Volume 537, January 2012
|Number of page(s)||10|
|Section||Galactic structure, stellar clusters and populations|
|Published online||12 January 2012|
A VIMOS spectroscopy study of photometric variables and straggler candidates in ω Centauri⋆
1 Nicolaus Copernicus Astronomical Center, ul. Bartycka 18, 00-716 Warszawa, Poland
2 Pontificia Universidad Católica de Chile, Departamento de Astronomía y Astrofísica, Av. Vicuña MacKenna 4860, 782-0436 Macul, Santiago, Chile
Received: 8 July 2011
Accepted: 25 October 2011
We report a spectroscopic study of 19 photometric variables and 55 blue, yellow, and red straggler candidates in the field of ω Centauri. We confirm the cluster membership of 18 variables and 54 straggler candidates. Velocity variations are detected in 22 objects, and another 17 objects are suspected to be velocity-variable. The velocities of 11 objects vary consistently with their photometric periods, allowing their mass functions to be calculated. Among them, we find no indication of the presence of a massive degenerate component. On the basis of both photometric and spectroscopic data, we estimate that the fraction of binaries among blue stragglers may be as high as 69 per cent.
Key words: binaries: close / binaries: spectroscopic / blue stragglers / globular clusters: individual: NGC 5139 (ωCentauri)
© ESO, 2012
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