Atomic Transition Probabilities for Transitions of Si i and Si ii and the Silicon Abundances of Several Very Metal-poor Stars
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Hartog, E. A. Den; Lawler, J. E.; Sneden, Christopher; Roederer, Ian U.; Cowan, J. J.

doi:10.3847/1538-4365/acb642

Cited by 7 publications

(1 citation statement)

References 46 publications

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“…NIST (Ralchenko & Kramida 2020) quote a value of −3.34 dex based on theoretical calculations, with an uncertainty ranking of "E" (>50% uncertainty). Recent experiments (Den Hartog et al 2023) put the value 0.3 dex higher, -3.03 ± 0.08 dex, corresponding to around a 0.31 dex reduction in inferred silicon abundance. In .…”

Section: Comparison To Previous Resultsmentioning

confidence: 88%

On the Pair-instability Supernova Origin of J1010+2358*

Skúladóttir,

Koutsouridou,

Vanni

et al. 2024

ApJL

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The first (Population III) stars formed only out of H and He and were likely more massive than present-day stars. Massive Population III stars in the range 140–260 M ⊙ are predicted to end their lives as pair-instability supernovae (PISNe), enriching the environment with a unique abundance pattern, with high ratios of odd to even elements. Recently, the most promising candidate for a pure descendant of a zero-metallicity massive PISN (260 M ⊙) was discovered by the LAMOST survey, the star J1010+2358. However, key elements to verify the high PISN contribution, C and Al, were missing from the analysis. To rectify this, we obtained and analyzed a high-resolution Very Large Telescope/UVES spectrum, correcting for 3D and/or non-local thermodynamic equilibrium effects. Our measurements of both C and Al give much higher values (∼1 dex) than expected from a 260 M ⊙ PISN. Furthermore, we find significant discrepancies with the previous analysis and therefore a much less pronounced odd–even pattern. Our results show that J1010+2358 cannot be a pure descendant of a 260 M ⊙ PISN. Instead, we find that the best-fit model consists of a 13 M ⊙ Population II core-collapse supernova combined with a Population III supernova. Alternative, less favored solutions ( χ 2 / χ best 2 ≈ 2.3 ) include a 50% contribution from a 260 M ⊙ PISN or a 40% contribution from a Population III Type Ia supernova. Ultimately, J1010+2358 is certainly a unique star giving insights into the earliest chemical enrichment; however, this star is not a pure PISN descendant.

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Section: Comparison To Previous Resultsmentioning

confidence: 88%

On the Pair-instability Supernova Origin of J1010+2358*

Skúladóttir,

Koutsouridou,

Vanni

et al. 2024

ApJL

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GHOST commissioning science results – II: a very metal-poor star witnessing the early galactic assembly

Sestito,

Hayes,

Venn

et al. 2024

Monthly Notices of the Royal Astronomical Society

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This study focuses on Pristine$\_180956.78$−294759.8 (hereafter P180956, [Fe/H] = −1.95 ± 0.02), a star selected from the Pristine Inner Galaxy Survey (PIGS), and followed-up with the recently commissioned Gemini High-resolution Optical SpecTrograph (GHOST) at the Gemini South telescope. The GHOST spectrograph’s high efficiency in the blue spectral region (3700 − 4800 Å) enables the detection of elemental tracers of early supernovae (e.g., Al, Mn, Sr, Eu). The star exhibits chemical signatures resembling those found in ultra-faint dwarf systems, characterised by very low abundances of neutron-capture elements (Sr, Ba, Eu), which are uncommon among stars in the Milky Way halo. Our analysis suggests that P180956 bears the chemical imprints of a small number (2 or 4) of low-mass hypernovae (∼10 − 15 M⊙), which are needed to mostly reproduce the abundance pattern of the light-elements (e.g., [Si, Ti/Mg, Ca] ∼0.6), and one fast-rotating intermediate-mass supernova (∼300 km/s, ∼80 − 120 M⊙), which is the main channel contributing to the high [Sr/Ba] (∼+1.2). The small pericentric (∼0.7 kpc) and apocentric (∼13 kpc) distances and its orbit confined to the plane (≲ 2 kpc), indicate that this star was likely accreted during the early Galactic assembly phase. Its chemo-dynamical properties suggest that P180956 formed in a system similar to an ultra-faint dwarf galaxy accreted either alone, as one of the low-mass building blocks of the proto-Galaxy, or as a satellite of Gaia-Sausage-Enceladus. The combination of Gemini’s large aperture with GHOST’s high efficiency and broad spectral coverage makes this new spectrograph one of the leading instruments for near-field cosmology investigations.

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Three-Dimensional Nonlocal Thermodynamic Equilibrium Abundance Analyses of Late-Type Stars

Lind,

Amarsi

2024

Annual Review of Astronomy and Astrophysics

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The chemical compositions of stars encode the history of the universe and are thus fundamental for advancing our knowledge of astrophysics and cosmology. However, measurements of elemental abundances ratios, and our interpretations of them, strongly depend on the physical assumptions that dictate the generation of synthetic stellar spectra. Three-dimensional radiation-hydrodynamic (3D RHD) box-in-a-star simulations of stellar atmospheres offer a more realistic representation of surface convection occurring in late-type stars than do traditional one-dimensional (1D) hydrostatic models. As evident from a multitude of observational tests, the coupling of 3D RHD models with line formation in nonlocal thermodynamic equilibrium (non-LTE) today provides a solid foundation for abundance analysis for many elements. This review describes the ongoing and transformational work to advance the state of the art and replace 1D LTE spectrum synthesis with its 3D non-LTE counterpart. In summary: ▪ 3D and non-LTE effects are intricately coupled, and consistent modeling thereof is necessary for high-precision abundances; such modeling is currently feasible for individual elements in large surveys. Mean 3D (〈3D〉) models are not adequate as substitutes. ▪ The solar abundance debate is presently dominated by choices and systematic uncertainties that are not specific to 3D non-LTE modeling. ▪ 3D non-LTE abundance corrections have a profound impact on our understanding of FGK-type stars, exoplanets, and the nucleosynthetic origins of the elements.

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Atomic Transition Probabilities for Transitions of Si i and Si ii and the Silicon Abundances of Several Very Metal-poor Stars ^∗

Cited by 7 publications

References 46 publications

On the Pair-instability Supernova Origin of J1010+2358*

On the Pair-instability Supernova Origin of J1010+2358*

GHOST commissioning science results – II: a very metal-poor star witnessing the early galactic assembly

Three-Dimensional Nonlocal Thermodynamic Equilibrium Abundance Analyses of Late-Type Stars

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Atomic Transition Probabilities for Transitions of Si i and Si ii and the Silicon Abundances of Several Very Metal-poor Stars ∗

Cited by 7 publications

References 46 publications

On the Pair-instability Supernova Origin of J1010+2358*

On the Pair-instability Supernova Origin of J1010+2358*

GHOST commissioning science results – II: a very metal-poor star witnessing the early galactic assembly

Three-Dimensional Nonlocal Thermodynamic Equilibrium Abundance Analyses of Late-Type Stars

Contact Info

Product

Resources

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Atomic Transition Probabilities for Transitions of Si i and Si ii and the Silicon Abundances of Several Very Metal-poor Stars ^∗