All Figures

$\begin{figure} \par\includegraphics[width=8.5cm,clip]{MS3549f1.eps} \end{figure}$ Figure 1: Two possible configurations considered in the present model: a) the whole disk is incompressible and extends onto the proto-star; and b) the disk is incompressible until an "interaction radius'' imposed for instance by a magnetic field.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=8.2cm,clip]{MS3549f2.ps} \end{figure}$ Figure 2: Velocity profile in a circumstellar disk in the viscous regime, with Keplerian velocity in the outer part, and smooth matching onto the central object at the interaction radius. For this example, the mass of the central star has been taken as a solar mass.
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In the text

$\begin{figure} \par\includegraphics[width=8.3cm,clip]{MS3549f3.eps} \end{figure}$ Figure 3: Midplane ionization fraction due to thermal contribution (dot-dashed line) and X-ray contribution (dot-dotted line). The solid line is the limiting ionization fraction, below which the ionization does not influence molecular transport. The shaded area is the region whereionization has to be taken into account in the computation of theviscosity.
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In the text

$\begin{figure} \par\includegraphics[width=8.1cm,clip]{MS3549f4.eps} \end{figure}$ Figure 4: Physical local Reynolds number in circumstellar disks as a function of radius (dotted-line with symbols). The dashed-dotted line and the full line are the critical Reynolds number deduced from laboratory experiments, see Dubrulle et al. (2004).
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In the text

$\begin{figure} \par\includegraphics[width=8.5cm,clip]{MS3549f5.eps} \end{figure}$ Figure 5: Comparison between the non-dimensional energy dissipation predicted from laboratory measurements in the wide gap limit ( dotted lines) or in the small gap limit ( plain lines) and observed in circumstellar disks ( symbols), as a function of the Reynolds number ${\rm Re}_{\rm phys}$ . For an easier comparison, the mean energy dissipation has been translated into the non-dimensional accretion rate $\dot{M}/\dot{M}_{0}$ (computed using Eq. (45) and observationally determined parameters reported in Table 1). The symbols $\boxplus$ report the value using $r_{\rm i}=r_{\rm coro}$ , which provides an upper bound of the energy dissipation. The circles report the value using $r_{\rm i}=r_\ast$ , which provides the lower bound of the energy dissipation. All the quantities have been computed using temperature and density estimated for the DM Tau system using the results of Guilloteau & Dutrey (1998), so there is no adjustable parameter in this plot.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=7.9cm,clip]{MS3549f6.ps} \end{figure}$ Figure 6: Distribution of luminosity fluctuations observed disk around BP Tau ( symbols) compared with a log-normal distribution of various variance $\Delta$ ( plain line). The value of $\Delta$ is indicated beside each line.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=7.8cm,clip]{MS3549f7.ps} \end{figure}$ Figure 7: Distribution of luminosity fluctuations observed disk around V1057 Cyg ( symbols) compared with a log-normal distribution of variance $\Delta =0.03$ ( plain line).
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In the text

$\begin{figure} \par\includegraphics[width=8.5cm,clip]{MS3549f1.eps} \end{figure}$	Figure 1: Two possible configurations considered in the present model: a) the whole disk is incompressible and extends onto the proto-star; and b) the disk is incompressible until an "interaction radius'' imposed for instance by a magnetic field.
Open with DEXTER

$\begin{figure} \par\includegraphics[angle=270,width=8.2cm,clip]{MS3549f2.ps} \end{figure}$	Figure 2: Velocity profile in a circumstellar disk in the viscous regime, with Keplerian velocity in the outer part, and smooth matching onto the central object at the interaction radius. For this example, the mass of the central star has been taken as a solar mass.
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$\begin{figure} \par\includegraphics[width=8.3cm,clip]{MS3549f3.eps} \end{figure}$	Figure 3: Midplane ionization fraction due to thermal contribution (dot-dashed line) and X-ray contribution (dot-dotted line). The solid line is the limiting ionization fraction, below which the ionization does not influence molecular transport. The shaded area is the region whereionization has to be taken into account in the computation of theviscosity.
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$\begin{figure} \par\includegraphics[width=8.1cm,clip]{MS3549f4.eps} \end{figure}$	Figure 4: Physical local Reynolds number in circumstellar disks as a function of radius (dotted-line with symbols). The dashed-dotted line and the full line are the critical Reynolds number deduced from laboratory experiments, see Dubrulle et al. (2004).
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$\begin{figure} \par\includegraphics[angle=270,width=7.9cm,clip]{MS3549f6.ps} \end{figure}$	Figure 6: Distribution of luminosity fluctuations observed disk around BP Tau ( symbols) compared with a log-normal distribution of various variance $\Delta$ ( plain line). The value of $\Delta$ is indicated beside each line.
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$\begin{figure} \par\includegraphics[angle=270,width=7.8cm,clip]{MS3549f7.ps} \end{figure}$	Figure 7: Distribution of luminosity fluctuations observed disk around V1057 Cyg ( symbols) compared with a log-normal distribution of variance $\Delta =0.03$ ( plain line).
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