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Abundances of iron-...
Abundances of iron-peak elements in accreted and in situ born Galactic halo stars
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- Nissen, P. E. (author)
- Aarhus Univ, Dept Phys & Astron, Ny Munkegade 120, DK-8000 Aarhus C, Denmark.
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- Amarsi, Anish M. (author)
- Uppsala universitet,Teoretisk astrofysik
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- Skúladóttir, Á. (author)
- Univ Firenze, Dipartimento Fis & Astron, via G Sansone 1, I-50019 Sesto Fiorentino, Italy.;INAF Osservatorio Astrofisico Arcetri, Largo E Fermi 5, I-50125 Florence, Italy.
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- Schuster, W. J. (author)
- Univ Nacl Autonoma Mexico, Inst Astron, AP 106, Ensenada 22800, BC, Mexico.
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Aarhus Univ, Dept Phys & Astron, Ny Munkegade 120, DK-8000 Aarhus C, Denmark Teoretisk astrofysik (creator_code:org_t)
- EDP Sciences, 2024
- 2024
- English.
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 682
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Abstract
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- Context. Studies of the element abundances and kinematics of stars belonging to the Galactic halo have revealed the existence of two distinct populations: accreted stars with a low [α/Fe] ratio and in situ born stars with a higher ratio.Aims. Previous work on the abundances of C, O, Na, Mg, Si, Ca, Ti, Cr, Mn, Fe, Ni, Cu, and Zn in high-α and low-α halo stars is extended to include the abundances of Sc, V, and Co, enabling us to study the nucleosynthesis of all iron-peak elements along with the lighter elements.Methods. The Sc, V, and Co abundances were determined from a 1D MARCS model-atmosphere analysis of equivalent widths of atomic lines in high signal-to-noise, high resolution spectra assuming local thermodynamic equilibrium (LTE). In addition, new 3D and/or non-LTE calculations were used to correct the 1D LTE abundances for several elements including consistent 3D non-LTE calculations for Mg.Results. The two populations of accreted and in situ born stars are well separated in diagrams showing [Sc/Fe], [V/Fe], and [Co/Fe] as a function of [Fe/H]. The [X/Mg] versus [Mg/H] trends for high-α and low-α stars were used to determine the yields of core-collapse and Type Ia supernovae. The largest Type Ia contribution occurs for Cr, Mn, and Fe, whereas Cu is a pure core-collapse element. Sc, Ti, V, Co, Ni, and Zn represent intermediate cases. A comparison with yields calculated for supernova models shows poor agreement for the core-collapse yields. The Ia yields suggest that sub-Chandrasekhar-mass Type Ia supernovae provide a dominant contribution to the chemical evolution of the host galaxies of the low-α stars. A substructure in the abundances and kinematics of the low-α stars suggests that they arise from at least two different satellite accretion events, Gaia-Sausage-Enceladus and Thamnos.
Subject headings
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Keyword
- stars: abundances
- stars: atmospheres
- supernovae: general
- Galaxy: formation
- Galaxy: halo
Publication and Content Type
- ref (subject category)
- art (subject category)
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