Age dependence of the radial metallicity gradient in the Galactic disc with LAMOST and Gaia
6 affiliations
- 1Qinghai University Department of Physics and Astronomy, , Xining, 810016 ,
- 2Research Center of Astronomy, Qinghai University , Xining, 810016 ,
- 3General Education Center, Qinghai Institute of Technology , No. 2, Xining, 810016 ,
- 4Lanzhou Center for Theoretical Physics, Key Laboratory of Theoretical Physics of Gansu Province, Key Laboratory of Quantum Theory and Applications of MoE, Gansu Provincial Research Center for Basic Disciplines of Quantum Physics , Lanzhou University, Lanzhou 730000 ,
- 5School of Computer Technology and Application , Qinghai University, Xining 810016 ,
- 6Qinghai Provincial Key Laboratory of Media Integration Technology and Communication, Qinghai University , Xining 810016 ,
Abstract
We investigate the stellar radial metallicity ([Fe/H]) gradient–age relation (MGAR) of the Galactic disc using a solar-neighbourhood sample of 580 037 FGK dwarf and turn-off stars from LAMOST DR7, Gaia DR3, and the corrected StarHorse age catalogue. The fiducial MGAR is non-monotonic, with relatively strong negative gradients at intermediate ages followed by substantial flattening towards older populations. The most negative gradient occurs at 6–8 Gyr in the adopted 2-Gyr bins, although the 4–6 Gyr slope is statistically similar, indicating a broad intermediate-age turnover rather than a sharply defined transition. The flattening persists within the low-α population, indicating that chemical-population mixing alone cannot explain the full-sample relation, and is also recovered under alternative guiding-radius definitions, radial fitting ranges, vertical-orbit selections, propagation of the reported random age uncertainties, and an alternative stellar-age scale. In contrast, controlling the age-dependent Teff–log g distribution substantially reduces the absolute gradient amplitudes and modifies the younger-age behaviour. A same-star comparison with APOGEE DR17 further shows that the broad age dependence of the controlled MGAR is recovered using an external [Fe/H] scale. We therefore identify the intermediate-to-old-age flattening as the most robust feature of the observed MGAR, whereas the precise location and depth of the intermediate-age minimum and the detailed younger-age morphology are less stable. These results indicate that stellar-parameter selection can contribute to the diversity of MGAR morphologies reported in previous studies.
Related
- An Analytic Model for Stellar Metallicity Gradient Residuals in Cold, Phase-Mixed Galactic Disks
- Changing-look Active Galactic Nuclei from SDSS, LAMOST and DESI Surveys
- Testing Chemical Tagging with LAMOST: Intrinsic Abundance Dispersion of Subgiant Stars in the Galactic Disk
- Galactic HII regions in LAMOST Medium-Resolution Spectroscopic Survey of Nebulae
- Cepheid Metallicity in the Leavitt Law (C-MetaLL) survey: X First spectroscopic characterization of Galactic Type II Cepheids and calibration of the Period-Wesenheit-Metallicity relations
BibTeX
@article{jing2026dependence,
title = {{Age dependence of the radial metallicity gradient in the Galactic disc with LAMOST and Gaia}},
author = {Yi-De Jing and Duojie Jia and Bin Wang and Yulong Gao and Liyuan Lu and Zheng-Jun Du and Zenghui Zou},
journal = {Monthly Notices of the Royal Astronomical Society},
year = {2026},
month = oct,
doi = {10.1093/mnras/stag2006},
url = {https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/stag2006/8979808},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Age dependence of the radial metallicity gradient in the Galactic disc with LAMOST and Gaia
AU - Yi-De Jing
AU - Duojie Jia
AU - Bin Wang
AU - Yulong Gao
AU - Liyuan Lu
AU - Zheng-Jun Du
AU - Zenghui Zou
PY - 2026
DA - 2026/10/22
JO - Monthly Notices of the Royal Astronomical Society
DO - 10.1093/mnras/stag2006
UR - https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/stag2006/8979808
AB - We investigate the stellar radial metallicity ([Fe/H]) gradient–age relation (MGAR) of the Galactic disc using a solar-neighbourhood sample of 580 037 FGK dwarf and turn-off stars from LAMOST DR7, Gaia DR3, and the corrected StarHorse age catalogue. The fiducial MGAR is non-monotonic, with relatively strong negative gradients at intermediate ages followed by substantial flattening towards older populations. The most negative gradient occurs at 6–8 Gyr in the adopted 2-Gyr bins, although the 4–6 Gyr slope is statistically similar, indicating a broad intermediate-age turnover rather than a sharply defined transition. The flattening persists within the low-α population, indicating that chemical-population mixing alone cannot explain the full-sample relation, and is also recovered under alternative guiding-radius definitions, radial fitting ranges, vertical-orbit selections, propagation of the reported random age uncertainties, and an alternative stellar-age scale. In contrast, controlling the age-dependent Teff–log g distribution substantially reduces the absolute gradient amplitudes and modifies the younger-age behaviour. A same-star comparison with APOGEE DR17 further shows that the broad age dependence of the controlled MGAR is recovered using an external [Fe/H] scale. We therefore identify the intermediate-to-old-age flattening as the most robust feature of the observed MGAR, whereas the precise location and depth of the intermediate-age minimum and the detailed younger-age morphology are less stable. These results indicate that stellar-parameter selection can contribute to the diversity of MGAR morphologies reported in previous studies.
SN - 0035-8711
SN - 1365-2966
ER -