All Figures

$\begin{figure} \par {\hbox{ \includegraphics[width=8cm]{6193f1a.ps} \includegra... ...ce*{4.1cm} \includegraphics[width=8cm]{6193f1i.ps}\hspace*{4.1cm}} \end{figure}$ Figure 1: Light curves of the nine stars. Counts from all EPIC detectors have been combined, except for SU Aur and AB Aur, where data only from the two MOS detectors were available. Binning is to 1 ks, except for AB Aur, where 5 ks bins are used. Count rates refer to the energy range of 0.5-7.3 keV (except for AB Aur, where we used the range 0.3-4 keV). The size of the crosses in the x direction represent the bin width. Hardness is given by the ratio between the hard band (1-4 keV for AB Aur, 2-7.3 keV for all other stars) and the soft band (0.3-1 keV for AB Aur, 0.3-2 keV for all other stars). The dashed line in the light curve of V410 Tau separates the observations of XEST-23 and XEST-24. The dashed lines in the BP Tau light curve mark the flaring time interval excluded from the spectral fit. The dotted curve overplotted on the AB Aur light curve shows a sinusoidal fit.
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In the text

$\begin{figure} \par\includegraphics[width=12cm,clip]{6193f2.ps} \end{figure}$ Figure 2: EPIC MOS1 spectra of the nine target stars. For plotting purposes the spectra have been multiplied with different factors: 10^-5 for DN Tau, 10^-4 for BP Tau and DH Tau, 10^-3 for HP Tau/G2, 10^-2 for SU Aur, 10^-1 for V410 Tau, 1 for V773 Tau, and 10 for HD 283572.
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In the text

$\begin{figure} \par\includegraphics[width=17cm,clip]{6193f3.ps} \end{figure}$ Figure 3: Co-added and fluxed spectra from the RGS1 and RGS2 instruments. The spectra are background subtracted and are binned to a bin width of 0.066 Å for HP Tau/G2, 0.058 Å for DN Tau and DH Tau, 0.050 Å for BP Tau, 0.042 Å for AB Aur, and 0.035 Å for the other stars. In each spectrum we also plot the typical 1 $\sigma$ errors at 14.5 Å and at 21.6 Å (at the position of the O VII line). The arrow in the HD 283572 spectrum indicates the precise wavelength of the O VII He $\beta$ line at 18.63 Å.
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In the text

$\begin{figure} \par\includegraphics[width=12cm,clip]{6193f4.ps} \end{figure}$ Figure 4: Data and best-fit spectrum (EMD model) for V773 Tau. The best-fit model is shown by the histograms in the wavelength regions used for the fit.
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In the text

$\begin{figure} \par\includegraphics[width=7.2cm,clip]{6193f5a.ps}\hspace*{4mm} \includegraphics[width=7.2cm,clip]{6193f5b.ps} \end{figure}$ Figure 5: Element abundances normalized to solar photospheric values (Anders & Grevesse 1989 and Grevesse & Sauval 1999 for Fe) derived from the EMD and 3T fits. Open circles for AB Aur: values normalized to the AB Aur photospheric abundances (Acke & Waelkens 2004).
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In the text

$\begin{figure} \par\includegraphics[angle=-90, width=8cm]{6193f6a.ps} \includegraphics[angle=-90, width=8cm]{6193f6b.ps} \end{figure}$ Figure 6: Fit of the O VII triplets using variable electron density. Top panel, BP Tau: The best fit for $n_{\rm e} = 3.4 \times 10^{11}$ cm^-3 is plotted as a solid histogram, while the lower density limit ( $n_{\rm e} = 6.4 \times 10^{10}$ cm^-3, 90% confidence) is shown by the dotted line. Bottom panel, AB Aur: The solid histogram gives the best fit ( $n_{\rm e}~{\protect\la}~ 10^{10}$ cm^-3), while the dotted histogram is for the 90% upper limit to $n_{\rm e}$ ( $n_{\rm e} < 1.3\times 10^{11}$ cm^-3).
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In the text

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{6193f7a.ps}\par\vspace*{2mm} \includegraphics[width=7.5cm,clip]{6193f7b.ps} \end{figure}$ Figure 7: Fe/O abundance ratio as a function of the Fe/Ne ratio for abundances derived using an EMD model (a) and a 2/3-T model (b). The K-M type stars are plotted in black, while the G-type stars are in red. The ZAMS 47 Cas B and EK Dra are plotted in blue for comparison in both plots (from Telleschi et al. 2005). The T Tau star TWA 5, the post T Tau star PZ Tel, the ZAMS AB Dor, TW Hya1 and 2 are plotted in (a) for comparison (the analysis were based on an EMD method; see Kastner et al. 2002; Argiroffi et al. 2005,2004; García-Alvarez et al. 2005; Stelzer & Schmitt 2004). CR Cha and TW Hya3 have been added to (b) according to 3T fits reported by Robrade & Schmitt (2006).
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In the text

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{6193f8.ps} \end{figure}$ Figure 8: Ratio of the fluxes measured in the O VII triplet and the O VIII Ly $\alpha$ line as a function of $N_{\rm H}$ . The sample of young stars presented in this paper is plotted with circles, while values taken from the literature are plotted with squares. The diamonds represent the main-sequence solar analogs of Telleschi et al. (2005). HD 283572 is plotted with a triangle because the O VII line counts are not measured but derived from the best-fit model. Filled symbols denote accreting stars, open symbols are WTTS. Errors are 1 $\sigma$ . The dotted lines show the theoretical O VII/O VIII ratios for isothermal plasma at a given temperature as a function of $N_{\rm H}$ .
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{6193f9a.ps}\par\vspace*{2mm} \includegraphics[width=8cm,clip]{6193f9b.ps} \end{figure}$ Figure 9: Temperature corresponding to the observed O VII/O VIII count ratio as a function of H $\alpha$ equivalent width ( top) and as a function of the accretion rate $\dot{M}$ ( bottom). Errors in $\log T_{\rm oxy}$ are 1 $\sigma$ .
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In the text

$\begin{figure} \par\includegraphics[width=12cm,clip]{6193f2.ps} \end{figure}$	Figure 2: EPIC MOS1 spectra of the nine target stars. For plotting purposes the spectra have been multiplied with different factors: 10^-5 for DN Tau, 10^-4 for BP Tau and DH Tau, 10^-3 for HP Tau/G2, 10^-2 for SU Aur, 10^-1 for V410 Tau, 1 for V773 Tau, and 10 for HD 283572.
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$\begin{figure} \par\includegraphics[width=12cm,clip]{6193f4.ps} \end{figure}$	Figure 4: Data and best-fit spectrum (EMD model) for V773 Tau. The best-fit model is shown by the histograms in the wavelength regions used for the fit.
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$\begin{figure} \par\includegraphics[width=7.2cm,clip]{6193f5a.ps}\hspace*{4mm} \includegraphics[width=7.2cm,clip]{6193f5b.ps} \end{figure}$	Figure 5: Element abundances normalized to solar photospheric values (Anders & Grevesse 1989 and Grevesse & Sauval 1999 for Fe) derived from the EMD and 3T fits. Open circles for AB Aur: values normalized to the AB Aur photospheric abundances (Acke & Waelkens 2004).
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$\begin{figure} \par\includegraphics[width=8cm,clip]{6193f9a.ps}\par\vspace*{2mm} \includegraphics[width=8cm,clip]{6193f9b.ps} \end{figure}$	Figure 9: Temperature corresponding to the observed O VII/O VIII count ratio as a function of H $\alpha$ equivalent width ( top) and as a function of the accretion rate $\dot{M}$ ( bottom). Errors in $\log T_{\rm oxy}$ are 1 $\sigma$ .
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