Year: 2024
Type: article
Abstract: The most metal-poor stars provide valuable insights into the early chemical enrichment history of a system, carrying the chemical imprints of the first generations of supernovae. The most metal-poor region of the Sagittarius dwarf galaxy remains inadequately observed and characterised. To date, only ∼4 stars with [Fe/H] < −2.0 have been chemically analysed with high-resolution spectroscopy. In this study, we present the most extensive chemical abundance analysis of 12 low-metallicity stars with metallicities down to [Fe/H] = −3.26 and located in the main body of Sagittarius. These targets, selected from the Pristine Inner Galaxy Survey, were observed using the MIKE high-resolution spectrograph at the Magellan-Clay telescope, which allowed us to measure up to 17 chemical species. The chemical composition of these stars reflects the imprint of a variety of type II supernovae (SNe II). A combination of low- to intermediate-mass high-energy SNe and hypernovae (∼10 − 70 M⊙) is required to account for the abundance patterns of the lighter elements up to the Fe-peak. The trend of the heavy elements suggests the involvement of compact binary merger events and fast-rotating (up to ∼300 km s−1) intermediate-mass to massive metal-poor stars (∼25 − 120 M⊙) that are the sources of rapid and slow processes, respectively. Additionally, asymptotic giant branch stars contribute to a wide dispersion of [Ba/Mg] and [Ba/Eu]. The absence of an α−knee in our data indicates that type Ia supernovae did not contribute in the very metal-poor region ([Fe/H] ≤ −2.0). However, they might have started to pollute the interstellar medium at [Fe/H] > −2.0, given the relatively low [Co/Fe] in this metallicity region.
Authors: Federico Sestito, Sara Vitali, Paula Jofre, Kim A. Venn, David S. Aguado, Claudia Aguilera-Gómez, Anke Ardern-Arentsen, Danielle de Brito Silva, Raymond Carlberg, Camilla J. L. Eldridge, Felipe Gran, Vanessa Hill, Pascale Jablonka, Georges Kordopatis, Nicolas F. Martin, Tadafumi Matsuno, Samuel Rusterucci, Else Starkenburg, Akshara Viswanathan
Institutions: University of Victoria, Universidad Diego Portales, Universidad de La Laguna, Instituto de Astrofísica de Canarias, Pontificia Universidad Católica de Chile, University of Cambridge, University of Toronto, Centre National de la Recherche Scientifique, Université Côte d'Azur, Lagrange Laboratory, Observatoire de la Côte d’Azur, Université Paris Sciences et Lettres, Observatoire de Paris, Galaxies, Etoiles, Physique et Instrumentation, École Polytechnique Fédérale de Lausanne, Observatoire astronomique de Strasbourg, Max Planck Institute for Astronomy, Université de Strasbourg, Heidelberg University, University of Groningen
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W6922154772
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