Blue Straggler Stars in Galactic Open Clusters and the effect of field star contamination

Abstract

We investigate the distribution of Blue Straggler stars in the field of three open star clusters. The main purpose is to highlight the crucial role played by general Galactic disk fore-/back-ground field stars, which are often located in the same region of the Color Magnitude Diagram as Blue Straggler stars. We analyze photometry taken from the literature of 3 open clusters of intermediate/old age rich in Blue Straggler stars, and which are projected in the direction of the Perseus arm, and study their spatial distribution and the Color Magnitude Diagram. As expected, we find that a large portion of the Blue Straggler population in these clusters are simply young field stars belonging to the spiral arm. This result has important consequences on the theories of the formation and statistics of Blue Straggler stars in different population environments: open clusters, globular clusters or dwarf galaxies. As previously emphasized by many authors, a detailed membership analysis is mandatory before comparing the Blue Straggler population in star clusters against theoretical models. Moreover, these sequences of young field stars (blue plumes) are potentially powerful tracers of Galactic structure which require further consideration.

11 pages, 4 figurs, in press as Research Note in A&A

References in corpus (4)

• Spiral structure in the outer Galactic disk. I. The Third Galactic Quadrant
• Spiral structure of the Third Galactic Quadrant and the solution to the Canis Major debate
• Search and analysis of blue straggler stars in open clusters
• The population in the background of open clusters: Tracer of the Norma-Cygnus arm

Cited by in corpus (6)

• A new, Gaia based, catalogue of blue straggler stars in open clusters
• Blue Straggler Populations of Seven Open Clusters with Gaia DR2
• The blue straggler population of the old open cluster Berkeley 17
• A study of the blue straggler population of the old open cluster Collinder 261
• Updated properties of the old open cluster Melotte 66: Searching for multiple stellar populations
• The blue straggler population of the open clusters Trumpler 5, Trumpler 20, and NGC 2477