Identifying Sagittarius Stream Stars by Their APOGEE Chemical Abundance Signatures

Hasselquist, S.; Carlin, Jeffrey L.; Holtzman, Jon A.; Shetrone, Matthew; Hayes, Christian R.; Cunha, Katia; Smith, Verne; Beaton, Rachael L.; Sobeck, Jennifer; Allende Prieto, C.; Majewski, Steven R.; Anguiano, Borja; Bizyaev, Dmitry; García-Hernández, D. A.; Lane, Richard R.; Pan, Kaike; Nidever, David L.; Fernández-Trincado, José. G.; Wilson, John C.; Zamora, O.
Referencia bibliográfica

The Astrophysical Journal, Volume 872, Issue 1, article id. 58, 14 pp. (2019).

Fecha de publicación:
2
2019
Número de autores
20
Número de autores del IAC
3
Número de citas
39
Número de citas referidas
38
Descripción
The SDSS-IV Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey provides precise chemical abundances of 18 chemical elements for ∼176,000 red giant stars distributed over much of the Milky Way Galaxy (MW), and includes observations of the core of the Sagittarius dwarf spheroidal galaxy (Sgr). The APOGEE chemical abundance patterns of Sgr have revealed that it is chemically distinct from the MW in most chemical elements. We employ a k-means clustering algorithm to six-dimensional chemical space defined by [(C+N)/Fe], [O/Fe], [Mg/Fe], [Al/Fe], [Mn/Fe], and [Ni/Fe] to identify 62 MW stars in the APOGEE sample that have Sgr-like chemical abundances. Of the 62 stars, 35 have Gaia kinematics and positions consistent with those predicted by N-body simulations of the Sgr stream, and are likely stars that have been stripped from Sgr during the last two pericenter passages (<2 Gyr ago). Another 20 of the 62 stars exhibit chemical abundances indistinguishable from the Sgr stream stars, but are on highly eccentric orbits with median r apo ∼ 25 kpc. These stars are likely the “accreted” halo population thought to be the result of a separate merger with the MW 8–11 Gyr ago. We also find one hypervelocity star candidate. We conclude that Sgr was enriched to [Fe/H] ∼ ‑0.2 before its most recent pericenter passage. If the “accreted halo” population is from one major accretion event, then this progenitor galaxy was enriched to at least [Fe/H] ∼ ‑0.6, and had a similar star formation history to Sgr before merging.
Proyectos relacionados
Project Image
Nucleosíntesis y procesos moleculares en los últimos estados de la evolución estelar
Las estrellas de masa baja e intermedia (M < 8 masas solares, Ms) representan la mayoría de estrellas en el Cosmos y terminan sus vidas en la Rama Asintótica de las Gigantes (AGB) - justo antes de formar Nebulosas Planetarias (NPs) - cuando experimentan procesos nucleosintéticos y moleculares complejos. Las estrellas AGB son importantes
Domingo Aníbal
García Hernández
spectrum of mercury lamp
Abundancias Químicas en Estrellas
La espectroscopía de estrellas nos permite determinar las propiedades y composiciones químicas de las mismas. A partir de esta información para estrellas de diferente edad en la Vía Láctea es posible reconstruir la evolución química de la Galaxia, así como el origen de los elementos más pesados que el boro, forjados principalmente en los interiores
Carlos
Allende Prieto