Disks of Other Spirals

Abundance gradients in dex/kpc are known to exist also in the disk of other spirals showing that they are steeper in smaller disks, but this correlation disappears if the 

FIGURE 5. Comparison between data (dotted lines) and model predictions for the metallicity distribution of bulge stars. The data are from McWilliam Rich (1994) and the models (continuous lines) from Matteucci et al. (1999). Each panel corresponds to a model with a different IMF slope, as indicated. 

The SFR is measured mainly from Ha emission (Kennicutt, 1998b) and implies a correlation with the total surface gas density (HI+H2) as discussed in section 2.1. 

Gas distributions, especially the HI distribution is known for a fair sample of spirals. There are indications of differences between field and cluster spirals (e.g. Skillman et al. 1996). 

Studies of integrated colors of spiral disks reflect the observed abundance gradients and are well reproduced by an inside-out formation of disks similar to what assumed for the Milky Way (Josey Arimoto 1992 Jimenez et al. 1998 Prantzos Boissier 2000). 

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The properties of the disks of other spirals also indicate an inside-out disk formation. 

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