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Related papers: Challenges to the Two-Infall Scenario by Large Ste…

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We show that the bulge and the disk of the Milky Way (MW) at R$\lesssim$7~kpc are well described by a unique chemical evolution and a two-phase star-formation history (SFH). We argue that the populations within this inner disk, not the…

Astrophysics of Galaxies · Physics 2018-10-17 Misha Haywood , Paola Di Matteo , Matthew Lehnert , Owain Snaith , Francesca Fragkoudi , Sergey Khoperskov

Abundance of chemical elements in the stars provides important clues regarding galaxy formation. The most powerful diagnostics is the relative abundance of {\alpha}-elements (O, Mg, Si, S, Ca, and Ti) with respect to iron (Fe),…

Astrophysics of Galaxies · Physics 2018-09-10 Masafumi Noguchi

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…

Astrophysics of Galaxies · Physics 2021-08-04 Sanjib Sharma , Michael R. Hayden , Joss Bland-Hawthorn

The age-metallicity relation is fundamental to study the formation and evolution of the disk. Observations have shown that this relation has a large scatter which can not be explained by observational errors only. That scatter is hence…

Astrophysics of Galaxies · Physics 2021-10-20 Paula Jofre

The detailed age-chemical abundance relations of stars measures time-dependent chemical evolution.These trends offer strong empirical constraints on nucleosynthetic processes, as well as the homogeneityof star-forming gas. Characterizing…

Astrophysics of Galaxies · Physics 2022-03-23 Yuxi , Lu , Melissa Ness , Tobias Buck , Joel Zinn

We analyze high quality abundances data of solar neighborhood stars and show that there are two distinct regimes of [alpha/Fe] versus age which we identify as the epochs of the thick and thin disk formation. A tight correlation between…

Astrophysics of Galaxies · Physics 2015-06-16 M. Haywood , P. Di Matteo , M. Lehnert , D. Katz , A. Gomez

We conduct a quantitative analysis of the star formation history (SFH) of the Milky Way's bulge by exploiting the constraining power of its stellar [Fe/H] and [Mg/Fe] distribution functions. Using APOGEE data, we confirm the…

One of the Milky Way's characteristic features is a strongly bimodal distribution of $\alpha$-process elements, such as Mg, at fixed [Fe/H] in stellar abundances. We examine patterns in [Mg/Fe] versus [Fe/H] in FIRE-2 simulations of Milky…

Astrophysics of Galaxies · Physics 2026-01-07 Megan Barry , Andrew Wetzel , Sarah Loebman , Jeremy Bailin , Hanna Parul

In order to understand the roles of metal flows in galaxy formation and evolution, we analyse our self-consistent cosmological chemo-dynamical simulation of a Milky Way like galaxy during its thin-disc phase. Our simulated galaxy disc…

Astrophysics of Galaxies · Physics 2020-06-03 Fiorenzo Vincenzo , Chiaki Kobayashi

Chemical abundances are an essential tool in untangling the Milky Way's enrichment history. However, the evolution of the interstellar medium abundance gradient with cosmic time is lost as a result of radial mixing processes. For the first…

Both simulations and observations suggest that the disk assembly of galaxies is governed by the interplay between coplanar gas inflow, ex-planar gas outflow and in-situ star formation on the disk, known as the leaky accretion disk. This…

Astrophysics of Galaxies · Physics 2024-06-18 Enci Wang , Jianhui Lian , Yingjie Peng , Xin Wang

The Milky Way hosts at least two modes in its present day distribution of Fe and alpha-elements. The exact cause of this bimodality is disputed, but one class of explanations involves the merger between the Milky Way and a relatively…

Astrophysics of Galaxies · Physics 2025-07-24 Angus Beane , James Johnson , Vadim Semenov , Lars Hernquist , Vedant Chandra , Charlie Conroy

The formation timescale of the Milky Way thick disk is one of the central debates in Galactic archaeology. The age-metallicity relation (AMR), formation timescale, and chemical evolution gradients are frequently used to infer a rapid…

Astrophysics of Galaxies · Physics 2026-05-25 Zhipeng Zhang

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 have investigated the abundance of several chemical elements in two large stellar samples kinematically representative of the thin and the thick disks of the Galaxy. Chemical, kinematical and age data have been collected from high…

Astrophysics · Physics 2007-05-23 Pascal Girard , Caroline Soubiran

We analyse the stellar distributions on the [Fe/H]-[Mg/Fe] plane for 11 Milky Way-mass galaxies from the FIRE-2 cosmological baryonic zoom-in simulations. Alpha-element bimodality, in the form of two separate sequences on the [Fe/H]-[Mg/Fe]…

Astrophysics of Galaxies · Physics 2025-01-22 Hanna Parul , Jeremy Bailin , Sarah R. Loebman , Andrew Wetzel , Megan Barry , Binod Bhattarai

Recent spectroscopic observations in the Milky Way suggest that the chemically defined thick disk (stars with high [alpha/Fe] ratios and thus old) has a significantly smaller scale-length than the thin disk. This is in apparent…

Astrophysics of Galaxies · Physics 2015-06-24 I. Minchev , M. Martig , D. Streich , C. Scannapieco , R. S. de Jong , M. Steinmetz

Recent observations of the Milky Way and galaxies at high redshifts suggest that galaxy discs were already in place soon after the Big Bang. While the gas infall history of the Milky Way in the inner disc has long been assumed to be…

Astrophysics of Galaxies · Physics 2022-03-14 Owain Snaith , Misha Haywood , Paola Di Matteo , Matthew Lehnert , David Katz , Sergey Khoperskov

Recent observations demonstrate that the thin and thick disks of the Galaxy have different chemical abundance trends and evolution timescales. The relative abundances of $\alpha$-elements in the thick Galactic disk are increased relative to…

Astrophysics · Physics 2009-11-11 T. V. Nykytyuk , T. V. Mishenina

With the wealth of information from large surveys and observational campaigns in the contemporary era, it is critical to properly exploit the data to constrain the parameters of Galactic chemical evolution models and quantify the associated…

Astrophysics of Galaxies · Physics 2020-03-11 E. Spitoni , K. Verma , V. Silva Aguirre , F. Calura