Mackereth, J. TedSchiavon, Ricardo P.Pfeffer, JoelHayes, Christian R.Bovy, JoAnguiano, BorjaPrieto, Carlos AllendeHasselquist, StenHoltzman, JonJohnson, Jennifer A.Majewski, Steven R.O’Connell, RobertShetrone, MatthewTissera, Patricia B.Fernandez-Trincado, J. G.2023-06-072023-06-072019-01-21Monthly Notices of the Royal Astronomical Society Volume 482, Issue 3, Pages 3426 - 3442 21 January 20190035-8711https://repositorio.unab.cl/xmlui/handle/ria/50409Indexación ScopusKinematics of halo stars. We show that ∼2/3 of nearby halo stars have high orbital eccentricities (e 0.8), and abundance patterns typical of massive Milky Way dwarf galaxy satellites today, characterized by relatively low [Fe/H], [Mg/Fe], [Al/Fe], and [Ni/Fe]. The trend followed by high-e stars in the [Mg/Fe]-[Fe/H] plane shows a change of slope at [Fe/H] ∼ -1.3, which is also typical of stellar populations from relatively massive dwarf galaxies. Low-e stars exhibit no such change of slope within the observed [Fe/H] range and show slightly higher abundances of Mg, Al, and Ni. Unlike their low-e counterparts, high-e stars show slightly retrograde motion, make higher vertical excursions, and reach larger apocentre radii. By comparing the position in [Mg/Fe]-[Fe/H] space of high-e stars with those of accreted galaxies from the EAGLE suite of cosmological simulations, we constrain the mass of the accreted satellite to be in the range 108.5≲ M ≲ 109M⊙ We show that the median orbital eccentricities of debris are largely unchanged since merger time, implying that this accretion event likely happened at z≲1.5. The exact nature of the low-e population is unclear, but we hypothesize that it is a combination of in situ star formation, high-|z| disc stars, lower mass accretion events, and contamination by the low-e tail of the high-e population. Finally, our results imply that the accretion history of the Milky Way was quite unusual.enGalaxyGalaxy: abundancesGalaxy: formationGalaxy: haloKinematics and dynamicsStellar contentArtículoAttribution 4.0 International (CC BY 4.0)10.1093/mnras/sty2955