Stinson, G.S.Bovy, J.Rix, H.W.Brook, C.Roškar, R.Dalcanton, J.J.Macciò, A.V.Wadsley, J.Couchman, H.M.P.Quinn, T.R.2020-06-302020-06-302013Monthly Notices of the Royal Astronomical Society, 2013; 436(1):625-6340035-87111365-2966http://hdl.handle.net/2440/126306We analyse the structure and chemical enrichment of a Milky Way-like galaxy with a stellar mass of 2 × 1010 M⊙, formed in a cosmological hydrodynamical simulation. It is disc dominated with a flat rotation curve, and has a disc scalelength similar to the Milky Way's, but a velocity dispersion that is ∼50 per cent higher. Examining stars in narrow [Fe/H] and [α/Fe] abundance ranges, we find remarkable qualitative agreement between this simulation and observations. (a) The old stars lie in a thickened distribution with a short scalelength, while the young stars form a thinner disc, with scalelengths decreasing, as [Fe/H] increases. (b) Consequently, there is a distinct outward metallicity gradient. (c) Mono-abundance populations exist with a continuous distribution of scaleheights (from thin to thick). However, the simulated galaxy has a distinct and substantive very thick disc (hz ∼ 1.5 kpc), not seen in the Milky Way. The broad agreement between simulations and observations allows us to test the validity of observational proxies used in the literature: we find in the simulation that mono-abundance populations are good proxies for single age populations (<1 Gyr) for most abundances.en© 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical SocietyHydrodynamics, galaxies: formation, galaxies: structureJournal article003011036010.1093/mnras/stt16000003264351000732-s2.0-84887100416463239Brook, C. [0000-0002-0534-4115]