Relative Frequencies of Blue Stragglers in Galactic Globular Clusters: Constraints for the Formation Mechanisms

By G. Piotto, F. De Angeli, Ivan R. King, S. George Djorgovski, G. Bono, Santi Cassisi, G. Meylan, A. Recio-Blanco, R. Rich, M. Davies. 2004

139 citations recorded by the source corpus.

We discuss the main properties of the Galactic globular cluster (GC) blue straggler stars (BSSs), as inferred from our new catalog containing nearly 3000 BSSs. The catalog has been extracted from the photometrically homogeneous V versus (B-V) color-magnitude diagrams (CMDs) of 56 GCs, based on Wide Field Planetary Camera 2 images of their central cores. In our analysis, we used consistent relative distances based on the same photometry and calibration. The number of BSSs has been normalized to obtain relative frequencies (FBSS) and specific densities (NS) using different stellar populations extracted from the CMD. The cluster FBSS is significantly smaller than the relative frequency of field BSSs. We find a significant anticorrelation between the BSS relative frequency in a cluster and its total absolute luminosity (mass). There is no statistically significant trend between the BSS frequency and the expected collision rate. The value of FBSS does not depend on other cluster parameters, apart from a mild dependence on the central density. Post-core-collapse clusters act like normal clusters as far as the BSS frequency is concerned. We also show that the BSS luminosity function for the most luminous clusters is significantly different, with a brighter peak and extending to brighter luminosities than in the less luminous clusters. These results imply that the efficiency of BSS production mechanisms and their relative importance vary with the cluster mass.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/4ee31b84b310c8153976874721c0935ca150d7b2

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In Astronomy and Astrophysics

1. Jay Anderson
2. G. Piotto
3. Aaron Dotter
4. L. Bedin
5. A. Milone
6. F. Rasio
7. A. Renzini
8. F. Antonini

In Instrumentation

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

Citations in the corpus

• The ACS survey of Galactic globular clusters. XII. Photometric binaries along the main sequence (2011, background): “…and gammacolN seem to suggest a mild correlation between binary fraction and the collisional parameter, while there is no significant correlation between the BSS frequency and the collisional parameter (e. g. Piotto et al. 2004, Davies et al. 2004, Leigh Sills, & Knigge 2007, Moretti et al. 2008).”
• THE QUENCHING OF THE ULTRA-FAINT DWARF GALAXIES IN THE REIONIZATION ERA (2014, background): “In globular clusters,NBS/NHB typically ranges from 0.1 to 1 (e.g., Piotto et al. 2004; Ferraro et al. 2014).”
• The White Dwarf Cooling Sequence of NGC 6397 (2005, background): “Davies, Piotto, & De Angeli (2004), based on observational evidence by Piotto et al. (2004), show that the number of BSs coming from evolving binaries should have been much larger in the first few Gyr of the life of the cluster.”
• BLACK HOLE MERGERS AND BLUE STRAGGLERS FROM HIERARCHICAL TRIPLES FORMED IN GLOBULAR CLUSTERS (2015, background): “…number of BSSs produced in a cluster and several dynamically important observed cluster properties, including the total mass, total number of binaries, and the central collision/interaction rate, and what they mean (Piotto et al. 2004; Leigh et al. 2007; Knigge et al. 2009; Chatterjee et al. 2013).”
• THE HUBBLE SPACE TELESCOPE UV LEGACY SURVEY OF GALACTIC GLOBULAR CLUSTERS. I. OVERVIEW OF THE PROJECT AND DETECTION OF MULTIPLE STELLAR POPULATIONS (2014, methodology): “Since they arhotter than 6000–7000 K, they are best detectable at UV wavelengths, so that we can use the UV surveydata to obtain complete samples of BSSs in the central regions of GCs, with a significant improvement in completeness over that of previous efforts (e.g., Piotto et al. 2004).”