Metallicity gradients in the Milky Way

TL;DR

This paper reviews recent observational evidence of metallicity gradients in the Milky Way, examining their magnitude, spatial variation, and potential temporal evolution, and discusses theoretical model predictions.

Contribution

It compiles and analyzes recent observational data on metallicity gradients in the Milky Way from various objects and discusses their implications for chemical evolution models.

Findings

Gradients vary in magnitude across different objects.

Evidence suggests possible temporal changes in gradients.

Theoretical models predict specific gradient behaviors over time.

Abstract

Radial metallicity gradients are observed in the disks of the Milky Way and in several other spiral galaxies. In the case of the Milky Way, many objects can be used to determine the gradients, such as HII regions, B stars, Cepheids, open clusters and planetary nebulae. Several elements can be studied, such as oxygen, sulphur, neon, and argon in photoionized nebulae, and iron and other elements in cepheids, open clusters and stars. As a consequence, the number of observational characteristics inferred from the study of abundance gradients is very large, so that in the past few years they have become one of the main observational constraints of chemical evolution models. In this paper, we present some recent observational evidences of abundance gradients based on several classes of objects. We will focus on (i) the magnitude of the gradients, (ii) the space variations, and (iii) the evidences of a time variation of the abundance gradients. Some comments on recent theoretical models are also given, in an effort to highlight their predictions concerning abundance gradients and their variations.