All Figures

$\begin{figure} \par\includegraphics[width=7.4cm,clip]{1396fig1.ps} \end{figure}$ Figure 1: The observed Chandra LETGS spectrum of nova V4743 Sgr. There are absorption lines and probably weak emission lines in the spectrum. The strongest lines are from the two highest ionisation stages of C, N, and O (Ness et al. 2003).
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.85cm,clip]{1396fig2.ps} \includegraphics[width=8.1cm,clip]{1396fig3.ps} \end{figure}$ Figure 2: Upper: model spectrum calculated with the "old bremsstrahlung'' continuum. Because these are test models, there are only spectral lines from H, He, C, and N. Lower: model spectrum calculated with the "new bremsstrahlung'' continuum and spectral lines of H, He, C, N, O, and Fe. There are mainly absorption lines in the spectrum.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{1396fig4.ps} \end{figure}$ Figure 3: NLTE Model spectrum (calculated with the "new bremsstrahlung'') with solar abundances plotted over the first 15 ks of the March observation. There is a very good agreement. A best-fit is provided with an effective temperature of $T_{\rm eff} = 5.8$ $\times$ 10⁵ K ( $L_{\rm bol} = 50~000~L_{\odot}$ , $v_{\rm out} = 2500$ km s^-1, $p_{\rm ref} = 10^{-2}$ dyn/cm², N = 3). The absorption lines and the continuum absorption are too weak in the model. Interstellar absorption was taken into account (n_h = 4.0 $\times$ 10²¹ cm^-2).
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=6.6cm,clip]{1396fig5.ps} \includegraph... ...,clip]{1396fig7.ps} \includegraphics[width=6.6cm,clip]{1396fig8.ps} \end{figure}$ Figure 4: Departure coefficients b_i from the best-fit model for the first 5 levels of the H-, C-, N-, and O-ions considered in these models. There are departure coefficients with values of 6 mag larger or smaller than 1. For all elements the departures from LTE are strong. As expected, the departures are strongest for outer layers and there is no departure from LTE at large optical depths (b_i = 1).
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.2cm,clip]{1396fig9.ps} \includegraphics[width=7.4cm,clip]{1396figA.ps} \end{figure}$ Figure 5: Upper: radius of the nova atmosphere plotted against the standard optical depth. The nova atmosphere is very extended, with a radius of $r \approx 10^{12}$ cm at $\tau _{\rm std} = 10^{-10}$ . Lower: temperature distribution in the atmosphere plotted against the standard optical depth. There is a wide variety of temperatures in the atmosphere. In the inner layers the temperature is several 10⁶ K high.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8.1cm,clip]{1396figB.ps} \end{figure}$ Figure 6: Partial pressures of FeIX-XXVII. The highest ionization stages of iron exist at the deepest layers of the nova atmosphere. In the outer layers FeXVII is most abundant. The partial pressures of FeI to FeVIII are very small and lie below the range of the y-axis. Only ions from FeXV are abundant enough in the line forming region and therefore important.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.4cm,clip]{1396fig1.ps} \end{figure}$	Figure 1: The observed Chandra LETGS spectrum of nova V4743 Sgr. There are absorption lines and probably weak emission lines in the spectrum. The strongest lines are from the two highest ionisation stages of C, N, and O (Ness et al. 2003).
Open with DEXTER

$\begin{figure} \par\includegraphics[width=7.85cm,clip]{1396fig2.ps} \includegraphics[width=8.1cm,clip]{1396fig3.ps} \end{figure}$	Figure 2: Upper: model spectrum calculated with the "old bremsstrahlung'' continuum. Because these are test models, there are only spectral lines from H, He, C, and N. Lower: model spectrum calculated with the "new bremsstrahlung'' continuum and spectral lines of H, He, C, N, O, and Fe. There are mainly absorption lines in the spectrum.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=8.1cm,clip]{1396figB.ps} \end{figure}$	Figure 6: Partial pressures of FeIX-XXVII. The highest ionization stages of iron exist at the deepest layers of the nova atmosphere. In the outer layers FeXVII is most abundant. The partial pressures of FeI to FeVIII are very small and lie below the range of the y-axis. Only ions from FeXV are abundant enough in the line forming region and therefore important.
Open with DEXTER