SCYON Abstract

Received on October 16 2006

A population of binaries in the Asymptotic Giant Branch of 47 Tucanae?

AuthorsGiacomo Beccari (1,2,3), Francesco R. Ferraro (4), Barbara Lanzoni (1), and Michele Bellazzini (1)
Affiliation
(1) INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127 Bologna, Italy
(2) Dipartimento di Scienze della Comunicazione, 3, Universitá degli Studi di Teramo, Italy
(3) INAF-Osservatorio Astronomico di Collurania, Via Mentore Maggini, I-64100 Teramo, Italy
(4) Dipartimento di Astronomia, Universitá degli Studi di Bologna, via Ranzani 1, I-40127 Bologna, Italy
To appear inApJ Letter
Contactgiacomo.beccari@bo.astro.it
URLhttp://www.arxiv.org/abs/astro-ph/0610289
Links

Abstract

We have used a set of archived Hubble Space Telescope/ACS images to probe the evolved populations of the globular cluster 47 Tucanae. We find an excess of Asymptotic Giant Branch (AGB) stars in the cluster core. We interpret this feature as the signature of an extra-population likely made by the progeny of massive stars originated by the evolution of binary systems. Indeed the comparison with theoretical tracks suggests that the AGB population of 47 Tuc can be significantly contaminated by more massive stars currently experiencing the first ascending Red Giant Branch.