Sales-Silva, JV, Cunha, K, Smith, VV, Daflon, S, Souto, D, Guerco, R, Queiroz, A, Chiappini, C, Hayes, CR, Masseron, T, Hasselquist, S, Horta, D, Prantzos, N, Zoccali, M, Allende Prieto, C, Barbuy, B, Beaton, R, Bizyaev, D, Fernandez-Trincado, JG, Frinchaboy, PM et al, Holtzman, JA, Johnson, JA, Joensson, H, Majewski, SR, Minniti, D, Nidever, DL, Schiavon, RP, Schultheis, M, Sobeck, J, Stringfellow, GS and Zasowski, G (2024) A Perspective on the Milky Way Bulge Bar as Seen from the Neutron-capture Elements Cerium and Neodymium with APOGEE. The Astrophysical Journal, 965 (2). ISSN 0004-637X

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Abstract

This study probes the chemical abundances of the neutron-capture elements cerium and neodymium in the inner Milky Way from an analysis of a sample of ∼2000 stars in the Galactic bulge bar spatially contained within ∣XGal∣ < 5 kpc, ∣YGal∣ < 3.5 kpc, and ∣ZGal∣ < 1 kpc, and spanning metallicities between −2.0 ≲ [Fe/H] ≲ +0.5. We classify the sample stars into low- or high-[Mg/Fe] populations and find that, in general, values of [Ce/Fe] and [Nd/Fe] increase as the metallicity decreases for the low- and high-[Mg/Fe] populations. Ce abundances show a more complex variation across the metallicity range of our bulge-bar sample when compared to Nd, with the r-process dominating the production of neutron-capture elements in the high-[Mg/Fe] population ([Ce/Nd] < 0.0). We find a spatial chemical dependence of Ce and Nd abundances for our sample of bulge-bar stars, with low- and high-[Mg/Fe] populations displaying a distinct abundance distribution. In the region close to the center of the MW, the low-[Mg/Fe] population is dominated by stars with low [Ce/Fe], [Ce/Mg], [Nd/Mg], [Nd/Fe], and [Ce/Nd] ratios. The low [Ce/Nd] ratio indicates a significant contribution in this central region from r-process yields for the low-[Mg/Fe] population. The chemical pattern of the most metal-poor stars in our sample suggests an early chemical enrichment of the bulge dominated by yields from core-collapse supernovae and r-process astrophysical sites, such as magnetorotational supernovae.

Item Type:	Article
Uncontrolled Keywords:	0201 Astronomical and Space Sciences; 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics; 0306 Physical Chemistry (incl. Structural); Astronomy & Astrophysics
Subjects:	Q Science > QB Astronomy Q Science > QC Physics
Divisions:	Astrophysics Research Institute
Publisher:	American Astronomical Society
SWORD Depositor:	A Symplectic
Date Deposited:	29 Oct 2024 15:22
Last Modified:	29 Oct 2024 15:30
DOI or ID number:	10.3847/1538-4357/ad28c2
URI:	https://researchonline.ljmu.ac.uk/id/eprint/24616

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