Modelling the broken age–[Fe/H] relation and metallicity distribution function of mono-age populations
- 1South-Western Institute for Astronomy Research, Yunnan University , Kunming, Yunnan 650091 ,
- 2Yunnan Key Laboratory of Survey Science, Yunnan University , Kunming, Yunnan 650500 ,
Abstract
This study investigates the chemical evolution history and radial migration in the Milky Way utilizing high-precision age measurements based on large-scale stellar spectroscopic surveys. Recent observational data have revealed a distinct break in the age–metallicity relation of stars in the solar neighbourhood, suggesting that stellar populations of the Milky Way can be divided into two evolutionary sequences. Based on Galactic chemical evolution models, we confirm that this break in the age–metallicity relation can be explained by a recent major gas accretion event, which diluted the metallicity in the disc and triggered a starburst, leading to the formation of an independent age–metallicity sequence. To assess the impact of stellar radial migration, we incorporate a simplified treatment of this process into our multi-zone chemical evolution model. Radial migration is modelled as a probabilistic diffusion process, characterized by a Gaussian distribution. By fitting the model-predicted metallicity distribution functions (MDFs) of mono-age stellar populations to observations, we infer a migration strength of σ = 2.15+0.100−0.103 kpc for stars with ages between 2 and 6 Gyr located at 9.5–11.5 kpc, corresponding to an average radial displacement of 1.92 kpc over 10 Gyr. This result is lower than previous estimates of stellar radial migration, suggesting that the role of radial migration in shaping the chemical structure of the Milky Way is less important than previously estimated.
Related
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BibTeX
@article{shao2026modelling,
title = {{Modelling the broken age–[Fe/H] relation and metallicity distribution function of mono-age populations}},
author = {Qinhao Shao and Jianhui Lian},
journal = {Monthly Notices of the Royal Astronomical Society},
year = {2026},
month = oct,
doi = {10.1093/mnras/stag1894},
url = {https://academic.oup.com/mnras/article/doi/10.1093/mnras/stag1894/8898884},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Modelling the broken age–[Fe/H] relation and metallicity distribution function of mono-age populations
AU - Qinhao Shao
AU - Jianhui Lian
PY - 2026
DA - 2026/10/09
JO - Monthly Notices of the Royal Astronomical Society
DO - 10.1093/mnras/stag1894
UR - https://academic.oup.com/mnras/article/doi/10.1093/mnras/stag1894/8898884
AB - This study investigates the chemical evolution history and radial migration in the Milky Way utilizing high-precision age measurements based on large-scale stellar spectroscopic surveys. Recent observational data have revealed a distinct break in the age–metallicity relation of stars in the solar neighbourhood, suggesting that stellar populations of the Milky Way can be divided into two evolutionary sequences. Based on Galactic chemical evolution models, we confirm that this break in the age–metallicity relation can be explained by a recent major gas accretion event, which diluted the metallicity in the disc and triggered a starburst, leading to the formation of an independent age–metallicity sequence. To assess the impact of stellar radial migration, we incorporate a simplified treatment of this process into our multi-zone chemical evolution model. Radial migration is modelled as a probabilistic diffusion process, characterized by a Gaussian distribution. By fitting the model-predicted metallicity distribution functions (MDFs) of mono-age stellar populations to observations, we infer a migration strength of σ = 2.15^+0.100_−0.103 kpc for stars with ages between 2 and 6 Gyr located at 9.5–11.5 kpc, corresponding to an average radial displacement of 1.92 kpc over 10 Gyr. This result is lower than previous estimates of stellar radial migration, suggesting that the role of radial migration in shaping the chemical structure of the Milky Way is less important than previously estimated.
SN - 0035-8711
SN - 1365-2966
ER -