All Figures

$\begin{figure} \par\includegraphics[width=8.15cm,clip]{4433_f01.eps} \end{figure}$ Figure 1: Example of an HII galaxy spectrum (UM 69, taken on August, the 18th, 1998).
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=14.2cm,clip]{4433_f02.eps} \end{figure}$ Figure 2: Illustration of the six indices using UM 69 (the spectrum shown in Fig. 1) as an example. The dashed lines show the limits of the bands. The bands that enter with a positive sign into the calculation of the respective index are shaded with dotted lines running from the upper left to the lower right, and the bands that have a negative sign are shaded with dotted lines running from the upper right to the lower left. For a more detailed description of the indices, see the text.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=14cm,clip]{4433_f03.eps} \end{figure}$ Figure 3: Distribution of the sample spectra (symbols) in different two-index planes compared with SSPs (lines). The solid lines represent the evolutionary paths of SSPs of different metallicities between ${\rm [Fe/H]}=-2.25$ and ${\rm [Fe/H]}=+0.35$ , and the dashed lines represent the locus of SSPs of constant ages ranging from 0 to 20 Gyr. The dotted lines show the values of the indices at which SSPs of average metallicity ( ${\rm [Fe/H]}\sim -1$ ) reach an age of around 2 Gyr, to demarcate the ranges of young/intermediate populations and old populations. Young populations tend to be in the left part of the diagrams, old ones in the right part. The typical errors in the indices are shown as error bars in the corners of the different panels.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=14cm,clip]{4433_f04.eps} \end{figure}$ Figure 4: Distribution of the sample of spectra (symbols) in different two-index planes compared with composite stellar populations (lines). In relation to Fig. 3, the range of the indices has been centered on the region where most of the observed data lie. The solid lines represent the compositions of an old population (age 5 Gyr, ${\rm [Fe/H]}=-1.5$ ) and a young or intermediate one ( ${\rm [Fe/H]}=-1$ ) with different mass ratios ranging from M_y+i: $M_{\rm o} = 0{:}1$ (only an old population) to 1:0 (only a young/intermediate population). The mass of the young population decreases with increasing line thickness, and the age of the young population varies along the lines. The dashed lines are lines of constant age of the young/intermediate population varying from 0 to 500 Myr (increasing line thickness means increasing age), whereas the mass ratio between the two populations varies along the lines. They converge towards the point where the mass of the young/intermediate population is zero. The typical errors in the indices are shown as error bars in the corners of the different panels.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=13.4cm,clip]{4433_f05.eps} \end{figure}$ Figure 5: Example of a "best fit''. The thin line represents the empirical spectrum (UM 137(W), taken on August, the 18th, 1998), the thick solid white line shows the best fit spectrum obtained using the "BC99'' library, and the thick dashed white line (which sometimes hides the solid line) shows the best fit using "Starburst''.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8.35cm,clip]{4433_f06.eps} \end{figure}$ Figure 6: Ages of the best fits performed on "BC-2000'' synthetic SSPs as a function of their ages. The solid line shows the best fits using the "BC99'' library, and the dashed line shows the best fits using "Starburst''. The dotted line represents identity.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=16.3cm,clip]{4433_f07.eps} \end{figure}$ Figure 7: The ages of the young+intermediate population as a function of the indices of the spectra. The crosses represent the solutions found using "BC99'', and the squares represent the "Starburst'' solutions. The typical errors in the indices are shown as error bars in the upper left corners of the different panels.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=16.9cm,clip]{4433_f08.eps} \end{figure}$ Figure 8: The indices of the empirical spectra vs. the same indices of the synthetic spectra (thus the reproduction of these indices). The crosses represent the solutions found using "BC99'', and the squares represent the "Starburst'' solutions. The lines represent identity (perfect reproduction). The typical errors in the observed indices are shown as error bars in the upper left corners of the different panels.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8.3cm,clip]{4433_f09.eps} \end{figure}$ Figure 9: The number of cases, in which a certain value (x) of M_y+i: $M_{\rm o}$ was found using "BC99'' and another (y) value was found using "Starburst''.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{4433_f10.eps} \end{figure}$ Figure 10: The number of cases, in which a certain (x) value of ${\rm age}_{y+i}$ was found using "BC99'' and another (y) value was found using "Starburst''.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=16.9cm,clip]{4433_f11.eps} \end{figure}$ Figure 11: Comparison of the indices of the solutions obtained with "BC99'' and "Starburst'' (crosses). The lines represent identity.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{4433_f12.eps} \end{figure}$ Figure 12: Comparison of the $\chi ^{2}$ of the solutions obtained with "BC99'' and "Starburst'' (crosses). The line represents identity.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8.2cm,clip]{4433_f13.eps} \end{figure}$ Figure 13: Histogram of the best fitting M_y+i: $M_{\rm o}$ for the two different libraries. Upper panel: all apertures in all galaxies. Lower panel: one aperture (the lowest M_y+i: $M_{\rm o}$ value) for each galaxy.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8.25cm,clip]{4433_f14.eps} \end{figure}$ Figure 14: Histogram of the best fitting $\log~({\rm age}_{y+i})$ using the two different libraries. Upper panel: all apertures in all galaxies. Lower panel: one aperture (the highest young+intermediate age) for each galaxy. The dotted line corresponds to the maximum duration of an SSP burst, which means that for ages younger than 10⁷ yr, the young+intermediate population found could consist of only the young component.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8.15cm,clip]{4433_f01.eps} \end{figure}$	Figure 1: Example of an HII galaxy spectrum (UM 69, taken on August, the 18th, 1998).
Open with DEXTER

$\begin{figure} \par\includegraphics[width=13.4cm,clip]{4433_f05.eps} \end{figure}$	Figure 5: Example of a "best fit''. The thin line represents the empirical spectrum (UM 137(W), taken on August, the 18th, 1998), the thick solid white line shows the best fit spectrum obtained using the "BC99'' library, and the thick dashed white line (which sometimes hides the solid line) shows the best fit using "Starburst''.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=8.35cm,clip]{4433_f06.eps} \end{figure}$	Figure 6: Ages of the best fits performed on "BC-2000'' synthetic SSPs as a function of their ages. The solid line shows the best fits using the "BC99'' library, and the dashed line shows the best fits using "Starburst''. The dotted line represents identity.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=16.3cm,clip]{4433_f07.eps} \end{figure}$	Figure 7: The ages of the young+intermediate population as a function of the indices of the spectra. The crosses represent the solutions found using "BC99'', and the squares represent the "Starburst'' solutions. The typical errors in the indices are shown as error bars in the upper left corners of the different panels.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=8.3cm,clip]{4433_f09.eps} \end{figure}$	Figure 9: The number of cases, in which a certain value (x) of M_y+i: $M_{\rm o}$ was found using "BC99'' and another (y) value was found using "Starburst''.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=8cm,clip]{4433_f10.eps} \end{figure}$	Figure 10: The number of cases, in which a certain (x) value of ${\rm age}_{y+i}$ was found using "BC99'' and another (y) value was found using "Starburst''.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=16.9cm,clip]{4433_f11.eps} \end{figure}$	Figure 11: Comparison of the indices of the solutions obtained with "BC99'' and "Starburst'' (crosses). The lines represent identity.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=8cm,clip]{4433_f12.eps} \end{figure}$	Figure 12: Comparison of the $\chi ^{2}$ of the solutions obtained with "BC99'' and "Starburst'' (crosses). The line represents identity.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=8.2cm,clip]{4433_f13.eps} \end{figure}$	Figure 13: Histogram of the best fitting M_y+i: $M_{\rm o}$ for the two different libraries. Upper panel: all apertures in all galaxies. Lower panel: one aperture (the lowest M_y+i: $M_{\rm o}$ value) for each galaxy.
Open with DEXTER