Age dependence of the Milky Way warp

Determine whether and how the structure and kinematics of the Milky Way’s Galactic warp depend on stellar age by quantitatively comparing the warp traced by young Classical Cepheids with that traced by older populations such as red clump giants, red giant branch stars, and older star clusters, and ascertain whether significant discrepancies exist between the warps of younger and older populations.

Background

The paper compares the Cepheid-based warp with results from multiple tracers (HI, dust, OB stars, red clump, K-type stars, and star clusters) and finds broad agreement among young tracers but mixed and model-dependent agreement with older populations. Some models for older populations either significantly deviate from the young-tracer warp or have uncertainties large enough to obscure any age-related differences.

Because current measurements impose different symmetry assumptions, have limited azimuthal/radial coverage, and suffer from selection effects, the authors emphasize that present data do not allow a definitive conclusion about whether the warp varies with the age of the stellar tracer.