Chemical evolution of the Milky Way: constraints on the formation of the thick and thin discs

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  • M. Palla, Dipartimento di Fisica, Sezione di Astronomia, Universitá degli Studi di Trieste, via G. B. Tiepolo 11, I-34131, Trieste, Italy 0000-0002-3574-9578 marco.ball94@gmail.com
  • ,
  • F. Matteucci, Dipartimento di Fisica, Sezione di Astronomia, Universitá degli Studi di Trieste, via G. B. Tiepolo 11, I-34131, Trieste, Italy francesca.matteucci@inaf.it, INAF, Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, I-34131 Trieste, Italy
  • ,
  • E. Spitoni
  • F. Vincenzo, Center for Cosmology and AstroParticle Physics, The Ohio State University, 191 West Woodruff Avenue, Columbus, OH 43210, USA 0000-0002-0743-9994
  • ,
  • V. Grisoni, INAF, Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, I-34131, Trieste, Italy 0000-0001-7366-7699, Scuola Internazionale Superiore di Studi Avanzati (SISSA)
We study the evolution of Milky Way thick and thin discs in the light of the most recent observational data. In particular, we analyse abundance gradients of O, N, Fe, and Mg along the thin disc as well as the [Mg/Fe] versus [Fe/H] relations and the metallicity distribution functions at different Galactocentric distances. We run several models starting from the two-infall paradigm, assuming that the thick and thin discs formed by means of two different infall episodes, and we explore several physical parameters, such as radial gas flows, variable efficiency of star formation, different times for the maximum infall on to the disc, different distributions of the total surface mass density of the thick disc, and enriched gas infall. Our best model suggests that radial gas flows and variable efficiency of star formation should be acting together with the inside-out mechanism for the thin disc formation. The time-scale for maximum infall on to the thin disc, which determines the gap between the formation of the two discs, should be tmax ≃ 3.25 Gyr. The thick disc should have an exponential, small-scale length density profile and gas infall on the inner thin disc should be enriched. We also compute the evolution of Gaia-Enceladus system and study the effects of possible interactions with the thick and thin discs. We conclude that the gas lost by Enceladus or even part of it could have been responsible for the formation of the thick disc but not the thin disc.
OriginalsprogEngelsk
TidsskriftMonthly Notices of the Royal Astronomical Society
Vol/bind498
Nummer2
Sider (fra-til)1710-1725
ISSN0035-8711
DOI
StatusUdgivet - okt. 2020

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