Research Division Seminar
The abundance gradients in the Milky Way: tracing the chemical composition of the ISM using H II regions
The emission line spectrum of H II regions provides information about the chemical composition of the present-day interstellar medium. The study as a function of their galactocentric distances helps to constrain chemical evolution models. In this talk, I present a reanalysis of the abundance gradients of C, N, O, Ne, S, Cl, and Ar for a sample of 33 Galactic H II regions covering a range in Galactocentric Distances from 6-17 kpc. New values of the Galactocentric distances were calculated using Gaia DR2 parallaxes for some objects. We study in detail the different ICF schemes to improve the results of the total abundances in Galactic H II regions. We found that the re-evaluation of the distances using Gaia DR2 parallaxes produces an O gradient that discards a flattening of the gradient in the inner part of the Galaxy. The radial distribution of Ne/O, S/O, Cl/O and Ar/O are almost flat confirming a lockstep evolution of those elements respect to O. Our Galaxy also shows an almost flat N/O gradient respect to other nearby spiral galaxies. We compare our results with those from B type stars and cepheids, young planetary nebulae and those slopes using optical and infrared data for H II regions.
About the talk