All Figures

$\begin{figure} \includegraphics[width=9.43cm]{9010f1a.ps}\hspace*{-1.0mm} \includegraphics[width=8.312cm]{9010f1b.ps} \end{figure}$ Figure 1: Flux calibrated spin-averaged blue and red UVES spectra of EX Hya (black curves) superposed on the overall spectral energy distribution of Eisenbart et al. (2002) (green curves). Also shown is the spectrophotometry of Bath et al. (1981) (small dots, see text), the Walraven photometry of (Siegel et al. 1989) (open circles), and unpublished UBVRIJHK photometry (open triangles, see text). Also shown is the optical/infrared spectrum of the dM5.5 star Gl473AB (Eisenbart et al. 2002) adjusted to the flux level of the secondary star in EX Hya.
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In the text

$\begin{figure} \par\includegraphics[width=8.24cm]{9010f2.ps} \end{figure}$ Figure 2: Flux calibrated red UVES spectra of the M6 dwarf Gl406 and the M425 dwarf Gl300 (shifted upwards by two units). The ``residual'' spectra shown as the two bottom curves refer to our method of analyzing the EX Hya spectra and are explained in Sect. 3.3. The bottom one refers to Gl406 and is shifted downwards by one unit.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm]{9010f3.ps} \end{figure}$ Figure 3: Mean normalized spectrum of EX Hya in the vicinity of the NaI $\lambda 8183/8195$ doublet. Wavelength bins are 41 mÅ and the FWHM spectral resolution is 175 mÅ. The two spectra shown at the top are explained in Sect. 3.3. The NaI doublet becomes detectable only after telluric correction.
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In the text

$\begin{figure} \par\includegraphics[width=8.7cm]{9010f4.ps} \end{figure}$ Figure 4: Flux-calibrated light curves of EX Hya obtained on January 23, 2004. The bands U' and B refer to the mean flux in the intervals 3770-4000 Å and 4000-4800 Å, respectively. The integrated flux of the H $\beta$ emission line is given in units of 10^-13 erg cm^-2 s^-1. The triangles indicate the times of spin maxima predicted by the quadratic ephemeris of Hellier & Sproats (1992).
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In the text

$\begin{figure} \par\includegraphics[width=18cm,clip]{9010f5.eps}\par \end{figure}$ Figure 5: Phase-resolved and telluric line-corrected ``residual'' spectra of EX Hya collected into 16 phase bins and repeated for two orbits (see Sect. 3.3). Numerous emission and absorption features from the secondary star are visible, most prominent the TiO band heads at 7589 and 8432 Å, the KI $\lambda 7665/7699$ and NaI $\lambda 8183/8195$ emission/absorption lines, and CaII $\lambda 8498$ in emission. The broad HeI, OI, and Paschen lines are from the accretion disk and funnel. The displayed intensities are relative to the orbital mean, the zero level is shaded gray, lower and higher intensities appear darker and lighter, respectively.
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In the text

$\begin{figure} \includegraphics[width=8.4cm]{9010f6a.ps}\hspace*{1mm} \includegr... ...9010f6b.ps}\hspace*{1mm} \includegraphics[width=4.85cm]{9010f6c.ps} \end{figure}$ Figure 6: Absolute ``residual'' spectral fluxes $f_{i}(\lambda )$ of EX Hya for the illuminated face of the secondary star ( top, black data train, shifted upwards by three units) and its dark side ( center and bottom, black data train, unshifted and shifted downwards by three units, respectively). The spectra are shifted in wavelength to the respective rest frame before averaging them over the orbital phase intervals indicated in the figure (see text). Shown for comparison are the correspondingly constructed ``residual'' fluxes of the M6 dwarf Gl406 and the M4.25 dwarf Gl300.
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In the text

$\begin{figure} \par\includegraphics[width=8.6cm]{9010f7a.ps}\par\includegraphics[width=8.8cm]{9010f7b.ps} \end{figure}$ Figure 7: Top: orbital light curve of the CaII $\lambda 8498$ integrated emission line flux (black histogram) and model fit (green curves). The two components refer to the white dwarf (WD) and the hot spot (HS) as irradiation sources. Bottom: flux at 7550 Å relative to 7720 Å. The dip indicates a weakening of the TiO $\lambda 7589$ band strength on the illuminated face of the secondary star. The abscissa is orbital phase calculated from Eq. (4).
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In the text

$\begin{figure} \par\includegraphics[width=9cm]{9010f8.ps} \end{figure}$ Figure 8: Radial velocity curves of NaI $\lambda 8183/8195$ in absorption ( $\medcirc$ ) and emission (+) (left hand scale) and of the CaII $\lambda 8498$ emission line (+) (right hand scale) vs. orbital phase $\varphi _{\rm 98,HS}$ (Hellier & Sproats 1992). Solid lines represent sinusoids least squares-fitted to the data (see Sect. 4.2). The error bars are smaller than the data points.
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In the text

$\begin{figure} \par\includegraphics[width=8cm]{9010f9.ps} \end{figure}$ Figure 9: Limb darkening of the angle-dependent intensity deficit integrated over the NaI doublet for a $\log g$ = 5 star with $T_{\rm eff}$ = 3000 K (Derek Homeier, private communication). The solid line is a fitted square root law with fit parameters c and d given in the text.
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In the text

$\begin{figure} \par\includegraphics[width=7.95cm]{9010f10.ps} \end{figure}$ Figure 10: Variation of the flux in the CaII $\lambda 8498$ emissivity as a function of $\eta={\rm cos}~\vartheta$ for irradiation by a point source. The green line is for emission proportional to the energy influx, the black curve, for a simple analytical model that concentrates the emission closer to the terminator, and the open circles for the numerical tomographic model.
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In the text

$\begin{figure} \includegraphics[width=8.8cm]{9010f11.ps} \end{figure}$ Figure 11: Result of the multiparameter fit for the numerical model of the CaII emissivities of Fig. 10. The NaI value $\chi ^2_{\rm Na}$ (open circles) is shown as a function of total mass M with the other parameters free, the CaII value $\chi ^2_{\rm Ca}$ (+) is slaved to reach its minimum at the same value of M (requiring $c_{\rm lim}=-0.085$ ). The green curve is a parabola fit and the dotted line indicates the 99% confidence level.
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In the text

$\begin{figure} \hspace{9.3mm} \includegraphics[width=18cm,clip]{9010f12.eps}\par \end{figure}$ Figure 12: a)- f) Sections of Fig. 5 containing the NaI $\lambda 8183/8195$ doublet and the CaII $\lambda 8498$ emission line. The Paschen background has been subtracted in the latter. The three panels each ( a)- c) and d)- f)) show the data ( left, a), d)), the model ( center, b), e)), and the residual fluxes ( right, c), f)). The displayed intensities are relative to the orbital mean, the zero level is shaded gray, lower and higher intensities appear darker and lighter, respectively. FeI $\lambda 8220.4$ appears as a very faint emission line in panels a) and c), rows 7 to 10. The gray scales in the NaI and CaII images differ.
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In the text

$\begin{figure} \mbox{\includegraphics[width=90mm,clip]{9010f13a.ps}\hspace*{6mm} \includegraphics[width=85.5mm,clip]{9010f13b.ps} }\end{figure}$ Figure 13: a), b) Comparison of observed phase-resolved line profiles (data points) and best-fit model spectra (green curves) for the NaI $\lambda 8183/8195$ doublet ( left, a)) and the CaII $\lambda 8498$ emission line ( right, b)). The Paschen background has been subtracted in the latter.
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In the text

$\begin{figure} \hspace*{5mm} \includegraphics[width=7.5cm]{9010f14.ps} \end{figure}$ Figure 14: Observed (black) and fitted (green) line profiles of the NaI line for the illuminated ( top) and dark side ( bottom) of the secondary star. Same data as in Fig. 13 shifted into the respective rest system and co-added for two phase intervals (see Sect. 5.4). See text for further explanation.
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In the text

$\begin{figure} \par\includegraphics[width=18cm,clip]{9010f15.eps} \end{figure}$ Figure 15: a), b) Tomographic images of the secondary star of EX Hya seen at $\phi _{98}=0.75$ and $i=77.8^\circ$ for the numerical model of the emissivities of Fig. 10. a) Left: NaI $\lambda 8183/8195$ absorption/emission, b) right: CaII $\lambda 8498$ emission. The x'-z' plane is perpendicular to the line of sight and coordinates are relative to the binary separation a with the origin in the white dwarf. The geometric terminator for illumination by a point source at the white dwarf is indicated by the dashed line. The intensity scales differ for both images. In the left hand panel, black is absorption, white emission, and the red rim represents zero intensity, while the dark side of the star in the right panel denotes zero line flux that increases over red to white. Faint emission in the disk shadow and beyond the terminator is due to irradiation by the ``hot spot''.
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In the text

$\begin{figure} \par\includegraphics[width=8.24cm]{9010f2.ps} \end{figure}$	Figure 2: Flux calibrated red UVES spectra of the M6 dwarf Gl406 and the M425 dwarf Gl300 (shifted upwards by two units). The ``residual'' spectra shown as the two bottom curves refer to our method of analyzing the EX Hya spectra and are explained in Sect. 3.3. The bottom one refers to Gl406 and is shifted downwards by one unit.
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$\begin{figure} \par\includegraphics[width=8.8cm]{9010f3.ps} \end{figure}$	Figure 3: Mean normalized spectrum of EX Hya in the vicinity of the NaI $\lambda 8183/8195$ doublet. Wavelength bins are 41 mÅ and the FWHM spectral resolution is 175 mÅ. The two spectra shown at the top are explained in Sect. 3.3. The NaI doublet becomes detectable only after telluric correction.
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$\begin{figure} \par\includegraphics[width=8.7cm]{9010f4.ps} \end{figure}$	Figure 4: Flux-calibrated light curves of EX Hya obtained on January 23, 2004. The bands U' and B refer to the mean flux in the intervals 3770-4000 Å and 4000-4800 Å, respectively. The integrated flux of the H $\beta$ emission line is given in units of 10^-13 erg cm^-2 s^-1. The triangles indicate the times of spin maxima predicted by the quadratic ephemeris of Hellier & Sproats (1992).
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$\begin{figure} \par\includegraphics[width=9cm]{9010f8.ps} \end{figure}$	Figure 8: Radial velocity curves of NaI $\lambda 8183/8195$ in absorption ( $\medcirc$ ) and emission (+) (left hand scale) and of the CaII $\lambda 8498$ emission line (+) (right hand scale) vs. orbital phase $\varphi _{\rm 98,HS}$ (Hellier & Sproats 1992). Solid lines represent sinusoids least squares-fitted to the data (see Sect. 4.2). The error bars are smaller than the data points.
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$\begin{figure} \par\includegraphics[width=8cm]{9010f9.ps} \end{figure}$	Figure 9: Limb darkening of the angle-dependent intensity deficit integrated over the NaI doublet for a $\log g$ = 5 star with $T_{\rm eff}$ = 3000 K (Derek Homeier, private communication). The solid line is a fitted square root law with fit parameters c and d given in the text.
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$\begin{figure} \par\includegraphics[width=7.95cm]{9010f10.ps} \end{figure}$	Figure 10: Variation of the flux in the CaII $\lambda 8498$ emissivity as a function of $\eta={\rm cos}~\vartheta$ for irradiation by a point source. The green line is for emission proportional to the energy influx, the black curve, for a simple analytical model that concentrates the emission closer to the terminator, and the open circles for the numerical tomographic model.
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$\begin{figure} \mbox{\includegraphics[width=90mm,clip]{9010f13a.ps}\hspace*{6mm} \includegraphics[width=85.5mm,clip]{9010f13b.ps} }\end{figure}$	Figure 13: a), b) Comparison of observed phase-resolved line profiles (data points) and best-fit model spectra (green curves) for the NaI $\lambda 8183/8195$ doublet ( left, a)) and the CaII $\lambda 8498$ emission line ( right, b)). The Paschen background has been subtracted in the latter.
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$\begin{figure} \hspace*{5mm} \includegraphics[width=7.5cm]{9010f14.ps} \end{figure}$	Figure 14: Observed (black) and fitted (green) line profiles of the NaI line for the illuminated ( top) and dark side ( bottom) of the secondary star. Same data as in Fig. 13 shifted into the respective rest system and co-added for two phase intervals (see Sect. 5.4). See text for further explanation.
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