All Figures

$\begin{figure} \par\resizebox{6.5cm}{!}{\includegraphics[clip=true]{9587f1.eps}} \par\end{figure}$ Figure 1: Fe I 4896.4 ( $D \simeq 8$ %) and Fe I 6024.1 ( $D \simeq 30$ %) spectral lines evolution of $\beta$ Dor. Pulsation phases are given on the left of each profile. Wavelengths have been translated into velocities for comparison (positive velocities correspond to a redshift, motion toward us). Thesystematic difference in lines asymmetries and velocities is clear. The solid and dashed lines at $\phi =0.61$ show that modifying artificiallythe line asymmetry induces a change in the resulting centroid velocity (see Sect. 4).
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In the text

$\begin{figure} \par\resizebox{18cm}{!}{\includegraphics[clip=true]{9587f2.eps}} \end{figure}$ Figure 2: $RV_{{\rm c}}$ a) and A b) are represented as a function of the pulsation phase for three spectral lines in the case of $\beta$ Dor: Fe I 4896.4 (dashed line), Fe I 5373.7 (solid line), and Fe I 6024.1 (dot-dashed line). The $RV_{{\rm c}}$ curves include only the GCD $\gamma$ -velocity correction. The actual measurements (crosses) are only indicated in the case of the Fe I 5373.7 line. The corresponding uncertainties are too small to be visible in the plot. Horizontal lines correspond to the average values $V_{\gamma }$ and $A_{\gamma }$ of the interpolated curves, respectively. c) $RV_{{\rm c}}-A$ plots and the corresponding ( $A_{\gamma }$ , $V_{\gamma }$ ) average values (crosses) for the three different lines. Although the $RV_{{\rm c}}-A$ plots have different shapes, the average values are aligned. (d) Generalization of diagram c) for all spectral lines. The $RV_{{\rm c}}-A$ plots are not included for clarity. The upper values are without any correction except the GCD $\gamma$ -velocity. The origin of the plot is then used as a physical reference for all spectral line $\gamma$ -velocities of the star (lower values). The $V_{\gamma } A_{\gamma }$ correlation found is a strong indication that $\gamma$ -velocities are related to intrinsic physical properties of Cepheids' atmospheres.
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In the text

$\begin{figure} \par\resizebox{18cm}{!}{\includegraphics[clip=true]{9587f3.eps}} \end{figure}$ Figure 3: Same as Fig. 2d for all Cepheids of our sample. The origin of the $V_{\gamma } A_{\gamma }$ plots are used as physical references. The correction applied ( $V_{\gamma \star }=V_{\gamma }{\rm GCD}+b_{{\rm0}}$ ), together with the slope values ( $a_{{\rm0}}$ ), are indicated in Table 1. In the last panel an weighted average is done over all stars. The resulting $V_{\gamma } A_{\gamma }$ linear curve is very precise ( $a_{{\rm0}}=0.15 \pm 0.01$ ).
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In the text

$\begin{figure} \par\resizebox{8.8cm}{!}{\includegraphics[clip=true]{9587f4.eps}} \end{figure}$ Figure 4: Radius (in solar radii) as a function of the pulsation phase for spectral lines of our sample. The radial velocity curves have been corrected from their $\gamma$ -velocities in order to investigate phase shifts. Important differences are found from one line to the other, which are mainly due to the velocity gradient within the atmosphere. Actually, there is a linear relation between the amplitude of the radius variation and the line depth (see for instance Fig. 4 of Paper II). This indicates why it is essential to use dynamic projection factors. A phase shift is observed only for R TrA and RS Pup.
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In the text

$\begin{figure} \par\resizebox{8.8cm}{!}{\includegraphics[clip=true]{9587f5.eps}} \end{figure}$ Figure 5: $A_{\gamma }$ averaged (without weighting) over all lines is given as a function of the pulsation period of the star. The plot is a generalization of Fig. 14a of Paper I.
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In the text

$\begin{figure} \par\resizebox{8.8cm}{!}{\includegraphics[clip=true]{9587f5.eps}} \end{figure}$	Figure 5: $A_{\gamma }$ averaged (without weighting) over all lines is given as a function of the pulsation period of the star. The plot is a generalization of Fig. 14a of Paper I.
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