The HST Large Programme on omega Centauri -- VI. The radial gradient of the stellar populations

TL;DR

This study uses HST data to analyze the radial distribution of different stellar populations in Omega Centauri, revealing that certain populations are more centrally concentrated, indicating complex formation and evolutionary processes.

Contribution

It provides the first detailed analysis of radial gradients of multiple stellar populations in Omega Centauri using combined HST data, highlighting population-specific spatial distributions.

Findings

bMS is more centrally concentrated than rMS

Less populous populations show weaker radial gradients

MSe population shows no significant radial variation

Abstract

In this paper we present the analysis of Hubble Space Telescope (HST) observations of the globular cluster Omega Centauri. Our analysis combines data obtained in this work with previously published HST data from an earlier article of this series and encompasses a broad portion of the cluster's radial extension. Our findings reveal a significant radial variation in the fraction of stars within the two most populous stellar populations showing that one of the main second-population groups (referred to as bMS) is more centrally concentrated than the first-population group (referred to as rMS). Additionally, we explore the spatial variations of the other less populous stellar populations (referred to as MSa and MSd) and find a qualitatively similar, but weaker, radial decrease in the fraction of stars in these populations at larger distances from the cluster centre. Only one of the populations identified (MSe) does not show any significant radial variation.