Fast Rotating Blue Straggler Stars in the globular cluster NGC 1851

Fuente: arXiv
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Autores principales: Billi, Alex, Monaco, Lorenzo, Ferraro, Francesco R., Mucciarelli, Alessio, Lanzoni, Barbara, Cadelano, Mario, Trangolao, Israel
Formato: Preprint
Publicado: 2025
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author Billi, Alex
Monaco, Lorenzo
Ferraro, Francesco R.
Mucciarelli, Alessio
Lanzoni, Barbara
Cadelano, Mario
Trangolao, Israel
author_facet Billi, Alex
Monaco, Lorenzo
Ferraro, Francesco R.
Mucciarelli, Alessio
Lanzoni, Barbara
Cadelano, Mario
Trangolao, Israel
contents In this work we study the rotational velocities of a sample of blue straggler stars (BSSs) and reference stars belonging to the Galactic globular cluster NGC 1851, using high-resolution spectra acquired with FLAMES-GIRAFFE at the ESO/VLT. After field decontamination based on radial velocities and proper motions, the final sample of member stars is composed of 15 BSSs and 45 reference stars populating the red giant and horizontal branches of the cluster. In agreement with previous findings, the totality of reference stars has negligible rotation (lower than 15 km/s). In contrast, we find high values of rotational velocity (up to $\sim$ 150 km/s) for a sub-sample of BSSs. By defining the threshold for fast rotating BSSs at 40 km/s, we found 4 fast-rotating BSSs out of 15, corresponding to a percentage of 27 $\pm$ 14 %. This results delineates a monotonically decreasing trend (instead of a step function) between the percentage of fast spinning BSSs and the central concentration and density of the host cluster, supporting a scenario where recent BSS formation preferentially occurs in low-density environments from the evolution of binary systems.
format Preprint
id arxiv_https___arxiv_org_abs_2511_10109
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Fast Rotating Blue Straggler Stars in the globular cluster NGC 1851
Billi, Alex
Monaco, Lorenzo
Ferraro, Francesco R.
Mucciarelli, Alessio
Lanzoni, Barbara
Cadelano, Mario
Trangolao, Israel
Solar and Stellar Astrophysics
Astrophysics of Galaxies
In this work we study the rotational velocities of a sample of blue straggler stars (BSSs) and reference stars belonging to the Galactic globular cluster NGC 1851, using high-resolution spectra acquired with FLAMES-GIRAFFE at the ESO/VLT. After field decontamination based on radial velocities and proper motions, the final sample of member stars is composed of 15 BSSs and 45 reference stars populating the red giant and horizontal branches of the cluster. In agreement with previous findings, the totality of reference stars has negligible rotation (lower than 15 km/s). In contrast, we find high values of rotational velocity (up to $\sim$ 150 km/s) for a sub-sample of BSSs. By defining the threshold for fast rotating BSSs at 40 km/s, we found 4 fast-rotating BSSs out of 15, corresponding to a percentage of 27 $\pm$ 14 %. This results delineates a monotonically decreasing trend (instead of a step function) between the percentage of fast spinning BSSs and the central concentration and density of the host cluster, supporting a scenario where recent BSS formation preferentially occurs in low-density environments from the evolution of binary systems.
title Fast Rotating Blue Straggler Stars in the globular cluster NGC 1851
topic Solar and Stellar Astrophysics
Astrophysics of Galaxies
url https://arxiv.org/abs/2511.10109