Ages and Heavy Element Abundances from Very Metal-poor Stars in the Sagittarius Dwarf Galaxy

Camilla Juul Hansen, Mariam El-Souri, Lorenzo Monaco, Sandro Villanova, Piercarlo Bonifacio, Elisabetta Caffau, Luca Sbordone

Resultado de la investigación: Article

Resumen

Sagittarius (Sgr) is a massive disrupted dwarf spheroidal galaxy in the Milky Way halo that has undergone several stripping events. Previous chemical studies were restricted mainly to a few, metal-rich ([Fe/H] ) stars that suggested a top-light initial mass function (IMF). Here we present the first high-resolution, very metal-poor ([Fe/H] =-1 to -3) sample of 13 giant stars in the main body of Sgr. We derive abundances of 13 elements, namely C, Ca, Co, Fe, Sr, Ba, La, Ce, Nd, Eu, Dy, Pb, and Th, that challenge the interpretation based on previous studies. Our abundances from Sgr mimic those of the metal-poor halo, and our most metal-poor star ([Fe/H] ) indicates a pure r-process pollution. Abundances of Sr, Pb, and Th are presented for the first time in Sgr, allowing for age determination using nuclear cosmochronology. We calculate ages of . Most of the sample stars have been enriched by a range of asymptotic giant branch (AGB) stars with masses between 1.3 and 5 M o. Sgr J190651.47-320147.23 shows a large overabundance of Pb (2.05 dex) and a peculiar abundance pattern best fit by a 3 M o AGB star. Based on star-to-star scatter and observed abundance patterns, a mixture of low- and high-mass AGB stars and supernovae (15-25 M o) is necessary to explain these patterns. The high level (0.29 0.05 dex) of Ca indicates that massive supernovae must have existed and polluted the early ISM of Sgr before it lost its gas. This result is in contrast with a top-light IMF with no massive stars polluting Sgr.

IdiomaEnglish
Número de artículo83
PublicaciónAstrophysical Journal
Volumen855
Número de edición2
DOI
EstadoPublished - 10 mar 2018

Huella dactilar

heavy elements
dwarf galaxies
asymptotic giant branch stars
stars
metal
metals
supernovae
halos
giant stars
chronology
age determination
pollution
stripping
massive stars
high resolution
gases
gas

Keywords

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science

    Citar esto

    Hansen, C. J., El-Souri, M., Monaco, L., Villanova, S., Bonifacio, P., Caffau, E., & Sbordone, L. (2018). Ages and Heavy Element Abundances from Very Metal-poor Stars in the Sagittarius Dwarf Galaxy. Astrophysical Journal, 855(2), [83]. https://doi.org/10.3847/1538-4357/aa978f
    Hansen, Camilla Juul ; El-Souri, Mariam ; Monaco, Lorenzo ; Villanova, Sandro ; Bonifacio, Piercarlo ; Caffau, Elisabetta ; Sbordone, Luca. / Ages and Heavy Element Abundances from Very Metal-poor Stars in the Sagittarius Dwarf Galaxy. En: Astrophysical Journal. 2018 ; Vol. 855, N.º 2.
    @article{244cf84bfa1347429ea3e04081ffce66,
    title = "Ages and Heavy Element Abundances from Very Metal-poor Stars in the Sagittarius Dwarf Galaxy",
    abstract = "Sagittarius (Sgr) is a massive disrupted dwarf spheroidal galaxy in the Milky Way halo that has undergone several stripping events. Previous chemical studies were restricted mainly to a few, metal-rich ([Fe/H] ) stars that suggested a top-light initial mass function (IMF). Here we present the first high-resolution, very metal-poor ([Fe/H] =-1 to -3) sample of 13 giant stars in the main body of Sgr. We derive abundances of 13 elements, namely C, Ca, Co, Fe, Sr, Ba, La, Ce, Nd, Eu, Dy, Pb, and Th, that challenge the interpretation based on previous studies. Our abundances from Sgr mimic those of the metal-poor halo, and our most metal-poor star ([Fe/H] ) indicates a pure r-process pollution. Abundances of Sr, Pb, and Th are presented for the first time in Sgr, allowing for age determination using nuclear cosmochronology. We calculate ages of . Most of the sample stars have been enriched by a range of asymptotic giant branch (AGB) stars with masses between 1.3 and 5 M o. Sgr J190651.47-320147.23 shows a large overabundance of Pb (2.05 dex) and a peculiar abundance pattern best fit by a 3 M o AGB star. Based on star-to-star scatter and observed abundance patterns, a mixture of low- and high-mass AGB stars and supernovae (15-25 M o) is necessary to explain these patterns. The high level (0.29 0.05 dex) of Ca indicates that massive supernovae must have existed and polluted the early ISM of Sgr before it lost its gas. This result is in contrast with a top-light IMF with no massive stars polluting Sgr.",
    keywords = "galaxies: dwarf, galaxies: evolution, Galaxy: halo, nuclear reactions, nucleosynthesis, abundances, stars: abundances, stars: chemically peculiar",
    author = "Hansen, {Camilla Juul} and Mariam El-Souri and Lorenzo Monaco and Sandro Villanova and Piercarlo Bonifacio and Elisabetta Caffau and Luca Sbordone",
    year = "2018",
    month = "3",
    day = "10",
    doi = "10.3847/1538-4357/aa978f",
    language = "English",
    volume = "855",
    journal = "Astrophysical Journal",
    issn = "0004-637X",
    publisher = "IOP Publishing Ltd.",
    number = "2",

    }

    Hansen, CJ, El-Souri, M, Monaco, L, Villanova, S, Bonifacio, P, Caffau, E & Sbordone, L 2018, 'Ages and Heavy Element Abundances from Very Metal-poor Stars in the Sagittarius Dwarf Galaxy' Astrophysical Journal, vol. 855, n.º 2, 83. https://doi.org/10.3847/1538-4357/aa978f

    Ages and Heavy Element Abundances from Very Metal-poor Stars in the Sagittarius Dwarf Galaxy. / Hansen, Camilla Juul; El-Souri, Mariam; Monaco, Lorenzo; Villanova, Sandro; Bonifacio, Piercarlo; Caffau, Elisabetta; Sbordone, Luca.

    En: Astrophysical Journal, Vol. 855, N.º 2, 83, 10.03.2018.

    Resultado de la investigación: Article

    TY - JOUR

    T1 - Ages and Heavy Element Abundances from Very Metal-poor Stars in the Sagittarius Dwarf Galaxy

    AU - Hansen, Camilla Juul

    AU - El-Souri, Mariam

    AU - Monaco, Lorenzo

    AU - Villanova, Sandro

    AU - Bonifacio, Piercarlo

    AU - Caffau, Elisabetta

    AU - Sbordone, Luca

    PY - 2018/3/10

    Y1 - 2018/3/10

    N2 - Sagittarius (Sgr) is a massive disrupted dwarf spheroidal galaxy in the Milky Way halo that has undergone several stripping events. Previous chemical studies were restricted mainly to a few, metal-rich ([Fe/H] ) stars that suggested a top-light initial mass function (IMF). Here we present the first high-resolution, very metal-poor ([Fe/H] =-1 to -3) sample of 13 giant stars in the main body of Sgr. We derive abundances of 13 elements, namely C, Ca, Co, Fe, Sr, Ba, La, Ce, Nd, Eu, Dy, Pb, and Th, that challenge the interpretation based on previous studies. Our abundances from Sgr mimic those of the metal-poor halo, and our most metal-poor star ([Fe/H] ) indicates a pure r-process pollution. Abundances of Sr, Pb, and Th are presented for the first time in Sgr, allowing for age determination using nuclear cosmochronology. We calculate ages of . Most of the sample stars have been enriched by a range of asymptotic giant branch (AGB) stars with masses between 1.3 and 5 M o. Sgr J190651.47-320147.23 shows a large overabundance of Pb (2.05 dex) and a peculiar abundance pattern best fit by a 3 M o AGB star. Based on star-to-star scatter and observed abundance patterns, a mixture of low- and high-mass AGB stars and supernovae (15-25 M o) is necessary to explain these patterns. The high level (0.29 0.05 dex) of Ca indicates that massive supernovae must have existed and polluted the early ISM of Sgr before it lost its gas. This result is in contrast with a top-light IMF with no massive stars polluting Sgr.

    AB - Sagittarius (Sgr) is a massive disrupted dwarf spheroidal galaxy in the Milky Way halo that has undergone several stripping events. Previous chemical studies were restricted mainly to a few, metal-rich ([Fe/H] ) stars that suggested a top-light initial mass function (IMF). Here we present the first high-resolution, very metal-poor ([Fe/H] =-1 to -3) sample of 13 giant stars in the main body of Sgr. We derive abundances of 13 elements, namely C, Ca, Co, Fe, Sr, Ba, La, Ce, Nd, Eu, Dy, Pb, and Th, that challenge the interpretation based on previous studies. Our abundances from Sgr mimic those of the metal-poor halo, and our most metal-poor star ([Fe/H] ) indicates a pure r-process pollution. Abundances of Sr, Pb, and Th are presented for the first time in Sgr, allowing for age determination using nuclear cosmochronology. We calculate ages of . Most of the sample stars have been enriched by a range of asymptotic giant branch (AGB) stars with masses between 1.3 and 5 M o. Sgr J190651.47-320147.23 shows a large overabundance of Pb (2.05 dex) and a peculiar abundance pattern best fit by a 3 M o AGB star. Based on star-to-star scatter and observed abundance patterns, a mixture of low- and high-mass AGB stars and supernovae (15-25 M o) is necessary to explain these patterns. The high level (0.29 0.05 dex) of Ca indicates that massive supernovae must have existed and polluted the early ISM of Sgr before it lost its gas. This result is in contrast with a top-light IMF with no massive stars polluting Sgr.

    KW - galaxies: dwarf

    KW - galaxies: evolution

    KW - Galaxy: halo

    KW - nuclear reactions, nucleosynthesis, abundances

    KW - stars: abundances

    KW - stars: chemically peculiar

    UR - http://www.scopus.com/inward/record.url?scp=85044074823&partnerID=8YFLogxK

    U2 - 10.3847/1538-4357/aa978f

    DO - 10.3847/1538-4357/aa978f

    M3 - Article

    VL - 855

    JO - Astrophysical Journal

    T2 - Astrophysical Journal

    JF - Astrophysical Journal

    SN - 0004-637X

    IS - 2

    M1 - 83

    ER -