Bibcode
Sestito, Federico; Zaremba, Daria; Venn, Kim A.; D'Aoust, Lina; Hayes, Christian; Jensen, Jaclyn; Navarro, Julio F.; Jablonka, Pascale; Fernández-Alvar, Emma; Glover, Jennifer; McConnachie, Alan W.; Chené, André-Nicolas
Referencia bibliográfica
Monthly Notices of the Royal Astronomical Society
Fecha de publicación:
10
2023
Número de citas
20
Número de citas referidas
13
Descripción
Stellar candidates in the Ursa Minor (UMi) dwarf galaxy have been found using a new Bayesian algorithm applied to Gaia EDR3 data. Five of these targets are located in the extreme outskirts of UMi, from ~5 to 12 elliptical half-light radii (rh), where rh(UMi) = 17.32 ± 0.11 arcmin, and have been observed with the high-resolution Gemini Remote Access to CFHT ESPaDOnS Spectrograph at the Gemini North telescope. Precise radial velocities (σRV < 2 km s-1) and metallicities ($\sigma _{\rm {{\rm [Fe/H]}}}\ \lt\ 0.2$ dex) confirm their memberships of UMi. Detailed analysis of the brightest and outermost star (Target 1, at ~12rh), yields precision chemical abundances for the α (Mg, Ca, and Ti), odd-Z (Na, K, and Sc), Fe-peak (Fe, Ni, and Cr), and neutron-capture (Ba) elements. With data from the literature and APOGEE data release 17, we find the chemical patterns in UMi are consistent with an outside-in star-formation history that includes yields from core-collapse supernovae, asymptotic giant branch stars, and Type Ia supernovae. Evidence for a knee in the [α/Fe] ratios near [Fe/H] ~ -2.1 indicates a low star-formation efficiency similar to that in other dwarf galaxies. Detailed analysis of the surface number density profile shows evidence that UMi's outskirts have been populated by tidal effects, likely as a result of completing multiple orbits around the Galaxy.
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Evolución Galáctica en el Grupo Local
La formación y evolución de galaxias es un problema fundamental en Astrofísica. Su estudio requiere “viajar atrás en el tiempo”, para lo cual hay dos enfoques complementarios. El mas extendido consiste en analizar las propiedades de las galaxias a diferentes distancias cosmológicas. Nuestro equipo se concentra en el otro enfoque, denominado
Matteo
Monelli