$\begin{figure} \par\includegraphics[width=7cm,clip]{0441fig1.ps} \end{figure}$ Figure 1: Fractional abundance of selected species over time; T=10 K, n(H₂)=10⁴ cm^-3. The filled symbols are the RATE99 model, the hollow symbols are the NSM model.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=14cm,clip]{0441fig2.eps} \end{figure}$ Figure 2: Fractionation of selected species vs. time from the accretion models; T=10 K, n(H₂)=10⁶ cm^-3. Left: RATE99 model; right: NSM model.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=14cm,clip]{0441fig3.eps} \end{figure}$ Figure 3: Fractional abundance of selected species vs. time from the accretion models; T=10 K, n(H₂)=10⁶ cm^-3. Left: RATE99 model; right: NSM model.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[angle=270,width=8.4cm,clip]{0441fig4.ps} \end{figure}$ Figure 4: Model predictions for D₂CO fractionation as a function of CO depletion at 10 K, from the RATE99 model at various densities, compared with the observations of Bacmann et al. (2002, 2003) towards prestellar cores.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[angle=270,width=8.4cm,clip]{0441fig5.ps} \end{figure}$ Figure 5: Model predictions for the rise in D₂CO fractionation at 10 K (right-hand axis) as CO freezes out (left-hand axis). The solid lines are for n(H₂)=10⁶ cm^-3; the dashed lines are for n(H₂)=10⁵ cm^-3.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[angle=270,width=8.4cm,clip]{0441f6a.ps}\par\vspace*{2mm} \includegraphics[angle=270,width=8.4cm,clip]{0441f6b.ps} \end{figure}$ Figure 6: Physical parameters of prestellar cores as a function of radius. Top: L1544 (Tafalla et al. 2002); bottom: Oph D (Motte et al. 1998; Bergin et al. 2002). The dark lines represent the best fit to the observations, while the lighter `stairs' show the model fits we have adopted.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[angle=270,width=8.4cm,clip]{0441fig8.ps} \end{figure}$ Figure 8: Molecular D/H ratios vs. radius for selected molecules in L1544, using the density and temperature profiles from Fig. 6.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7cm,clip]{0441fig1.ps} \end{figure}$	Figure 1: Fractional abundance of selected species over time; T=10 K, n(H₂)=10⁴ cm^-3. The filled symbols are the RATE99 model, the hollow symbols are the NSM model.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=14cm,clip]{0441fig2.eps} \end{figure}$	Figure 2: Fractionation of selected species vs. time from the accretion models; T=10 K, n(H₂)=10⁶ cm^-3. Left: RATE99 model; right: NSM model.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=14cm,clip]{0441fig3.eps} \end{figure}$	Figure 3: Fractional abundance of selected species vs. time from the accretion models; T=10 K, n(H₂)=10⁶ cm^-3. Left: RATE99 model; right: NSM model.
Open with DEXTER

$\begin{figure} \par\includegraphics[angle=270,width=8.4cm,clip]{0441fig4.ps} \end{figure}$	Figure 4: Model predictions for D₂CO fractionation as a function of CO depletion at 10 K, from the RATE99 model at various densities, compared with the observations of Bacmann et al. (2002, 2003) towards prestellar cores.
Open with DEXTER

$\begin{figure} \par\includegraphics[angle=270,width=8.4cm,clip]{0441fig5.ps} \end{figure}$	Figure 5: Model predictions for the rise in D₂CO fractionation at 10 K (right-hand axis) as CO freezes out (left-hand axis). The solid lines are for n(H₂)=10⁶ cm^-3; the dashed lines are for n(H₂)=10⁵ cm^-3.
Open with DEXTER

$\begin{figure} \par\includegraphics[angle=270,width=8.4cm,clip]{0441f6a.ps}\par\vspace*{2mm} \includegraphics[angle=270,width=8.4cm,clip]{0441f6b.ps} \end{figure}$	Figure 6: Physical parameters of prestellar cores as a function of radius. Top: L1544 (Tafalla et al. 2002); bottom: Oph D (Motte et al. 1998; Bergin et al. 2002). The dark lines represent the best fit to the observations, while the lighter `stairs' show the model fits we have adopted.
Open with DEXTER

$\begin{figure} \par\includegraphics[angle=270,width=8.4cm,clip]{0441f7a.ps}\par\vspace*{2mm} \includegraphics[angle=270,width=8.4cm,clip]{0441f7b.ps} \end{figure}$	Figure 7: Fractional abundances vs. radius for selected molecules in L1544, using the density and temperature profiles from Fig. 6.
Open with DEXTER

$\begin{figure} \par\includegraphics[angle=270,width=8.4cm,clip]{0441fig8.ps} \end{figure}$	Figure 8: Molecular D/H ratios vs. radius for selected molecules in L1544, using the density and temperature profiles from Fig. 6.
Open with DEXTER

$\begin{figure} \par\includegraphics[angle=270,width=8.4cm,clip]{0441f9a.ps}\par\... ...space*{4mm}\includegraphics[angle=270,width=8.4cm,clip]{0441f9b.ps} \end{figure}$	Figure 9: Fractional abundances ( top) and molecular D/H ratios ( bottom) vs. radius for selected molecules in Oph D, using the density and temperature profiles from Fig. 6.
Open with DEXTER