Stellar population evolution

This is the step where observables are generated. With a given percentage (such as 50%) of mass that is in visible stars, and the IMF, stellar evolution from the ZAMS are followed. Evolutionary tracks from the ZAMS provide the internal clock of galaxy evolution. Assume a single stellar population SED (t), then the SED for a galaxy is the convolution:

S(t)=0t(t-t1) (t1).

Note that the evolving spectra should be convolved with the response function of the filters to yield observable values.

The Bruzual & Charlot (1993) model does include AGB and post AGB stars in a semi-empirical way, and it can account for arbitrarily short star bursts. But it assumes solar metallicity and no chemical evolution. The models by Guiderdoni & Rocca-Volmerange (1987, 1988) can deal with chemical evolution using an Instant Recycling Approximation.

References page
Introduction page

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Fan Fang       Last update: 26-July-99