| DOI | Trouver le DOI : https://doi.org/10.1093/mnras/stz2854 |
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| Auteur | Rechercher : Longeard, Nicolas; Rechercher : Martin, Nicolas; Rechercher : Starkenburg, Else; Rechercher : Ibata, Rodrigo A.; Rechercher : Collins, Michelle L. M.Identifiant ORCID : https://orcid.org/0000-0002-1693-3265; Rechercher : Laevens, Benjamin P. M.; Rechercher : Mackey, Dougal; Rechercher : Rich, R. MichaelIdentifiant ORCID : https://orcid.org/0000-0003-0427-8387; Rechercher : Aguado, David S.; Rechercher : Arentsen, AnkeIdentifiant ORCID : https://orcid.org/0000-0002-0544-2217; Rechercher : Jablonka, Pascale; Rechercher : González Hernández, Jonay I.; Rechercher : Navarro, Julio F.; Rechercher : Sánchez-Janssen, Rubén1Identifiant ORCID : https://orcid.org/0000-0003-4945-0056 |
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| Affiliation | - Conseil national de recherches du Canada. Herzberg en astronomie et en astrophysique
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| Format | Texte, Article |
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| Sujet | galaxies: dwarf; local group |
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| Résumé | We present an extensive study of the Sagittarius II (Sgr II) stellar system using MegaCam g and i photometry, narrow-band, metallicity-sensitive calcium H&K doublet photometry and Keck II/DEIMOS multiobject spectroscopy. We derive and refine the Sgr II structural and stellar properties inferred at the time of its discovery. The colour–magnitude diagram implies Sgr II is old (12.0 ± 0.5 Gyr) and metal poor. The CaHK photometry confirms the metal-poor nature of the satellite ([Fe/H] CaHK = −2.32 ± 0.04 dex) and suggests that Sgr II hosts more than one single stellar population (σCaHK[FeH]=0.11+0.05−0.03 dex). Using the Ca infrared triplet measured from our highest signal-to-noise spectra, we confirm the metallicity and dispersion inferred from the Pristine photometric metallicities ([Fe/H]spectro = −2.23 ± 0.05 dex, σspectro[Fe/H]=0.10+0.06−0.04 dex). The velocity dispersion of the system is found to be σv=2.7+1.3−1.0kms−1 after excluding two potential binary stars. Sgr II’s metallicity and absolute magnitude (MV = −5.7 ± 0.1 mag) place the system on the luminosity–metallicity relation of the Milky Way dwarf galaxies despite its small size. The low but resolved metallicity and velocity dispersions paint the picture of a slightly dark-matter-dominated satellite (M/L=23.0+32.8−23.0 M⊙ L−1⊙). Furthermore, using the Gaia Data Release 2, we constrain the orbit of the satellite and find an apocentre of 118.4+28.4−23.7kpc and a pericentre of 54.8+3.3−6.1kpc. The orbit of Sgr II is consistent with the trailing arm of the Sgr stream and indicates that it is possibly a satellite of the Sgr dSph that was tidally stripped from the dwarf’s influence. |
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| Date de publication | 2019-10-12 |
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| Maison d’édition | Oxford University Press |
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| Dans | |
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| Langue | anglais |
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| Publications évaluées par des pairs | Oui |
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| Exporter la notice | Exporter en format RIS |
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| Signaler une correction | Signaler une correction (s'ouvre dans un nouvel onglet) |
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| Identificateur de l’enregistrement | 5c774c03-c5b7-4720-94e8-951893d1dc5f |
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| Enregistrement créé | 2020-10-30 |
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| Enregistrement modifié | 2021-09-17 |
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