High-precision chemical abundances of Galactic building blocks

Matsuno, Tadafumi; Koppelman, Helmer H.; Helmi, Amina; Aoki, Wako; Ishigaki, Miho N.; Suda, Takuma; Yuan, Zhen; Hattori, Kohei

doi:10.1051/0004-6361/202142752

Cited by 27 publications

(21 citation statements)

References 90 publications

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“…Adding several measurements of additional neutron-capture elements for some of the NS11 stars, Fishlock et al (2017) find a general pattern that light s-process elements (ls: Y and Zr) are underabundant compared to heavy s-process elements (hs: Ba, La, Ce, and Nd) in low-α stars, along with slightly higher [Eu/Fe], lower [ls/Eu], and slightly lower [hs/Eu]. Similar patterns have been found in stars associated with accretion fragments (Aguado et al 2021;Matsuno et al 2021Matsuno et al , 2022aMatsuno et al , 2022bCarrillo et al 2022). Lower [ls/hs] is naturally explained by the contribution of low-mass (<3M e ) metal-poor AGB stars, whose production strongly favors the hs over ls elements (Busso et al 1999;Fishlock et al 2014).…”

Section: Sfr or Imf?supporting

confidence: 59%

Alpha Element Populations Among Local Halo Stars

Reinhard,

Laird

2023

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Previous studies have shown that the halo of the Milky Way galaxy is made up of two distinct stellar populations, one from dissipative collapse and the other accreted. Elemental abundances with small relative uncertainties along with kinematics are determined for 20 local halo stars in the metallicity range −2.2 ≤ [Fe/H] ≤−1.2. Stars with metallicities [Fe/H] > −1.75 show clear separation into high-α and low-α groups. New results extend the work of Nissen & Schuster to the elements Co and K and to lower metallicities. The five program stars with [Fe/H] < −1.75 appear to follow the low-α sequence and may be distinguishable by lower [Ba/Fe] abundances. The results for potassium help to clarify its behavior for −2.2 ≤ [Fe/H] ≤ −1.2 with [K/Fe] ∼ 0.25 and approximately constant with [Fe/H]. Evidence is discussed regarding the cause of the low [α/Fe] abundances, i.e., whether a lower star-formation rate resulted in slower chemical evolution or if the initial mass function was deficient in high-mass stars. The low-α stars show larger dispersions in U and W velocities, as expected for an accreted population, but unlike Nissen & Schuster we find that the high-α and low-α stars do not have significantly different net orbital rotation (V).

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Section: Sfr or Imf?supporting

confidence: 59%

Alpha Element Populations Among Local Halo Stars

Reinhard,

Laird

2023

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“…We advert that these high-energy retrograde stars essentially overlap with GSE in all panels of Figure 2 (also Horta et al 2022). Recently, Matsuno et al (2022) argued that sufficiently high precision (0.07 dex) in abundance estimates should allow us to distinguish between Sequoia and GSE. Despite the nominal uncertainties for [Mg/Fe] in our clean APOGEE DR17 data being small enough (<0.05 dex) for the majority (∼97%) of all metal-poor ([Fe/H] < −1.0) stars, we did not find differences nearly as clear as reported by these authors (their Figure 5).…”

Section: Gse and Sequoiamentioning

confidence: 75%

Reconstructing the Disrupted Dwarf Galaxy Gaia-Sausage/Enceladus Using Its Stars and Globular Clusters

Limberg¹,

Souza

Pérez-Villegas

et al. 2022

ApJ

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We combine spectroscopic, photometric, and astrometric information from APOGEE data release 17 and Gaia early data release 3 to perform a self-consistent characterization of Gaia-Sausage/Enceladus (GSE), the remnant of the last major merger experienced by the Milky Way, considering stars and globular clusters (GCs) altogether. Our novel set of chemodynamical criteria to select genuine stars of GSE yields a metallicity distribution function with a median [Fe/H] of −1.22 and 0.23 dex dispersion. Stars from GSE present an excess of [Al/Fe] and [Mg/Mn] (also [Mg/Fe]) in comparison to surviving Milky Way dwarf satellites, which can be explained by differences in star formation efficiencies and timescales between these systems. However, stars from Sequoia, another proposed accreted halo substructure, essentially overlap the GSE footprint in all analyzed chemical-abundance spaces, but present lower metallicities. Among the probable GCs of GSE with APOGEE observations available, we find no evidence for atypical [Fe/H] spreads with the exception of ω Centauri (ωCen). Under the assumption that ωCen is a stripped nuclear star cluster, we estimate the stellar mass of its progenitor to be M ⋆ ≈ 1.3 × 109 M ⊙, well within literature expectations for GSE. This leads us to envision GSE as the best available candidate for the original host galaxy of ωCen. We also take advantage of Gaia's photometry and APOGEE metallicities as priors to determine fundamental parameters for eight high-probability (>70%) GC members of GSE via statistical isochrone fitting. Finally, the newly determined ages and APOGEE [Fe/H] values are utilized to model the age–metallicity relation of GSE.

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“…We advert that members of Sequoia essentially overlap with GSE in all panels of Figure 2. Recently, Matsuno et al (2022) argued that sufficiently high precision ( 0.07 dex) in abundance estimates should allow us to distinguish between these populations. Despite the nominal uncertainties for [Mg/Fe] in our clean APOGEE DR17 data being small enough (<0.05 dex) for the majority (∼97%) of all metal-poor ([Fe/H] < −1.0) stars, we did not find differences nearly as clear as reported by these authors (their figure 5).…”

Section: Gse and Sequoiamentioning

confidence: 99%

Reconstructing the Disrupted Dwarf Galaxy $Gaia$-Sausage/Enceladus Using its Stars and Globular Clusters

Limberg¹,

Souza²,

Pérez-Villegas³

et al. 2022

Preprint

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We combine spectroscopic, photometric, and astrometric information from APOGEE data release 17 and Gaia early data release 3 to perform a self-consistent characterization of Gaia-Sausage/Enceladus (GSE), the remnant of the last major merger experienced by the Milky Way, considering stars and globular clusters (GCs) altogether. Our novel set of chemodynamical criteria to select genuine stars of GSE yields a metallicity distribution function with a median [Fe/H] of −1.22 dex and 0.23 dex dispersion. Stars from GSE present an excess of [Al/Fe] and [Mg/Mn] (also [Mg/Fe]) in comparison to surviving Milky Way dwarf satellites, which can be explained by differences in star-formation efficiencies and timescales between these systems. However, stars from Sequoia, another proposed accreted halo substructure, essentially overlap the GSE footprint in all analyzed chemical-abundance spaces, but present lower metallicities. Among probable GCs of GSE with APOGEE observations available, we find no evidence for atypical [Fe/H] spreads with the exception of ω Centauri (ωCen). Under the assumption that ωCen is a stripped nuclear star cluster, we estimate the stellar mass of its progenitor to be M ≈ 1.3 × 10 9 M , well-within literature expectations for GSE. This leads us to envision GSE as the best available candidate for the original host galaxy of ωCen. We also take advantage of Gaia's photometry and APOGEE metallicities as priors to determine fundamental parameters for eight highprobability (>70%) GC members of GSE via statistical isochrone fitting. Finally, the newly determined ages and APOGEE [Fe/H] values are utilized to model the age-metallicity relation of GSE.

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High-precision chemical abundances of Galactic building blocks

Cited by 27 publications

References 90 publications

Alpha Element Populations Among Local Halo Stars

Alpha Element Populations Among Local Halo Stars

Reconstructing the Disrupted Dwarf Galaxy Gaia-Sausage/Enceladus Using Its Stars and Globular Clusters

Reconstructing the Disrupted Dwarf Galaxy $Gaia$-Sausage/Enceladus Using its Stars and Globular Clusters

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