Stellar kinematical signatures of disk non-axisymmetries in the extended solar neighbourhood

TL;DR

This paper reviews how stellar kinematics in the solar neighborhood reveal the presence and effects of non-axisymmetric features like bars and spirals in the Milky Way, using recent six-dimensional phase-space data.

Contribution

It synthesizes recent observational evidence of disk non-axisymmetries from stellar kinematic data, highlighting their dynamical signatures and constraints in the Milky Way.

Findings

Detection of resonant moving groups in the solar neighborhood

Non-zero Oort constants C and K indicating non-axisymmetry

Radial velocity gradient of 4 km/s/kpc in extended solar neighborhood

Abstract

Bars and spirals are among the main drivers of the secular evolution of galactic disks, and it is, thus, of prime importance to better understand their exact nature and dynamics. In this respect, the Milky Way provides a unique laboratory in which to study a snapshot of their detailed dynamical influence in six-dimensional phase-space. With the advent of present and future astrometric and spectroscopic surveys, such six-dimensional phase-space data can be obtained for stars in an increasingly large volume around the Sun. Here, we review the signatures of - and constraints on - disk non-axisymmetries obtained from recent stellar kinematical data sets, including (i) the detection of resonant moving groups in the solar neighbourhood, (ii) the non-zero value of the Oort constants C and K, and (iii) the detection of a radial velocity gradient of 4 km/s/kpc in the extended solar neighbourhood (d<2 kpc).