All Figures

$\begin{figure} {\psfig{file=h4276f1.eps,width=8.8cm} } \end{figure}$ Figure 1: The line intensity ratio I(SiO, J=2 $\rightarrow$ 1)/I(CO, J=1 $\rightarrow$ 0) as a function of a mass-loss rate measure (detections are shown as filled symbols, while tentative and negative results are shown as open symbols; see Olofsson et al. 1998 for more details).
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In the text

$\begin{figure} {\psfig{file=aah4276f2.eps,width=8cm} } \end{figure}$ Figure 2: $\chi ^2$ contours (at the 1, 2, and 3 $\sigma$ levels) in the SiO abundance and envelope size plane for two stars. In the case of RX Boo there is a sufficient number of lines, including high-J ones, to constrain the size of the SiO envelope. In the case of R Dor the high-J line data are missing and only a lower limit can be obtained (since we do not expect the SiO envelope to be larger than the CO envelope).
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In the text

$\begin{figure} {\psfig{file=h4276f3.eps,width=8.8cm,angle=-90} } \end{figure}$ Figure 3: SiO photodissociation radii (obtained using the unshielded photodissociation rate G₀ = 2.5 $\times$ 10^-10 s^-1) versus the estimated sizes of the SiO envelopes (IRV: square; SRV: circle; Mira: triangle). The dashed line shows the one-to-one relation.
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In the text

$\begin{figure} {\psfig{file=h4276f4.eps,width=8.8cm,angle=-90} } \end{figure}$ Figure 4: The sizes of the SiO envelopes estimated from the SiO line modelling are plotted versus a density measure (open circles). The dashed line gives the relation between the SiO envelope size and the density measure given in Eq. (13). Half intensity radii derived from interferometric SiO(J=2 $\rightarrow$ 1) observations are shown as solid circles. The solid line is the fit to the data given in Eq. (14).
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In the text

$\begin{figure} {\psfig{file=h4276f5.eps,width=8.8cm,angle=-90} } \end{figure}$ Figure 5: SiO fractional abundances versus the mass-loss rate (IRV: square, SRV: circle, Mira: triangle). The horizontal line marks the maximum abundance allowed by solar abundances. The dashed line shows the expected $f(\infty )$ (scaled to $5\times 10^{-5}$ , roughly the expected abundance from stellar equilibrium chemistry, at very low mass-loss rates) for the parameters given in Sect. 8.
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In the text

$\begin{figure} {{\includegraphics[width=18cm]{h4276f6.eps} }} \end{figure}$ Figure 6: Comparison of observed CO (upper) and SiO (lower) line profiles (in histogram form) for R Dor (left) and R Hya (middle) and GX Mon (right). The corresponding best-fit (i.e., to all observed line intensities) model SiO lines are also shown as solid lines.
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In the text

$\begin{figure} {\psfig{file=h4276f7.eps,width=8.8cm,angle=-90} } \end{figure}$ Figure 7: The derived CO gas expansion velocities as a function of the mass-loss rates for the IRV (squares), SRV (circles), and Mira (triangles) samples. The dashed line shows the correlation found for the IRV/SRV sample (see text).
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In the text

$\begin{figure} \par\includegraphics[width=14.7cm,clip]{h4276f8.eps} \end{figure}$ Figure 8: L² Pup SiO line spectra and a CO(J=3 $\rightarrow$ 2) spectrum (from Olofsson et al. 2002).
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In the text

$\begin{figure} \par\includegraphics[width=18cm,clip]{h4276fb1.eps} \end{figure}$ Figure B.1: SiO spectra of M-type IRVs. Note the heliocentric velocity scale.

In the text

$\begin{figure} \par\includegraphics[width=18cm,clip]{h4276fb2.eps} \end{figure}$ Figure B.2: SiO spectra of M-type SRVs (Part 1). Note the heliocentric velocity scale.

In the text

$\begin{figure} \par\includegraphics[width=18cm,clip]{h4276fb3.eps} \end{figure}$ Figure B.3: SiO spectra of M-type SRVs (Part 2). Note the heliocentric velocity scale.

In the text

$\begin{figure} \par\includegraphics[width=18cm,clip]{h4276fb4.eps} \end{figure}$ Figure B.4: SiO spectra of M-type SRVs (Part 3). Note the heliocentric velocity scale.

In the text

$\begin{figure} \par\includegraphics[width=18cm,clip]{h4276fb5.eps} \end{figure}$ Figure B.5: SiO spectra of M-type Miras. Note the LSR velocity scale.

In the text

$\begin{figure} {\psfig{file=h4276f1.eps,width=8.8cm} } \end{figure}$	Figure 1: The line intensity ratio I(SiO, J=2 $\rightarrow$ 1)/I(CO, J=1 $\rightarrow$ 0) as a function of a mass-loss rate measure (detections are shown as filled symbols, while tentative and negative results are shown as open symbols; see Olofsson et al. 1998 for more details).
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$\begin{figure} {\psfig{file=h4276f3.eps,width=8.8cm,angle=-90} } \end{figure}$	Figure 3: SiO photodissociation radii (obtained using the unshielded photodissociation rate G₀ = 2.5 $\times$ 10^-10 s^-1) versus the estimated sizes of the SiO envelopes (IRV: square; SRV: circle; Mira: triangle). The dashed line shows the one-to-one relation.
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$\begin{figure} {\psfig{file=h4276f5.eps,width=8.8cm,angle=-90} } \end{figure}$	Figure 5: SiO fractional abundances versus the mass-loss rate (IRV: square, SRV: circle, Mira: triangle). The horizontal line marks the maximum abundance allowed by solar abundances. The dashed line shows the expected $f(\infty )$ (scaled to $5\times 10^{-5}$ , roughly the expected abundance from stellar equilibrium chemistry, at very low mass-loss rates) for the parameters given in Sect. 8.
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$\begin{figure} {{\includegraphics[width=18cm]{h4276f6.eps} }} \end{figure}$	Figure 6: Comparison of observed CO (upper) and SiO (lower) line profiles (in histogram form) for R Dor (left) and R Hya (middle) and GX Mon (right). The corresponding best-fit (i.e., to all observed line intensities) model SiO lines are also shown as solid lines.
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$\begin{figure} {\psfig{file=h4276f7.eps,width=8.8cm,angle=-90} } \end{figure}$	Figure 7: The derived CO gas expansion velocities as a function of the mass-loss rates for the IRV (squares), SRV (circles), and Mira (triangles) samples. The dashed line shows the correlation found for the IRV/SRV sample (see text).
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$\begin{figure} \par\includegraphics[width=14.7cm,clip]{h4276f8.eps} \end{figure}$	Figure 8: L² Pup SiO line spectra and a CO(J=3 $\rightarrow$ 2) spectrum (from Olofsson et al. 2002).
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