The detailed chemical abundance patterns of accreted halo stars from the optical to infrared

Carrillo, Andreia; Hawkins, Keith; Jofré, P.; Silva, Danielle de Brito; Das, Payel; Lucey, Madeline

doi:10.1093/mnras/stac518

Cited by 25 publications

(12 citation statements)

References 146 publications

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“…The reliability of the GMM decomposition reported here can be established by comparing the chemical properties of the known and well-studied halo components to those reported in the literature. For example, our view of the GS/E chemical fingerprint is in full agreement with the recent studies (see, e.g., Das et al 2020;Aguado et al 2021a;Buder et al 2021a;Hasselquist et al 2021;Matsuno et al 2021;Carrillo et al 2022;Horta et al 2022;Naidu et al 2022). Similarly, we demonstrate that across all chemical dimensions investigated Splash is indistinguishable from the high-α (thick-disk) stars of the Milky Way.…”

Section: Discussionsupporting

confidence: 93%

Milky Way's Eccentric Constituents with Gaia, APOGEE, and GALAH

Belokurov

Aguado

Evans

et al. 2022

ApJ

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We report the results of an unsupervised decomposition of the local stellar halo in the chemodynamical space spanned by the abundance measurements from APOGEE DR17 and GALAH DR3. In our Gaussian mixture model, only four independent components dominate the halo in the solar neighborhood, three previously known, Aurora, Splash, and Gaia-Sausage/Enceladus (GS/E), and one new, Eos. Only one of these four is of accreted origin, namely, the GS/E, thus supporting the earlier claims that the GS/E is the main progenitor of the Galactic stellar halo. We show that Aurora is entirely consistent with the chemical properties of the so-called Heracles merger. In our analysis in which no predefined chemical selection cuts are applied, Aurora spans a wide range of [Al/Fe] with a metallicity correlation indicative of a fast chemical enrichment in a massive galaxy, the young Milky Way. The new halo component dubbed Eos is classified as in situ given its high mean [Al/Fe]. Eos shows strong evolution as a function of [Fe/H], where it changes from being the closest to GS/E at its lowest [Fe/H] to being indistinguishable from the Galactic low-α population at its highest [Fe/H]. We surmise that at least some of the outer thin disk of the Galaxy started its evolution in the gas polluted by the GS/E, and Eos is evidence of this process.

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Section: Discussionsupporting

confidence: 93%

Milky Way's Eccentric Constituents with Gaia, APOGEE, and GALAH

Belokurov

Aguado

Evans

et al. 2022

ApJ

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“…2 , the distributions of the stellar populations in the dwarf galaxies and GE/S stars are shown in the chemical plane of [Fe/H]-[Mg/Fe] across 11 panels, each displayed alongside the stellar populations of the low-and high-α discs of the MW, whose chemical compositions range roughly within ∼−1.2 < [Fe/H] < + 0.65 and −0.2 < [Mg/Fe] < + 0.4. These numbers are in good agreement with independent studies based on abundance analysis of high-resolution optical spectra, such as those by Aguado et al ( 2021 ), Matsuno et al ( 2021 ), andCarrillo et al ( 2022 ).…”

Section: Magnesiumsupporting

confidence: 91%

A comparative analysis of the chemical compositions of Gaia-Enceladus/Sausage and Milky Way satellites using APOGEE

Fernandes

Mason

Horta

et al. 2022

Monthly Notices of the Royal Astronomical Society

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We use data from the 17th data release of the Apache Point Observatory Galactic Evolution Experiment (APOGEE 2) to contrast the chemical composition of the recently discovered Gaia Enceladus/Sausage system (GE/S) to those of ten Milky Way (MW) dwarf satellite galaxies: LMC, SMC, Boötes I, Carina, Draco, Fornax, Sagittarius, Sculptor, Sextans and Ursa Minor. Our main focus is on the distributions of the stellar populations of those systems in the [Mg/Fe]-[Fe/H] and [Mg/Mn]-[Al/Fe] planes, which are commonly employed in the literature for chemical diagnosis and where dwarf galaxies can be distinguished from in situ populations. We show that, unlike MW satellites, a GE/S sample defined purely on the basis of orbital parameters falls almost entirely within the locus of ‘accreted’ stellar populations in chemical space, which is likely caused by an early quenching of star formation in GE/S. Due to a more protracted history of star formation, stars in the metal-rich end of the MW satellite populations are characterized by lower [Mg/Mn] than those of their GE/S counterparts. The chemical compositions of GE/S stars are consistent with a higher early star formation rate than MW satellites of comparable and even higher mass, suggesting that star formation in the early universe was strongly influenced by other parameters in addition to mass. We find that the direction of the metallicity gradient in the [Mg/Mn]–[Al/Fe] plane of dwarf galaxies is an indicator of the early star formation rate of the system.

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“…-[Mg/Fe] across eleven panels, each displayed alongside the stellar populations of the low-and high-𝛼 disks of the MW, whose chemical compositions range roughly between ∼ −1.2 < [Fe/H] < +0.65 and −0.2 < [Mg/Fe] < +0.4. These numbers are in good agreement with independent studies based on abundance analysis of high resolution optical spectra, such as those byAguado et al (2021),Matsuno et al (2021), andCarrillo et al (2022).…”

supporting

confidence: 92%

A Comparative Analysis of the Chemical Compositions of Gaia-Enceladus/Sausage and Milky Way Satellites using APOGEE

Fernandes¹,

Mason²,

Horta³

et al. 2023

Preprint

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We use data from the 17 th data release of the Apache Point Observatory Galactic Evolution Experiment (APOGEE 2) to contrast the chemical composition of the recently discovered Gaia Enceladus/Sausage system (GE/S) to those of ten Milky Way (MW) dwarf satellite galaxies: LMC, SMC, Boötes I, Carina, Draco, Fornax, Sagittarius, Sculptor, Sextans and Ursa Minor. Our main focus is on the distributions of the stellar populations of those systems in the [Mg/Fe]-[Fe/H] and [Mg/Mn]-[Al/Fe] planes, which are commonly employed in the literature for chemical diagnosis and where dwarf galaxies can be distinguished from in situ populations. We show that, unlike MW satellites, a GE/S sample defined purely on the basis of orbital parameters falls almost entirely within the locus of "accreted" stellar populations in chemical space, which is likely caused by an early quenching of star formation in GE/S. Due to a more protracted history of star formation, stars in the metal-rich end of the MW satellite populations are characterized by lower [Mg/Mn] than those of their GE/S counterparts. The chemical compositions of GE/S stars are consistent with a higher early star formation rate than MW satellites of comparable and even higher mass, suggesting that star formation in the early universe was strongly influenced by other parameters in addition to mass. We find that the direction of the metallicity gradient in the [Mg/Mn]-[Al/Fe] plane of dwarf galaxies is an indicator of the early star formation rate of the system.

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The detailed chemical abundance patterns of accreted halo stars from the optical to infrared

Cited by 25 publications

References 146 publications

Milky Way's Eccentric Constituents with Gaia, APOGEE, and GALAH

Milky Way's Eccentric Constituents with Gaia, APOGEE, and GALAH

A comparative analysis of the chemical compositions of Gaia-Enceladus/Sausage and Milky Way satellites using APOGEE

A Comparative Analysis of the Chemical Compositions of Gaia-Enceladus/Sausage and Milky Way Satellites using APOGEE

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