Kinematic groups across the MW disc: insights from models and from the RAVE catalogue

TL;DR

This study combines models and RAVE data to analyze how stellar kinematic groups in the Milky Way disc vary with galactic position, revealing large-scale structures influenced by spiral arms and bar dynamics.

Contribution

It provides the first combined analysis of model predictions and RAVE observations to understand the spatial dependence of kinematic groups in the Milky Way disc.

Findings

Kinematic groups vary significantly with galactic position.

More and stronger groups are near spiral arms.

Observed groups are consistent with previous surveys, confirming their large-scale nature.

Abstract

With the advent of the Gaia data, the unprecedented kinematic census of great part of the Milky Way disc will allow us to characterise the local kinematic groups and new groups in different disc neighbourhoods. First, we show here that the models predict a stellar kinematic response to the spiral arms and bar strongly dependent on disc position. For example, we find that the kinematic groups induced by the spiral arm models change significantly if one moves only ~ 0.6 kpc in galactocentric radius, but ~ 2 kpc in azimuth. There are more and stronger groups as one approaches the spiral arms. Depending on the spiral pattern speed, the kinematic imprints are more intense in nearby vicinities or far from the Sun. Secondly, we present a preliminary study of the kinematic groups observed by RAVE. This sample will allow us, for the first time, to study the dependence on Galactic position of the (thin and thick) disc moving groups. In the solar neighbourhood, we find the same kinematics groups as detected in previous surveys, but now with better statistics and over a larger spatial volume around the Sun. This indicates that these structures are indeed large scale kinematic features.