All Figures

$\begin{figure} \par\includegraphics[width=8.2cm,clip]{3097fig1.eps}\end{figure}$ Figure 1: Profiles of the [S II], [Fe II] and H₂ emission along the HH1 jet. Vertical dashed lines indicate the range coadded to obtain individual knot fluxes. The [Fe II] profile was used to define the knot separation.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{3097fig2.eps} \end{figure}$ Figure 2: Combined EFOSC2 + SofI spectrum from 0.6 to 2.5 $\mu$ m of knot G of the HH1 jet. The stronger lines are identified.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{3097fig3.eps} \end{figure}$ Figure 3: Relative intensity profiles of several optical and infrared lines as a function of distance from the shock-front for a 70 km s^-1 shock. These profiles have been calculated taking the temperature, density and ionization fraction profiles from Fig. 1 of Hartigan et al. (1994).
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In the text

$\begin{figure} \par\includegraphics[width=8.3cm,clip]{3097fig4.eps}\end{figure}$ Figure 4: Derived physical parameters along the HH1 jet. Open circles refer to parameters estimated using diagnostics based on [Fe II] lines, while filled triangles refer to values determined through the BE99 technique. Error sources are described in Table 2.
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In the text

$\begin{figure} \par\includegraphics[width=8.1cm,clip]{3097fig5.eps}\end{figure}$ Figure 5: Comparison between predicted (filled circle) and observed (crosses) dereddened ratios [N I]1.04 $\mu$ m/[N II] $\lambda$ 6583 ( upper panel) and [S II]1.03 $\mu$ m/[S II] $\lambda$ $\lambda$ 6716, 6731 ( lower panel). NIR lines were observed only in knots L-I, H and G.
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In the text

$\begin{figure} \par\includegraphics[width=8.1cm,clip]{3097fig6.eps}\end{figure}$ Figure 6: Diagnostic diagram based on [Fe II] line ratios. The grid is constructed for electron densities of 10³, 10⁴, and 10⁵ cm^-3 (dashed lines), and for electron temperatures of 4, 5, 6, 8, 10, 15 $\times$ 10³ K (solid lines). The symbols indicate the line ratios observed in the HH1 jet knots and dereddened assuming the $A_{\rm V}$ values in Table 2.
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In the text

$\begin{figure} \par\includegraphics[width=8.45cm,clip]{3097fig7.eps}\end{figure}$ Figure 7: Dereddened [Fe II] intensity ratios with respect to the 1.64 $\mu$ m line in knot G (open circles) against a model with $T_{\rm e}$ = 11 500 K and $n_{\rm e}$ = 5 $\times$ 10³ cm^-3 (filled triangles). Intensities are normalized to the 1.64 $\mu$ m line.
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In the text

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{3097fig8.eps}\end{figure}$ Figure 8: Calculated Ca II $\lambda$ 8542/[Ca II] $\lambda$ 7291 ratio, as a function of the electron density and temperature. The solid lines indicate the range of values observed in the HH1 jet.
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In the text

$\begin{figure} \par\includegraphics[width=8.2cm,clip]{3097fig9.eps}\end{figure}$ Figure 9: Observed values of the ratio [Fe II] $\lambda$ 7155/ $\lambda$ 8617, which is a tracer of high density regions. The two horizontal lines indicate the value expected for densities of 10⁵ and 6 $\times$ 10⁶ cm^-3 in a collisionally excited gas at T = 10 000 K (Bautista & Pradhan 1998).
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{3097fig10.eps}\end{figure}$ Figure 10: Comparison of the $\dot{M}$ determinations along the HH1 jet derived adopting different methods and lines. Filled squares refer to $\dot{M}$ values directly measured from our derived total density and the knot radius taken from Reipurth et al. (2000), assuming complete beam filling. Filled circles are mass loss rates estimated from [S II] $\lambda \lambda$ 6716, 6731 and [OI] $\lambda$ 6300 luminosities. The two values coincide inside the symbol. Finally, crosses and triangles refer to the $\dot{M}$ value derived from the [Fe II]1.64 $\mu$ m and H₂ 2.12 $\mu$ m luminosities.
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In the text

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{3097fig11.eps}\end{figure}$ Figure 11: Ratios of [Fe II]8617 Å line with respect to [S II] $\lambda$ $\lambda$ 6716, 6731 and [O I] $\lambda$ 6300 in the various knots. Crosses: measured de-reddened values. Filled circles: predicted values assuming $T_{\rm e}$ and $n_{\rm e}$ derived from the BE99 analysis. Fe and S have been assumed completely ionized once, while the O⁺/O⁰ fraction has been calculated using the ionization model for this species.
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In the text

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{3097fig12.eps}\end{figure}$ Figure 12: Observed [Fe II]1.25 $\mu$ m/[PII]1.18 $\mu$ m ratios in knots L-I, H, G and F. The line represents the predicted value expected if all the iron is in gaseous form and assuming a [Fe]/[P] solar abundance ratio of 112.
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In the text

$\begin{figure} \par\includegraphics[width=8.15cm,clip]{3097fig13.eps}\end{figure}$ Figure 13: Dereddened ratios of lines from refractory species (crosses): a) [C I] $\lambda$ $\lambda$ 9824, 9850/[S II] $\lambda$ $\lambda$ 6716, 6730, b) [Ca II] $\lambda$ $\lambda$ 7291, 7324/ [S II] $\lambda$ $\lambda$ 6716, 6730, c) [Ni II] $\lambda$ 7378/[Fe II] $\lambda$ 8617, d) [Cr II] $\lambda$ 8000/ [Fe II] $\lambda$ 8617. In panels a) and b), filled circles are the predicted values assuming Ca, C and S have solar abundances, C all neutral and Ca, S all singly ionized. Open circles in panel a) refer to predictions where the C⁰/C⁺ abundance ratio has been computed through ionization equilibrium analysis.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{3097figB1.eps}\end{figure}$ Figure B.1: Observed variations along the HH1 jet of the reddening sensitive [Fe II] line ratios 1.64/1.25 $\mu$ m a) and 1.64/1.32 $\mu$ m b). Panel c) shows the derived $A_{\rm V}$ values from the two ratios assuming an interpolation of the Rieke & Lebofsky (1985) extinction law and transition probabilities from Nussbaumer & Storey (1988). Circles and triangles are the $A_{\rm V}$ values measured from the 1.64/1.25 and 1.64/1.32 line ratios, respectively.

In the text

$\begin{figure} \par\includegraphics[width=8.2cm,clip]{3097fig1.eps}\end{figure}$	Figure 1: Profiles of the [S II], [Fe II] and H₂ emission along the HH1 jet. Vertical dashed lines indicate the range coadded to obtain individual knot fluxes. The [Fe II] profile was used to define the knot separation.
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{3097fig2.eps} \end{figure}$	Figure 2: Combined EFOSC2 + SofI spectrum from 0.6 to 2.5 $\mu$ m of knot G of the HH1 jet. The stronger lines are identified.
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{3097fig3.eps} \end{figure}$	Figure 3: Relative intensity profiles of several optical and infrared lines as a function of distance from the shock-front for a 70 km s^-1 shock. These profiles have been calculated taking the temperature, density and ionization fraction profiles from Fig. 1 of Hartigan et al. (1994).
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$\begin{figure} \par\includegraphics[width=8.3cm,clip]{3097fig4.eps}\end{figure}$	Figure 4: Derived physical parameters along the HH1 jet. Open circles refer to parameters estimated using diagnostics based on [Fe II] lines, while filled triangles refer to values determined through the BE99 technique. Error sources are described in Table 2.
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$\begin{figure} \par\includegraphics[width=8.1cm,clip]{3097fig5.eps}\end{figure}$	Figure 5: Comparison between predicted (filled circle) and observed (crosses) dereddened ratios [N I]1.04 $\mu$ m/[N II] $\lambda$ 6583 ( upper panel) and [S II]1.03 $\mu$ m/[S II] $\lambda$ $\lambda$ 6716, 6731 ( lower panel). NIR lines were observed only in knots L-I, H and G.
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$\begin{figure} \par\includegraphics[width=8.1cm,clip]{3097fig6.eps}\end{figure}$	Figure 6: Diagnostic diagram based on [Fe II] line ratios. The grid is constructed for electron densities of 10³, 10⁴, and 10⁵ cm^-3 (dashed lines), and for electron temperatures of 4, 5, 6, 8, 10, 15 $\times$ 10³ K (solid lines). The symbols indicate the line ratios observed in the HH1 jet knots and dereddened assuming the $A_{\rm V}$ values in Table 2.
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$\begin{figure} \par\includegraphics[width=8.45cm,clip]{3097fig7.eps}\end{figure}$	Figure 7: Dereddened [Fe II] intensity ratios with respect to the 1.64 $\mu$ m line in knot G (open circles) against a model with $T_{\rm e}$ = 11 500 K and $n_{\rm e}$ = 5 $\times$ 10³ cm^-3 (filled triangles). Intensities are normalized to the 1.64 $\mu$ m line.
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$\begin{figure} \par\includegraphics[width=7.8cm,clip]{3097fig8.eps}\end{figure}$	Figure 8: Calculated Ca II $\lambda$ 8542/[Ca II] $\lambda$ 7291 ratio, as a function of the electron density and temperature. The solid lines indicate the range of values observed in the HH1 jet.
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$\begin{figure} \par\includegraphics[width=8.2cm,clip]{3097fig9.eps}\end{figure}$	Figure 9: Observed values of the ratio [Fe II] $\lambda$ 7155/ $\lambda$ 8617, which is a tracer of high density regions. The two horizontal lines indicate the value expected for densities of 10⁵ and 6 $\times$ 10⁶ cm^-3 in a collisionally excited gas at T = 10 000 K (Bautista & Pradhan 1998).
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$\begin{figure} \par\includegraphics[width=7.5cm,clip]{3097fig12.eps}\end{figure}$	Figure 12: Observed [Fe II]1.25 $\mu$ m/[PII]1.18 $\mu$ m ratios in knots L-I, H, G and F. The line represents the predicted value expected if all the iron is in gaseous form and assuming a [Fe]/[P] solar abundance ratio of 112.
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