The impact of bar origin and morphology on stellar migration

TL;DR

This study investigates how the origin and morphology of galactic bars influence stellar migration, orbital properties, and metallicity distributions using simulated galaxy models, revealing distinguishable effects based on formation mechanisms.

Contribution

It demonstrates that bar origin significantly affects stellar migration patterns and metallicity gradients, providing new insights into galaxy evolution based on formation scenarios.

Findings

Tidal bars show larger stellar migration and metallicity differences.

Bar morphology influences vertical stellar motion and metallicity evolution.

Closest approach impacts stellar populations formed at different times.

Abstract

Different mechanisms driving bar structure formation indicate that bar origins should be distinguishable in the stellar populations of galaxies. To study how these origins affect different bar morphologies and impact stellar orbits and migration, we analyse three simulated discs which are representative of bar formation under isolated evolution motivated by disc instability, and interaction driven tidal development. The first isolated disc and the tidally driven disc produce similar bar structure, while the second isolated disc, generated by the tidal initial condition without the companion, is visibly dissimilar. Changes to radial and vertical positions, angular momentum in the disc-plane, orbital eccentricity and the subsequent disc metallicities are assessed, as is the dependence on stellar age and formation radii. Bar origin is distinguishable, with the tidal disc displaying larger migration overall, higher metallicity difference between the inner and outer disc, as well as a population of inner disc stars displaced to large radii and below the disc-plane. The affect of closest approach on populations of stars formed before, after and during this period is evident. However, bar morphology is also found to be a significant factor in the evolution of disc stellar properties, with similar bars producing similar traits in migration tendency with radius, particularly in vertical stellar motion and in the evolution of central metallicity features.