The ACS Survey Of Galactic Globular Clusters. VII. Relative Ages

  title={The ACS Survey Of Galactic Globular Clusters. VII. Relative Ages},
  author={Antonio Mar{\'i}n-Franch and Antonio Aparicio and Giampaolo Piotto and Alfred Rosenberg and Brian Chaboyer and Ata Sarajedini and Michael H. Siegel and Jay Anderson and Luigi R. Bedin and Aaron Dotter and Maren Hempel and Ivan R. King and Steven R. Majewski and Antonino P. Milone and Nathaniel E. Q. Paust and I. N. Reid},
  journal={The Astrophysical Journal},
The ACS Survey of Galactic globular clusters is a Hubble Space Telescope Treasury program designed to provide a new large, deep, and homogeneous photometric database. Based on observations from this program, we have measured precise relative ages for a sample of 64 Galactic globular clusters by comparing the relative position of the clusters' main-sequence (MS) turnoffs, using MS fitting to cross-compare clusters within the sample. This method provides relative ages to a formal precision of 2… 
The ACS survey of Galactic globular clusters. XII. Photometric binaries along the main sequence
Context. The fraction of binary stars is an important ingredient to interpret globular cluster dynamical evolution and their stellar population. Aims. We investigate the properties of main-sequence
The ACS survey of Galactic globular clusters – XIV. Bayesian single-population analysis of 69 globular clusters
We use Hubble Space Telescope (HST) imaging from the ACS Treasury Survey to determine fits for single population isochrones of 69 Galactic globular clusters. Using robust Bayesian analysis
New insight into the stellar mass function of Galactic globular clusters
We present the results of the analysis of deep photometric data of 32 Galactic globular clusters. We analysed 69 parallel field images observed with the Wide Field Channel of the Advanced Camera for
A survey for dwarf galaxy remnants around 14 globular clusters in the outer halo
We report the results of a systematic photometric survey of the peripheral regions of a sample of 14 globular clusters in the outer halo of the Milky Way at distances d_(GC) > 25 kpc from the
Exploring the nature and synchronicity of early cluster formation in the Large Magellanic Cloud - II. Relative ages and distances for six ancient globular clusters
We analyze Hubble Space Telescope observations of six globular clusters in the Large Magellanic Cloud from program GO-14164 in Cycle 23. These are the deepest available observations of the LMC
The globular cluster system of NGC 6822
We present a comprehensive analysis of the globular cluster (GC) system of the Local Group dwarf irregular galaxy NGC 6822. Our study is based on homogeneous optical and near-IR photometry, as well
GeMS MCAO observations of the Galactic globular cluster NGC 2808: the absolute age
Context. Globular clusters are the oldest stellar systems in the Milky Way, and they probe the early epoch of the Galaxy formation. However, the uncertainties on their absolute age are still too
The environment of formation as a second parameter for globular cluster classification
We perform an evolutionary multivariate analysis of a sample of 54 Galactic globular clusters with high-quality colour–magnitude diagrams and well-determined ages. The four parameters adopted for the
We use a sample of newly-discovered globular clusters from the Pan-Andromeda Archaeological Survey (PAndAS) in combination with previously-catalogued objects to map the spatial distribution of
Chemical tagging in the SDSS-III/APOGEE survey: new identifications of halo stars with globular cluster origins
We present new identifications of five red giant stars in the Galactic halo with chemical abundance patterns that indicate they originally formed in globular clusters. Using data from the Apache


Galactic Globular Cluster Relative Ages
We present accurate relative ages for a sample of 55 Galactic globular clusters. The ages have been obtained by measuring the difference between the horizontal branch and the turnoff in two
The Relative Ages of Galactic Globular Clusters
We present a review of the present state of knowledge regarding the relative ages of Galactic globular clusters. First, we discuss the relevant galaxy formation models and describe the detailed
Globular Cluster Ages and the Formation of the Galactic Halo
Main sequence turnoff magnitudes from the recent set of Yale isochrones (Chaboyer et al. 1995) have been combined with a variety of relations for the absolute magnitude of RR Lyr stars (Mv(RR)) to
Abundances for globular cluster giants: I. homogeneous metallicities for 24 clusters
We have obtained high resolution, high signal-to-noise ratio CCD echelle spectra of 10 bright red giants in 3 globular clusters (47 Tuc, NGC 6752 and NGC 6397) roughly spanning the whole range of
The ACS Survey of Galactic Globular Clusters. I. Overview and Clusters without Previous Hubble Space Telescope Photometry
We present the first results of a large Advanced Camera for Surveys (ACS) survey of Galactic globular clusters. This Hubble Space Telescope (HST) Treasury project is designed to obtain photometry
The ACS Survey of Galactic Globular Clusters: M54 and Young Populations in the Sagittarius Dwarf Spheroidal Galaxy*
As part of the ACS Survey of Galactic Globular Clusters, we present new Hubble Space Telescope photometry of the massive globular cluster M54 (NGC 6715) and the superposed core of the tidally
The Relative Ages of Galactic Globular Clusters
We discuss the present state of knowledge and thought concerning the spread in age found among Galactic globular clusters, with some discussion of the implications for what happened during the
Age Gradient and the Second Parameter Problem in the Galactic Halo
We establish a framework for determing absolute ages of Galactic globular clusters and then use these ages to investigate the age-metallicity and age-Galactocentric distance relations for the 36
The ACS Survey of Galactic Globular Clusters. II. Stellar Evolution Tracks, Isochrones, Luminosity Functions, and Synthetic Horizontal-Branch Models*
The ACS Survey of Galactic Globular Clusters, an HST Treasury Project, will deliver high-quality, homogeneous photometry of 65 globular clusters. This paper introduces a new collection of stellar
Exploring Halo Substructure with Giant Stars: Spectroscopy of Stars in the Galactic Anticenter Stellar Structure
To determine the nature of the recently discovered, ringlike stellar structure at the Galactic anticenter, we have collected spectra of a set of presumed constituent M giants selected from the Two