Volume 632, December 2019
|Number of page(s)||6|
|Section||Galactic structure, stellar clusters and populations|
|Published online||16 December 2019|
The chemistry of stars in the bar of the Milky Way
Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, France
e-mail: firstname.lastname@example.org; email@example.com
2 Max-Planck-Institut für Extraterrestrische Physik, Gießenbachstraße, 85748 Garching, Germany
3 Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna, 4860 Santiago, Chile
4 Millennium Institute of Astrophysics, Av. Vicuña Mackenna, 4860 Santiago, Chile
Accepted: 15 November 2019
We use a sample of 938 red clump giant stars located in the direction of the Galactic long bar to study the chemistry of Milky Way bar stars. Kinematically separating stars on bar orbits from stars with inner disc orbits, we find that stars on bar-like orbits are more metal rich with a mean iron abundance of ⟨[Fe/H]⟩ = +0.30 compared to ⟨[Fe/H]⟩ = +0.03 for the inner disc. Spatially selecting bar stars is complicated by a strong vertical metallicity gradient of −1.1 dex kpc−1, but we find the metallicity distribution varies in a manner consistent with our orbital selection. Our results have two possible interpretations. The first is that the most metal rich stars in the inner Galaxy pre-existed the bar, but were kinematically cold at the time of bar formation and therefore more easily captured onto bar orbits when the bar formed. The second is that the most metal rich stars formed after the bar, either directly onto the bar following orbits or were captured by the bar after their formation.
Key words: Galaxy: abundances / Galaxy: kinematics and dynamics / Galaxy: center
© C. Wegg et al. 2019
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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