All Figures

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1463fig1.ps} \end{figure}$ Figure 1: Triplot of the polarization spectra for a rotating disk seen at 3 different inclinations. The assumed Stokes I spectrum is shown in the lowest panel, the degree of linear polarization %Pol is indicated in the middle panel, whilst the PA ( $\theta$ ; see Eq. (2)) is plotted in the upper panel. The solid line is for the disk seen at 30 $^{\circ }$ , the dashed line at 60 $^{\circ }$ , and the dashed-solid line for 85 $^{\circ }$ , which yields the largest continuum polarization, and the smallest PA line-centre rotation.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1463fig2.ps} \end{figure}$ Figure 2: The case of the undisrupted disk. The model inclinations are 15 $^{\circ }$ , 30 $^{\circ }$ , 45 $^{\circ }$ , 60 $^{\circ }$ , and 75 $^{\circ }$ , with the lowest inclination 15 $^{\circ }$ model represented by the solid line, and a gradual decrease in the PA amplitude for increasing inclinations. Note that although the level of continuum polarization is higher for higher inclinations - typically reaching a few percent - they are not all shown, as neither the widths, nor the overall shapes, change in any significant way.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1463fig3.ps} \end{figure}$ Figure 3: QU-plane representation of a double PA rotation. Actually, the normalized Stokes parameters u = U/I and q = Q/I are plotted. The figure represent the case of an undisrupted disk, at an inclination of 15 $^{\circ }$ . The continuum points are situated at the (Q,U) position of (0.35, 0), and the direction of the arrows denotes the increase in wavelength across the line. There are 2 ellipses visible, representative of the double PA rotations in Fig. 2.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1463fig4.ps} \end{figure}$ Figure 4: Varying the size of the disk inner edge: $R_{\rm in}$ = 1, 2, 3 and 5 R_* for an inclination of 45 $^{\circ }$ . The dotted line is for the model $R_{\rm in}$ = 1 R_* (the undisrupted disk), which has the largest PA amplitude.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1463fig5.ps} \end{figure}$ Figure 5: Similar as Fig. 4, but now with the PA axis blown-up, and only with the cases of $R_{\rm in}$ = 3 (dashed) and 5 R_* (solid) repeated.
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In the text

$\begin{figure} \par\includegraphics[width=8.6cm,clip]{1463fig6.ps}\hspace*{4mm} ... ...g8.ps}\hspace*{4mm} \includegraphics[width=8.6cm,clip]{1463fig9.ps} \end{figure}$ Figure 6: QU plane representation of the triplots of Fig. 5. Actually, the normalized Stokes parameters u = U/I and q = Q/I are plotted again. The transition from $R_{\rm in}$ = 1, 2, 3 to 5 R_* is accompanied with a QU transition with the double loop for the undisrupted case, with $R_{\rm in}$ = 1 R_*, through a "butterfly'' shape in the diagram for 3 R_*, to a single QU loop for 5 R_*. The continuum points are situated at a (Q,U) position of approximately (2.5, 0), and the direction of increasing wavelength, as most easily identified in the last plot, is clockwise. Note that at i = 45 $^{\circ }$ these shapes are flatter (narrower in U) than at i = 15 $^{\circ }$ , cf. Fig. 3.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1463fi10.eps} \end{figure}$ Figure 7: The boundaries between the double (grey shaded) and single (black) PA rotations for a range of inclination angles. By convention, 90 $^{\circ }$ is edge-on, 0 $^{\circ }$ is pole-on. In between the single and double PA rotations, one finds transitional (white) behaviour. Note that the kinks in the boundaries are artifacts of the plotting technique.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1463fi11.ps} \end{figure}$ Figure 8: Similar to Figs. 4 and 5, but for an inclination of 60 $^{\circ }$ . The solid line is for the undisrupted disk of 1 R_*, the dashed line is for a disk inner rim at 2 R_*, while the dashed-dotted line is for a disk truncation radius of 5 R_*.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1463fi12.ps} \end{figure}$ Figure 9: Same as in Fig. 8, but for an inclination of 75 $^{\circ }$ .
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1463fi13.ps} \end{figure}$ Figure 10: The amplitude of the double PA rotation, $\sin$ $\Delta$ PA, as a function of disk inclination, $\sin$ i, for the theta disk. The solid line connects the individual data points.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1463fig4.ps} \end{figure}$	Figure 4: Varying the size of the disk inner edge: $R_{\rm in}$ = 1, 2, 3 and 5 R_* for an inclination of 45 $^{\circ }$ . The dotted line is for the model $R_{\rm in}$ = 1 R_* (the undisrupted disk), which has the largest PA amplitude.
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1463fig5.ps} \end{figure}$	Figure 5: Similar as Fig. 4, but now with the PA axis blown-up, and only with the cases of $R_{\rm in}$ = 3 (dashed) and 5 R_* (solid) repeated.
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1463fi10.eps} \end{figure}$	Figure 7: The boundaries between the double (grey shaded) and single (black) PA rotations for a range of inclination angles. By convention, 90 $^{\circ }$ is edge-on, 0 $^{\circ }$ is pole-on. In between the single and double PA rotations, one finds transitional (white) behaviour. Note that the kinks in the boundaries are artifacts of the plotting technique.
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1463fi11.ps} \end{figure}$	Figure 8: Similar to Figs. 4 and 5, but for an inclination of 60 $^{\circ }$ . The solid line is for the undisrupted disk of 1 R_, the dashed line is for a disk inner rim at 2 R_, while the dashed-dotted line is for a disk truncation radius of 5 R_*.
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1463fi12.ps} \end{figure}$	Figure 9: Same as in Fig. 8, but for an inclination of 75 $^{\circ }$ .
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1463fi13.ps} \end{figure}$	Figure 10: The amplitude of the double PA rotation, $\sin$ $\Delta$ PA, as a function of disk inclination, $\sin$ i, for the theta disk. The solid line connects the individual data points.
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