The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XXII. Relative ages of multiple populations in five Globular Clusters

TL;DR

This study introduces a new method to estimate the relative ages of multiple stellar populations in five globular clusters using HST UV data, revealing that most populations are nearly coeval within a few hundred million years.

Contribution

The paper presents a novel technique for accurately determining the relative ages of multiple stellar populations in globular clusters using color-magnitude diagrams from HST UV data.

Findings

NGC 104 and NGC 6121 populations are coeval within ~220 Myr.

NGC 6352, NGC 6362, and NGC 6723 populations are coeval within 336-634 Myr.

Most globular cluster populations studied are nearly coeval within a few hundred million years.

Abstract

Aims. We present a new technique to estimate the relative ages of multiple stellar populations hosted by five globular clusters: NGC 104 (47 Tuc), NGC 6121 (M4), NGC 6352, NGC 6362 and NGC 6723. Methods. We used the catalogs of the database "HST UV Globular cluster Survey (HUGS)" to create color-magnitude and two-color diagrams of the Globular Clusters. We identified the multiple populations within each globular cluster, and we divided them into two main stellar populations: POPa or first generation (1G) and POPb, composed of all the successive generations of stars. The new technique allows us to obtain an accurate estimate of the relative ages between POPa and POPb. Results. The multiple populations of NGC 104 and NGC 6121 are coeval within 220 Myr and 214 Myr, while those of NGC 6352, NGC 6362 and NGC 6723 are coeval within 336 Myr, 474 Myr and 634 Myr, respectively. These results were obtained combining all the sources of uncertainties.