2018A&A...609A..13K


C.D.S. - SIMBAD4 rel 1.7 - 2019.12.13CET09:29:04

2018A&A...609A..13K - Astronomy and Astrophysics, volume 609A, 13-13 (2018/1-1)

Detailed chemical abundance analysis of the thick disk star cluster Gaia 1.

KOCH A., HANSEN T.T. and KUNDER A.

Abstract (from CDS):

Star clusters, particularly those objects in the disk-bulge-halo interface are as yet poorly charted, despite the fact that they carry important information about the formation and the structure of the Milky Way. Here, we present a detailed chemical abundance study of the recently discovered object Gaia 1. Photometry has previously suggested it as an intermediate-age, moderately metal-rich system, although the exact values for its age and metallicity remained ambiguous in the literature. We measured detailed chemical abundances of 14 elements in four red giant members, from high-resolution (R=25000) spectra that firmly establish Gaia 1 as an object associated with the thick disk. The resulting mean Fe abundance is -0.62±0.03(stat.)±0.10(sys.)dex, which is more metal-poor than indicated by previous spectroscopy from the literature, but it is fully in line with values from isochrone fitting. We find that Gaia 1 is moderately enhanced in the α-elements, which allowed us to consolidate its membership with the thick disk via chemical tagging. The cluster's Fe-peak and neutron-capture elements are similar to those found across the metal-rich disks, where the latter indicate some level of s-process activity. No significant spread in iron nor in other heavy elements was detected, whereas we find evidence of light-element variations in Na, Mg, and Al. Nonetheless, the traditional Na-O and Mg-Al (anti-)correlations, typically seen in old globular clusters, are not seen in our data. This confirms that Gaia 1 is rather a massive and luminous open cluster than a low-mass globular cluster. Finally, orbital computations of the target stars bolster our chemical findings of Gaia 1's present-day membership with the thick disk, even though it remains unclear which mechanisms put it in that place.

Abstract Copyright: © ESO, 2017

Journal keyword(s): Stars: abundances - Galaxy: abundances - Galaxy: structure - open clusters and associations: individual: Gaia 1 - Galaxy: disk - globular clusters

VizieR on-line data: <Available at CDS (J/A+A/609/A13): table2.dat>

Simbad objects: 8

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Number of rows : 8

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 * alf CMa SB* 06 45 08.91728 -16 42 58.0171 -1.51 -1.46 -1.46 -1.46 -1.43 A1V+DA 1377 0
2 2MASS J06454977-1644464 * 06 45 49.7832584095 -16 44 46.530969804           ~ 1 0
3 2MASS J06455382-1645322 * 06 45 53.8216975023 -16 45 32.290342688           ~ 1 0
4 2MASS J06455593-1643469 * 06 45 55.9355550004 -16 43 47.072288684           ~ 1 0
5 2MASS J06455764-1640110 * 06 45 57.6470276717 -16 40 11.050761701           ~ 1 0
6 ESO 452-11 GlC 16 39 25.50 -28 23 52.0           ~ 38 0
7 NGC 6440 GlC 17 48 52.67 -20 21 34.5   12.01 10.10     ~ 456 1
8 NAME Galactic Bulge reg ~ ~           ~ 3264 0

    Equat.    Gal    SGal    Ecl

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2019.12.13-09:29:04

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