7: Upper panel: metallicity distributions of 44 M dwarfs without known planets (gray shading) and of the 5 M dwarfs known to host planets (black shading). Bottom panel: corresponding cumulative distributions (solid and dashed lines, respectively).
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