Astronomy & Astrophysics

All Figures

$\begin{figure} \par\includegraphics[width=6.7cm,clip]{1954Fig_1.eps} \end{figure}$ Figure 1: alpha Ara flux measured by the VLTI/MIDI (8-13 $\mu$ m) instrument with ISO data (2.5-11.5 $\mu$ m) plotted as solid line compared with the theoretical SED of the star alone (dashed line) and the star+envelope emission (dotted line) assuming a distance of 105 pc. Note the IR excess starting around 5 $\mu$ m, i.e. log $\lambda =0.7$ .
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In the text

$\begin{figure} \par\includegraphics[width=6.4cm,clip]{1954Fig_2a.eps}\hspace*{9mm} \includegraphics[width=6.4cm,clip]{1954Fig_2b.eps} \end{figure}$ Figure 2: H $\alpha$ and H $\beta$ line profiles observed in mid-1999 (solid lines) compared with the best SIMECA fits (dotted lines).
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In the text

$\begin{figure} \par\includegraphics[width=6.7cm,clip]{1954Fig_3a.eps}\hspace*{6mm} \includegraphics[width=6.7cm,clip]{1954Fig_3b.eps} \end{figure}$ Figure 3: a) Observed Pa $\beta$ line profile (mid-2003, solid line) compared to the modeled one based on the parameters determined by the fit of the 1999 H $\alpha$ and H $\beta$ line profiles (dotted line). b) Observed Pa $\beta$ line profile (solid line) and the best fit from the SIMECA code (dotted line). To compensate for the effects of non-simultaneous observations, the density of the disk was allowed to vary in a small range. This fit has been obtained with a disk density lower by 25% compared to the best model based on 1999 H $\alpha$ and H $\beta$ lines.
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In the text

$\begin{figure} \par\includegraphics[width=6.6cm,clip]{1954Fig_4.eps} \end{figure}$ Figure 4: Variation of the H $\alpha$ equivalent width ( EW) with time. The data were taken from Dachs et al. (1990): crosses; Hanuschik et al. (1995): stars and this work: diamond.
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In the text

$\begin{figure} \par\includegraphics[width=6.4cm,clip]{1954Fig_5.eps} \end{figure}$ Figure 5: H $\alpha$ line profile obtained in April 1999 with the HEROS instrument at la Silla (Chile) and the SIMECA fit (dotted line) for the base density used to fit the 2003 Pa $\beta$ profile. The strength of the line is comparable of the one reported in 1982 or 1987, for instance see Fig. 2 by Hanuschik et al. (1995).
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In the text

$\begin{figure} \par\includegraphics[width=6.2cm,clip]{1954Fig_6a.eps}\hspace*{7mm} \includegraphics[width=6.2cm,clip]{1954Fig_6b.eps} \end{figure}$ Figure 6: VLTI/MIDI data for the 79 m ( left) and 102 m ( right) baselines and theoretical visibilities from SIMECA (dashed line) for the distance of 105 pc estimated from our SED fit (see Fig. 1). The error bars are equivalent to one sigma.
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In the text

$\begin{figure} \par\includegraphics[width=6.2cm,clip]{1954Fig_7a.eps}\hspace*{7mm} \includegraphics[width=6.2cm,clip]{1954Fig_7b.eps} \end{figure}$ Figure 7: VLTI/MIDI data for the 79 m ( left) and 102 m ( right) baselines and theoretical visibilities from SIMECA (dashed line) for a truncated disk at 22 $R_{\star }$ by a possible companion. The error bars are equivalent to one sigma.
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In the text

$\begin{figure} \par\includegraphics[width=6.2cm,clip]{1954Fig_8a.eps}\hspace*{7mm} \includegraphics[width=6.2cm,clip]{1954Fig_8b.eps}\par\end{figure}$ Figure 8: a) Theoretical visibilities for the H $\alpha$ , H $\beta$ , Pa $\beta$ and Br $\gamma$ lines for baseline orientations corresponding to the ones observed on June 16, i.e. PA = 7 $\hbox {$^\circ $ }$ onto the sky plane, for both scenarios discussed; b) model data for a disk with the parameters which fits the 2003 Pa $\beta$ line profile, but not in agreement with the VLTI/MIDI visibilities (Fig. 6). On the right side model data for a disk truncated at 22 $R_{\star }$ , e.g. by a putative companion, is presented, being in agreement with the observed visibilities (Fig. 7).
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In the text

$\begin{figure} \par\includegraphics[width=5.8cm,clip]{1954Fig_9.ps} \end{figure}$ Figure 9: Diagram of alpha Ara circumstellar envelope projected onto the sky plane (with arbitrary oblateness) based on polarization (P) measurements (PA = 172 $\hbox {$^\circ $ }$ ) obtained by McLean & Clarke (1979) and Yudin et al. (1998). The actually observed VLTI baseline positions are shown for June, 16: PA = 7 $\hbox {$^\circ $ }$ , B=102 m and June, 17: PA = 55 $\hbox {$^\circ $ }$ , B=79 m.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=7.6cm,clip]{1954Fig_10.ps} \end{figure}$ Figure 10: Variation of the height ratio of violet and red emission peaks of the H $\beta$ line during the H EROS observations 1999.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=7.6cm,clip]{1954Fig_11.ps} \end{figure}$ Figure 11: Radial velocity changes of the central depression of H $\beta$ during the H EROS observations 1999.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=8.1cm,clip]{1954Fig_12.ps} \end{figure}$ Figure 12: Average of the IUE-spectra of alpha Ara (dotted) compared to a theoretical spectrum with $T_{\rm eff}=18~000$ K and $\log g = 4.0$ (solid line).
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In the text

$\begin{figure} \par\includegraphics[width=8.4cm,clip]{1954Fig_13.ps} \end{figure}$ Figure 13: Schematic view of the alpha Ara circumstellar environment as used in this work (see Table 4).
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In the text

$\begin{figure} \par\includegraphics[width=6.7cm,clip]{1954Fig_1.eps} \end{figure}$	Figure 1: alpha Ara flux measured by the VLTI/MIDI (8-13 $\mu$ m) instrument with ISO data (2.5-11.5 $\mu$ m) plotted as solid line compared with the theoretical SED of the star alone (dashed line) and the star+envelope emission (dotted line) assuming a distance of 105 pc. Note the IR excess starting around 5 $\mu$ m, i.e. log $\lambda =0.7$ .
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$\begin{figure} \par\includegraphics[width=6.4cm,clip]{1954Fig_2a.eps}\hspace*{9mm} \includegraphics[width=6.4cm,clip]{1954Fig_2b.eps} \end{figure}$	Figure 2: H $\alpha$ and H $\beta$ line profiles observed in mid-1999 (solid lines) compared with the best SIMECA fits (dotted lines).
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$\begin{figure} \par\includegraphics[width=6.6cm,clip]{1954Fig_4.eps} \end{figure}$	Figure 4: Variation of the H $\alpha$ equivalent width ( EW) with time. The data were taken from Dachs et al. (1990): crosses; Hanuschik et al. (1995): stars and this work: diamond.
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$\begin{figure} \par\includegraphics[width=6.4cm,clip]{1954Fig_5.eps} \end{figure}$	Figure 5: H $\alpha$ line profile obtained in April 1999 with the HEROS instrument at la Silla (Chile) and the SIMECA fit (dotted line) for the base density used to fit the 2003 Pa $\beta$ profile. The strength of the line is comparable of the one reported in 1982 or 1987, for instance see Fig. 2 by Hanuschik et al. (1995).
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$\begin{figure} \par\includegraphics[width=6.2cm,clip]{1954Fig_6a.eps}\hspace*{7mm} \includegraphics[width=6.2cm,clip]{1954Fig_6b.eps} \end{figure}$	Figure 6: VLTI/MIDI data for the 79 m ( left) and 102 m ( right) baselines and theoretical visibilities from SIMECA (dashed line) for the distance of 105 pc estimated from our SED fit (see Fig. 1). The error bars are equivalent to one sigma.
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$\begin{figure} \par\includegraphics[width=6.2cm,clip]{1954Fig_7a.eps}\hspace*{7mm} \includegraphics[width=6.2cm,clip]{1954Fig_7b.eps} \end{figure}$	Figure 7: VLTI/MIDI data for the 79 m ( left) and 102 m ( right) baselines and theoretical visibilities from SIMECA (dashed line) for a truncated disk at 22 $R_{\star }$ by a possible companion. The error bars are equivalent to one sigma.
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$\begin{figure} \par\includegraphics[angle=270,width=7.6cm,clip]{1954Fig_10.ps} \end{figure}$	Figure 10: Variation of the height ratio of violet and red emission peaks of the H $\beta$ line during the H EROS observations 1999.
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$\begin{figure} \par\includegraphics[angle=270,width=7.6cm,clip]{1954Fig_11.ps} \end{figure}$	Figure 11: Radial velocity changes of the central depression of H $\beta$ during the H EROS observations 1999.
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$\begin{figure} \par\includegraphics[angle=270,width=8.1cm,clip]{1954Fig_12.ps} \end{figure}$	Figure 12: Average of the IUE-spectra of alpha Ara (dotted) compared to a theoretical spectrum with $T_{\rm eff}=18~000$ K and $\log g = 4.0$ (solid line).
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$\begin{figure} \par\includegraphics[width=8.4cm,clip]{1954Fig_13.ps} \end{figure}$	Figure 13: Schematic view of the alpha Ara circumstellar environment as used in this work (see Table 4).
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