scholarly journals Observations and Simulations of the Blue Straggler Star Radial Distribution: Clues on the Formation Mechanisms

2007 ◽  
Vol 3 (S246) ◽  
pp. 326-330
Author(s):  
Barbara Lanzoni
Keyword(s):  
Mass Transfer ◽  
Monte Carlo ◽  
Radial Distribution ◽  
Globular Clusters ◽  
Formation Mechanisms ◽  
Wide Field ◽  
Field Observations ◽  
Blue Stragglers ◽  
Blue Straggler ◽  
Dynamical Simulations

AbstractBy means of high-resolution and wide-field observations in the UV and optical bands we have derived the radial distribution of the Blue Stragglers Star (BSS) population in a number of galactic globular clusters. Monte-Carlo dynamical simulations have then been used to interpret the observed radial distributions in terms of percentage of collisional and mass-transfer BSS populating each cluster. I will present the main results thus obtained and an overall cluster–to–cluster comparison for the whole sample collected so far, mainly focusing on the clues that such an approach provides about the BSS formation mechanisms.

scholarly journals Observations of blue straggler stars in globular clusters

2006 ◽  
Vol 2 (14) ◽  
pp. 438-439
Author(s):  
Francesco R. Ferraro ◽  
Barbara Lanzoni
Keyword(s):  
Globular Clusters ◽  
Binary Systems ◽  
Stellar Population ◽  
Main Sequence ◽  
Formation Mechanisms ◽  
Main Sequence Stars ◽  
Blue Stragglers ◽  
Photometric And Spectroscopic Observations ◽  
Blue Straggler ◽  
Dynamical Simulations

AbstractBlue stragglers stars (BSS) define a sparsely populated sequence extending to higher luminosity than the turnoff point of normal main sequence stars in the color magnitude diagrams of stellar aggregates, thus mimicking a rejuvenated (more massive) stellar population. The nature of these stars has been a puzzle for many years and their formation mechanism is not completely understood, yet. Two mechanisms have been proposed to produce BSS: (i) the mass transfer in binary systems; and ((ii) the merger of two stars induced by stellar interactions. In this contribution we schematically report on the main properties of BSS in globular clusters (GCs) in the light of the most recent photometric and spectroscopic observations. These results, combined with dynamical simulations, indicate that both the proposed formation mechanisms play an important role in the production of BSS in GCs.

scholarly journals Blue Straggler Stars in Galactic Globular Clusters: Tracing the Effect of Dynamics on Stellar Evolution

2007 ◽  
Vol 3 (S246) ◽  
pp. 281-290
Author(s):  
Francesco R. Ferraro ◽  
Barbara Lanzoni
Keyword(s):  
Chemical Composition ◽  
Radial Distribution ◽  
Stellar Evolution ◽  
Globular Clusters ◽  
Blue Stragglers ◽  
Blue Straggler ◽  
Galactic Globular Clusters

AbstractIn this contribution we review the main observational properties of Blue Stragglers Stars (BSS) in galactic GCs. A flower of results on the BSS frequency, radial distribution, and chemical composition are presented and discussed.

scholarly journals Exotic populations in globular clusters: blue stragglers as tracers of the internal dynamical evolution of stellar systems

2014 ◽  
Vol 10 (S312) ◽  
pp. 171-180
Author(s):  
Francesco R. Ferraro
Keyword(s):  
Radial Distribution ◽  
Globular Clusters ◽  
Stellar Population ◽  
Dynamical Evolution ◽  
Stellar Systems ◽  
Internal Dynamics ◽  
Blue Stragglers ◽  
Blue Straggler ◽  
Specific Frequency ◽  
Definition Of

AbstractIn this paper I present an overview of the main observational properties of a special class of exotic objects (the so-called Blue Straggler Stars, BSSs) in Galactic Globular Clusters (GCs). The BSS specific frequency and their radial distribution are discussed in the framework of using this stellar population as probe of GC internal dynamics. In particular, the shape of the BSS radial distribution has been found to be a powerful tracer of the dynamical evolution of stellar systems, thus allowing the definition of an empirical “clock”able to measure the dynamical age of stellar aggregates from pure observational properties.

Binary evolution and double sequences of blue stragglers in globular clusters

2018 ◽  
Vol 14 (S343) ◽  
pp. 427-428
Author(s):  
Dengkai Jiang ◽  
Xuefei Chen ◽  
Lifang Li ◽  
Zhanwen Han
Keyword(s):  
Mass Transfer ◽  
Globular Clusters ◽  
Double Sequences ◽  
Single Star ◽  
Blue Stragglers ◽  
Blue Straggler ◽  
Magnitude Diagram ◽  
Blue Component ◽  
Binary Evolution ◽  
Red Sequence

AbstractBinary evolution can produce different blue-straggler binaries, for example, blue stragglers with a bright, red component, or with a faint, blue component. In globular clusters, these blue-straggler binaries are generally observed as a single star, because two components can not be distinguished. Therefore, these blue-straggler binaries can be located in different regions of the color-magnitude diagram of globular clusters, e.g. blue sequence and red sequence observed in M30. We suggest that binary evolution can contribute to the blue stragglers in both of the sequences. Some blue stragglers in the blue sequence may have a faint white dwarf companion, while the red sequence includes some binaries experiencing mass transfer. It should be noted that the red sequence may also have other binaries, for example, the binaries just finished the mass transfer, and the binaries including a blue straggler (the accretors) that have evolved away from the blue sequence.

scholarly journals Environmental Effects on the Globular Cluster Blue Straggler Population: a Statistical Approach

2007 ◽  
Vol 3 (S246) ◽  
pp. 369-370
Author(s):  
Alessia Moretti ◽  
Francesca De Angeli ◽  
Giampaolo Piotto
Keyword(s):  
Stellar Evolution ◽  
Globular Clusters ◽  
Statistical Approach ◽  
Principal Component ◽  
Formation Mechanisms ◽  
Homogeneous Sample ◽  
Blue Stragglers ◽  
Parent Cluster ◽  
Blue Straggler ◽  
Environmental Dependence

AbstractBlue stragglers stars (BSS) constitute an ubiquitous population of objects whose origin involves both dynamical and stellar evolution. We took advantage of the homogeneous sample of 56 Galactic globular clusters observed with WFPC2/HST by Piotto et al. (2002) to investigate the environmental dependence of the BSS formation mechanisms. We explore possible monovariate relations between the frequency of BSS (divided in different subsamples according to their location with respect to the parent cluster core radius and half mass radius) and the main parameters of their host GC. We also performed a Principal Component Analysis to extract the main parent cluster parameters which characterise the BSS family.

scholarly journals The blue straggler population of the old open cluster Berkeley 17

2019 ◽  
Vol 624 ◽  
pp. A26 ◽  
Author(s):  
Souradeep Bhattacharya ◽  
Kaushar Vaidya ◽  
W. P. Chen ◽  
Giacomo Beccari
Keyword(s):  
Radial Distribution ◽  
Globular Clusters ◽  
Minimum Spanning Tree ◽  
Open Cluster ◽  
Dynamical Evolution ◽  
Open Clusters ◽  
Blue Straggler ◽  
Magnitude Diagram ◽  
First Time ◽  
Giant Branch Stars

Context. Blue straggler stars (BSSs) are observed in Galactic globular clusters and old open clusters. The radial distribution of BSSs has been used to diagnose the dynamical evolution of globular clusters. For the first time, with a reliable sample of BSSs identified with Gaia DR2, we conduct such an analysis for an open cluster. Aims. We aim to identify members, including BSSs, of the oldest known Galactic open cluster Berkeley 17 with the Gaia DR2 proper motions and parallaxes. We study the radial distribution of the BSS population to understand the dynamical evolution of the cluster. Methods. We selected cluster members to populate the colour magnitude diagram in the Gaia filters. Cluster parameters are derived using the brightest members. The BSSs and giant branch stars are identified, and their radial distributions are compared. The segregation of BSSs is also evaluated with respect to the giant branch stars using the minimum spanning tree (MST) analysis. Results. We determine Berkeley 17 to be at 3138.6−352.9+285.5 pc. We find 23 BSS cluster members, only two of which were previously identified. We find a bimodal radial distribution of BSSs supported by findings from the MST method. Conclusions. The bimodal radial distribution of BSSs in Berkeley 17 indicates that they have just started to sink towards the cluster centre, placing Berkeley 17 with globular clusters of intermediate dynamical age. This is the first such determination for an open cluster.

Discovery of Another Peculiar Radial Distribution of Blue Stragglers in Globular Clusters: The Case of 47 Tucanae

2004 ◽  
Vol 603 (1) ◽  
pp. 127-134 ◽  
Author(s):  
Francesco R. Ferraro ◽  
Giacomo Beccari ◽  
Robert T. Rood ◽  
Michele Bellazzini ◽  
Alison Sills ◽  
...  
Keyword(s):  
Radial Distribution ◽  
Globular Clusters ◽  
Blue Stragglers

scholarly journals Blue stragglers in star clusters and the conventional SSP models

2009 ◽  
Vol 5 (S266) ◽  
pp. 556-556
Author(s):  
Yu Xin ◽  
Richard de Grijs ◽  
Licai Deng ◽  
Pavel Kroupa
Keyword(s):  
Stellar Evolution ◽  
Stellar Population ◽  
Broad Band ◽  
Star Clusters ◽  
Open Clusters ◽  
Formation Mechanisms ◽  
Evolution Theory ◽  
Blue Stragglers ◽  
Blue Straggler ◽  
Conventional Picture

AbstractThe presence of blue straggler stars (BSs) as secure members of star clusters poses a major challenge to the conventional picture of simple stellar population (SSP) models. The models are based on the stellar evolution theory of single stars, while the major formation mechanisms of BSs are all correlated with stellar interactions. Based on a sufficient working sample including 100 Galactic open clusters, one Galactic globular cluster, and seven Magellanic Cloud star clusters, we discuss the modifications of the properties of broad-band colors and Lick indices of the standard SSP models due to BS populations.

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