What do planetary nebulae and H II regions reveal about the chemical evolution of nearby dwarf galaxies?

Abstract

The Local Group contains a great number of dwarf irregulars and spheroidals, for which the spectroscopy of individual stars can be obtained. Thus, the chemical evolution of these galaxies can be traced, with the only need of finding populations spanning a large age range and such that we can accurately derive the composition. Planetary nebulae (PNe) are old-and intermediate-age star remnants and their chemical abundances can be obtained up to 3-4 Mpc. H ii regions, which are brighter and much easily detected, represent galaxies young content. PNe and H ii regions share similar spectroscopic features and are analysed in the same way. Both are among the best tracers of the chemical evolution allowing to draw the chemical time line of nearby galaxies. The focus in this review are the PN and H ii region populations as constraints to the chemical evolution models and the mass-metallicity relation of the local Universe.

Distance mapping applied to four well-known planetary nebulae and a nova shell

“…Planetary nebulae (PNe) represent the final stage in the evolution of low-to intermediate-mass stars and they are important tools for the study of stellar evolution and gas dynamics (Kwok 2007), as well as tracers of the chemical abundance in nearby galaxies (Magrini et al 2012;Gonçalves 2019). PN studies rely on the knowledge of their physical properties such as the formation rate, Galactic distribution, total and ionized nebular masses, sizes, ages, luminosities and evolutionary states of their central stars (CSs), among others (Gurzadyan 1997;Osterbrock & Ferland 2006;Kwok 2007).…”