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 multi-epoch Hubble Space Telescope (HST) imaging of nine MWGCs located towards 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. (2013, 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$\pm$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.

arXiv commentAJ Accepted. 15 pages, 5 figures, 3 tables

References in corpus (73)

• The Gaia mission
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• Na-O Anticorrelation and HB. VII. The chemical composition of first and second-generation stars in 15 globular clusters from GIRAFFE spectra
• Intrinsic iron spread and a new metallicity scale for Globular Clusters
• A large stellar evolution database for population synthesis studies. II. Stellar models and isochrones for an alpha-enhanced metal distribution
• Gaia Data Release 2: Kinematics of globular clusters and dwarf galaxies around the Milky Way
• Na-O Anticorrelation and HB. VIII. Proton-capture elements and metallicities in 17 globular clusters from UVES spectra
• Reddening and Extinction Toward the Galactic Bulge from OGLE-III: The Inner Milky Way's Rv ~ 2.5 Extinction Curve
• The ACS Survey of Galactic Globular Clusters. I. Overview and Clusters Without Previous HST Photometry
• Properties of stellar generations in Globular Clusters and relations with global parameters
• The ACS Survey of Galactic Globular Clusters. VII. Relative Ages
• The Ages of 55 Globular Clusters as Determined Using an Improved delta V_TO^HB Method Along with Color-Magnitude Diagram Constraints, and Their Implications for Broader Issues
• Gaia EDR3 view on Galactic globular clusters
• The ACS Survey of Galactic Globular Clusters. XII. Photometric Binaries along the Main-Sequence
• The ACS Survey of Galactic Globular Clusters. IX. Horizontal Branch Morphology and the Second Parameter Phenomenon
• Mean proper motions, space orbits and velocity dispersion profiles of Galactic globular clusters derived from Gaia DR2 data
• Origin of the system of globular clusters in the Milky Way
• The formation and assembly history of the Milky Way revealed by its globular cluster population
• Synthetic Stellar Photometry - I. General considerations and new transformations for broad-band systems
• Kraken reveals itself -- the merger history of the Milky Way reconstructed with the E-MOSAICS simulations
• Homogeneous age dating of 55 Galactic globular clusters. Clues to the Galaxy formation mechanisms
• The Optical-Infrared Extinction Curve and its Variation in the Milky Way
• Galactic Globular Cluster Relative Ages. II
• The Bifurcated Age-Metallicity Relation of Milky Way Globular Clusters and its Implications For the Accretion History of the Galaxy
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XVI. The helium abundance of multiple populations
• The Sausage Globular Clusters
• Accreted versus In Situ Milky Way Globular Clusters
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters - XVII. Public Catalogue Release
• Hubble Space Telescope Proper Motion (HSTPROMO) Catalogs of Galactic Globular Clusters. I. Sample Selection, Data Reduction and NGC 7078 Results
• The State-of-the-Art HST Astro-Photometric Analysis of the core of $\omega$ Centauri. I. The Catalog
• Stellar Models with Enhanced Abundances of C, N, O, Ne, Na, Mg, Si, S, Ca, and Ti, in Turn, at Constant Helium and Iron Abundances
• The E-MOSAICS project: tracing galaxy formation and assembly with the age-metallicity distribution of globular clusters
• Interstellar Extinction Curve Variations Toward the Inner Milky Way: A Challenge to Observational Cosmology
• Uncloaking globular clusters in the inner Galaxy
• Extinction Map of the Galactic center: OGLE-II Galactic bulge fields
• The HST large programme on $\omega$ Centauri - II. internal kinematics
• FORS2/VLT survey of Milky Way globular clusters II. Fe and Mg abundances of 51 Milky Way globular clusters on a homogeneous scale
• Isochrones for Old (> 5 Gyr) Stars and Stellar Populations. I. Models for $-2.4\le$ [Fe/H] $\le +0.6$, $0.25\le Y\le 0.33$, and $-0.4\le$ [$\alpha$\Fe] $\le +0.4$
• Near Infrared properties of 12 Globular Clusters toward the inner Bulge of the Galaxy
• Absolute HST Proper Motion (HSTPROMO) of Distant Milky Way Globular Clusters: Galactocentric Space Velocities and the Milky Way Mass
• Red Giant Branch Bump Brightness and Number Counts in 72 Galactic Globular Clusters Observed with the Hubble Space Telescope
• Hubble Space Telescope Proper motion (HSTPROMO) Catalogs of Galactic Globular Clusters. VI. Improved data reduction and internal-kinematic analysis of NGC 362
• Near-Infrared Photometry of Globular Clusters Towards the Galactic Bulge: Observations and Photometric Metallicity Indicators
• Absolute Ages and Distances of 22 GCs using Monte Carlo Main-Sequence Fitting
• Variable stars in the VVV globular clusters. I. 2MASS-GC02 and Terzan10
• High resolution infrared spectra of NGC 6342 and NGC 6528: two moderately reddened Bulge Globular Clusters
• Globular clusters in the inner Galaxy classified from dynamical orbital criteria
• Constraining Globular Cluster Age Uncertainties Using the IR Color-Magnitude Diagram
• The chemical composition of the low-mass Galactic globular cluster NGC 6362
• The peculiar Na-O anticorrelation of the bulge globular cluster NGC 6440
• A panchromatic view of the bulge globular cluster NGC 6569
• Homogeneous metallicities and radial velocities for Galactic globular clusters. II. New CaT metallicities for 28 distant and reddened globular clusters
• Where did the globular clusters of the Milky Way form? Insights from the E-MOSAICS simulations
• Exploring the nature and synchronicity of early cluster formation in the Large Magellanic Cloud: II. Relative ages and distances for six ancient globular clusters
• A spectroscopic study of the Globular Cluster M28 (NGC~6626)
• The State-of-the-Art HST Astro-Photometric Analysis of the core of $\omega$ Centauri. II. Differential-Reddening Map
• Deriving Metallicities from Calcium Triplet Spectroscopy in combination with Near Infrared Photometry
• High-resolution abundance analysis of four red giants in the globular cluster NGC 6558
• The kinematics of globular cluster populations in the E-MOSAICS simulations and their implications for the assembly history of the Milky Way
• Digging for relics of the past: the ancient and obscured bulge globular cluster NGC6256
• Chemical Complexity in the Eu-enhanced Monometallic Globular Cluster NGC 5986
• Exploring the Chemical Composition and Double Horizontal Branch of the Bulge Globular Cluster NGC 6569
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XX. Ages of single and multiple stellar populations in seven bulge globular clusters
• The Age of the Old Metal-Poor Globular Cluster NGC6397 Using WFC3/IR Photometry
• High-resolution extinction map in the direction of the bulge globular cluster NGC 6440
• The Chemical Composition of Red Giant Branch Stars in the Galactic Globular Clusters NGC 6342 and NGC 6366
• APOGEE-2S Discovery of Light- and Heavy-Element Abundance Correlations in the Bulge Globular Cluster NGC 6380
• Structure and Internal Kinematics of Nine Inner Milky Way Globular Clusters
• Project AMIGA: Distance and Metallicity Gradients Along Andromeda's Giant Southern Stream from the Red Clump
• Halo intruders in the Galactic bulge revealed by HST and Gaia: the globular clusters Terzan 10 and Djorgovski 1
• Chemical analysis of eight giant stars of the globular cluster NGC 6366
• The Interstellar Extinction Toward the Milky Way Bulge with Planetary Nebulae, Red Clump, and RR Lyrae stars
• Variable stars in the bulge globular cluster NGC 6401

Cited by in corpus (4)

• A time-resolved picture of our Milky Way's early formation history
• Digging into the Galactic Bulge: stellar population and structure of the poorly studied cluster NGC 6316
• Classifying globular clusters and applying them to estimate the mass of the Milky Way
• Ca Triplet Metallicities and Velocities for twelve Globular Clusters towards the Galactic Bulge