The Stellar Disk Structure Rrevealed by the Mono-age Populations of the LAMOST Red Clump Sample

TL;DR

This study uses a large sample of red clump stars to analyze the Milky Way's disk structure, revealing age-dependent scale height variations and disk flaring, which inform models of Galactic formation and evolution.

Contribution

It provides a detailed analysis of mono-age populations in the Galactic disk, highlighting age-related structural differences and disk flaring, based on extensive LAMOST and Gaia data.

Findings

Vertical profiles fit a dual-component disk model with flaring.

Scale heights increase with age for the thin disk component.

Radial density peaks are within 7.5-8.5 kpc.

Abstract

Understanding the structure of the Galactic disk is crucial for understanding the formation and evolutionary history of the Milky Way. This study examines the structure of the Galactic disk by analyzing a sample of 138,667 primary red clump (RC) stars from the LAMOST and Gaia datasets. We have categorized these RC stars into mono-age populations and investigated their spatial distributions within the R - Z plane, estimating scale heights and lengths through the fitting of their vertical and radial density profiles. Our analysis indicates that the vertical profiles of these mono-age populations fit a dual-component disk model, where both components exhibit significant flaring, particularly in the outer disk regions. Within a constant Galactocentric radius R, the scale heights of the first component, representing the morphologically thin disk, rise with age. In contrast, the scale heights of the second component, corresponding to the morphologically thick disk, remain comparatively stable across different age groups. Additionally, the radial density profiles of both disk components predominantly peak within a radial range of 7.5-8.5 kpc. These findings underscore the importance of age as a crucial factor in shaping the spatial distribution and structural evolution of the Galactic disk, offering valuable insights into its complex dynamics and history.