The input parameters that the user should supply to IAC-star are the following:
It is usefull for many purposes to allow metallicity dispersion at any time. For this, a second metallicity law can be introduced. If so, for any time, actual metallicities of synthetic stars are randomly distributed between the values of the two laws. If an unique, well defined metallicity for each age is required, the parameters of the second law must be all them 0 or leaved blank.
and are the initial and final metallicities; is the final gas fraction, and and are the infall and outflow parameters. These parameters are provided in the program input. Constant yield and are assumed. The latter is obtained for a stellar system in which star formation has gone on at a constant rate from 13 Gyr ago to date. Small, probably not significant differences are found for other SFRs and depending on metallicity.
Since they are governed by different equations, infall and outflow can not be included simultaneously. However, an approximation is obtained if the infall case is used with as parameter. It must be noted, however, that the approximation refers only to the CEL morphology, but not to the physical scenario. In particular, the yield becomes rather unrealistic.
In general, the infall and outflow parameters should be and to have physical sense. Moreover they must verify the conditions , for the infall scenario, and , for the outflow one. The cases , (infall scenario) and (outflow scenario), are overcome by the code by substituting these values by ; , and respectively. In this way, the code can produce the closed-box case and the infall limit case, in which infall is balanced by star formation.
As in the case (i), a second law can be defined if metallicity dispersion is required.
It must finally be mentioned that, in any case, the metallicity distribution is truncated to the range , which are the current limits of the used library.