All Figures

$\begin{figure} \par\includegraphics[width=6.2cm,clip]{h3573f1.ps}\end{figure}$ Figure 1: a) Functions s₁(m) and s₂(m), of the isotropic R^1/4 model, versus the mass coordinate m, and function m-m^1/c (for the case c=0.7, dashed curve), see text. b) As in panel a) but for the anisotropic R^1/4 model with anisotropy radius $r_{\rm a}=1$ .
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{h3573f2.ps}\end{figure}$ Figure 2: SSP index Mg₂ versus metal abundance Z, for the Salpeter's mass exponent x=2.35: i) from Bressan et al. (1996) (solid curves) for the ages of 5, 9, and 13 Gyr (from bottom to top); ii) from Buzzoni et al. (1992) for the age of 15 Gyr (dashed curve); iii) from Worthey (1994, dotted-dashed curves) for the ages of 8, 12, and 17 Gyr (from bottom to top); iv) from Vazdekis et al. (1996, filled circles) and Vazdekis (1999, filled squares), for the age of 13 Gyr, for the sake of comparison. The thick mark on the abscissae indicates the solar metallicity.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{h3573f3.ps}\end{figure}$ Figure 3: The Mg₂ profile from the Worthey (1994) library and for the isotropic R^1/4 model with an age spread among the stellar populations (see text). The projected radial distance R is in units of the effective radius $R_{\rm e}(B)$ , the radius of a centered circular aperture containing half of the total Blight. a) The initial age $\tau _0$ is 13 Gyr for all the profiles and the final ages $\tau _{\rm w}$ are (from top to bottom) 13, 11, 9, 5, and 2 Gyr, respectively. The profile with $\tau _{\rm w}=13$ Gyr has no age spread and is shown for the sake of comparison. b) Two profiles correspond to model ellipticals with the bulk of star formation occurring from 13 to 11 Gyr ago and a delayed final burst, 1 Gyr long starting from 5 Gyr ago and involving the remaining fractional masses of 0.05 (solid curve) and 0.1 (dashed curve). The profile for a model at the age of 13 Gyr and with no age spread is also plotted for the sake of comparison (dotted curve).
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{h3573f4.ps}\end{figure}$ Figure 4: Mean ages $<\tau _V>$ (in Gyr), weighted by the V luminosity and as a function of the aperture radius R, for two model ellipticals considered in Fig. 3b. In the first model (solid curve) all stars form from 13 to 11 Gyr ago; in the second model (dashed curve) the fraction 0.95 of all stars forms from 13 to 11 Gyr ago and the remaining fraction 0.05 between 5 and 4 Gyr ago. $R_{\rm e}(B)$ is as in Fig. 3.
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In the text

$\begin{figure} \par\includegraphics[width=5cm,clip]{h3573f5.ps}\end{figure}$ Figure 5: Mg₂ profiles, for the isotropic R^1/4 model, versus the projected radial distance R in units of $R_{\rm e}(B)$ , with $R_{\rm e}(B)$ as in Fig. 3. a) Age-metallicity degeneracy by using the Worthey (1994) library: profiles for the age of 8 Gyr (solid curves) with $p=Z_{\odot }$ and $1.7~Z_{\odot}$ (bottom to top), compared to profiles for the age of 17 Gyr (dashed curves) with $p=0.63~Z_{\odot}$ and $Z_{\odot }$ (bottom to top). b) Profiles, for the age of 15 Gyr and corresponding to $p=1.5~Z_{\odot}$ , from the Buzzoni et al. (1992) library (solid curve) and Worthey (1994) library (dashed curve). c) Profiles, for the age of 13 Gyr and corresponding to $p=1.5~Z_{\odot}$ , from the Bressan et al. (1996) library (solid curve) and Worthey (1994) library (dashed curve).
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In the text

$\begin{figure} \par\includegraphics[width=5cm,clip]{h3573f6.ps}\end{figure}$ Figure 6: a) Radial profiles of Mg₂ versus log $(R/R_{\rm e})$ for the R^1/4-mass model, Concentration Models with c=0.75, and the labelled values of $p/Z_{\odot }$ . The solid curves refer to the isotropic models and the dashed curves to the anisotropic models with $r_{\rm a}=1$ . $R_{\rm e}(B)$ is the effective radius in the B band. b) As in a) but for Concentration Models with $p=Z_{\odot }$ and the labelled values of c. c) As in a) but for Concentration Models with $c=0.75, p=Z_{\odot }$ , and isotropic R^1/n-mass models with n=2 (short-dashed curve), 4 (solid curve), 6 (long-dashed curve), and 8 (short-dashed-long-dashed curve). The anisotropic ( $r_{\rm a}=1$ ) R^1/n models, omitted for clarity reasons, behave like the isotropic ones.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{h3573f7.ps}\end{figure}$ Figure 7: Mg₂ profiles for the isotropic R^1/4 model and with the consideration of a terminal wind removing the gas mass $g_{\rm w}=0.05$ from model ellipticals (see text for further details). The projected radial distance Ris in units of $R_{\rm e}(B)$ , as in Fig. 3. All profiles are from the Bressan et al. (1996) library, for the age of 13 Gyr, and correspond to $p=Z_{\odot }$ . For each value of the concentration index c (labelling the curves), there are a profile with a terminal wind (solid curve) and a profile without a terminal wind (dashed curve).
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{h3573f8.ps}\end{figure}$ Figure 8: Radial profiles of Mg₂ versus log $(R/R_{\rm e})$ , as measured by Davies et al. (1993) in the two indicated galaxies, compared to model profiles (solid curves) obtained from the Bressan et al. (1996) library and with the parameters for the Concentration Model and R^1/n-mass model as specified in Table 1. Two further profiles are added for NGC 3379: i) a profile (short-dashed curve) from the Bressan et al. (1996) library for the age of 13 Gyr and with parameters as specified in Table 1, except $s_1(m_{\rm w})=0$ and $R_{\rm e}(B)/R_{\rm e}^0=1.504$ ; ii) a profile (dotted curve) from the Worthey (1994) library and with a star formation proceeding from 13 to 2 Gyr (according to Eq. (6) with k=1), and with parameters as specified in Table 1, except $s_1(m_{\rm w})=0, p=1.2~Z_{\odot}$ , and $R_{\rm e}(B)/R_{\rm e}^0=1.22$ . An additional profile (dashed curve) is also shown for NGC 4261: it was computed from the Worthey (1994) library for the age of 13 Gyr and with parameters as listed in Table 1, except $p=1.45~Z_{\odot}$ and $R_{\rm e}(B)/R_{\rm e}^0=1.445$ . The radial distances R are in units of $R_{\rm e}$ (second column in Table 1, unless otherwise indicated) for the observational points and in units of $R_{\rm e}(B)$ (last column in Table 1) for the model profiles. The crosses on the model profiles correspond to the radius (3'') of the seeing disk.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{h3573f9.ps}\end{figure}$ Figure 9: As in Fig. 8 but with the solid curve for NGC 4636 and the dashed curve for NGC 7626, and with both curves from the Bressan et al. (1996) library for the age of 13 Gyr (see Table 1). An additional profile (dotted curve) for NGC 7626 was derived from the Worthey (1994) library for the age of 13 Gyr and with parameters as listed in Table 1, except $p=1.45~Z_{\odot}$ and $R_{\rm e}(B)/R_{\rm e}^0=1.974$ .
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{h3573f10.ps}\end{figure}$ Figure 10: As in Fig. 8 but with the solid curve for NGC 315, the short-dashed curve for NGC 741, and the long-dashed curve for NGC 4472. All curves are from the Bressan et al. (1996) library for the age of 13 Gyr (see Table 1).
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{h3573f11.ps}\end{figure}$ Figure 11: As in Fig. 8 but with the solid curve for NGC 1600, the short-dashed curve for NGC 4278, and the long-dashed curve for NGC 4374. All curves are from the Bressan et al. (1996) library for the age of 13 Gyr (see Table 1).
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{h3573f12.ps}\end{figure}$ Figure 12: As in Fig. 8 but for NGC 4486 with model profiles from: i) the Bressan et al. (1996) library for the age of 13 Gyr and parameters as in Table 1 (solid curve), ii) from the Worthey (1994) library for the age of 13 Gyr and parameters as in Table 1, except $p=1.7~Z_{\odot}$ and $R_{\rm e}(B)/R_{\rm e}^0=1.881$ (dashed curve).
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In the text

$\begin{figure} \par\includegraphics[width=6.2cm,clip]{h3573f1.ps}\end{figure}$	Figure 1: a) Functions s₁(m) and s₂(m), of the isotropic R^1/4 model, versus the mass coordinate m, and function m-m^1/c (for the case c=0.7, dashed curve), see text. b) As in panel a) but for the anisotropic R^1/4 model with anisotropy radius $r_{\rm a}=1$ .
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{h3573f10.ps}\end{figure}$	Figure 10: As in Fig. 8 but with the solid curve for NGC 315, the short-dashed curve for NGC 741, and the long-dashed curve for NGC 4472. All curves are from the Bressan et al. (1996) library for the age of 13 Gyr (see Table 1).
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{h3573f11.ps}\end{figure}$	Figure 11: As in Fig. 8 but with the solid curve for NGC 1600, the short-dashed curve for NGC 4278, and the long-dashed curve for NGC 4374. All curves are from the Bressan et al. (1996) library for the age of 13 Gyr (see Table 1).
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{h3573f12.ps}\end{figure}$	Figure 12: As in Fig. 8 but for NGC 4486 with model profiles from: i) the Bressan et al. (1996) library for the age of 13 Gyr and parameters as in Table 1 (solid curve), ii) from the Worthey (1994) library for the age of 13 Gyr and parameters as in Table 1, except $p=1.7~Z_{\odot}$ and $R_{\rm e}(B)/R_{\rm e}^0=1.881$ (dashed curve).
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