The Gaia-ESO Survey. Mg-Al anti-correlation in iDR4 globular clustersReport as inadecuate

The Gaia-ESO Survey. Mg-Al anti-correlation in iDR4 globular clusters

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Publication Date: 2017-03-02

Journal Title: Astronomy and Astrophysics

Publisher: EDP Sciences

Language: English

Type: Article

This Version: AM

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Citation: Pancino, E., Romano, D., Tang, B., Tautvaisiene, G., Casey, A. R., Gruyters, P., Geisler, D., & et al. (2017). The Gaia-ESO Survey. Mg-Al anti-correlation in iDR4 globular clusters. Astronomy and Astrophysics

Abstract: We use Gaia-ESO Survey iDR4 data to explore the Mg-Al anti-correlation in globular clusters, that were observed as calibrators, as a demonstration of the quality of Gaia-ESO Survey data and analysis. The results compare well with the available literature, within 0.1 dex or less, after a small (compared to the internal spreads) offset between the UVES and the GIRAFFE data of 0.10-0.15 dex was taken into account. In particular, we present for the first time data for NGC 5927, one of the most metal-rich globular clusters studied in the literature so far with [Fe/H]=–0.49 dex, that was included to connect with the open cluster regime in the Gaia-ESO Survey internal calibration. The extent and shape of the Mg-Al anti-correlation provide strong constraints on the multiple population phenomenon in globular clusters. In particular, we studied the dependency of the Mg-Al anti-correlation extension with metallicity, present-day mass, and age of the clusters, using GES data in combination with a large set of homogenized literature measurements. We find a dependency with both metallicity and mass, that is evident when fitting for the two parameters simultaneously, but no significant dependency with age. We confirm that the Mg-Al anti-correlation is not seen in all clusters, but disappears for the less massive or most metal-rich ones. We also use our dataset to see whether a normal anti-correlation would explain the low [Mg/α] observed in some extragalactic globular clusters, but find that none of the clusters in our sample can reproduce it, and more extreme chemical compositions (like the one of NGC 2419) would be required. We conclude that GES iDR4 data already meet the requirements set by the main survey goals, and can be used to study in detail globular clusters even if the analysis procedures were not specifically designed for them.

Keywords: surveys, stars: abundances, globular clusters: general, globular clusters: individual : NGC 5927

Sponsorship: l. This work was partly supported by the European Union FP7 programme through ERC grant number 320360 and by the Leverhulme Trust through grant RPG-2012-541. We acknowledge the support from INAF and Ministero dell’ Istruzione, dell’ Università e della Ricerca (MIUR) in the form of the grant Premiale VLT 2012. The results presented here benefit from discussions held during the Gaia-ESO workshops and conferences supported by the ESF (European Science Foundation) through the GREAT Research Network Programme. M.T.C. acknowledges the financial support from the Spanish Ministerio de Economía y Competitividad, through grant AYA2013-40611-P. E.P. and D.R. benefited from the International Space Science Institute (ISSI, Bern, CH), through funding of the International Team “The Formation and Evolution of the Galactic Halo. S.G.S acknowledges the support by Fundação para a Ciência e Tecnologia (FCT) through national funds and a research grant (project ref. UID/FIS/04434/2013, and PTDC/FISAST/7073/2014). S.G.S. also acknowledge the support from FCT through Investigador FCT contract of reference IF/00028/2014 and POPH/FSE (EC) by FEDER funding through the program “Programa Operacional de Factores de Competitividade – COMPETE. D.G., B.T., and S.V. gratefully acknowledge support from the Chilean BASAL Centro de Excelencia en Astrofísica y Tecnologías Afines (CATA) grant PFB-06/2007. L.M. acknowledges support from Proyecto Interno of the Universidad Andres Bello. E.J.A was supported by Spanish MINECO under grant AYA2016-75931-C2-1-P with FEDER funds. R.S. acknowledges support from the Polish Ministry of Science and Higher Education (660/E-60/STYP/10/2015).


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Author: Pancino, ERomano, DTang, BTautvaisiene, G Casey, Andrew RaithbyGruyters, PGeisler, DSan Roman, IShow moreShow less



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