Spinning like a Blue Straggler: the population of fast rotating Blue Straggler stars in Omega Centauri

Abstract

By using high-resolution spectra acquired with FLAMES-GIRAFFE at the ESO/VLT, we measured radial and rotational velocities for 110 Blue Straggler stars (BSSs) in Omega Centauri, the globular cluster-like stellar system harboring the largest known BSS population. According to their radial velocities, 109 BSSs are members of the system. The rotational velocity distribution is very broad, with the bulk of BSSs spinning at less than ~40 km/s (in agreement with the majority of such stars observed in other globular clusters) and a long tail reaching ~200 km/s. About 40% of the sample has vsini >40 km/s and about 20% has vsini >70 km/s. Such a large fraction is very similar to the percentage of of fast rotating BSSs observed in M4. Thus, Omega Centauri is the second stellar cluster, beyond M4, with a surprisingly high population of fast spinning BSSs. We found a hint of a radial behaviour of the fraction of fast rotating BSSs, with a mild peak within one core radius, and a possibile rise in the external regions (beyond four core radii). This may suggest that recent formation episodes of mass transfer BSSs occurred preferentially in the outskirts of Omega Centauri, or that braking mechanisms able to slow down these stars are least efficient in lowest density environments.

Accepted for publication by ApJ. 30 pages, 11 figures, 1 table

References in corpus (12)

• Gemini and Hubble Space Telescope Evidence for an Intermediate Mass Black Hole in omega Centauri
• Dynamical age differences among coeval star clusters as revealed by blue stragglers
• Discovery of Carbon/Oxygen depleted Blue Straggler Stars in 47 Tucanae: the chemical signature of a mass-transfer formation process
• The radial distribution of blue straggler stars and the nature of their progenitors
• Another Non-segregated Blue Straggler Population in a Globular Cluster: the Case of NGC 2419
• The surface density profile of NGC 6388: a good candidate for harboring an intermediate-mass black hole
• Blue Straggler Stars in the Unusual Globular Cluster NGC 6388
• A Panchromatic Study of the Globular Cluster NGC 1904. I: The Blue Straggler Population
• The Blue Straggler Population of the Globular Cluster M5
• The Rotation of Sub-Populations in omega Centauri
• Detailed maps of interstellar clouds in front of omega Centauri: Small-scale structures in the Galactic Disc-Halo interface
• An Overview of the Rotational Behavior of Metal--Poor Stars

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• On the Use of Field RR Lyrae as Galactic Probes. V. Optical and radial velocity curve templates
• A study of the blue straggler population of the old open cluster Collinder 261
• The blue straggler population of the open clusters Trumpler 5, Trumpler 20, and NGC 2477
• High-speed stars. II. An unbound star, young stars, bulge metal-poor stars, and Aurora candidates
• Rotation of Kepler field dwarfs and sub giants: Spectroscopic $v\sin I$ from APOGEE
• Globular Cluster UVIT legacy Survey (GlobUleS) III. Omega Centauri in Far-Ultraviolet
• Rotational velocities of Blue Straggler Stars in the Globular Cluster M55
• Fast Rotating Blue Straggler Stars in the globular cluster NGC 1851