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Related papers: Geometric properties of galactic discs with clumpy…

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We used the spectroscopic and astrometric data provided from the GALAH DR2 and Gaia DR2, respectively, for a large sample of stars to investigate the behaviour of the [$\alpha$/Fe] abundances via two procedures, i.e. kinematically and…

Astrophysics of Galaxies · Physics 2019-11-13 S. Karaali , S. Bilir , E. Yaz Gokce , O. Plevne

We investigate, using the Gaia-ESO Survey internal Data-Release 2, the properties of the double sequence of the Milky Way discs (defined chemically as the high-alpha and low-alpha populations), and discuss their compatibility with discs…

It is well established that the chemical structure of the Milky Way exhibits a bimodality with respect to the $\alpha$-enhancement of stars at a given [Fe/H]. This has been studied largely based on a bulk $\alpha$ abundance, computed as a…

Astrophysics of Galaxies · Physics 2019-09-20 Kirsten Blancato , Melissa Ness , Kathryn V. Johnston , Jan Rybizki , Megan Bedell

We analyse a set of very metal-poor stars for which accurate chemical abundances have been obtained as part of the ESO Large Program "First stars" in the light of the Gaia DR2 data. The kinematics and orbital properties of the stars in the…

Astrophysics of Galaxies · Physics 2020-04-29 P. Di Matteo , M. Spite , M. Haywood , P. Bonifacio , A. Gómez , F. Spite , E. Caffau

Spectroscopic surveys of the Galaxy reveal that its disc stars exhibit a spread in $\mathrm{[\alpha/Fe]}$ at fixed $\mathrm{[Fe/H]}$, manifest at some locations as a bimodality. The origin of these diverse, and possibly distinct, stellar…

Astrophysics of Galaxies · Physics 2018-05-02 J. Ted Mackereth , Robert A. Crain , Ricardo P. Schiavon , Joop Schaye , Tom Theuns , Matthieu Schaller

Studying the Milky Way disk structure using stars in narrow bins of [Fe/H] and [alpha/Fe] has recently been proposed as a powerful method to understand the Galactic thick and thin disk formation. It has been assumed so far that these…

Astrophysics of Galaxies · Physics 2017-01-04 I. Minchev , M. Steinmetz , C. Chiappini , M. Martig , F. Anders , G. Matijevic , R. S. de Jong

We explore the structure of the element abundance--age--orbit distribution of the stars in the Milky Way's low-$\alpha$ disk, by (re-)deriving precise [Fe/H], [X/Fe] and ages, along with orbits, for red clump stars from the APOGEE survey.…

Solar and Stellar Astrophysics · Physics 2019-10-09 Melissa K. Ness , Kathryn V. Johnston , Kirsten Blancato , Hans-Walter Rix , Angus Beane , Jonathan C. Bird , Keith Hawkins

We combine the estimated metallicities [Fe/H], abundances [\alpha/Fe], positions and motions of a sample of 27,500 local (7<R/kpc<9, 0.5<|z|/kpc<2.5) SDSS/SEGUE G-type dwarf stars to investigate the chemo-orbital properties of the Milky…

Astrophysics of Galaxies · Physics 2015-06-03 Chao Liu , Glenn van de Ven

Observational data have revealed a clear dichotomy in the [{\alpha}/Fe] vs. [Fe/H] diagram of the Milky Way thick and thin disc stars. Many recent studies have shown evidences of a co-evolution phase between the high- and low-{\alpha} disc…

Astrophysics of Galaxies · Physics 2026-05-12 V. Grisoni , E. Spitoni , F. Matteucci

We highlight some results from our detailed abundance analysis study of 703 kinematically selected F and G dwarf stars in the solar neighbourhood. The analysis is based on spectra of high-resolution (R=45000 to 110000) and high…

Astrophysics of Galaxies · Physics 2015-05-30 T. Bensby , S. Feltzing

The emergence of the disc in our Galaxy and the relation of the thick and thin disc formation and evolution is still a matter of debate. The chemo-dynamical characterization of disc stars is key to resolve this question, in particular at…

The measurement of the structure of stellar populations in the Milky Way disk places fundamental constraints on models of galaxy formation and evolution. Previously, the disk's structure has been studied in terms of populations defined…

The chemical dichotomy in the [$\alpha$/Fe]-[Fe/H] plane is a consequence of the complex processes underlying the formation and evolution of disc galaxies such as observed in the stellar Milky Way disc. We determine what can drive an…

We aim to quantify the chemical and kinematical properties of the Galactic disks with a sample of 119,558 giant stars having abundances and 3D velocities taken or derived from the APOGEE DR17 and Gaia EDR3 catalogs. The Gaussian Mixture…

Astrophysics of Galaxies · Physics 2022-04-20 Guozhen Hu , Zhengyi Shao

We use several smoothed particle hydrodynamics+N-body models as part of the GASTRO library to study the role of high-density star-forming clumpy regions and a single merger on the formation of the $\alpha$-rich and $\alpha$-poor populations…

We study the formation of chemical sequences in the stellar disc of Milky Way (MW)-mass galaxies in a full cosmological context with the auriga simulations. We focus on the conditions giving rise to bi-modal $\alpha$-chemistry in the MW…

Astrophysics of Galaxies · Physics 2025-12-24 Matthew D. A. Orkney , Chervin F. P. Laporte , Robert J. J. Grand , Volker Springel

We present the abundance analysis of 97 nearby metal-poor (-3.3<[Fe/H]<-0.5) stars having kinematics characteristics of the Milky Way (MW) thick disk, inner, and outer stellar halos. The high-resolution, high-signal-to-noise optical spectra…

Astrophysics of Galaxies · Physics 2015-06-05 M. N. Ishigaki , M. Chiba , W. Aoki

Recent determinations of the radial distributions of mono-metallicity populations (MMPs, i.e., stars in narrow bins in [Fe/H] within wider [$\alpha$/Fe] ranges) by the SDSS-III/APOGEE DR12 survey cast doubts on the classical thin - thick…

Astrophysics of Galaxies · Physics 2017-09-06 R. Domínguez-Tenreiro , A. Obreja , C. B. Brook , F. J. Martínez-Serrano , A. Serna

[Abridged] In this first paper of this series, we present a new approach for studying the chemo-dynamical evolution in disk galaxies, which consists of fusing disk chemical evolution models with compatible numerical simulations of galactic…

Astrophysics of Galaxies · Physics 2015-06-11 I. Minchev , C. Chiappini , M. Martig

Despite the recent advancements in the field of galaxy formation and evolution, fully self-consistent simulations are still unable to make the detailed predictions necessary for the planned and ongoing large spectroscopic and photometry…

Astrophysics of Galaxies · Physics 2019-08-19 Ivan Minchev , Cristina Chiappini , Marie Martig