Chemical abundance analysis of red giant branch stars in the globular cluster E3
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Fecha
2018-08
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Facultad/escuela
Idioma
en
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EDP Sciences
Nombre de Curso
Licencia CC
Licencia CC
Resumen
Context. Globular clusters are known to host multiple stellar populations, which are a signature of their formation process. The globular cluster E3 is one of the few low-mass globulars that is thought not to host multiple populations. Aims. We investigate red giant branch stars in E3 with the aim of providing a first detailed chemical inventory for this cluster, we determine its radial velocity, and we provide additional insights into the possible presence of multiple populations in this cluster. Methods. We obtained high-resolution FLAMES-UVES/VLT spectra of four red giant branch stars likely members of E3. We performed a local thermodynamic equilibrium abundance analysis based on one-dimensional plane parallel ATLAS9 model atmospheres. Abundances were derived from line equivalent widths or spectrum synthesis. Results. We measured abundances of Na and of iron peak (Fe, V, Cr, Ni, Mn), α(Mg, Si, Ca, Ti), and neutron capture elements (Y, Ba, Eu). The mean cluster heliocentric radial velocity, metallicity, and sodium abundance ratio are ν helio = 12.6 ± 0.4 km s -1 (σ = 0.6 ± 0.2 km s -1 ), [Fe/H] = -0.89 ± 0.08 dex, and [Na/Fe] = 0.18 ± 0.07 dex, respectively. The low Na abundance with no appreciable spread is suggestive of a cluster dominated by first-generation stars in agreement with results based on lower resolution spectroscopy. The low number of stars observed does not allow us to rule out a minor population of second-generation stars. The observed chemical abundances are compatible with the trends observed in Milky Way stars. © ESO 2018.
Notas
Indexación: Scopus.
4 IRAF is distributed by the National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation.
Acknowledgements. We thank the anonymous referee for a careful reading of the paper and constructive comments which improved the quality of the presentation. L.M. acknowledges support from “Proyecto Interno” of the Univer-sidad Andres Bello. S.V. and C.M.B. gratefully acknowledge the support provided by FONDECYT N.1170518 and 1150060, respectively. This research has made use of the NASA Astrophysics Data System and of the SIMBAD database, operated at CDS, Strasbourg, France. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www. cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/ consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.
4 IRAF is distributed by the National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation.
Acknowledgements. We thank the anonymous referee for a careful reading of the paper and constructive comments which improved the quality of the presentation. L.M. acknowledges support from “Proyecto Interno” of the Univer-sidad Andres Bello. S.V. and C.M.B. gratefully acknowledge the support provided by FONDECYT N.1170518 and 1150060, respectively. This research has made use of the NASA Astrophysics Data System and of the SIMBAD database, operated at CDS, Strasbourg, France. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www. cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/ consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.
Palabras clave
Globular clusters: individual: E3, Stars: abundances, Stars: atmospheres
Citación
Astronomy and Astrophysics, 616, art. no. A181.