All Figures

$\begin{figure} \par\epsfxsize= 9 cm \epsfbox{Fig1.eps} \end{figure}$ Figure 1: The temperature of the neutral fluid, $T_{\rm n}$ , and the fractional abundances of OH and O₂ ( top panels) and of Si, SiO, and silicon in the grain mantles, $\Sigma$ Si* ( bottom panels), as functions of the flow time of the charged fluid, for two reference C-type shock models: $n_{\rm H} = 10^4$ cm^-3, b = 1, $v_{\rm s} = 25$ km s^-1 ( left-hand panels) and 50 km s^-1 ( right-hand panels). In both models, it is assumed that 5% of the elemental silicon is initially in the mantles, in the form of SiO.
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In the text

$\begin{figure} \par\epsfxsize= 9 cm \epsfbox{Fig2.eps} \end{figure}$ Figure 2: The integrated intensity of the SiO(5-4) line, $\int {T{\rm d}v}(5-4)$ , as a function of the percentage of SiO initially in the grain mantles, for both of the C-type shock models: $n_{\rm H} = 10^4$ cm^-3, b = 1, $v_{\rm s} = 25$ km s^-1 ( lower curve) and 50 km s^-1 ( upper curve). At the lower shock speed, the erosion of Si from the grain cores is negligible compared with the release of SiO from the mantles. The SiO(5-4) intensities observed in L1157 and L1448 are indicated by the horizontal lines.
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In the text

$\begin{figure} \par\epsfxsize= 9 cm \epsfbox{Fig3.eps} \end{figure}$ Figure 3: The integrated intensities of rotational transitions of SiO, relative to the (5-4) line, in stationary C-type shock waves: $n_{\rm H} = 10^4$ cm^-3, b = 1, $v_{\rm s} = 25$ km s^-1 ( upper panel) and 50 km s^-1 ( lower panel). The observational data relate to L1157 B1. The initial fraction of silicon in the form of SiO in the grain mantles varies from 0% to 10%, as indicated. In the lower limit, the SiO which is seen in this figure arises from the erosion of silicates in the grain cores.
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In the text

$\begin{figure} \par\epsfxsize= 9 cm \epsfbox{Fig4.eps} \end{figure}$ Figure 4: Profiles of the SiO rotational transitions (2-1), (3-2), (5-4), (6-5), (8-7), and (10-9) computed in stationary C-type shock waves, for $n_{\rm H} = 10^4$ cm^-3, b = 1, $v_{\rm s} = 25$ km s^-1 ( left panel) and 50 km s^-1 ( right panel). 5% of the elemental silicon is assumed to be initially in the grain mantles, in the form of SiO. The flow speed is in the reference frame of the preshock gas. $T_{\rm n}$ is the temperature of the neutral fluid.
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In the text

$\begin{figure} \par\epsfxsize= 9 cm \epsfbox{Fig5.eps} \end{figure}$ Figure 5: Profiles of the CJ-type shocks specified in Sect. 3.1. The corresponding steady-state C-type shock models are shown also. Left-hand panels: $v_{\rm s} = 25$ km s^-1; right-hand panels: $v_{\rm s} = 50$ km s^-1. In the middle panels, the full curves correspond to the neutrals and the broken curves to the ions. In the bottom panels, the full curves correspond to the compression factor, and the broken curves to the fractional abundance of H₂.
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In the text

$\begin{figure} \par\epsfxsize= 9 cm \epsfbox{Fig6.eps} \end{figure}$ Figure 6: Synthetic H₂ excitation diagrams for the CJ-type shocks specified in Sect. 3.1.
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In the text

$\begin{figure} \par\epsfxsize= 9 cm \epsfbox{Fig7.eps} \end{figure}$ Figure 7: The temperature of the neutral fluid, $T_{\rm n}$ , and the fractional abundances of OH and O₂ ( left-hand panels) and of Si, SiO, and silicon in the grain mantles, $\Sigma$ Si* (right-hand panels), as functions of the flow time of the charged fluid, for the CJ-type shock model in which $n_{\rm H} = 10^4$ cm^-3, b = 1, and $v_{\rm s} = 50$ km s^-1. The shock age increases from top to bottom: 500, 1800, 3800 yr, and steady-state. In these calculations, there is no SiO in the grain mantles, and the gas-phase silicon is produced solely by erosion of the silicate grain cores.
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In the text

$\begin{figure} \par\epsfxsize= 8.2 cm \epsfbox{Fig8.eps} \end{figure}$ Figure 8: The integrated intensities, $\int {T{\rm d}v}$ , of the SiO (2-1), (5-4) and (10-9) rotational transitions, as functions of the flow time of the charged fluid, for the CJ-type shock model in which $n_{\rm H} = 10^4$ cm^-3, b = 1, and $v_{\rm s} = 50$ km s^-1. The shock age increases from top to bottom: 500, 1800, 3800 yr, and steady-state. The temperature of the neutral fluid, $T_{\rm n}$ , is plotted also. In these calculations, there is no SiO in the grain mantles, and the gas-phase silicon is produced solely by erosion of the silicate grain cores.
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In the text

$\begin{figure} \par\epsfxsize= 9 cm \epsfbox{Fig9.eps} \end{figure}$ Figure 9: Integrated SiO line intensities, relative to the (5-4) transition, for the CJ-type shock model in which $n_{\rm H} = 10^4$ cm^-3, b = 1, and $v_{\rm s} = 50$ km s^-1. The shock ages are 500, 1800, 3800 yr, and the corresponding steady-state results are plotted also. In these calculations, there is no SiO in the grain mantles, and the gas-phase silicon is produced solely by erosion of the silicate grain cores. The observed points, with error bars, relate to L1157 B1.
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In the text

$\begin{figure} \par\epsfxsize= 9 cm \epsfbox{Fig10.eps} \end{figure}$ Figure 10: The integrated intensity of the SiO(5-4) line, $\int {T{\rm d}v}(5-4)$ , as a function of the age of the shock wave and the percentage of silicon initially in the form of SiO in the grain mantles; $n_{\rm H} = 10^4$ cm^-3, b = 1, $v_{\rm s} = 25$ km s^-1 ( upper panel) and 50 km s^-1 ( lower panel). The points corresponding to the limit of steady-state are plotted on the right-hand y-axis. The SiO(5-4) intensities observed in L1157 and L1448 are indicated by the horizontal lines.
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In the text

$\begin{figure} \par\epsfxsize= 9 cm \epsfbox{Fig11.eps} \end{figure}$ Figure 11: Integrated SiO line intensities, relative to the (5-4) transition, for the CJ-type shock models in which $n_{\rm H} = 10^4$ cm^-3, b = 1, and $v_{\rm s} = 25$ km s^-1 ( upper panel) and $v_{\rm s} = 50$ km s^-1 ( lower panel). The evolutionary ages of the shocks are indicated, and the corresponding steady-state results are plotted also. In these calculations, 5% of the elemental silicon is assumed to be initially in the grain mantles, in the form of SiO. The observed points, with error bars, relate to L1157 B1. The highest rotational level for which observations are available, $j_{\rm up} = 10$ , lies 115 K above the ground state.
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In the text

$\begin{figure} \par\epsfxsize= 9 cm \epsfbox{Fig12.eps} \end{figure}$ Figure 12: Composite H₂ excitation diagrams, corrected for reddening with $A_{\rm V} = 2$ ; see text, Sect. 4.1. The excitation temperatures deduced from each set of observations are indicated.
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In the text

$\begin{figure} \par\epsfxsize= 9 cm \epsfbox{Fig13.eps} \end{figure}$ Figure 13: The observed and calculated values of the H₂ 0-0 S(5) emission line flux, plotted as functions of the mean excitation temperature of the rotational lines within the v = 0 vibrational ground state. The corresponding values of the column density per magnetic sub-level are given on the right-hand axis for the (v = 0, j = 7) emitting level, whose degeneracy is g₇ = 45. Results are given for L1157 B1, as observed by ISO (two separate pixels, pix1 and pix2) and for a series of models of (stationary) C-type (b = 1) shock waves (red curve) for ranges of the shock speed, $v_{\rm s}$ , in steps of 5 km s^-1 between the limiting values indicated. Also shown are the results for an evolutionary sequence of non-stationary CJ-type (b = 1) models (green curve), for $v_{\rm s} = 25$ km s^-1, and for J-type (b = 0.1) models (blue curve) with $v_{\rm s} = 20$ , 25 and 30 km s^-1. In all cases, the pre-shock density is $n_{\rm H} = 10^4$ cm^-3.
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In the text

$\begin{figure} \par\epsfxsize= 9 cm \epsfbox{Fig14.eps} \end{figure}$ Figure 14: Three models of the H₂ excitation diagram of L1157 B1: CJ-type $n_{\rm H} = 10^4$ cm^-3, $v_{\rm s} = 20$ km s^-1, b = 1, age 850 yr ( top panel); CJ-type $n_{\rm H} = 10^{5}$ cm^-3, $v_{\rm s} = 12$ km s^-1, b = 1, age 240 yr ( middle panel); J-type $n_{\rm H} = 10^{5}$ cm^-3, $v_{\rm s} = 12$ km s^-1, b = 0.1 ( bottom panel). The observations are from Caratti o Garatti et al. (2006) and Cabrit et al. (1999); see also Appendix A.
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In the text

$\begin{figure} \par\epsfxsize= 9 cm \epsfbox{Fig15.eps} \end{figure}$ Figure 15: The integrated intensity of the SiO(5-4) line, $\int {T{\rm d}v}(5-4)$ , against the magnetic field parameter, b, for CJ-type shocks of various ages in which the pre-shock density $n_{\rm H} = 10^4$ cm^-3, the shock velocity $v_{\rm s} = 20$ , 22, and 25 km s^-1 ( upper panel), and $n_{\rm H} = 10^{5}$ cm^-3, $v_{\rm s} = 12$ and 15 km s^-1 ( lower panel). Results were obtained assuming either 10% (full curves) or 1% (broken curves) of the silicon is initially SiO in the grain mantles.
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In the text

$\begin{figure} \par\epsfxsize= 9 cm \epsfbox{Fig16.eps} \end{figure}$ Figure 16: The best-fitting models of the H₂ and SiO observations of L1157 B1: CJ-type shocks for which $n_{\rm H} = 10^4$ cm^-3 and $v_{\rm s} = 20$ km s^-1; the magnetic field parameter, b and the evolutionary age are varied simultaneously. 10% of the silicon is initially SiO in the grain mantles.
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In the text

$\begin{figure} \par\epsfxsize= 9 cm \epsfbox{FigA1.eps} \end{figure}$ Figure A.1: A map of the L1157 outflow (Cabrit et al. 1999) obtained with ISOCAM in a narrow filter ( $R \approx 40$ ), centered on the 0-0 S(5) line at 6.9 $\mu$ m, and superposed on the CO map of Bachiller & Pérez-Guttiérez (1997).
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In the text

$\begin{figure} \par\epsfxsize= 9 cm \epsfbox{FigA2.eps} \end{figure}$ Figure A.2: Left panel: the LW3 ISOCAM image of the southern blue lobe of L1157 superposed on the SiO (2-1) contours of Gueth et al. (1998). Right panel: the LW2 ISOCAM image of the southern blue lobe of L1157 superposed on the contours of the H₂ 2.12 $\mu$ m (plus continuum) emission from Davis & Eisloeffel (1995).
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In the text

$\begin{figure} \par\epsfxsize= 9 cm \epsfbox{FigB1.eps} \end{figure}$ Figure B.1: The integrated intensities of the CO rotational lines, $\int {T{\rm d}v}$ , for CJ-type shocks for which $n_{\rm H} = 10^4$ cm^-3 and $v_{\rm s} = 20$ km s^-1; the magnetic field parameter, b and the evolutionary age are varied simultaneously.
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In the text

$\begin{figure} \par\epsfxsize= 9 cm \epsfbox{Fig6.eps} \end{figure}$	Figure 6: Synthetic H₂ excitation diagrams for the CJ-type shocks specified in Sect. 3.1.
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$\begin{figure} \par\epsfxsize= 9 cm \epsfbox{Fig12.eps} \end{figure}$	Figure 12: Composite H₂ excitation diagrams, corrected for reddening with $A_{\rm V} = 2$ ; see text, Sect. 4.1. The excitation temperatures deduced from each set of observations are indicated.
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$\begin{figure} \par\epsfxsize= 9 cm \epsfbox{Fig16.eps} \end{figure}$	Figure 16: The best-fitting models of the H₂ and SiO observations of L1157 B1: CJ-type shocks for which $n_{\rm H} = 10^4$ cm^-3 and $v_{\rm s} = 20$ km s^-1; the magnetic field parameter, b and the evolutionary age are varied simultaneously. 10% of the silicon is initially SiO in the grain mantles.
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$\begin{figure} \par\epsfxsize= 9 cm \epsfbox{FigA1.eps} \end{figure}$	Figure A.1: A map of the L1157 outflow (Cabrit et al. 1999) obtained with ISOCAM in a narrow filter ( $R \approx 40$ ), centered on the 0-0 S(5) line at 6.9 $\mu$ m, and superposed on the CO map of Bachiller & Pérez-Guttiérez (1997).
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$\begin{figure} \par\epsfxsize= 9 cm \epsfbox{FigA2.eps} \end{figure}$	Figure A.2: Left panel: the LW3 ISOCAM image of the southern blue lobe of L1157 superposed on the SiO (2-1) contours of Gueth et al. (1998). Right panel: the LW2 ISOCAM image of the southern blue lobe of L1157 superposed on the contours of the H₂ 2.12 $\mu$ m (plus continuum) emission from Davis & Eisloeffel (1995).
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$\begin{figure} \par\epsfxsize= 9 cm \epsfbox{FigB1.eps} \end{figure}$	Figure B.1: The integrated intensities of the CO rotational lines, $\int {T{\rm d}v}$ , for CJ-type shocks for which $n_{\rm H} = 10^4$ cm^-3 and $v_{\rm s} = 20$ km s^-1; the magnetic field parameter, b and the evolutionary age are varied simultaneously.
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