Astronomy & Astrophysics

All Figures

$\begin{figure} \par\includegraphics[angle=-90,width=17cm]{7334fig01.ps} \end{figure}$ Figure 1: The grid of stellar atmospheric parameters $T_{\rm eff}$ , $\log~g$ , and ${\rm [Fe/H]}$ . The synthetic parameters (plus symbols) are presented in comparison with previously estimated atmospheric parameters (dots) for 38 731 SDSS/SEGUE spectra.
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In the text

$\begin{figure} \par\includegraphics[width=15cm,clip]{7334fig02CMJN.eps} \end{figure}$ Figure 2: Reconstruction of SDSS/SEGUE spectra by projection onto synthetic principal components. In each row, the spectrum on the left is the original and the following show the reconstruction using increasing numbers of principal components. The residual spectrum (original minus reconstructed) is shown in the bottom of each panel. The quoted atmospheric parameters are taken from a preliminary version of the processing pipeline SSPP.
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In the text

$\begin{figure} \par\includegraphics[width=15cm]{7334fig03CMJN.eps}\end{figure}$ Figure 3: As Fig. 2 but for principal components built from real spectra.
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In the text

$\begin{figure} \par\resizebox{8.8cm}{!} {\includegraphics[angle=-90,width=8.8cm]{7334fig04.ps}} \end{figure}$ Figure 4: PCA spectral reconstruction error, Q (defined in Eq. 6) on the evaluation data set for SR/RR/SS (solid/dashed/dotted lines, respectively) as a function of the number of eigenvectors, r, used for reconstruction.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=15cm]{7334fig05.ps} \end{figure}$ Figure 5: Atmospheric parameters estimation with the RR model. We compare our estimated $\log~T_{\rm eff}$ , $\log~g$ , and ${\rm [Fe/H]}$ with those from a preliminary version of the SSPP on the 19 000 stars in the evaluation set. The perfect correlation and a linear fit to the data are shown with the solid and dashed lines respectively. The histogram of the discrepancies (our estimates minus SSPP estimates) are shown in the lower panels.
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In the text

$\begin{figure} \par\resizebox{8.8cm}{!} {\includegraphics[angle=-90,width=8.8cm]{7334fig06.ps}} \end{figure}$ Figure 6: Histogram of the SNR distribution for all 38 731 stars of the real sample. For each of them, the value for SNR has been estimated from the stellar spectrum.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=17cm]{7334fig07.ps} \end{figure}$ Figure 7: Atmospheric parameters estimation with the SR model. Comparison between our derived $\log~T_{\rm eff}$ , $\log~g$ , ${\rm [Fe/H]}$ and those estimated by a preliminary version of SSPP for a set of 38 731 stars. The perfect correlation and a linear fit to the data are shown with the solid and dashed lines respectively. The distribution of the residuals (model minus SSPP) are shown in the bottom panels.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=17cm]{7334fig08.ps} \end{figure}$ Figure 8: More detailed visualization of the SR model discrepancies (Fig. 7). The diamonds joined by lines show mean absolute residual (solid lines) and mean residual (dashed lines) for low metallicity ( ${\rm [Fe/H]}< -1.5$ , white lines) and high metallicity ( ${\rm [Fe/H]}> -1.5$ , grey lines) averaged over all stars in a bin which has the diamond point as its centre. The mean residual traces the systematic offset (bias), the mean absolute the scatter.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=17cm]{7334fig09.ps} \end{figure}$ Figure 9: Comparison between SR and RR estimations on the 19 000 real spectra in common in their evaluation sets. The line shows the perfect correlation and the bottom panels the distributions of residuals.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=7.5cm,clip]{aa7334fig10NEW.ps}\end{figure}$ Figure 10: Distribution on the sky of the 526 stars present from SDSS/SEGUE plates 1960 and 1962. The box defines the selection criteria ( $322\hbox{$.\!\!^\circ$ }25 < {\rm RA} < 322\hbox{$.\!\!^\circ$ }75$ and $11\hbox{$.\!\!^\circ$ }90 < {\rm Dec} < 12\hbox{$.\!\!^\circ$ }40$ ) which produces 133 ${\rm M~15}$ candidates.
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In the text

$\begin{figure} \par\includegraphics[angle=0,width=7.5cm,clip]{7334fig11.ps} \end{figure}$ Figure 11: Distribution of ${\rm [Fe/H]}$ vs. $\log~g$ for the 133 positionally-selected ${\rm M~15}$ candidates from Fig. 10. Atmospheric parameters are from the RR ( top) and SR ( bottom) models. Of these 133 candidates, we retain only 46 (RR) or 45 (SR) stars in the low-metallicity group as likely cluster members. Among these, 8 (RR) or 7 (SR) identified as main sequence stars (asterisks) and 40 by radial-velocity selection (filled dots). Those also selected as members in a preliminary analysis are highlighted in grey; members find to be doubtful (due to their measured abundances or lack of any metallicity estimate) are marked with a plus sign.
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In the text

$\begin{figure} \par\resizebox{18cm}{!}{\includegraphics[angle=-90,width=17cm] {7334fig12.ps}} \end{figure}$ Figure 12: The left panel shows the colour-magnitude diagram for M 15, and the two other panels the distribution of atmospheric parameters $\log~g$ vs. $\log~T_{\rm eff}$ from the RR ( middle) and SR ( right) models. Of the stars selected as candidates, the asterisks denote main sequence metal-poor stars, the filled dots the members based on radial velocity constrain. Confirmed and doubtful members assigned in a preliminary analysis are coloured grey and marked as plus sign respectively. Overplotted are isochrones from Girardi et al. (2004) with metallicities and ages which bracket the values given in Table 4, i.e. at Z=0.0001 (solid), Z=0.0004 (dashed) for ages of 12.59 Gyr (black) and 14.13 Gyr (grey).
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=16cm]{7334fig13.ps} \end{figure}$ Figure 13: As Fig. 12. Top: ${\rm M~13}$ (globular cluster) candidates. Centre: ${\rm M~2}$ (globular cluster) candidates. Bottom: ${\rm NGC~2420}$ (open cluster) candidates. For the globular clusters, isochrones at Z=0.0001 (solid), Z=0.0004 (dashed) for ages of 12.59 Gyr (black) and 14.13 Gyr (grey); for the open cluster, isochrones at Z=0.004 (solid), Z=0.008 (dashed) for ages of 3.162 Gyr (black) and 3.548 Gyr (grey).
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=17cm]{7334fig01.ps} \end{figure}$	Figure 1: The grid of stellar atmospheric parameters $T_{\rm eff}$ , $\log~g$ , and ${\rm [Fe/H]}$ . The synthetic parameters (plus symbols) are presented in comparison with previously estimated atmospheric parameters (dots) for 38 731 SDSS/SEGUE spectra.
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$\begin{figure} \par\includegraphics[width=15cm]{7334fig03CMJN.eps}\end{figure}$	Figure 3: As Fig. 2 but for principal components built from real spectra.
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$\begin{figure} \par\resizebox{8.8cm}{!} {\includegraphics[angle=-90,width=8.8cm]{7334fig04.ps}} \end{figure}$	Figure 4: PCA spectral reconstruction error, Q (defined in Eq. 6) on the evaluation data set for SR/RR/SS (solid/dashed/dotted lines, respectively) as a function of the number of eigenvectors, r, used for reconstruction.
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$\begin{figure} \par\resizebox{8.8cm}{!} {\includegraphics[angle=-90,width=8.8cm]{7334fig06.ps}} \end{figure}$	Figure 6: Histogram of the SNR distribution for all 38 731 stars of the real sample. For each of them, the value for SNR has been estimated from the stellar spectrum.
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$\begin{figure} \par\includegraphics[angle=-90,width=17cm]{7334fig09.ps} \end{figure}$	Figure 9: Comparison between SR and RR estimations on the 19 000 real spectra in common in their evaluation sets. The line shows the perfect correlation and the bottom panels the distributions of residuals.
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$\begin{figure} \par\includegraphics[angle=-90,width=7.5cm,clip]{aa7334fig10NEW.ps}\end{figure}$	Figure 10: Distribution on the sky of the 526 stars present from SDSS/SEGUE plates 1960 and 1962. The box defines the selection criteria ( $322\hbox{$.\!\!^\circ$ }25 < {\rm RA} < 322\hbox{$.\!\!^\circ$ }75$ and $11\hbox{$.\!\!^\circ$ }90 < {\rm Dec} < 12\hbox{$.\!\!^\circ$ }40$ ) which produces 133 ${\rm M~15}$ candidates.
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