6. A WISH LIST FOR THE WORLD SPACE OBSERVATORY-UV

In the context of what we have discussed above, the WSO-UV (Shustov et al. 2009) will undoubtedly impact our knowledge on the UV properties of evolved populations. With its large aperture (as compared to its UV predecesors) and enhanced detectors sensitivities will:

• Significantly increase the quality (and quantity) of stars enabling us to construct a robust empirical database. As quoted by Chavez et al. (2007) and Maraston et al. (2009), the IUE stellar library has prevailed as the most complete for the analyses of stellar aggregates. We, however, badly need to cope with the pausity in the coverage of the parameter space, particularly the metallicities.

• Increase the number of globular clusters (and old open clusters) to re-test the adequacy of SSP models. Of fundamental importance will be to empirically judge the effects of non solar-scaled abundances and to better assess the impact of the horizontal branch morphology on mid-UV spectroscopic indices.

• Cast light on the nature of the objects giving rise to the far-UV up-turn. At this wavelength the IUE-archive includes a rather small number of elliptical galaxies and none with data of enough quality to firmly establish the chemical composition of the undelying population of hot stars in these systems.

Acknowledgements     MC is pleased to aknowledge the organizing committee for the invitation to attend the conference UV Universe 2010 and for partial financial support. MC and EB would like to thank financial support from CONACyT through the grant 49231-E.