Relative Ages of Nine Inner Milky Way Globular Clusters from Proper-motion-cleaned Color–Magnitude Diagrams

Abstract Our picture of the age–metallicity relation for Milky Way globular clusters (MWGCs) is still highly incomplete, and the majority of MWGCs lack self-consistent age measurements. Here, we exploit deep, homogenous multiepoch Hubble Space Telescope imaging of nine MWGCs located toward the inner...

Full description

Saved in:

Bibliographic Details
Published in:	The Astronomical journal 2021-12, Vol.162 (6), p.228
Main Authors:	Cohen, Roger E., Bellini, Andrea, Casagrande, Luca, Brown, Thomas M., Correnti, Matteo, Kalirai, Jason S.
Format:	Article
Language:	eng
Subjects:	Age Astronomy Bolometers Extinction Globular clusters Hubble Space Telescope Metallicity Milky Way Proper motion Space telescopes
Online Access:	Get full text
Tags:	Add Tag No Tags, Be the first to tag this record!

Description
Summary:	Abstract Our picture of the age–metallicity relation for Milky Way globular clusters (MWGCs) is still highly incomplete, and the majority of MWGCs lack self-consistent age measurements. Here, we exploit deep, homogenous multiepoch Hubble Space Telescope imaging of nine MWGCs located toward the inner Milky Way to measure their relative ages, in most cases for the first time. Our relative age measurements are designed to be directly comparable to the large set of MWGC ages presented by VandenBerg et al. (V13), using identical filters, evolutionary models, and bolometric corrections, extended to the higher extinction values relevant to our target clusters. Adopting the V13 MWGC age scale, our relative age measurements imply that our target clusters are consistently very old, with a mean age of 12.9 ± 0.4 Gyr, with the exception of the young metal-rich MWGC NGC 6342. We perform two tests to validate the precision of our methodology, and discuss the implications of our target cluster loci in the MWGC age–metallicity plane. In addition, we use our fully self-consistent bolometric corrections to assess the systematic impact of variations in the total-to-selective extinction ratio R V on relative age measurements.
ISSN:	0004-6256 1538-3881