Astronomy & Astrophysics

All Figures

$\begin{figure} \par\includegraphics[width=8cm,clip]{2595fig1.eps} \end{figure}$ Figure 1: A schematic representation of a uniform ellipsoid and one orbit.
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In the text

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{2595fig2.eps} \end{figure}$ Figure 2: Lagrangian radii (10, 20, ..., 90%) for the simulation with a=50 pc and $\rho /\rho _{0}=0.1$ . The large figure shows the time interval during which the distribution is stable; the small figure shows the whole simulation.
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In the text

$\begin{figure} \par\includegraphics[width=7.4cm,clip]{2595fig3.eps} \end{figure}$ Figure 3: Dissolution time as a function of the initial density of the particle distribution for different values of a. Three-pointed stars correspond to a=50 pc, crosses to a=500 pc and five-pointed stars to a=1000 pc. The dissolution time is a decreasing function of $\rho$ , except for $\rho /\rho _{0} > 1.0$ . In this case the distribution is indeed unstable (according to our criterion), but before expanding it undergoes a slight initial collapse which leaves behind a small bound core.
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In the text

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{2595fig4.eps}\vspace*{2mm} \par\includegraphics[width=7.5cm,clip]{2595fig5.eps} \end{figure}$ Figure 4: Upper: orbits (in the co-moving cluster frame, for $t\leq 2$ Gyr) of three particles in the simulation with a=50 pc and $\rho /\rho _{0}=0.1$ . For clarity two of the orbits have been shifted in the x-direction by $\pm 100$ pc. One clearly sees the growing deviation from simple epicyclic motion. Lower: x (short dashed) and y (solid) residuals (i.e. coordinates with the epicyclic solution subtracted) for the above three particles as functions of time. The dotted (x) and long dashed (y) lines show fitting functions for an exponential growing solution. Again for clarity the curves of two particles are shifted by $\pm 25$ pc.
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In the text

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{2595fig6.eps}\vspace*{2mm} \par\includegraphics[width=7.3cm,clip]{2595fig7.eps} \end{figure}$ Figure 5: Upper: difference between the current half-mass radius $r_{\rm h}$ and the half-mass radius at the beginning of the calculations $r_{\rm h,0}$ . All values are taken from simulations with a=50 pc and varying density (from left to right: 1.0, 0.5, 0.1, 0.05 and 0.01 times the background density). Lower: ratio of $r_{\rm h}$ and $r_{\rm h,0}$ for the same calculations. (The almost horizontal plot is a test calculation in which self-gravity was neglected in both the initial conditions and in the run. For this model the only evolutionary mechanism is the inexactness of the epicyclic approximation.) The phase of exponential growth is clearly visible. If the half-mass radius gets very large then the self-gravity of the system is negligible, and one sees the effects of epicyclic drift: the curves change to a linear growth.
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In the text

$\begin{figure} \par\includegraphics[width=7.1cm,clip]{2595fig8.eps} \end{figure}$ Figure 6: Dissolution time as a function of the size a of the system. The density is kept constant at $\rho /\rho _{0}=0.1$ .
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In the text

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{2595fig9.eps} \end{figure}$ Figure 7: Surface density profile of the simulation with a=50 pc and $\rho /\rho _{0}=0.1$ at times t=1 Gyr (crosses), t=5 Gyr (five-pointed stars) and t=10 Gyr (six-pointed stars) measured in concentric radial bins centred on the object and looking along the Z-axis. Also shown are the fitting lines for the t=10 Gyr data. Short dashed line is the horizontal fit for the inner part, long dashed line the power law fit for the outer part and the solid curve is an exponential fit.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{2595fig1.eps} \end{figure}$	Figure 1: A schematic representation of a uniform ellipsoid and one orbit.
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$\begin{figure} \par\includegraphics[width=7.5cm,clip]{2595fig2.eps} \end{figure}$	Figure 2: Lagrangian radii (10, 20, ..., 90%) for the simulation with a=50 pc and $\rho /\rho _{0}=0.1$ . The large figure shows the time interval during which the distribution is stable; the small figure shows the whole simulation.
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$\begin{figure} \par\includegraphics[width=7.1cm,clip]{2595fig8.eps} \end{figure}$	Figure 6: Dissolution time as a function of the size a of the system. The density is kept constant at $\rho /\rho _{0}=0.1$ .
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