The ACS survey of Galactic globular clusters. XII. Photometric binaries along the main sequence

By A. Milone, G. Piotto, L. Bedin, A. Aparicio, Jay Anderson, A. Sarajedini, A. Marino, A. Moretti, M. B. Davies, B. Chaboyer and 8 more. 2011

368 citations recorded by the source corpus.

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 binaries measured in a uniform photometric sample of 59 Galactic globular clusters that were observed by HST WFC/ACS as a part of the Globular Cluster Treasury project. Methods. We measured the fraction of binaries and the distribution of mass-ratio as a function of radial location within the cluster, from the central core to beyond the half-mass radius. We studied the radial distribution of binary stars, and the distribution of stellar mass ratios. We investigated monovariate relations between the fraction of binaries and the main parameters of their host clusters. Results. We found that in nearly all the clusters, the total fraction of binaries is significantly smaller than the fraction of binaries in the field, with a few exceptions only. Binary stars are significantly more centrally concentrated than single MS stars in most of the clusters studied in this paper. The distribution of the mass ratio is generally flat (for mass-ratio parameter q > 0.5). We found a significant anti-correlation between the binary fraction in a cluster and its absolute luminosity (mass). Some, less significant correlation with the collisional parameter, the central stellar density, and the central velocity dispersion are present. There is no statistically significant relation between the binary fraction and other cluster parameters. We confirm the correlation between the binary fraction and the fraction of blue stragglers in the cluster. (Less)

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/28b6468c4bd36862e12abc67b613f17e1dd4aa7e

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. Jay Anderson
2. G. Piotto
3. L. Bedin
4. A. Milone
5. A. Renzini
6. Santi Cassisi
7. F. D’Antona
8. A. Aparicio

In Instrumentation

1. Jay Anderson
2. G. Piotto
3. L. Bedin
4. A. Milone
5. F. D’Antona
6. A. Renzini
7. Santi Cassisi
8. A. Aparicio

Citations in the corpus

• A WFC3/HST VIEW OF THE THREE STELLAR POPULATIONS IN THE GLOBULAR CLUSTER NGC 6752 (2013, methodology): “…host multiple main sequences (MSs) including ω Centauri, NGC2808, 47 Tuc, NGC6752, and NGC6397 (Anderson 1997, Bedin et al. 2004, Piotto et al. 2007, Milone et al. 2010, 2012a,b), which have been associated with stellar populations with different helium abundances (D’Antona & Caloi 2004, Norris…”
• The SUMO project: a SUrvey of Multiple pOpulations in globular clusters (2013, methodology): “In case of NGC 104, there are two groups of CN-rich and CN-poor red-HB stars (Norris & Freeman 1982), that define two sequences along the red HB, when observed in appropriate filters (Milone et al. 2012).”
• THE HUBBLE SPACE TELESCOPE UV LEGACY SURVEY OF GALACTIC GLOBULAR CLUSTERS. I. OVERVIEW OF THE PROJECT AND DETECTION OF MULTIPLE STELLAR POPULATIONS (2014, methodology): “This technique has been successfully applied to a few GCs, and differences in helium among different stellar populations have been measured in 47 Tuc, NGC 6397, NGC 288 and NGC 6752 (Milone et al. 2013, and references therein).”
• THE QUENCHING OF THE ULTRA-FAINT DWARF GALAXIES IN THE REIONIZATION ERA (2014, background): “…(e.g., Duquennoy & Mayor QUENCHING OF THEULTRA-FAINT DWARF GALAXIES 7 1991), the UFDs have a binary fraction of nearly 50% (Geha et al. 2013) – much higher than the binary fraction in M92 (∼2%; Milone et al. 2012), which has been reduced through dynamical evolution (e.g., Ivanova et al. 2005).”
• THE DYNAMICAL EVOLUTION OF STELLAR BLACK HOLES IN GLOBULAR CLUSTERS (2014, background): “Milone et al. (2012) measure core binary fractions fb .”
• MOCCA code for star cluster simulations – IV. A new scenario for intermediate mass black hole formation in globular clusters (2015, background): “…was to explain the observedcorrelations: between cluster mass and binary fraction - the larger the cluster mass, the smaller the binary fraction (Milone et al.2012); and mass function (MF) power-law index and cluster concentration - the more concentrated the cluster, the larger the MF power-law…”