All Figures

$\begin{figure} \par\includegraphics[height=5.4cm,width=7.5cm,clip]{0435fig1.eps} \end{figure}$ Figure 1: Diffusivity: average radial magnetic diffusivity $\eta$ (m²/s) in the model of Betelgeuse as a function of radial distance in solar radii $R_{\odot }$ . Adopted from Dorch & Freytag (2002).
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In the text

$\begin{figure} \par\includegraphics[width=7cm,clip]{0435fig2.eps} \end{figure}$ Figure 2: Simulated surface intensity snapshots at four different instants, time = 256, 347, 457 and 494 years (from upper left to lower right).
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In the text

$\begin{figure} \par\includegraphics[width=6.5cm,clip]{0435fig3.eps} \end{figure}$ Figure 3: Powerspectrum of u²(k) at time = 457 years, and a line corresponding to Kolmogorov scaling (dashed line). The vertical lines, from left to right, denote the wavenumbers corresponding to the computational box size k₀, the stellar radius $k_{\rm R}$ , and the Nyquist frequency $k_{\rm Ny}$ (the numerical resolution).
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In the text

$\begin{figure} \par\includegraphics[width=6.4cm,clip]{0435fig4.eps} \end{figure}$ Figure 4: Linear regime: energy as a function of Betelgeusian time in years. The upper almost horizontal line is total thermal energy $E_{\rm th}$ (dashed-dotted), middle curve with wiggles is total kinetic energy $E_{\rm kin}$ (dotted), and lower full curve is $E_{\rm mag}$ . The three thin dashed lines corresponding to exponential growth with characteristic time-scales of 3.8, 25 and $\infty$ years.
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In the text

$\begin{figure} \par\includegraphics[width=7cm,clip]{0435fig5.eps} \end{figure}$ Figure 5: Transition to the non-linear regime: rms magnetic field B in the whole computational box in Gauss as a function of Betelgeusian time in years. The upper curve is the equipartition field strength $B_{\rm eq}$ corresponding to the average kinetic energy density of the fluid motions (dotted curve) and the lower full curve is the actual rms field strength B (full curve). The dashed thin curve correspond to growth times of 25 years and a horizontal reference line at a field strength of 100 Gauss.
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In the text

$\begin{figure} \par\includegraphics[width=7cm,clip]{0435fig6.eps} \end{figure}$ Figure 6: Distribution of magnetic field strength: PDF for the magnetic field |B| (in kG) at time = 732 years within the non-linear saturated regime.
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In the text

$\begin{figure} \par\includegraphics[width=7cm,clip]{0435fig7.eps} \end{figure}$ Figure 7: Energy spectra of the magnetic energy density $B^2/2\mu _0(k)$ (solid curve) and kinetic energy density $\frac{1}{2} \rho {u}^2(k)$ (dashed curve) at time = 512 years, and a line corresponding to a power-law with an exponent of -2/3 (dashed-dotted line). The vertical lines, from left to right, denote the wavenumbers corresponding to the computational box size k₀, the stellar radius $k_{\rm R}$ , and the Nyquist frequency $k_{\rm Ny}$ (the numerical resolution).
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In the text

$\begin{figure} \par\includegraphics[width=7cm,clip]{0435fig8.eps} \end{figure}$ Figure 8: Magnetic filling factor as a function of radius (solid curve): shown is the relative volume that is occupied by a field stronger than 1% of the maximum magnetic field strength at time = 695 years, which is 1.4 kG. Also shown is the average field $\langle {B} \rangle$ scaled to fit the maximum of the filling factor (dashed curve).
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In the text

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{0435fg9a.eps}\hspace*{4mm} \includegraphics[width=8.2cm,clip]{0435fg9b.eps} \end{figure}$ Figure 9: An illustration of the unsigned magnetic field strength |B|at the spherical surface r = R of the model star using an orthographic map projection. The darkest patches correspond to a maximum field strength of 500 Gauss (black on the continuous scale bar). From a snapshot at time = 695 years. The views are centered on longitudes of $100\hbox {$^\circ $ }$ ( left) and $-100\hbox {$^\circ $ }$ ( right). The grid indicated has a longitudinal spacing of $40\hbox {$^\circ $ }$ and a latitudinal spacing of $20\hbox {$^\circ $ }$ . The numerical resolution of the map is 180² grid points.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{0435fg10.eps} \end{figure}$ Figure 10: A 3-d volume rendering of magnetic field lines (white) and flux ropes (dark structures). Also show is a isosurface (transparent) at the surface temperature value.
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In the text

$\begin{figure} \par\includegraphics[height=5.4cm,width=7.5cm,clip]{0435fig1.eps} \end{figure}$	Figure 1: Diffusivity: average radial magnetic diffusivity $\eta$ (m²/s) in the model of Betelgeuse as a function of radial distance in solar radii $R_{\odot }$ . Adopted from Dorch & Freytag (2002).
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$\begin{figure} \par\includegraphics[width=7cm,clip]{0435fig2.eps} \end{figure}$	Figure 2: Simulated surface intensity snapshots at four different instants, time = 256, 347, 457 and 494 years (from upper left to lower right).
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$\begin{figure} \par\includegraphics[width=6.5cm,clip]{0435fig3.eps} \end{figure}$	Figure 3: Powerspectrum of u²(k) at time = 457 years, and a line corresponding to Kolmogorov scaling (dashed line). The vertical lines, from left to right, denote the wavenumbers corresponding to the computational box size k₀, the stellar radius $k_{\rm R}$ , and the Nyquist frequency $k_{\rm Ny}$ (the numerical resolution).
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$\begin{figure} \par\includegraphics[width=7cm,clip]{0435fig6.eps} \end{figure}$	Figure 6: Distribution of magnetic field strength: PDF for the magnetic field \|B\| (in kG) at time = 732 years within the non-linear saturated regime.
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$\begin{figure} \par\includegraphics[width=7cm,clip]{0435fig8.eps} \end{figure}$	Figure 8: Magnetic filling factor as a function of radius (solid curve): shown is the relative volume that is occupied by a field stronger than 1% of the maximum magnetic field strength at time = 695 years, which is 1.4 kG. Also shown is the average field $\langle {B} \rangle$ scaled to fit the maximum of the filling factor (dashed curve).
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{0435fg10.eps} \end{figure}$	Figure 10: A 3-d volume rendering of magnetic field lines (white) and flux ropes (dark structures). Also show is a isosurface (transparent) at the surface temperature value.
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