Invited_talk abstract details
Constraining the chemical evolution of the Local Group galaxies
Abstract
Planetary nebulae (PNe) are fundamental tools to investigate the chemical evolution of nearby galaxies.
PN progenitors do not modify, at least at zeroth approximation, the composition of $alpha$- elements such as oxygen, neon, argon, and sulfur, and thus are optimal tracers of the composition of the interstellar medium at the epoch of their formation.
The spectroscopy of PNe, combined with that of HII regions, is a powerful method which allows us to analyse the chemical enrichment history of galaxies, and in particular the time evolution of the distribution of metals.
I will review the recent results obtained in the study of the chemical abundances of extragalactic PNe (and HII regions), in particular dealing in the problem of the time variation of radial metallicity gradients in disk galaxies.
Chemical evolution models indeed predict different temporal behaviors of the metallicity gradient depending on assumptions such as gas inflow and outflow rate, and star and cloud
formation efficiencies. Observations are needed to constrain these theoretical scenarios, but so far they have been insufficient,
especially for the old populations. I will show how PNe (and HII regions) are helping to constrain such models and to understand the chemical evolution of nearby spiral galaxies, such as M33 and M81, and of Local Group dwarfs.
PN progenitors do not modify, at least at zeroth approximation, the composition of $alpha$- elements such as oxygen, neon, argon, and sulfur, and thus are optimal tracers of the composition of the interstellar medium at the epoch of their formation.
The spectroscopy of PNe, combined with that of HII regions, is a powerful method which allows us to analyse the chemical enrichment history of galaxies, and in particular the time evolution of the distribution of metals.
I will review the recent results obtained in the study of the chemical abundances of extragalactic PNe (and HII regions), in particular dealing in the problem of the time variation of radial metallicity gradients in disk galaxies.
Chemical evolution models indeed predict different temporal behaviors of the metallicity gradient depending on assumptions such as gas inflow and outflow rate, and star and cloud
formation efficiencies. Observations are needed to constrain these theoretical scenarios, but so far they have been insufficient,
especially for the old populations. I will show how PNe (and HII regions) are helping to constrain such models and to understand the chemical evolution of nearby spiral galaxies, such as M33 and M81, and of Local Group dwarfs.