All Figures

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{0514fig1.ps} \end{figure}$ Figure 1: Distribution of particle eccentricity vs. semimajor axis after t=50 000 years for a simulation where the gas drag is not included.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8.4cm,clip]{0514fig2.ps} \end{figure}$ Figure 2: Plot of $\Delta~v$ vs. radial distance to the star of the planetesimal swarm at t=50 000 years. Each dot stands for an encounter that has occurred at a velocity $\Delta v$ and at a distance r from the star during $\lbrack t - 10^{4}$ , $t+10^{4}\rbrack$ . The continuous line is the average encounter velocity at each distance from the star.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8.1cm,clip]{0514fig3.ps} \end{figure}$ Figure 3: Evolution of the average encounter velocity distribution, at 5 different epochs, for the gravitational model without gas drag in a disc initially truncated at 4 AU. $R_{{\rm acc}}$ is the size of the smallest body that can accrete matter, after a collision with an equal-sized object, for a given encounter velocity $\Delta v$ . It is given by $R_{{\rm acc}}= f \left( \frac{3} {8\pi \rho_{\rm p} G} \right)^{0.5}\Delta v$ , where $\rho_{\rm p}=3~$ g cm^-3 is the density of the body and f is a coefficient taking into account the energy dissipation in an impact. We adopt here the usual assumption that 90% of the energy is dissipated in the radial direction (e.g. Petit & Farinella 1993) which leads to $\langle f \rangle \simeq 0.7$ .
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.4cm,clip]{0514fig4.ps} \end{figure}$ Figure 4: Eccentricities vs. semi-major axis at t=2500 years for 200 m-sized planetesimals. The gas density is taken from Bodenheimer et al. (2000) with a nominal Hayashi (1981) radial profile.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{0514fig5.ps} \end{figure}$ Figure 5: Eccentricity vs. semimajor axis plot after t=50 000 years for 10 km-sized planetesimals. The dashed line is the corresponding average encounter velocity distribution as a function of the distance to the star. Gas density is the same as in Fig. 4.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{0514fig6.ps} \end{figure}$ Figure 6: Same as Fig. 5 but for 50 km-sized bodies.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{0514fig7.ps} \end{figure}$ Figure 7: Mutual relative velocities, at t=30 000 years, for a disc with 3 different populations of objects: 1 km, 10 km and 50 km in sizes. The solid line stands for $\Delta v$ among 50 km bodies, the dashed line for $\Delta v$ between 50 km and 10 km bodies and the dotted line for $\Delta v$ between 50 km and 1 km bodies. The gas disc has the same characteristics as in Figs. 4-6.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{0514fig8.ps} \end{figure}$ Figure 8: Same as Fig. 6 (50 km bodies at t=50 000 years) for a planetesimal disc initially truncated at 3 AU. The gas density decreases radially as r^-1.5.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{0514fig9.ps} \end{figure}$ Figure 9: Impact velocities, at t=15 000 years, on 500 km bodies for 50 km (continuous line), 10 km (dased line) and 1 km (dotted line) impactors. Same high density truncated disc as in Fig. 8. The absence of $\Delta V$ values beyond 2.5 AU for 1 km impactors is due to the fast removal of such small objects from these regions.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8cm,clip]{0514fig10.ps} \end{figure}$ Figure 10: Migration of the growing core due to scattering of protoplanets. The initial disc extends from 1.5 to 2.5 AU and has a total mass of 75 $M_{\oplus }$ .
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8cm,clip]{0514fig11.ps} \end{figure}$ Figure 11: Evolution, in the (M, a) plane, of a $1~M_{\oplus}$ proto-core initially put in the outer disc and of the largest embryo growing in the inner region. The rapid growth of the inner embryo results in the capture of the outer proto-core (see text for details).
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[angle=-90,width=7.8cm,clip]{0514fig12.ps} \end{figure}$ Figure 12: Snapshots of protoplanet accretion in the $\gamma$ Cephei system. The initial mass in the embryos is 75 $M_{\oplus }$ and the superficial density $\sigma$ decreases with the radial distance as 1/r.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{0514fig1.ps} \end{figure}$	Figure 1: Distribution of particle eccentricity vs. semimajor axis after t=50 000 years for a simulation where the gas drag is not included.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=8.4cm,clip]{0514fig2.ps} \end{figure}$	Figure 2: Plot of $\Delta~v$ vs. radial distance to the star of the planetesimal swarm at t=50 000 years. Each dot stands for an encounter that has occurred at a velocity $\Delta v$ and at a distance r from the star during $\lbrack t - 10^{4}$ , $t+10^{4}\rbrack$ . The continuous line is the average encounter velocity at each distance from the star.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=7.4cm,clip]{0514fig4.ps} \end{figure}$	Figure 4: Eccentricities vs. semi-major axis at t=2500 years for 200 m-sized planetesimals. The gas density is taken from Bodenheimer et al. (2000) with a nominal Hayashi (1981) radial profile.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{0514fig5.ps} \end{figure}$	Figure 5: Eccentricity vs. semimajor axis plot after t=50 000 years for 10 km-sized planetesimals. The dashed line is the corresponding average encounter velocity distribution as a function of the distance to the star. Gas density is the same as in Fig. 4.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{0514fig6.ps} \end{figure}$	Figure 6: Same as Fig. 5 but for 50 km-sized bodies.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=8cm,clip]{0514fig7.ps} \end{figure}$	Figure 7: Mutual relative velocities, at t=30 000 years, for a disc with 3 different populations of objects: 1 km, 10 km and 50 km in sizes. The solid line stands for $\Delta v$ among 50 km bodies, the dashed line for $\Delta v$ between 50 km and 10 km bodies and the dotted line for $\Delta v$ between 50 km and 1 km bodies. The gas disc has the same characteristics as in Figs. 4-6.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{0514fig8.ps} \end{figure}$	Figure 8: Same as Fig. 6 (50 km bodies at t=50 000 years) for a planetesimal disc initially truncated at 3 AU. The gas density decreases radially as r^-1.5.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{0514fig9.ps} \end{figure}$	Figure 9: Impact velocities, at t=15 000 years, on 500 km bodies for 50 km (continuous line), 10 km (dased line) and 1 km (dotted line) impactors. Same high density truncated disc as in Fig. 8. The absence of $\Delta V$ values beyond 2.5 AU for 1 km impactors is due to the fast removal of such small objects from these regions.
Open with DEXTER

$\begin{figure} \par\includegraphics[angle=-90,width=8cm,clip]{0514fig10.ps} \end{figure}$	Figure 10: Migration of the growing core due to scattering of protoplanets. The initial disc extends from 1.5 to 2.5 AU and has a total mass of 75 $M_{\oplus }$ .
Open with DEXTER

$\begin{figure} \par\includegraphics[angle=-90,width=8cm,clip]{0514fig11.ps} \end{figure}$	Figure 11: Evolution, in the (M, a) plane, of a $1~M_{\oplus}$ proto-core initially put in the outer disc and of the largest embryo growing in the inner region. The rapid growth of the inner embryo results in the capture of the outer proto-core (see text for details).
Open with DEXTER

$\begin{figure} \par\includegraphics[angle=-90,width=7.8cm,clip]{0514fig12.ps} \end{figure}$	Figure 12: Snapshots of protoplanet accretion in the $\gamma$ Cephei system. The initial mass in the embryos is 75 $M_{\oplus }$ and the superficial density $\sigma$ decreases with the radial distance as 1/r.
Open with DEXTER