An estimate of the time variation of the abundance gradient from planetary nebulae II. Comparison with open clusters, cepheids and young objects

TL;DR

This study compares the temporal evolution of the Galaxy's radial abundance gradients using planetary nebulae, open clusters, cepheids, and young objects, finding evidence for gradient flattening over the last 8 billion years.

Contribution

It provides a comprehensive comparison of abundance gradient evolution across multiple stellar populations, supporting the gradient flattening over time with new observational data.

Findings

Gradients show flattening over the last 8 Gyr

Flattening rate estimated at 0.005-0.010 dex/kpc/Gyr

Consistent results across planetary nebulae, open clusters, and cepheids

Abstract

The temporal behaviour of the radial abundance gradients has important consequences for models of the chemical evolution of the Galaxy. We present a comparison of the time variation of the abundance gradients in the Milky Way disk as determined from a sample of planetary nebulae, open clusters, cepheids and young objects, such as stars in OB associations and HII regions. We conclude that the [Fe/H] gradients as measured in open cluster stars strongly support the time flattening of the abundance gradient as determined from O/H and S/H measurements in planetary nebulae. This conclusion is also supported by the cepheid variables, for which very accurate gradients and ages can be determined, and also by some recent estimates for OB stars and HII regions. It is estimated that the average flattening rate for the last 8 Gyr is in the range 0.005-0.010 dex/kpc/Gyr.