The AMBRE Project: Solar neighbourhood chemodynamical constraints on Galactic disc evolution

Santos-Peral, P.; Recio–Blanco, A.; Kordopatis, G.; Fernández-Alvar, Emma; Laverny, P. de

doi:10.1051/0004-6361/202040144

Cited by 19 publications

(10 citation statements)

References 140 publications

(320 reference statements)

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“…However, including older populations of stars leads to increasingly shallower gradients, resulting in greater discrepancies with observations. Some observations (for example Carrera & Pancino 2011;Cunha et al 2016;Netopil et al 2016;Donor et al 2020;Santos-Peral et al 2021) find that older star clusters in the MW have steeper abundance gradients than younger clusters, but our results imply the opposite, in agreement with [O/H] measurements from planetary nebulae in M81 (for example Stanghellini et al , 2014 and in the MW (Stanghellini & Haywood 2018). However, we do not measure the radial positions of stars at z = 0 as a function of age, although we plan to pursue this in future work.…”

Section: Discussionsupporting

confidence: 82%

3D elemental abundances of stars at formation across the histories of Milky Way-mass galaxies in the FIRE simulations

Bellardini,

Wetzel,

Loebman

et al. 2022

Preprint

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We characterize the 3-D spatial variations of [Fe/H], [Mg/H], and [Mg/Fe] in stars at the time of their formation, across 11 simulated Milky Way (MW)-and M31-mass galaxies in the FIRE-2 simulations, to inform initial conditions for chemical tagging. The overall scatter in [Fe/H] within a galaxy decreased with time until ≈ 7 Gyr ago, after which it increased to today: this arises from a competition between a reduction of azimuthal scatter and a steepening of the radial gradient in abundance over time. The radial gradient is generally negative, and it steepened over time from an initially flat gradient 12 Gyr ago. The strength of the present-day abundance gradient does not correlate with when the disk 'settled'; instead, it best correlates with the radial velocity dispersion within the galaxy. The strength of azimuthal variation is nearly independent of radius, and the 360 degree scatter decreased over time, from 0.17 dex at t lb = 11.6 Gyr to ∼ 0.04 dex at present day. Consequently, stars at t lb 8 Gyr formed in a disk with primarily azimuthal scatter in abundances. All stars formed in a vertically homogeneous disk, ∆[Fe/H]≤ 0.02 dex within 1 kpc of the galactic midplane, with the exception of the young stars in the inner ≈ 4 kpc at z ∼ 0. These results generally agree with our previous analysis of gas-phase elemental abundances, which reinforces the importance of cosmological disk evolution and azimuthal scatter in the context of stellar chemical tagging. We provide analytic fits to our results for use in chemical-tagging analyses.

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Section: Discussionsupporting

confidence: 82%

3D elemental abundances of stars at formation across the histories of Milky Way-mass galaxies in the FIRE simulations

Bellardini,

Wetzel,

Loebman

et al. 2022

Preprint

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“…Analysis of the Apache Point Observatory Galactic Evolution Experiment project (APOGEE) data (Nidever et al 2014;Hayden et al 2015;Ahumada et al 2020;Queiroz et al 2020;Vincenzo et al 2021) highlighted the presence of two distinct sequences in the [α/Fe] versus [Fe/H] abundance ratio space for disc stars: the so-called high-α sequence, classically associated with an old population of stars in the thick disc, and the low-α sequence, which is mostly comprised of relatively young stars in the thin disc. This dissection has also been revealed by other observational campaigns: the Gaia-ESO survey (e.g., Recio-Blanco et al 2014;Rojas-Arriagada et al 2016 and the Archéologie avec Matisse Basée sur les aRchives de l'ESO project (AMBRE; Mikolaitis et al 2017;Santos-Peral et al 2021), the Galactic Archaeology with HER-MES survey (GALAH; Buder et al 2019Buder et al , 2021, and the Large sky Area Multi Object fiber Spectroscopic Telescope (LAM-OST; Yu et al 2021).…”

Section: Introductionsupporting

confidence: 65%

Disc dichotomy signature in the vertical distribution of [Mg/Fe] and the delayed gas infall scenario

Spitoni

Børsen-Koch

Verma

et al. 2022

A&A

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Context. Analysis of the Apache Point Observatory Galactic Evolution Experiment project (APOGEE) data suggests the existence of a clear distinction between two sequences of disc stars in the [α/Fe] versus [Fe/H] abundance ratio space, known as the high- and low-α sequence, respectively. This dichotomy also emerges from an analysis of the vertical distribution of the [α/Fe] abundance ratio. Aims. We aim to test whether the revised two-infall chemical evolution models designed to reproduce the low- and high-α sequences in the [α/Fe] versus [Fe/H] ratios in the solar neighbourhood are also capable of predicting the disc bimodality observed in the vertical distribution of [Mg/Fe] in APOGEE DR16 data. Methods. Along with the chemical composition of the simple stellar populations born at different Galactic times predicted by our reference chemical evolution models in the solar vicinity, we provide their maximum vertical height above the Galactic plane |zmax| computed assuming the relation between the vertical action and stellar age in APOGEE thin-disc stars. Result. The vertical distribution of the [Mg/Fe] abundance ratio predicted by the reference chemical evolution models is in agreement with that observed when combining the APOGEE DR16 data (chemical abundances) with the astroNN catalogue (stellar ages, orbital parameters) for stars younger than 8 Gyr (only low-α sequence stars). Including the high-α disc component, the dichotomy in the vertical [Mg/Fe] abundance distribution is reproduced considering the observational cut in the Galactic height of |z|< 2 kpc. However, our model predicts an overly flat (almost constant) growth of the maximum vertical height |zmax| quantity as a function of [Mg/Fe] for high-α objects in contrast with the median values from APOGEE data. Possible explanations for such a tension are that: (i) the APOGEE sample with |z|< 2 kpc is more likely than ours to be contaminated by halo stars, causing the median values to be kinematically hotter, and (ii) external perturbations – such as minor mergers – that the Milky Way experienced in the past could have heated up the disc, and the heating of the orbits cannot be modeled by only scattering processes. Assuming a disc dissection based on chemistry for APOGEE-DR16 stars (|z|< 2 kpc), the observed |zmax| distributions for high-α and low-α sequences are in good agreement with our model predictions if we consider the errors in the vertical action estimates in the calculation. Moreover, a better agreement between predicted and observed stellar distributions at different Galactic vertical heights is achieved if asteroseismic ages are included as a constraint in the best-fit model calculations. Conclusions. The signature of a delayed gas infall episode, which gives rise to a hiatus in the star formation history of the Galaxy, are imprinted both in the [Mg/Fe] versus [Fe/H] relation and in vertical distribution of [Mg/Fe] abundances in the solar vicinity.

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“…In this way it is possible to test whether the discrepancy between the observed flat trend in the metal-rich disc and the steeper slope predicted by the models can be solved by these abundance measurements. The value of this dataset was even enhanced in Santos-Peral et al (2021), in which reliable stellar age estimates were presented for a subsample of MSTO stars. All the Santos-Peral et al (2020 data are crossmatched with the Gaia DR2 catalogue (Gaia Collaboration 2018) in order to extract the main kinematical and dynamical stellar parameters.…”

Section: Discussionmentioning

confidence: 99%

[Mg/Fe] ratios in the solar neighbourhood: Stellar yields and chemical evolution scenarios

Palla

Santos-Peral

Recio–Blanco

et al. 2022

A&A

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Context. The [Mg/Fe] abundance ratios are a fundamental fossil signature used to trace the chemical evolution of the disc and to divide it into low-α and high-α populations. Despite the huge observational and theoretical efforts, discrepancies between models and data are still present and several explanations have been put forward to explain the [α/Fe] bimodality. Aims. In this work we take advantage of a new AMBRE:HARPS dataset, which provides new more precise [Mg/Fe] estimations and reliable stellar ages for a subsample of stars, to study the [α/Fe] bimodality and the evolution of the solar neighbourhood. Methods. The data are compared with detailed chemical evolution models for the Milky Way, exploring the most used prescriptions for stellar yields and different formation scenarios for the Galactic disc (i.e. the delayed two-infall and the parallel models), including prescriptions for stellar radial migration. Results. We see that most of the stellar yield prescriptions struggle to reproduce the observed trend of the data and that semi-empirical yields describe best the [Mg/Fe] evolution in the thick and thin discs. In particular, most of the yields still predict a steeper decrease of the [Mg/Fe] ratio at high metallicity than shown by the data. The bulk of the data are well reproduced by the parallel and two-infall scenarios, but both scenarios have problems in explaining the most metal-rich and metal-poor tails of the low-α data. These tails can be explained in light of radial migration from the inner and outer disc regions, respectively. Conclusions. Despite the evidence of stellar migration, it is difficult to estimate the actual contribution of stars from other parts of the disc to the solar vicinity in the data we adopt. However, the comparison between data and models suggests that peculiar histories of star formation, such as that of the two-infall model, are still needed to reproduce the observed distribution of stars.

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The AMBRE Project: Solar neighbourhood chemodynamical constraints on Galactic disc evolution

Cited by 19 publications

References 140 publications

3D elemental abundances of stars at formation across the histories of Milky Way-mass galaxies in the FIRE simulations

3D elemental abundances of stars at formation across the histories of Milky Way-mass galaxies in the FIRE simulations

Disc dichotomy signature in the vertical distribution of [Mg/Fe] and the delayed gas infall scenario

[Mg/Fe] ratios in the solar neighbourhood: Stellar yields and chemical evolution scenarios

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