NGC 5694: another foster son of the Galactic halo

A. Mucciarelli*, M. Bellazzini, M. Catelan, E. Dalessandro, P. Amigo, M. Correnti, C. Cortés, V. D'Orazi

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

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    We present the results of the analysis of high-resolution spectra obtained with UVES-FLAMES at the Very Large Telescope for six red giant branch stars in the outer-halo metal-poor ([Fe/H] I = -1.98 and [Fe/H] II = -1.83) Galactic globular cluster NGC 5694, which has been suggested as a possible incomer by Lee et al. based on the anomalous chemical composition of a single cluster giant. We obtain accurate abundances for a large number of elements and we find that (a)the six target stars have the same chemical composition within the uncertainties, except for Na and Al; (b) the average cluster abundance of a elements (with the only exception of Si) is nearly solar, at odds with typical halo stars and globular clusters of similar metallicity; (c) Y, Ba, La and Eu abundances are also significantly lower than in Galactic field stars and star clusters of similar metallicity. Hence, we confirm the Lee et al. classification of NGC 5694 as a cluster of extragalactic origin. We provide the first insight on the Na-O and Mg-Al anticorrelations in this cluster: all the considered stars have very similar abundance ratios for these elements, except one that has significantly lower [Na/Fe] and [Al/Fe] ratios, suggesting that some degree of early self-enrichment has occurred also in this cluster.

    Original languageEnglish
    Pages (from-to)3667-3680
    Number of pages14
    JournalMonthly Notices of the Royal Astronomical Society
    Issue number4
    Publication statusPublished - Nov 2013

    Bibliographical note

    This article has been accepted for publication in Monthly notices of the Royal Astronomical Society. Copyright 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.


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