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The $([\alpha/{\rm Fe}],[{\rm Fe/H}])$ distribution of Milky Way stars shows at least two distinct sequences, which have traditionally been associated with the thin and thick disc components. The abundance distribution varies systematically…

星系天体物理 · 物理学 2021-08-04 Sanjib Sharma , Michael R. Hayden , Joss Bland-Hawthorn

A recent observational study of haloes of nearby Milky Way-like galaxies shows that only half (four out of eight) of the current sample exhibits strong negative metallicity ([Fe/H]) gradients. This is at odds with predictions from…

Current cosmological models indicate that the Milky Way's stellar halo was assembled from many smaller systems. Based on the apparent absence of the most metal-poor stars in present-day dwarf galaxies, recent studies claimed that the true…

星系天体物理 · 物理学 2015-05-14 Anna Frebel , Evan Kirby , Joshua D. Simon

(Abridged) The present-day spatial and kinematic distribution of stars in the Milky Way provides key constraints on its internal dynamics and evolutionary history. We select stars that are more metal-rich than the interstellar medium (ISM)…

The velocity dispersions of stars near the Sun are known to increase with stellar age, but age can be difficult to determine so a proxy like the abundance of alpha elements (e.g., Mg) with respect to iron, [alpha/Fe], is used. Here we…

The empirical model of Lu et al. 2014 is updated with recent data and used to study galaxy star formation and assembly histories. At $z > 2$, the predicted galaxy stellar mass functions are steep, and a significant amount of star formation…

星系天体物理 · 物理学 2015-06-22 Zhankui Lu , H. J. Mo , Yu Lu , Neal Katz , Martin D. Weinberg , Frank C. van den Bosch , Xiaohu Yang

(Abbreviated) We present a detailed analysis of the space motions of 1203 solar-neighborhood stars with metal abundances [Fe/H] <= -0.6, on the basis of a recently revised and supplemented catalog of metal-poor stars selected without…

天体物理学 · 物理学 2009-05-29 M. Chiba , T. C. Beers

Stars with higher aluminum and nitrogen enrichment are often the key pieces for the chemical makeup of multiple populations in almost all globular clusters (GCs). There is also compelling observational evidence that some Galactic components…

We have used photometric data on almost 91 000 fundamental-mode RR Lyrae stars (type RRab) detected by the OGLE survey to investigate properties of old populations in the Milky Way. Based on their metallicity distributions, we demonstrate…

The fastest moving stars provide insight into several fundamental properties of the Galaxy, including the escape velocity as a function of Galactocentric radius, the total mass, and the nature and frequency of stellar encounters with the…

太阳与恒星天体物理 · 物理学 2018-09-05 Keith Hawkins , Rosemary F. G. Wyse

We present first results concerning the metallicities and stellar populations of galaxies formed in a cosmologically motivated simulation. The calculations include dark matter, gas dynamics, radiation processes, star formation, supernovae…

天体物理学 · 物理学 2007-05-23 Matthias Steinmetz , Ewald Mueller

We study the evolution of Milky Way thick and thin discs in the light of the most recent observational data. In particular, we analyze abundance gradients of O, N, Fe and Mg along the thin disc as well as the [Mg/Fe] vs. [Fe/H] relations…

星系天体物理 · 物理学 2020-09-10 Marco Palla , Francesca Matteucci , Emanuele Spitoni , Fiorenzo Vincenzo , Valeria Grisoni

We report detailed analysis of high-resolution spectra of nine high velocity metal-rich dwarfs in the solar neighborhood. The stars are super metal-rich and 5 of them have [Fe/H]>=+0.4, making them the most metal-rich stars currently known.…

天体物理学 · 物理学 2009-10-30 S. Castro , R. M. Rich , M. Grenon , B. Barbuy , J. K. McCarthy

The Milky Way is a unique laboratory, where stellar properties can be measured and analyzed in detail. In particular, stars in the older populations encode information on the mechanisms that led to the formation of our Galaxy. In this…

We investigate the build-up of the accreted stellar and dark matter haloes of Milky Way-like galaxies in APOSTLE suite of cosmological hydrodynamics simulations. We show that the stellar halo is made up primarily of stars stripped from a…

星系天体物理 · 物理学 2023-02-15 Anna Genina , Alis Deason , Carlos Frenk

We study the ages of $\alpha$-rich and $\alpha$-poor stars in the halo using a sample of F and G dwarfs from the Sloan Digital Sky Survey (SDSS). To separate stars based on [$\alpha$/Fe], we have developed a new semi-empirical…

星系天体物理 · 物理学 2015-06-22 Keith Hawkins , Paula Jofre , Gerry Gilmore , Thomas Masseron

We have used data from the Sloan Digital Sky Survey (SDSS) Data Release 5 to explore the overall structure and substructure of the stellar halo of the Milky Way using about 4 million color-selected main sequence turn-off stars. We fit…

We present a comprehensive study of the abundance evolution of the elements from H to U in the Milky Way halo and local disk. We use a consistent chemical evolution model, metallicity dependent isotopic yields from low and intermediate mass…

星系天体物理 · 物理学 2018-02-21 N. Prantzos , C. Abia , M. Limongi , A. Chieffi , S. Cristallo

We study the formation of stellar haloes in three Milky Way-mass galaxies using cosmological smoothed particle hydrodynamics simulations, focusing on the subset of halo stars that form in situ, as opposed to those accreted from satellites.…

星系天体物理 · 物理学 2015-10-28 Andrew P. Cooper , Owen H. Parry , Ben Lowing , Shaun Cole , Carlos Frenk

We study the chemical evolution of the thick and thin discs of the Galaxy by comparing detailed chemical evolution models with recent data from the AMBRE Project. The data suggest that the stars in the thick and thin discs form two distinct…

星系天体物理 · 物理学 2017-11-08 V. Grisoni , E. Spitoni , F. Matteucci , A. Recio-Blanco , P. de Laverny , M. Hayden , Š. Mikolaitis , C. C. Worley
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