Astronomy & Astrophysics

All Figures

$\begin{figure} \par\includegraphics[width=8cm,clip]{5786fg01.ps}\end{figure}$ Figure 1: The field in OMC1 covered in the present observations. The data consist of three regions marked East, West and North. Data show emission in the H₂ v=1-0 S(1) line. The values on the greyscale bar are in units of 10^-5 W m^-2 sr^-1. Axes are labelled in arcseconds from the reference position of TCC0016: 05 $^{\rm h}$ 35 $^{\rm m}$ 14 $.\!\!^{\rm s}$ 91, -05 $^\circ$ 22 $^\prime$ 39 $.\!\!^{\prime\prime}$ 31 (J2000).
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In the text

$\begin{figure} \par\includegraphics[width=17cm,clip]{5786fg02CMJN.eps}\end{figure}$ Figure 2: A map of the approximate o/p ratio, $\phi _{10}$ , calculated from v=1-0 S(0) and S(1) emission, for the field identified in Fig. 1 estimated using Eq. (5). The area in grey represents regions in which emission is below specified signal levels (see text). The colour bar is for $\phi _{10}$ . Coordinates are relative to TCC0016 as in Fig. 1. Original images have been smoothed using a boxcar average over $7\times 7$ pixels. The three large squares delineated by grey borders are named East, West and North, as illustrated in Fig. 1. The black rectangles, A1+A2, B and C, delineate regions which have been chosen for special study.
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In the text

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{5786fg03.ps}\end{figure}$ Figure 3: a) Region North: brightness of v=1-0 S(1) vs. the line ratio R₁₀. b) Region West : similarly for the blueshifted clumps in this zone. c) Region East. All data have been rebinned to $500\times 500$ pixels from the original field size of $2000\times 2000$ pixels. The effective pixel size becomes 0 $.\!\!^{\prime\prime}$ 14 or 3 times better than the resolution. The grey oblongs identify those parts of the data whose characteristics are given in Table 1.
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In the text

$\begin{figure} \par\includegraphics[width=7.3cm,clip]{5786fg04.ps}\end{figure}$ Figure 4: Temporal evolution of the ${\it o/p}$ ratio in cold gas at T=10 K and $n_{\rm H}=10^5$ cm^-3 in a chemical steady-state gas-phase model. The initial o/p ratio is set to 3.0.
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In the text

$\begin{figure} \par\includegraphics[width=7.2cm,clip]{5786fg05.ps}\end{figure}$ Figure 5: Maximum local o/p ratios in C-type shocks, with magnetic scaling factor, b equal to 1, as a function of temperature for different preshock densities. Para- to ortho-H₂ interconversion begins at $\sim$ 800 K and is complete at $\sim$ 3200 K.
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In the text

$\begin{figure} \par\includegraphics[width=7.2cm,clip]{5786fg06.ps}\end{figure}$ Figure 6: Comparison of the ${\it o/p}$ ratio, local and integrated as specified, $\phi _{10}$ and R₁₀ as a function of position within a C-type shock with preshock density of $1\times 10^6$ cm^-3, shock velocity 20 km s^-1, initial ${\it o/p}$ ratio 0.01 and b=1.
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In the text

$\begin{figure} \par\includegraphics[width=7.2cm,clip]{5786fg07.ps}\end{figure}$ Figure 7: Maximum C-type shock temperature as a function of shock velocity for different preshock densities. The shaded area indicates the region in which net interconversion between ortho- and para-H₂ takes place ( $\sim$ 800-3200 K). The temperature is independent of initial o/p ratio and b=1.
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In the text

$\begin{figure} \par\includegraphics[width=7.2cm,clip]{5786fg08.ps}\end{figure}$ Figure 8: C-type shock widths as a function of shock velocity for different preshock densities (b=1).
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In the text

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{5786fg09.ps}\end{figure}$ Figure 9: Local brightness in v=1-0 S(1), S(0) and v=2-1 S(1) H₂ emission lines in the evolution of a C-type shock with initial shock velocity 20 km s^-1, preshock density $1\times 10^6$ cm^-3, initial o/p ratio 0.01 and the magnetic scaling factor, b, equal to 1. The kinetic temperature of the shock is shown as a solid line. Zero distance is set to be the point at which the kinetic temperature starts to rise.
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In the text

$\begin{figure} \par\includegraphics[width=7.2cm,clip]{5786fg10.ps}\end{figure}$ Figure 10: Brightness of the v=1-0 S(1) line as a function of C-type shock velocity for different preshock densities. The brightness is almost independent of initial ${\it o/p}$ ratio. It is shown here for ${\it o/p}_{\rm ini}=3$ .0 and b=1.
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In the text

$\begin{figure} \par\includegraphics[width=7.2cm,clip]{5786fg11.ps}\end{figure}$ Figure 11: Brightness of the v=1-0 S(0) line as a function of C-type shock velocity for different preshock densities and b=1, using the same linestyle as in Fig. 10. Each of the 4 diagrams shows a different value of ${\it o/p}_{\rm ini}$ as labelled.
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In the text

$\begin{figure} \par\includegraphics[width=7.2cm,clip]{5786fg12.ps}\end{figure}$ Figure 12: $\phi _{10}$ as a function of C-type shock velocity for different preshock densities and b=1. Each plot shows a different value of integrated o/p ranging from 0.01 to 3.0. Linestyles specifying pre-shock density are as in the previous Fig. 10.
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In the text

$\begin{figure} \par\includegraphics[width=7.4cm,clip]{5786fg13.ps}\end{figure}$ Figure 13: The confidence intervals of class A1. The contours are given at intervals of $\sigma$ from 2 $\sigma$ to 5 $\sigma$ . The models used to make this plot all have an ${\it o/p}_{\rm ini}$ of 0.01 and b=1.0. See Sect. 7.1 for further description.
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In the text

$\begin{figure} \par\includegraphics[width=7.4cm,clip]{5786fg14CMJN.eps}\end{figure}$ Figure 14: Map showing $\phi _{10}$ in objects 1, 2 and 3 identified in Fig. 15. The area in grey represents regions in which emission is below specified signal levels (see text). The colour bar is for $\phi _{10}$ and coordinates are in arcsec and relative to TCC0016 (see Fig. 1).
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In the text

$\begin{figure} \par\includegraphics[width=7.4cm,clip]{5786fg15.ps}\end{figure}$ Figure 15: ESO-VLT NACO images of three objects where the bowshocks have been resolved. The greyscale bar is in units of 10^-5 W m^-2 sr^-1 (Lacombe et al. 2004). Coordinates are as in Fig. 1.
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In the text

$\begin{figure} \par\includegraphics[width=7.4cm,clip]{5786fg16.ps}\end{figure}$ Figure 16: A plot brightness in the v=1-0 S(1) line for object 1 similar to Fig. 3 for object 1, but without spatial rebinning. The oblong encloses those data used for comparison with models.
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In the text

$\begin{figure} \par\includegraphics[width=7.4cm,clip]{5786fg17.ps}\end{figure}$ Figure 17: Confidence intervals for object 2. Model parameters are initial ${\it o/p}=0.01$ and b=1.0.
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In the text

$\begin{figure} \par\includegraphics[width=7.3cm,clip]{5786fg04.ps}\end{figure}$	Figure 4: Temporal evolution of the ${\it o/p}$ ratio in cold gas at T=10 K and $n_{\rm H}=10^5$ cm^-3 in a chemical steady-state gas-phase model. The initial o/p ratio is set to 3.0.
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$\begin{figure} \par\includegraphics[width=7.2cm,clip]{5786fg05.ps}\end{figure}$	Figure 5: Maximum local o/p ratios in C-type shocks, with magnetic scaling factor, b equal to 1, as a function of temperature for different preshock densities. Para- to ortho-H₂ interconversion begins at $\sim$ 800 K and is complete at $\sim$ 3200 K.
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$\begin{figure} \par\includegraphics[width=7.2cm,clip]{5786fg06.ps}\end{figure}$	Figure 6: Comparison of the ${\it o/p}$ ratio, local and integrated as specified, $\phi _{10}$ and R₁₀ as a function of position within a C-type shock with preshock density of $1\times 10^6$ cm^-3, shock velocity 20 km s^-1, initial ${\it o/p}$ ratio 0.01 and b=1.
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$\begin{figure} \par\includegraphics[width=7.2cm,clip]{5786fg07.ps}\end{figure}$	Figure 7: Maximum C-type shock temperature as a function of shock velocity for different preshock densities. The shaded area indicates the region in which net interconversion between ortho- and para-H₂ takes place ( $\sim$ 800-3200 K). The temperature is independent of initial o/p ratio and b=1.
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$\begin{figure} \par\includegraphics[width=7.2cm,clip]{5786fg08.ps}\end{figure}$	Figure 8: C-type shock widths as a function of shock velocity for different preshock densities (b=1).
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$\begin{figure} \par\includegraphics[width=7.2cm,clip]{5786fg10.ps}\end{figure}$	Figure 10: Brightness of the v=1-0 S(1) line as a function of C-type shock velocity for different preshock densities. The brightness is almost independent of initial ${\it o/p}$ ratio. It is shown here for ${\it o/p}_{\rm ini}=3$ .0 and b=1.
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$\begin{figure} \par\includegraphics[width=7.2cm,clip]{5786fg11.ps}\end{figure}$	Figure 11: Brightness of the v=1-0 S(0) line as a function of C-type shock velocity for different preshock densities and b=1, using the same linestyle as in Fig. 10. Each of the 4 diagrams shows a different value of ${\it o/p}_{\rm ini}$ as labelled.
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$\begin{figure} \par\includegraphics[width=7.2cm,clip]{5786fg12.ps}\end{figure}$	Figure 12: $\phi _{10}$ as a function of C-type shock velocity for different preshock densities and b=1. Each plot shows a different value of integrated o/p ranging from 0.01 to 3.0. Linestyles specifying pre-shock density are as in the previous Fig. 10.
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$\begin{figure} \par\includegraphics[width=7.4cm,clip]{5786fg13.ps}\end{figure}$	Figure 13: The confidence intervals of class A1. The contours are given at intervals of $\sigma$ from 2 $\sigma$ to 5 $\sigma$ . The models used to make this plot all have an ${\it o/p}_{\rm ini}$ of 0.01 and b=1.0. See Sect. 7.1 for further description.
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$\begin{figure} \par\includegraphics[width=7.4cm,clip]{5786fg14CMJN.eps}\end{figure}$	Figure 14: Map showing $\phi _{10}$ in objects 1, 2 and 3 identified in Fig. 15. The area in grey represents regions in which emission is below specified signal levels (see text). The colour bar is for $\phi _{10}$ and coordinates are in arcsec and relative to TCC0016 (see Fig. 1).
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$\begin{figure} \par\includegraphics[width=7.4cm,clip]{5786fg15.ps}\end{figure}$	Figure 15: ESO-VLT NACO images of three objects where the bowshocks have been resolved. The greyscale bar is in units of 10^-5 W m^-2 sr^-1 (Lacombe et al. 2004). Coordinates are as in Fig. 1.
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$\begin{figure} \par\includegraphics[width=7.4cm,clip]{5786fg16.ps}\end{figure}$	Figure 16: A plot brightness in the v=1-0 S(1) line for object 1 similar to Fig. 3 for object 1, but without spatial rebinning. The oblong encloses those data used for comparison with models.
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$\begin{figure} \par\includegraphics[width=7.4cm,clip]{5786fg17.ps}\end{figure}$	Figure 17: Confidence intervals for object 2. Model parameters are initial ${\it o/p}=0.01$ and b=1.0.
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