Artículo de revista
Metallicity and alpha-element abundance gradients along the Sagittarius Stream as seen by APOGEE
Fecha
2020Registro en:
Astrophysical Journal (2020) 889:artículo 63
10.3847/1538-4357/ab62ad
Autor
Hayes, Christian
Majewski, Steven
Hasselquist, Sten
Anguiano, Borja
Shetrone, Matthew
Law, David
Schiavon, Ricardo
Cunha, Katia
Smith, Verne
Beaton, Rachael
Price Whelan, Adrián
Allende Prieto, Carlos
Battaglia, Giuseppina
Bizyaev, Dimitry
Brownstein, Joel
Cohen, Roger
Frinchaboy, Peter
García Hernández, D. A.
Lacerna, Iván
Lane, Richard
Meszaros, Szabolcs
Moni Bidin, Christian
Muñoz Vidal, Ricardo
Nidever, David
Oravetz, Audrey
Oravetz, Daniel
Pan, Kaike
Román Lopes, Alexandre
Sobeck, Jennifer
Stringfellow, Guy
Institución
Resumen
Using 3D positions and kinematics of stars relative to the Sagittarius (Sgr) orbital plane and angular momentum, we identify 166 Sgr stream members observed by the Apache Point Observatory Galactic Evolution Experiment (APOGEE) that also have Gaia DR2 astrometry. This sample of 63/103 stars in the Sgr trailing/leading arm is combined with an APOGEE sample of 710 members of the Sgr dwarf spheroidal core (385 of them newly presented here) to establish differences of 0.6 dex in median metallicity and 0.1 dex in [alpha/Fe] between our Sgr core and dynamically older stream samples. Mild chemical gradients are found internally along each arm, but these steepen when anchored by core stars. With a model of Sgr tidal disruption providing estimated dynamical ages (i.e., stripping times) for each stream star, we find a mean metallicity gradient of 0.12 0.03 dex Gyr(-1) for stars stripped from Sgr over time. For the first time, an [alpha/Fe] gradient is also measured within the stream, at 0.02 0.01 dex Gyr(-1) using magnesium abundances and at 0.04 0.01 dex Gyr(-1) using silicon, which imply that the Sgr progenitor had significant radial abundance gradients. We discuss the magnitude of those inferred gradients and their implication for the nature of the Sgr progenitor within the context of the current family of Milky Way satellite galaxies, and we suggest that more sophisticated Sgr models are needed to properly interpret the growing chemodynamical detail we have on the Sgr system.
Ítems relacionados
Mostrando ítems relacionados por Título, autor o materia.