Volume 645, January 2021
|Number of page(s)||9|
|Section||Galactic structure, stellar clusters and populations|
|Published online||13 January 2021|
Purveyors of fine halos
Zentrum für Astronomie der Universität Heidelberg, Astronomisches Rechen-Institut, Mönchhofstr. 12, 69120 Heidelberg, Germany
2 Max-Planck Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
3 GEPI, Observatoire de Paris, Université PSL, CNRS, 5 place Jules Janssen, 92190 Meudon, France
Accepted: 5 November 2020
Globular clusters (GCs) are important donors to the build-up of the Milky Way (MW) stellar halo, having contributed at the ten percent level over the Galactic history. Stars that originated from the second generation of dissolved or dissolving clusters can be readily identified via distinct light-element signatures such as enhanced N and Na and simultaneously depleted C and O abundances. In this paper we present an extensive chemical abundance analysis of the halo star J110842, which was previously kinematically associated with the massive MW GC ω Centauri (ωCen), and we discuss viable scenarios from escape to encounter. Based on a high-resolution, high signal-to-noise spectrum of this star using the UVES spectrograph, we were able to measure 33 species of 31 elements across all nucleosynthetic channels. The star’s low metallicity of [Fe II/H] = −2.10 ± 0.02(stat.) ± 0.07(sys.) dex places it in the lower sixth percentile of ωCen’s metallicity distribution. We find that all of the heavier-element abundances, from α- and Fe-peak elements to neutron-capture elements are closely compatible with ωCen’s broad abundance distribution. However, given the major overlap of this object’s abundances with the bulk of all of the MW components, this does not allow for a clear-cut distinction of the star’s origin. In contrast, our measurements of an enhancement in CN and its position on the Na-strong locus of the Na-O anticorrelation render it conceivable that it originally formed as a second-generation GC star, lending support to a former association of this halo star with the massive GC ωCen.
Key words: Galaxy: abundances / Galaxy: formation / globular clusters: general / globular clusters: individual: ω Centauri / Galaxy: halo / Galaxy: stellar content
Full Table 2 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (220.127.116.11) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/645/A64
© ESO 2021
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.