The Pristine Dwarf-Galaxy survey - II. In-depth observational study of the faint Milky Way satellite Sagittarius II

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dc.contributor.authorLongeard, Nicolas
dc.contributor.authorMartin, Nicolas
dc.contributor.authorStarkenburg, Else
dc.contributor.authorIbata, Rodrigo A.
dc.contributor.authorCollins, Michelle L. M.
dc.contributor.authorLaevens, Benjamin P. M.
dc.contributor.authorMackey, Dougal
dc.contributor.authorRich, R. Michael
dc.contributor.authorAguado, David S.
dc.contributor.authorArentsen, Anke
dc.contributor.authorJablonka, Pascale
dc.contributor.authorHernandez, Jonay I. Gonzalez
dc.contributor.authorNavarro, Julio F.
dc.contributor.authorSanchez-Janssen, Ruben
dc.date.accessioned2025-01-23T19:54:44Z
dc.date.available2025-01-23T19:54:44Z
dc.date.issued2020
dc.description.abstractWe 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 (sigma(CaHK)([FeH]) = 0.11(-0.03)(+0.05) 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, sigma(spectro)([Fe/H]) = 0.10(-0.04)(+0.06) dex). The velocity dispersion of the system is found to be sigma(v) = 2.7(-1.0)(+1.3) km s(-1) after excluding two potential binary stars. Sgr II's metallicity and absolute magnitude (M-V = -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(-23.0)(+32.8) M-circle dot L-circle dot(-1)). Furthermore, using the Gaia Data Release 2, we constrain the orbit of the satellite and find an apocentre of 118.4(-23.7)(+28.4) kpc and a pericentre of 54.8(-6.1)(+3.3) kpc. 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.
dc.fuente.origenWOS
dc.identifier.doi10.1093/mnras/stz2854
dc.identifier.eissn1365-2966
dc.identifier.issn0035-8711
dc.identifier.urihttps://doi.org/10.1093/mnras/stz2854
dc.identifier.urihttps://repositorio.uc.cl/handle/11534/100695
dc.identifier.wosidWOS:000512163600025
dc.issue.numero1
dc.language.isoen
dc.pagina.final377
dc.pagina.inicio356
dc.revistaMonthly notices of the royal astronomical society
dc.rightsacceso restringido
dc.subjectgalaxies: dwarf
dc.subjectLocal Group
dc.titleThe Pristine Dwarf-Galaxy survey - II. In-depth observational study of the faint Milky Way satellite Sagittarius II
dc.typeartículo
dc.volumen491
sipa.indexWOS
sipa.trazabilidadWOS;2025-01-12
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