Estimating stellar birth radii and the time evolution of Milky Way’s ISM metallicity gradient

By I. Minchev, Friedrich Anders, A. Recio-Blanco, C. Chiappini, P. Laverny, A. Queiroz, Matthias Steinmetz, V. Adibekyan, I. Carrillo, G. Cescutti and 7 more. 2018

107 citations recorded by the source corpus.

We present a semi-empirical, largely model-independent approach for estimating Galactic birth radii, r_birth, for Milky Way disk stars. The technique relies on the justifiable assumption that a negative radial metallicity gradient in the interstellar medium (ISM) existed for most of the disk lifetime. Stars are projected back to their birth positions according to the observationally derived age and [Fe/H] with no kinematical information required. Applying our approach to the AMBRE:HARPS and HARPS-GTO local samples, we show that we can constrain the ISM metallicity evolution with Galactic radius and cosmic time, [Fe/H]_ISM(r, t), by requiring a physically meaningful r_birth distribution. We find that the data are consistent with an ISM radial metallicity gradient that flattens with time from ~-0.15 dex/kpc at the beginning of disk formation, to its measured present-day value (-0.07 dex/kpc). We present several chemo-kinematical relations in terms of mono-r_birth populations. One remarkable result is that the kinematically hottest stars would have been born locally or in the outer disk, consistent with thick disk formation from the nested flares of mono-age populations and predictions from cosmological simulations. This phenomenon can be also seen in the observed age-velocity dispersion relation, in that its upper boundary is dominated by stars born at larger radii. We also find that the flatness of the local age-metallicity relation (AMR) is the result of the superposition of the AMRs of mono-r_birth populations, each with a well-defined negative slope. The solar birth radius is estimated to be 7.3+-0.6 kpc, for a current Galactocentric radius of 8 kpc.

Subfields: Astronomy and Astrophysics

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Citations in the corpus

Yule-Simpson’s paradox in Galactic Archaeology (2019, methodology): “As in Minchev et al. (2018), we imposed the following quality criteria on ages and abundances: δ[Mg/Fe] < 0.07 dex, δage/age < 0.25 or δage < 1 Gyr, resulting in a sample of 603 stars.”
Measuring Radial Orbit Migration in the Galactic Disk (2018, background): “This quite precise Rbirth(Sun) estimate is in agreement with the broad prediction from chemo-dynamical simulations of Minchev et al. (2013) (between 4.4 and 7.7 kpc), but differs by 2 kpc from the recent results of Minchev et al. (2018) (7.3±0.6 kpc).”
The GALAH survey and Gaia DR2: dissecting the stellar disc’s phase space by age, action, chemistry, and location (2018, result): “Consistent with that picture, most migration models (Roškar et al. 2012; Vera-Ciro et al. 2014; Daniel & Wyse 2018; Minchev et al. 2018) find that stars on circular orbits and close to the plane are those that move most easily, and this is what we see (cf. Solway et al. 2012).”