The Lives of Stars: Insights From the TGAS-RAVE-LAMOST Dataset

TL;DR

This study analyzes the chemical and kinematic evolution of approximately 125,000 stars across different ages using diverse survey data, revealing insights into galactic enrichment, stellar motions, and churning effects.

Contribution

It provides a comprehensive analysis of stellar ages, metallicities, and kinematic properties, highlighting new findings on galactic enrichment history and stellar dynamics.

Findings

Inner disk regions enriched early

Outer regions enriched later

Evidence of stellar churning and its age distribution

Abstract

In this paper we investigate how the chemical and kinematic properties of stars vary as a function of age. Using data from a variety of photometric, astrometric and spectroscopic surveys, we calculate the ages, phase space information and orbits for $\sim$125,000 stars covering a wide range of stellar parameters. We find indications that the inner regions of the disk reached high levels of enrichment early, while the outer regions were more substantially enriched in intermediate and recent epochs. We consider these enrichment histories through comparison of the ages of stars, their metallicities, and kinematic properties, such as their angular momentum in the solar neighborhood (which is a proxy for orbital radius). We calculate rates at which the velocity dispersions evolve, investigate the Oort constants for different aged populations (finding a slightly negative $\partial V_{C} / \partial R$ and $\partial V_{R} / \partial R$ for all ages, being most negative for the oldest stars), as well as examine the behavior of the velocity vertex deviation angle as a function of age (which we find to fall from $\sim$15 degrees for the 2 Gyr aged population to $\sim$6 degrees at around 6.5 Gyr of age, after which it remains unchanged). We find evidence for stellar churning, and find that the churned stars have a slightly younger age distribution than the rest of the data.