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.

NGC 5694: another foster son of the Galactic halo / A. Mucciarelli;M. Bellazzini;M. Catelan;E. Dalessandro;P. Amigo;M. Correnti;C. Cortes;V. D'Orazi. - In: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. - ISSN 0035-8711. - ELETTRONICO. - 435:(2013), pp. 3667-3680. [10.1093/mnras/stt1558]

NGC 5694: another foster son of the Galactic halo

MUCCIARELLI, ALESSIO;DALESSANDRO, EMANUELE;
2013

Abstract

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.
2013
NGC 5694: another foster son of the Galactic halo / A. Mucciarelli;M. Bellazzini;M. Catelan;E. Dalessandro;P. Amigo;M. Correnti;C. Cortes;V. D'Orazi. - In: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. - ISSN 0035-8711. - ELETTRONICO. - 435:(2013), pp. 3667-3680. [10.1093/mnras/stt1558]
A. Mucciarelli;M. Bellazzini;M. Catelan;E. Dalessandro;P. Amigo;M. Correnti;C. Cortes;V. D'Orazi
File in questo prodotto:
Eventuali allegati, non sono esposti

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/396548
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 20
  • ???jsp.display-item.citation.isi??? 21
social impact