Sorry, I don't understand your search. ×
Back to Search Start Over

Spatial metallicity variations of mono-temperature stellar populations revealed by early-type stars in LAMOST

Authors :
Wang, Chun
Yuan, Haibo
Xiang, Maosheng
Ting, Yuan-Sen
Huang, Yang
Liu, Xiaowei
Source :
A&A 674, A129 (2023)
Publication Year :
2023

Abstract

We investigate the radial metallicity gradients and azimuthal metallicity distributions on the Galactocentric $X$--$Y$ plane using mono-temperature stellar populations selected from LAMOST MRS young stellar sample. The estimated radial metallicity gradient ranges from $-$0.015\,dex/kpc to $-$0.07\,dex/kpc, which decreases as effective temperature decreases (or stellar age increases) at $7500 < T_{\rm eff} < 12500$\,K ($\tau < $1.5 Gyr). The azimuthal metallicity excess (metallicity after subtracting radial metallicity gradient, $\Delta$\,[M/H]) distributions exhibit inhomogeneities with dispersions of 0.04\,dex to 0.07\,dex, which decrease as effective temperature decreases. We also identify five potential metal-poor substructures with large metallicity excess dispersions. The metallicity excess distributions of these five metal-poor substructures suggest that they contain a larger fraction of metal-poor stars compared to other control samples. These metal-poor substructures may be associated with high-velocity clouds that infall into the Galactic disk from the Galactic halo, which are not quickly well-mixed with the pre-existing ISM of the Galactic disk. As a result, these high-velocity clouds produce some metal-poor stars and the observed metal-poor substructures. The variations of metallicity inhomogeneities with different stellar populations indicate that high-velocity clouds are not well mixed with the pre-existing Galactic disk ISM within 0.3\,Gyr.<br />Comment: 14 pages, 12 figures, Accepted for publication in A&A

Details

Database :
arXiv
Journal :
A&A 674, A129 (2023)
Publication Type :
Report
Accession number :
edsarx.2304.02958
Document Type :
Working Paper
Full Text :
https://doi.org/10.1051/0004-6361/202245761