Contatto di riferimento: Alessio Mucciarelli
Partecipanti: Francesca Annibali (INAF-OABO)
Abstract
Star formation history (SFH) studies based on the resolved stars in dwarf irregular (dIrr) and blue compact dwarf (BCD) galaxies have shown that these systems, once suggested to be primeval galaxies because of their blue colors, low metallicities, and high gas content, were instead forming stars at epochs as old as ~ a Hubble time.
This poses a major challenge for chemical evolution models of dIrrs and BCDs, which have to reconcile the low observed metallicities with the old ages, roughly continuous SFHs, and fairly high star formation rates.
In this context, element abundance estimates in HII regions, defining the present-day chemical properties, and in individual stars or planetary nebulae (PNe), offering a view at earlier epochs, are fundamental to constrain chemical evolution models.
I will present our recent results from a project with FORS2@VLT aimed at deriving chemical abundances of PNe and HII regions in the BCD NGC 1705. I will also present very preliminary results from our MODS@LBT observations of PNe in the Irr NGC 4449.