The radial abundance gradients of O, Ne, S and Cl of the Milky Way

TL;DR

This study analyzes the radial abundance gradients of oxygen, neon, sulfur, and chlorine in the Milky Way using deep spectra from 35 H II regions, revealing complex gradient shapes and significant dispersions that suggest chemical inhomogeneities or methodological artifacts.

Contribution

It provides a homogeneous analysis of multiple elemental abundance gradients in the Milky Way, including a larger sample for chlorine, and discusses potential causes of observed dispersions.

Findings

Cl/H gradient of -0.034 dex kpc^-1 with 0.14 dex dispersion

Ne/H and S/H gradients of -0.038 and -0.046 dex kpc^-1 with >0.25 dex dispersion

High dispersion in abundance ratios may indicate chemical inhomogeneities or ionization correction artifacts

Abstract

We present preliminary results of the O, Ne, S and Cl abundance gradients of the Milky Way. We analyze in a homogenous way the physical conditions and chemical abundances of a sample of 35 H II regions with deep spectra observed mainly with the GTC and VLT telescopes. The sample covers a range in Galactocentric distances from 5 to 17 kpc. We reanalyze the O abundance gradient, obtaining a similar complex shape than previously reported in the literature. We calculate the Cl abundance gradient including a significantly larger number of objects than in previous works. Our results show a gradient for Cl/H of -0.034 dex kpc^-1 and a dispersion around the gradient of 0.14 dex. We obtain values for the Ne/H and S/H abundance gradients with slopes of -0.038 dex kpc^-1 and -0.046 dex kpc^-1, respectively, with dispersions around the gradient higher than 0.25 dex. We also report the values for the slopes of the Cl/O, Ne/O and S/O abundance ratio gradients, which show dispersions around the gradient up to 0.4 dex. Such high dispersion although may be interpreted as indications of chemical inhomogeneities in the Galactic ISM, it might be also an artifact produced by the selected ionization correction factor.